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Why is it not just GRAND but also HOT?


The built-in Power Soak lets you enjoy the benefits of full-blown power amp saturation at low volume, and its silent recording capability captures genuine tube-driven tone even without having to drive speakers. But how does it work? And what is it good for?

The secret of many great guitar recodings lies in fully cranked up tube amp settings. But the resulting volume level is way too loud for most applications. It needs to be reduced. But how can this be done without sacrificing the tone? And why does it affect it at all?

Let`s compare it with cooking coffee: to cook a good coffee, the water has to be steaming hot, but you won´t drink it directly. It needs to cool down a bit. A proper coffee is served in a thick-walled ceramic cup – for good reason: The ceramic cup works like a “powersoak” and absorbes some of the heat. In this case a “mastervolume” would only reduce the temperature of the water itself. Now imagine, how a coffee will taste like, cooking it with lukewarm water? The energy has to be reduced afterwards, and that is exactly what a power soak does.

When it comes to silent recording, some tube amps only offer the preamp signal after switching the power amp in Stand By mode. Technically this works, but the power-amp saturation is completely missing. The Red Box of the GrandMeister (and TubeMeister) captures the signal in between power amp and power soak, so even in silent recording mode (power soak set to 0 watts), you can enjoy full-blown power amp saturation.

What`s the trick behind it?



The power soak transforms power into heat, you can see resistors and coils when you look at the bottom plate of the GrandMeister. But it is quite impossible to integrate a power soak into an amp that reduces more than 20 watts – it will just get way too hot. So how could the power be reduced without burning the amp?

TSC, the built-in Tube Safety Control,  is not only able to switch off defective tubes but also shutting two of them down – anytime. So when you press the 18W button, TSC disables one pair of tubes to reduce the output power by half from 36 to 18 watts. That´s the trick! (By the way: In this case, TSC is simply indicating that two tubes are off, and not that it has detected a fault). When you press the 5W and 1W buttons, some of the power is converted into heat for further reduction, respectively.

Especially in silent recording mode the amp will get quite hot by turning up the master volume. But no worries: the metal case works as a heat sink feeling hotter than it actually is…


First published: April 15 2014. Most recent update: October 16 2015.

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Leave a comment

Matt on June 20, 2020 Reply

hello. My amp was working. Tubes got hot now noe sound. Tubes are on and and is on. Its the grand minster 40 delux.

    Hughes & Kettner Hughes & Kettner on July 24, 2020 Reply

    Hi Matt, do a TSC check and see what the results are! But take your amp ASAP to your local tech at the store where you got it, and they will fix this for you.

    Team H&K

Miguel Morales on May 12, 2020 Reply

Hi I am in love the sound of the Grandmeister 40. I want to record while getting a tube sound. I have heard the DI sound and I love it. But I was warned about DI-ing a tube head.

These are my questions about recording/DI-ing the Grandeister 40.

1. Is it true that using the DI will eventually damage the tubes and then the transformer?

2. If it is true, does the Red Box/GrandMeister 40 do something to address this?

3. Is there an estimated time of to use the amp should be used for recording that will protect it from “frying”, or a certain amount of time that passes where changing the tubes may help the logevity of the amp?

– Miguel

    Hughes & Kettner Hughes & Kettner on May 19, 2020 Reply

    Hi Miguel,

    Glad to hear you’re interested in the GM40! Where did you hear that information/warning about the DI?


    1. No, absolutely not!

    2. No, because it’s not true 😉

    3. No. The GM40 (and all the other H&K Meister amps) will get quite hot as part of their design. When you use the power soak feature, they can get warmer still. But this is no problem – as we said, it’s part of the design! If the amp does get too hot, simply switch it off for a few minutes, and start again later, or use a desktop fan to keep it cooler. When it comes to tubes, the tubes themselves are the things that will break after a period of time. This could be months or years – with tubes, it’s always a mystery how long they will survive! But none of this will affect the overall lifespan of the amp itself at all.

    In conclusion, the advice you received before was not true at all. You can be totally relaxed about using the amp at home under any conditions for recording, and for any amount of time. We hope this helps and makes you feel better about the amp!

    All the best,

    Team H&K

    P.S. If you do get the amp, you also have a 3-year warranty. So, even if something else were to go wrong, you would be covered under the warranty for those 3 years anyway 🙂

Dennison Smith on November 25, 2019 Reply

Thank you for the next question where can i purchase these tubes from as have looked on line but can’t find a dealer that stocks needs replaced thank you.

    Hughes & Kettner Hughes & Kettner on November 28, 2019 Reply

    Hi Dennison, these tubes will need to be ordered because they’re special NOS and otherwise not easy to find. The store you bought the amp from will be able to order replacements directly from us, so ask them and they’ll get it sorted!

    Team H&K

Dennison Smith on November 24, 2019 Reply

Am waiting for your response.I brought the amp new are 6n15n-eb power tubes el64,s or not??? They (6n15n-eb,s) came with the amp i brought new, you claim nos el84,s are in the hughes and kettner 30th anniversary tubemister 36 again i say they came with 6n15n-eb,s. The shop i brought it from can verify this fact can you clear this up please asap!!

    Hughes & Kettner Hughes & Kettner on November 25, 2019 Reply

    Hi Dennison. Sorry for the delay – it was the weekend, and we generally don’t work then. Now we’re back!

    But good news – those are the right tubes. The 6N15N-EBs are indeed a kind of EL84 tube (that’s just what’s marked on them!), and are the tubes we put in that amp as standard. So you’re all good to go with them!

    Team H&K

Dennison Smith on November 22, 2019 Reply

The amp was brought new from rock shop dunedin new Zealand. With 6n15n-eb tubes in it.Are they el 84,s?

Dennison Smith on November 22, 2019 Reply

Hi i did buy the head new from the rockshop new zealand and the tubes are 6n15n-eb

Dennison Smith on November 21, 2019 Reply

I bought a 30th anniversary tubemister 36 supposed to have el84,s but doesn’t. Why?

    Hughes & Kettner Hughes & Kettner on November 21, 2019 Reply

    Hi Dennison. All our Meister amps have EL84 power tubes in them – yours will too, if you bought it new!

    If you didn’t, it’s possible a previous owner has put something else in there, but that also won’t work because only EL84 tubes fit in those sockets.

    We’d suggest you check the tubes again just to make sure.

    Team H&K

kacamata hitam pria on November 16, 2019 Reply

This is truly an amazing product. I have one of the first TriAmps and the matching 4×12 slant cabinet, and it still has many great tones, but it is also way too much amp for most of my venues. I am hoping you have plans to offer the GrandMeister in a 12″ combo similar to the TubeMeister. The idea of a self-contained amp/speaker with the pure tube tones, onboard effects and programmable versatility of the GrandMeister makes it number one on my wish list. You guys really help the rest of us Rock!!!

    Hughes & Kettner Hughes & Kettner on November 19, 2019 Reply

    Thanks for the great feedback, and glad you’re still loving your TriAmp! Hmm, a GrandMeister combo might surface in the future, although there’s no concrete plans at the moment. Have you tried the Black Spirit 200 combo yet? That’s certainly worth a look/listen!

david zimmerman on December 16, 2018 Reply

Hi thanks for update, it appears all is ok but today mine died on me whilst practising at home for an hour. ( Like a previous User at a gig)

    Hughes & Kettner Hughes & Kettner on January 4, 2019 Reply

    Hi David, that’s not good. Died in what way? Have you sorted the problem since then?

david on December 12, 2018 Reply

Thanks for update, so the Clean channel when applying gain will not introduce any distortion – it just increases the volume ? The Crunch and Lead channels cater for distortion and Clean is Clean ! ?

    Hughes & Kettner Hughes & Kettner on December 13, 2018 Reply

    Hi David. With the clean channel, you will get some crunch in there as you push up the gain and volume – but not too much! (This also depends on what guitar pickups you use, etc.) But yes, generally clean is for clean sounds, crunch is for crunch and lead is for lead! Each channel does its own job. Of course, you could also use an FX pedal (like a Tubescreamer) to push the clean channel into overdrive more…

    Team H&K

Denis on December 11, 2018 Reply

Pleaaase keep harassing !

    Hughes & Kettner Hughes & Kettner on December 12, 2018 Reply

    Oh, we’re constantly on it 😉

david zimmerman on December 10, 2018 Reply

TubeMeister Deluxe 40 and not Midi, have FS2 Channel switch. I f I turn Clean volume to half way and gain to a quarter, it is not very loud compared to the Crunch and Lead channels with the same setting – this makes me think there is an issue. The first amp I returned and the shop agreed after trying it too.

    Hughes & Kettner Hughes & Kettner on December 12, 2018 Reply

    Hi David. So, we asked our tech experts about this. They told us that if you set all settings the same for all channels, the volume rises with the gain of the channels. It is quite normal that crunch is louder than clean and lead is louder than crunch… to check if the clean channel is running at full power you simply need to check the settings of the power soak: all LEDS should be off.

    Team H&K

David on December 9, 2018 Reply

I bought the 40w Deluxe head and 12 Cabinet recently, I tried it in 5w mode but when I switched back to 40w, the Clean channel did not operate in 40w volume, almost like it was ‘stuck’ in the 5w mode. The Crunch and Lead channels however were fine. I returned the amp to the shop and got a replacment Head, however, the same has happened to this one too after operating it in Amp only mode without the Speaker! Please advise.

    Hughes & Kettner Hughes & Kettner on December 10, 2018 Reply

    Hi David. Hmm, are you using a GrandMeister or TubeMeister Deluxe 40? And how are you selecting presets… via MIDI? Let us know and we’ll have a think 🙂

    Team H&K

Anthony on December 6, 2018 Reply

I’ve just bought a TM18 Head and just wanted to double check that it’s fine not to connect a speaker to it when I’m using the Redbox out in the “0” position?


    Hughes & Kettner Hughes & Kettner on December 6, 2018 Reply

    Hi Anthony, and congrats on your new TubeMeister 18! And yes, you’re absolutely fine to operate the amp at 0 watts with no speaker connected. As stated in the TM18 manual:

    “Note that if you choose to mute the amp, you do
    not need to connect a speaker to the TubeMeister
    18’s SPEAKER output. Designed to enable silent
    recording, this option provides the full signal to the
    RED BOX output.”

    So there you go – enjoy 🙂

    Team H&K

John on November 17, 2018 Reply

Hi guys,
I am worried. I bought the grand meister deluxe 40 a little over six months ago and although I am really pleased with the sounds the overheating is a problem. I had it cut out on me several times after about 4 months (playing in power soak mode) and then a tube went on me. I returned it to the store 4 weeks ago and they replaced the tubes (not free of charge). Yesterday during my first gig since then (again in 5W Powersoak mode as I was using the amp as a monitor and the Red Box over the PA) it died on me about an hour into the gig!! In front of 200 people!! Between songs I switched it off and then put it in 40 W mode (no power soak), after about 20 seconds it started working normally but then 20 minutes during encores it died again!!!!
I have got it running upstairs thismorning to see if it happens again once it is warmed up, but we have got a really important gig on the the 8th December and I cannot afford a repeat of this during this next gig! I don’t see any errors on the amp so it is difficult to show the problem at the shop, but if they send it in to you then I won’t have an amp at all for the gig : (((((
Need your advice here……
Regards John

    Hughes & Kettner Hughes & Kettner on November 23, 2018 Reply

    Hi John,

    Hmm, this is a tough situation. We’re sorry to hear you’ve had these issues. We would really recommend you get the amp seen to properly. However, we appreciate the gig is coming up fast and you need it for then!

    So, a couple of things. Firstly, we assume you’ve not got anything else directly sat on the amp? Or you’ve not got it in a rack without a cooling device? Because those could both cause overheating.

    We’d also recommend trying getting a simple desktop fan or something, and setting that up behind the amp. This will physically keep it cool, and is something we’ve tried ourselves in very hot conditions!

    Next, as you have tried, keep the amp in 40-watt mode all the time. The power soak produces even more heat.

    Finally, switch the amp off (to Standby mode) in-between sessions, sets, rehearsals – whenever you have a significant break.

    It’s a feature of the Meister amps that they get hot. But it does sound like something is not quite right with yours. If it’s cutting out, and tubes are going, it’s clearly too extreme. That’S why we recommend you get through the (if you feel comfortable doing that!) and then head to the tech to get this issue sorted once and for all.

    All the best for your gig, and please keep us informed of your progress.

    Team H&K

Hab on January 15, 2018 Reply

I have a grandmeister deluxe 40 and, when I use the “speaker off” option, the amp itselfs sounds without a speaker. Is it normal?

    Hughes & Kettner Hughes & Kettner on February 20, 2018 Reply

    Hi Hab, give us a bit more info. You mean, you switch the Red Box to 0 watts, but with a cab also connected, and you’re hearing sound from the cab? Let us know and we’ll ask the H&K techs 🙂

Denis on October 27, 2017 Reply

Hi there
So what about that 1×12 GrandMeister Deluxe combo we’ve all been hoping for? Please please please?

    Hughes & Kettner Hughes & Kettner on November 9, 2017 Reply

    We’re harassing the H&K R&D team about a combo on a daily basis Denis, so fingers crossed one day there will be one! 🙂

Chuck Hughes on October 19, 2017 Reply

My H&K amplifier feels very hot to touch. Is this normal?

    Hughes & Kettner Hughes & Kettner on October 19, 2017 Reply

    Hi Chuck. This depends on your interpretation of ‘very hot’. The Meister amps are designed to get hot to an extent, and using the power soak accentuates the effect, because power is dissipated through heat! But, that said, if at any point you feel like the amp is too hot – i.e. you can kind of sense it might be overheating to a dangerous degree – feel free to ask your local H&K dealer to check it over for you.

    Hope this helps a bit 🙂 Sorry we can’t be more specific, it’s just impossible to diagnose stuff like this without having an amp in the room with us.

    All the best,

    Team H&K in Germany

VP on January 14, 2017 Reply

Hi ! I bought your great GM36 amp while ago, but can’t seem to find a cabin that I like. I like the sounds I get from our dB FM8 active monitor which I connect to the Red box out and play in silent mode. My question is: can I split the signal from the red box out using an Y cable of which one end goes to my FM8 and one goes to PA mixer? Or will it do damage, sound bad or something else bad will happen??

    Hughes & Kettner Hughes & Kettner on January 27, 2017 Reply

    Hi VP, and thanks for your question! Well, it would work, but the dB FM series feature a link output that passes the signal through to a next monitor … or mixing desk. That is what techs would normally prefer, but you can use a split cable as well!

Peter on December 7, 2016 Reply

Hey hello guys haven’t checked in in a while hey I’m experiencing a little bit of a problem with my grandmeister 36 it may be just be as easy as swapping out a preamp tube but it appears that over the months the clean Channel in my preset levels has become louder than all of the other channels I keep trying to equalize them but every time I turn them on the clean Channel seems to be overpoweringly loud compared to the rest do you think this is something as easy as swapping out preamp tubes?

    Hughes & Kettner Hughes & Kettner on December 12, 2016 Reply

    Hi Peter. It could be, although of course we can’t say with any real certainty what it could be without having the amp in front of us. We’Re assuming your TSC power tubes readout is fine? Do any of the preamp tubes look different in any way, can you see any visual signs? Either way, we’d recommend the next course of action is taking your amp to your local tech and letting them have a look round it for you…

Denis on July 30, 2016 Reply

Like some others here, I’m eagerly waiting for you to release a 1×12 Grandmeister combo. Really.

    Hughes & Kettner Hughes & Kettner on August 8, 2016 Reply

    Arg, we get asked about that one all the time Denis. It’s on the wishlist, honestly, because it’d be an awesome solution for some players – whether we’ll ever actually make one is another issue 😉

John V on July 8, 2016 Reply

So I can connect the grandmesiter through the cab output at 1watt to my audio interface and I can get all the juicy preamp and power amp tone and I can use my custom cab impulse responses right? is it safe for the amp? is it safe for the audio interface? Do I need a load box? I have heard that using an amp without a cabinet could harm the tube amp.. If not that would be amazing I have found amazing results using custom impulse responses and I can not imagine how wonderful it could be with a real tube amp instead of a modeller amp.. I really want this amp and I am looking for an amp that let me choose my own impulse responses..

    Hughes & Kettner Hughes & Kettner on July 19, 2016 Reply

    Hi John, you sure can. We’re guessing it’s a fairly standard audio interface you’re using. And no, you won’t need a load box.

    With the vast majority of tube amps, you’re right that using them without a load/cab attached can cause problems. With the Meister amps, this is not an issue, because the technology built in looks after the amp for you and negates the need for a load.

    Here’s one more tip for you if you’re considering one of our amps though: the newer TubeMeister Deluxe amps have a more advanced vcersion of our Red Box DI than the GrandMeister. With the Deluxe amps, you can turn off the emulation and just feed tha amp’s pure tube tone straight into your DAW, so your custom impulse responses will be even better than with the GM36 🙂

Luke on June 3, 2016 Reply

I was wondring if i could order a replacement faceplate for my grandmeister, mine has a nasty scratch on it, wich on top of it gets illuminated too 🙂
By the way, love the amp!

    Hughes & Kettner Hughes & Kettner on June 3, 2016 Reply

    Hi Luke, sure 🙂 You can just ask your local H&K dealer and they will be able to order you one. FIne the closest store to you by going to the dealers page on our website, here:

    And thanks for the kind words – we hope you can get a shiny new, unscratched GrandMeister plate soon 🙂

alex on May 6, 2016 Reply

im curious about the “unofficial” way to record guitars via the speaker out at 1 watt. i understand that 1 watt is line level, but what is about impendance matching and the output transformer which expects load? in 1 watt we are not in silent mode right? im afraid to destroy something.

    Hughes & Kettner Hughes & Kettner on May 6, 2016 Reply

    Hi Alex, when using this so-called ‘unofficial’ method, 17 out of 18 watts actually go into the load, so you’re just fine 🙂

Peter Schaefer on March 3, 2016 Reply

Thank you!!

    Hughes & Kettner Hughes & Kettner on March 3, 2016 Reply


Peter Schaefer on March 1, 2016 Reply

Well as I have said before..I would like to see a 50 watt el34 Grandmeister combo or head 😉 😉
Otherwise a 50 watt el34 Coreblade combo 😉 ;).
I’ll leave it in the capable hands of the tone gods at Hughes & Kettner!

    Hughes & Kettner Hughes & Kettner on March 3, 2016 Reply

    Leave it with us – it’s on the wishlist… 😉

Nicholas DiLorenzo on February 18, 2016 Reply

I just recieved my Grandmeister 36 a few weeks ago. I adore it. The ONLY thing i wish it had was an acoustic simulator!! And maybe a looper.

I just wanted to share a few things that might help someone who just took it home or maybe someone looking to buy it thinking the same stuff as me.

First I’d like to say the stock tubes sound mean and sexy to me. I see no “gain” (see what i did there) in changing them unless you’re a name brand person.

Second, i do use the amp with a rack system. Im not concerned with the weight. I figure i just got rid of a 55 pound head for a 17 pound one. The rack system is a power conditioner, wireless system, tuner, bbe sonic maximer. The fx loop on this head is great. A word to the wise….if you ever decide to JUST TAKE THE HEAD to rehearsal and use the redbox( no speaker) it will work excellent (PROVIDED YOU SHUT YOUR FX LOOP BUTTON OFF ON ALL YOUR PRESETS!!!! Other wise just static and hiss happens.
Yes that happened to me and it was a blonde moment but oh well. Maybe someone else will have had this issue and read this???
Getting to the redbox. It does incorporate the fx both internal and loop. It sounds phenomenal!!! No more mics, stands, feedback from said mic, delay pedals, chorus pedals, blah blah. Use a mic and blend two channels if you want but i can tell you it is not needed as the red box is top notch.

The amp is metal and a tube amp. That being said internal rack fans do add noise. If you put it in a rack just slip it in there after removing it from the padded gig bag it comes shipped in. It fits nicely in a standard rack.

Also i wouldnt go wrapping it in foam like a live in road case. Leave an inch at the sides and maybe 3″ at the top for adequate ventilation.

Overall i could not be happier with the gm!! My rig/pedalboard is significantly smaller, lighter, and less sophisticated.

For anyone who cares here is the line up i use it with.

Ibanez jem or fender american hh strat —>tuner —> wah—-> wireless/amp. out to marshall 1960a cab. Fx loop to bbe sonicmaximer 882i and back in. Redbox out to PA. That’s it. Fs2 foot controller.

The equipment i have shed because of the gm!!!

Boss chorus ce5
Boss dd7 delay
Evh phaser
Lexicon reverb rack unit
Hum x
9 volt batteries
Ground loop eliminator
Ns2 noise suppressor
6 patch cables
Downsized pedal board.

Hope this helps. How about that acoustic simulator or loop station built in?

    Hughes & Kettner Hughes & Kettner on March 3, 2016 Reply

    Hi Nicholas, and thanks for all the great feedback! It’s always cool – and useful – for us to hear this sort of stuff from the players who are using our amps.

    Hmm, an acoustic simulator and a looper?! Well, we’ll add them to the always-growing H&K wishlist, so never say never 😉

    Like you say: just make sure your GrandMeister is getting the ventilation it needs in the rack – don’t have anything directly on top of it, and we would still recommend you have a fan system running so it stays cool enough. You wouldn’t want it to risk overheating.

    Happy to hear you’re getting so much great use out of the Red Box – we often find that once people give it a chance, they just ‘get’ it and will always use it from then on 🙂

    Sounds like a pretty awesome rig you’re running there, and it’s incredible just how much you’ve been able to throw out that the GM36 can replace!

    Now we’ll get thinking about how we can fit an acoustic simulator/looper in the next amp we make 😉 We wish you the most fun with your GrandMeister, and thanks again for the awesome feedback! 🙂

Peter Schaefer on February 5, 2016 Reply

Well thanks for the response! “Never say never?” …I can live with that.☺
I will continue to support Hughes and Kettner because not only do they make the best amps in the world, they also listen to their customers. With each progression in the programmable amp line they not only raise the bar each time but exceed expectations.

    Hughes & Kettner Hughes & Kettner on February 9, 2016 Reply

    Cheers Peter – we always at least try to listen to you guys 🙂 After all, you’rE the ones playing our amps every day, and you know what you want! So why wouldn’t we listen to what you have to say? We’re hopeful we can carry on exceeding your expectations for years to come!

Peter Schaefer on January 21, 2016 Reply

Hello guys..great blog and I have been a huge fan of H&K for some time now. Have owned a Triamp MK 2, Coreblade, Switchblade 100h and now the amazing Grandmeister!!
However I prefer EL 34 power tubes.
Any chance there will ever be a Grandmeister 50 el34?

Thanks and cheers!

    Hughes & Kettner Hughes & Kettner on February 2, 2016 Reply

    Thanks for the lovely feedback Peter! Hmm, an EL34-equipped GrandMeister? There’s no plans at the moment, but never say never 🙂

Cody on January 3, 2016 Reply

Hey H&K,
My band mate just got a tube Meister 36 combo (amazing amp btw), we run a pretty simple stage set up and run the “line outs” from our amps/amp heads to our PA mixer we only run those signals into monitors for our selves. Keeping just vocals and the kick drum going thru the mains. My question is regarding a traditional “line out” application on this amp. We noticed there is no line out but there is the red box. So can we just run a three pin mic cable from the red box output on the back of the amp into the mixer, or do we need to purchase a red box, or do we need to mic the cab to get a signal for monitoring use?? Thanks!

    Hughes & Kettner Hughes & Kettner on January 6, 2016 Reply

    Hey Cody, and thanks for your question! Yep, the Red Box is all you need (and is indeed built into the amp!) – just run it to your mixer via a standard XLR cable and you’re good to go.

    If you want, you can of course also run a mic too and blend the signals – this can help you conjure up some unique and cool guitar sounds – but really, all you need to get rocking is the amp itself connected directly to the PA. Hope this helps 🙂

MrJordn on December 14, 2015 Reply

Would you guys rather recommend a 2×12 or 4×12 cab?
I’ve read quite a few reviews so far, but still I have concerns about the amps power output.
Is the Grandmeister 36 powerful enough to properly drive a 4×12 cab?

    Hughes & Kettner Hughes & Kettner on January 6, 2016 Reply

    Hmm, well… We designed our TM112 (1×12) and TM212 (2×12) cabs to go with the Meister amps, so they fit perfectly. However, from our experience there’s more than enough juice in the GrandMeister to drive 4×12 cabs too! What we’d really recommend is that you try it for yourself though – tone is subjective, and what sounds good to us might not sound goofd to you, and vice versa 🙂 Give it a go and let us know what you think!

Nev on November 21, 2015 Reply

Quick question also related to TSC…

I have a 1×12 speaker that I’ve used previously with my GM36 just fine… Unfortunately the 2 wires that connect to the speaker have fallen off the connections and so I need to put them back on — the problem is neither the wires or the speaker have any identifiers as being + or –

Would I damage anything if I used trial and error to sort this…? (It’s either going to turn into a giant microphone or speaker haha….) I’m figuring since my GM36 has TSC it may be the safest unit to perform this trial and error to sort the wiring out? One wire is black one is white, but like I say, there is no + or – signifiers on the speaker itself…

I’m thinking I put my GM36 on to ‘silent record mode’ plug the speaker jack in (with the black cable connected to 1 speaker terminal and the white to the other….) and then take it off ‘0w’ to ‘1w’ and see if I get sound; and if not turn the GM36 off to standby immediately and reverse the connections as it would obviously be the other way round connection-wise…

Would TSC protect the tubes/transformer/amp in this scenario entirely? Would it also look after the speaker by default because of this? As obviously I wouldn’t want to cause any damage to any of my equipment!

I’m certain I’ve had my GM36 default to 0w before when no load is connected (great design feature!) but have no way of knowing if it is safe to do so with an “abnormal” load connected (potentially incorrectly connected if you get me?)

Thanks in advance!

    Hughes & Kettner Hughes & Kettner on November 24, 2015 Reply

    Hi Neville, we decided to get the knowledge of our expert techs for this one, so please bear with us until we hear back from them! 🙂

    Hughes & Kettner Hughes & Kettner on November 25, 2015 Reply

    Hi again Neville. Right, so the techs say:

    The amp’s not bothered whether the speaker is connected correctly in this case, and you can in fact mix up the + and – wires without anything happening to the amp. You probably won’t even notice any difference in sound whichever way you do it!

    However, what you must be aware of is this: if you connect a different speaker, it needs to be connected the same way as the speaker you’ve got now. If you mix that up, you’ll get ‘phase cancellation’, and although this won’t damage the amp, it’ll not sound good 😉

    TSC is there just to monitor and adjust the bias current of the tubes as and when necessary. But it doesn’t provide any protection against incorrectly connected impedances.

    The danger for you in this situation is that you need to make sure you have a speaker connected when you’ve got a jack in the ‘speaker out’ socket! If you don’t, and the power soak is not set to 0, you can (and probably will!) damage the amp’s output transformer.

    Hopefully this is helpful! 🙂

Vincent on September 1, 2015 Reply

@H&K thnx!

I got an error in the TSC in one of the middle tubes.
and the amp sounded like broken speakers.

after “rebooting”(is that even possible with an amp? 😛 well it’s got midi so there must be some kind of software in it (o; )
all went back to normal, but can’t have the risk of failure during gigs.
luckily this was at a rehearsal.. 🙂

There is a lot of good comments on JJ, but I hear also some very negative stories. Pricewise it’s would be a good option i think..

Are the Stock tubes available at my H&K dealer?

    Hughes & Kettner Hughes & Kettner on September 2, 2015 Reply

    Ah, interesting. You can do a Factory Reset for all the MIDI stuff on our amps, but it really does lose all settings there – see the manual for more info on that.

    The thing is, you always get mixed reviews on tubes – even on boutique ones 😉 The thing is, good tone is a totally personal thing, so you might love something we hate, and our favorite sound could be your worst nightmare… So it’s really worth trying the options for yourself and selecting the thing that makes you happiest. And yes, you can get replacement H&K tubes from our dealers, of course. Maybe your local store has a tube expert who could give you a few demos before you make a decision? TSC would make it easy for the tech to swap tubes around for you 🙂

Vincent on August 31, 2015 Reply

Which tubes do you recommend as replacement for the stock tubes in the grandmeister?

    Hughes & Kettner Hughes & Kettner on September 1, 2015 Reply

    Hi Vincent, that would depend on many factors. For example, the reason why you don’t like the stock ones – what other tonal nuances would you like that are not present in the stock tubes’ tone? Also, the kind of music you play, how much FX you use, your other gear, etc., etc.

    All that said, we’ve heard a lot of love for JJ tubes on the web recently, and they’re probably worth a shot. But your best bet woulds be to take your amp to a tube expert tech who could take you through the different characters of each and help you find the one you like most. Also, we did do a blog with a bit of info on the different power tube types – rewad that here for some more info:

    By the way, we tried loads of tube options out while designing and testing GrandMeister, and we think the stock tubes are awesome – that’s why we built them in there in the first place 😉 We wouldn’t change them…

Luke on May 25, 2015 Reply

Hi love the amp I was just wondering what the redbox out dbu output levels are I run the amp in to a strymon big sky that can take line levels up to +8 dbu but the signal is too hot I’m thinking of getting a reamp to drop the level dawn to instrument level before it reaches the big sky and just wondered haw much higher than +8dbu the red box outputs many thanks Luke

    Hughes & Kettner Hughes & Kettner on May 27, 2015 Reply

    Hi Luke, the Red Box filters the FULL amp signal (including power amp saturation) and sends it to the mixing console or Audio interface at line level. You can find all the precise figures you’Re after in the Red Box manual, which you can see here as a free PDF:

    Hope this helps, but let us know if you have any more questions!

Ron on May 23, 2015 Reply

Thanks for the reply. I’m in the Fort Worth, Texas area.

    Hughes & Kettner Hughes & Kettner on May 27, 2015 Reply

    Hi Ron. OK, so if the amp’s still under two years old, the USA warranty should still be working on it. Give Yorkville, our USA distributors, a call and they’ll let you know about how to go about getting this fixed. Here’s their details:

    Yorkville Sound, Inc
    4625 Witmer Industrial Estates
    14305 Niagara Falls
    Tel.: +1 7162972920

    Hope this helps, and let us know how you get on!

Ron on May 20, 2015 Reply

This is probably the wrong place to ask the question so please re-direct if needed. My Tube Meister suffered from a power outage (e.g. power went out and came back on). The tube indicators on the back of the amp indicate the tubes are ok but there is no sound coming out. Is it possible for me to send the amp to Hughes and Kettner to have a look, diagnose and repair. It is beyond the warranty as I’ve had it slightly over a year. I’ll cover all of the cost of shipping and repairs. I just hate not playing live gigs without this amp.


    Hughes & Kettner Hughes & Kettner on May 22, 2015 Reply

    Hi Ron, where are you based? The warranties are generally longer than a year. Let us know your location and we can help more, hopefully!

Steve Jones on May 5, 2015 Reply

Thanks for your reply, have you any idea why the sound was cut altogether?

I had to quickly hook up another amp as the GM36 wasn’t producing any sound at all, it works fine again now minus the faulty valve…

Thanks again


    Hughes & Kettner Hughes & Kettner on May 6, 2015 Reply

    Hmm, we reckon it’s tube related, but 1. that doesn’t explain why the amp cut out completely (TSC should have prevented this from happening) and 2. without having the amp physically in front of us it’s impossible to make a more specific diagnosis.

    It could be worth asking a qulaified tech to take a look at the insides of the amp – maybe something else will become apparent!

Steve Jones on May 4, 2015 Reply


Love the GM36, had it for about a year and mainly used it at home 1W or DI at gigs.

I used it for the first time this weekend plugged into a 4X12 Cabinet at the full 36W, Master Vol at about 1 o’clock.

The top of the amp was clear of obstruction but still got surprisingly hot given no power soak and after about 2 hours the sound cut out altogether. From the TSC it appears 1 of the valves needs replacing however the manual suggests that in this situation the gig can be saved by switching to 18W. Is this automatic or does it need to be done manually every time you select a new preset from the H&K Footswitch?

    Hughes & Kettner Hughes & Kettner on May 4, 2015 Reply

    Hi Steve. OK, so first off, glad you’re enjoying your GrandMeister!

    Right, so the heat is not a problem. Even in 36W mode, the metal plate on top of the GM36 acts as a heatsink, hence things getting a little toasty. The other option would’ve been for us to build the GM36 with a wooden housing, but this would’ve got just as hot, even though it wouldn’t have felt so hot to the touch on the outside.

    About TSC, you’re right: it will shut faulty tubes down automatically, so you don’t need to do anything. If it does shut tubes down, of course, they will need replacing after the gig… And of course we recommend you get a qualified tech to change tubes always 😉

    Hope this info helps!

jeff m on April 26, 2015 Reply

Hi i’m currently a coreblade/ two notes torpedo, but I’ve been taking a look at the grandmiester, do to it’s small size, and similar features, to the coreblade. I was thinking of downsizing to this, and rack mounting the GM as well, so this info was helpful info. One thing i would like to know is it is noted that the mkIII works with the coreblade, but it doesn’t really state anyware that i’ve been able to find, what features, of the pedal will not work with the coreblade amp. Could you give me a run down on what will work, and what will not work feature wise with the coreblade?

Oh, and is it possible to save patches/ banks of patches when it is connected to the app. On the coreblade, you can connect a usb, and save the patches, although I’ve never used this feature, I was just curious to know if it is possible.

    Hughes & Kettner Hughes & Kettner on April 28, 2015 Reply

    Hi Jeff. OK, so here’s some reading for you:

    Chapter 3: “What’s new”: here we mention what features only work with the GrandMeister.

    But in short: the Coreblade does not react on CC commands, just on program changes. So the real-time control of parameters like volume won’t work, or switching BOOST in StompBox Mode won’t work. If you do not use the StompBox Mode and the controller inputs, the Coreblade won’t notice if an MKII or an MKIII is connected.

    It’s the same the other way round too: if you only want to switch presets, an MKII will work with the GrandMeister, because it’s just standard MIDI! And yes, storing patches when it is connected to the app is possible. In the app, or in the amp, both works. Hope this helps!

gravydb on April 22, 2015 Reply

Neville – you’ll need three 12AX7 (also known as ECC83) preamp tubes, and four EL84 poweramp tubes (make sure they are ‘matched’). As far as what brand to get, that’s entirely subjective personal preference. JJ’s get my vote, mainly because I’ve had longterm positive experience with them in many amps. Honestly I don’t think the GM’s stock tubes are bad but everyone has their own tastes… I feel the JJ’s bring a little smoothness/warmness….

Neville on April 20, 2015 Reply

What valves do I need to replace/swap for the cheap Chinese ones it ships with in my GM36? Cheers

    Hughes & Kettner Hughes & Kettner on April 21, 2015 Reply

    Hmm, depends what kind of tone you’re after, etc., etc. We’ve heard many good things about JJs, so why not give some of them a try?

gravydb on April 14, 2015 Reply

Thanks for the quick reply 🙂 Scroll up to Nov 25 2014 and you’ll see the comment… someone from H&K states that the GM’s Red Box output is dry (no FX). I had a feeling that is incorrect but I just wanted to clarify.

BTW I happen to be in the camp that swears by the Red Box 🙂 I still have one that I bought 20+ yrs ago! Having it built into these ‘meister amps is genius (thanks!)!

    Hughes & Kettner Hughes & Kettner on April 21, 2015 Reply

    Oh yes 😉 We make so many comments on here, can’t remember them all! And yes, there is more than one H&K person who comments on here, so sometimes opinions can differ… Having said that, we think the comment is just worded strangely – so he doesn’t mean that the signal is dry, just that he thinks the tone is missing somehting with just the Red Box. Anyway, we’re happy to have cleared this up, and that you’re a Red Box fan anyway – enjoy 🙂

gravydb on April 13, 2015 Reply

Hey all. I recently upgraded from a TM18 to a GM and I’m loving it! I had owned the TM18 for a couple years and made extensive use of the Red Box for recording and live shows. I have not yet had the opportunity to use the GM’s Red Box – hopefully soon!

So anyway onto my question… I’m reading through this blog, and I was really surprised to see this comment regarding the GM’s Red Box (posted on Nov 25 2015):

“…a direct Red Box signal will be dry, and you’ll need the FOH guys to put some echo/reverb on your signal…”

Is this really true? The GM’s built-in FX do not go via Red Box?

    Hughes & Kettner Hughes & Kettner on April 14, 2015 Reply

    Hi there. Hmm, where exactly was that comment? It’s sort of opinion whether you find the Red Box signal pleasing to the ear or not – just like with any tone, really. However, the Red Box sound is not as airy as a micced cab, that’s for sure – which is why we recommend the Impulse Response, or blending a micced signal and the Red Box too.

    But some guys love and swear by the Red Box sound. We’d really say you just should give it a try and see what you think – and yes, the FX thing is no worries. Here’s a video from a friend of ours that proves it:

    Hope this helps!

Neville on April 8, 2015 Reply

Not long to go now though…! And you confessed!!! 😉

Hoping it will be small, light, smart, and ideally as cheap as possible!

    Hughes & Kettner Hughes & Kettner on April 9, 2015 Reply

    Ha ha, more info to come next week! 😉

Demetris on March 25, 2015 Reply

Yep, that pc editor is cool i am using that for now, though i am still looking to connect it to the ipad. Just maybe that wireless option would worth the money. Does this mean it would also work on an adroid tablet?

    Hughes & Kettner Hughes & Kettner on March 25, 2015 Reply

    Hi Demetris. Hmm, the wireless option will only work on the iPad app (because that’s our official app)…

Demetris on March 21, 2015 Reply

Its great to know that about the “no speaker”

Though for the irig midi this is not exactly helping (cause, part of it is my mistake as i didnt clarify that i have the ipad air with the smallest connector) so that would mean i would also need to buy an adaptor and with the shipping it would still be around 100 euros.

So then, no other option?

Thanks in any case guys.

    Hughes & Kettner Hughes & Kettner on March 24, 2015 Reply

    Ah right, so you’d need the iRig MIDI 2 for that, or more adapters – and yes, they do cost a bit more. Hmm, another option for you would be to use the desktop GM36 editor, assuming that’ds an option. Here it is, for Mac and PC (it’s not from us, a third party developed it, buzt it’s cool!):

    And the final option will be our new wireless adapter, which should be out around Musikmesse time. That’s going to be awesome, but also not cheaper than an iRig…

    Hopefully one of these will help!

Demetris on March 20, 2015 Reply

New quick question.

I bought some midi cables and manage to connect the amp to the pc. As of now i dont have a cabinet but the presets they are all in 36watt. Does that mean I should avoid changing presets for now till i get a cabinet? Or is it ok and the amp nomatter the preset will always be on “no speaker” because there isnt one connected in?

And final, just in case, do you have any suggestion for a cheaper midi interface on ipad? The irig one will cost me 100 euros and i cant justify spending so much money just for a midi interface.


Demetris on March 16, 2015 Reply

I guess so! Thanks for the support and the quick answers of my questions. You’ve been great!

    Hughes & Kettner Hughes & Kettner on March 18, 2015 Reply

    No worries, always happy to help!

Demetris on March 14, 2015 Reply

Thanks for the answers there.

So basically the amps needs to be in silent mode without a cabinet otherwise it would hurt itself? I am newby into tube amps and am learning as I go.

At the end I did use the gain of my card (babyface) in some occasions while getting awesome results! though the amp is getting pretty hot on the top and less hot on the front glass and right now the ambient temperature is 22 celsious, on the summer it can be as much as 29-30. Should that worry me?

I mean i really do enjoy the tone and the feeling and everything on it but on the back of my head this temperature thing doesnt exactly let me enjoy the full of it, if you know what I mean.


    Hughes & Kettner Hughes & Kettner on March 16, 2015 Reply

    It could hurt itself, yes. You should read our blog on impedance, which discusses this in more detail, here:

    But here’s possibly the most relevant extract for right now:

    “First of you all, you should commit this critical ground rule to memory: never – really, NEVER! – operate your tube amp without a load/speaker(s). If you do, the result will be a high level of induction voltage that could damage – or even destroy – your amp’s output transformer and tubes. As long as you remember this, you should be on the safe side, even with a mismatched setup.”

    The heat is normal with the power soak, and it’s nothing to be worried about. It’s just part of the process, and the design of the system. The ambient temperature won’t make a discernible difference either (well, within reason, of course!). Hope this allays your fears slightly! Heopfully, the more you play the amp (and the more nothing bad happens), the more you’ll get used to the idea…

Demetris on March 13, 2015 Reply

Hey there, great blog here and great support from you guys!
So here it is. I bought the grandmeister 36 yesterday but no cabinet yet, so far i am more than happy with the tone i get from the DI. Though i hhave a few concerns.
1. The volume from the DI is kinda low, I mean I need to almost crank up the master and the volume pot to get a decent recording level (especially on clean channel). On the back i have no cabinet connected and its on silent mode. Is it like that cause its working with two tubes? On 18 watt?
2. Can I disable the silent mode to get a full 36watt (to reduce heat) without a cabinet connected but just the DI?

Of course there are plans to later buy the matching cabinet but for money issues i am doing it slowly


    Hughes & Kettner Hughes & Kettner on March 13, 2015 Reply

    Thanks Demetris! Here’s the answers to your questions:

    1. If no cab is connected, the amp will automatically switch to silent mode to protect the power amp. The Red Box delivers line level that depends on the volume and master. No worries, you can crank it up and enjoy full power amp saturated tone – it’s especially made for that! If the level is still too low, just increase the gain of your desk and/or audio interface.

    2. The silent mode switches off two tubes (using TSC) to reduce the power to 18 watts to reduce heat. Otherwise 36 watts would have to be transformed into heat.

    Hope this helps, and enjoy your GrandMeister!

Nev on January 14, 2015 Reply

Nice one for getting back to me and hope you had a pleasant festive period!

There is a small gap above the amp (my TC G System rackmounted brain sits ‘on top’ of the sides of the GM36 – but they are higher than the chassis where the heat seems to collect… also the G Sys is less than half a unit DEEP)

Likewise the GM sides (it’s an extremely tight fit situation!!) sit on a vented shelf so that there is a small gap between the bottom plate once again and the shelf (which is vented anyway…) (I replaced the GM feet with smaller ones and drilled holes into the shelf so that the feet would ‘nestle’ into these holes allowing the GM sides to rest on the vented shelf — it’s the only way I could get all the gear inside the rack!)

Neville on December 10, 2014 Reply

OK, so I purchased a rack cooling fan (just-in-case!) don’t want my GM36 getting damaged…!

Would it be better to ‘blow hot air out’ of the rack case or to ‘suck cool air in’ ? As it can perform both duties depending on which way it is mounted…

And also, where would be best to aim the fans? (I’m thinking at the top of the chassis where the heat sink is – as this seems to be the location where the amp is most notably hot – so then it blows hot air of the top of the chassis and out the front of the rack in to open air (this will however also blow air into the amp where the valves sit – due to the gaps in the back of the GM36 – would this be an issue?)


    Hughes & Kettner Hughes & Kettner on January 5, 2015 Reply

    Happy new year Neville – we’re back and finally answering stuff again 😉

    In answer to your last three questions, please don’t remove the feet of the GM36 – the PowerSoak is on the bottom and the bottom plate needs some cooling as well. It is always better to suck hot air away from the amp than blowing cold air into it. In the best case, there is some space in between the bottom and the top plate, so that both plates can be cooled by sucking the hot air away. It’ll work if just the hot air from the inside of the rack is sucked out…

Neville on December 5, 2014 Reply

Ah yes, now I remember, good point!

So, best cable to use with the redbox??!

Cheers 🙂

Neville on November 29, 2014 Reply

All is forgiven because you are such heroes…

Well, all sorts of applications really…

(at home going into my Focusrite 18i20 to Logic ProX on an iMac for recording purposes – out through Mackie HR624mkii monitors)

(at practise/live situations, likely to a mixer for P.A. / F.O.H. to ‘beef’ up the sound in praccy and for audiences at gigs…)

they’re the only ones I can think of currently – but I’m sure there must be more!!! Just wondering also, can you use the redbox for stereo application as XLR as 3 pins – ‘crossover left & right’ – perhaps these signals can be split at the desk…?)


    Hughes & Kettner Hughes & Kettner on December 3, 2014 Reply

    Ah, thank you 😉

    But no, the three pins of XLR deliver a balanced signal. Unbalanced signals only use two pins: signal and ground. A balanced signal uses three pins: signal, phase inverted signal and ground.

    The trick is: if the signal and inverted signal run at the same time through a cable, any electrical interference will change the signal and inverted signal in the same way. On the other end of the cable, the balanced input will invert the already phase-inverted signal again and mix it to the normal signal. So the pure signals will add together, and the interferences will eliminate themselves (phase-cancelling). So this has nothing to do mono/stereo, it is made to guarantee loss-free and interference-free studio quality.

    Hope this explanation is easy to understand 😉

Neville on November 26, 2014 Reply

Great! Thank you kindly for those measurements! (I assume you meant centimetres 😉 …)

What is the best cable to use out of the redbox of the GM36? – would it be XLR to TS or XLR to TRS?


    Hughes & Kettner Hughes & Kettner on November 28, 2014 Reply

    Ahem. No, we didn’t. Er, we measured a scale model and gave those 😉 Not really – centimetres it is! Noe worries either way…

    Re: cables, are you going to a mixer, or what? Please let us know the specifics.

Clifford Cline, Jr. on November 25, 2014 Reply

Thank you so much for the quick response…didn’t realize that the effects wouldn’t come through…I really love this amp, the tone is unbelievable ! I was s little hesitant at to purchase it because of where it is built,but wow to my surprise it sounds great ! I hope to have the Tri amp one day that’s what i really wanted…so again thank you for your help !

    Hughes & Kettner Hughes & Kettner on November 26, 2014 Reply

    No worries Clifford – happy to help!

Clifford Cline, Jr. on November 24, 2014 Reply

This would be with the Grandmeister 36 head.

Clifford Cline, Jr. on November 24, 2014 Reply

I was wondering if it is necessary to have a speaker cabinet hooked up if you are in silent mode going through a P.A. system with the red box? Or can you just use the head?

This would be with the Grandmeister 36 head.

    Hughes & Kettner Hughes & Kettner on November 25, 2014 Reply

    Hi Clifford. Techincally, you could just have the head on stage with you, no problem. But you’d then need a cab or monitor to hear yourself onstage properly.

    Also, it’s worth checking out, because a direct Red Box signal will be dry, and you’ll need the FOH guys to put some echo/reverb on your signal or it could end up sounding thin. Of course, if you’ve thought of this already, then no problem!

    Give it a try, and let us know how you get on…

Neville on November 22, 2014 Reply

Perfect, the amp fits the tray…JUST!

Now just gotta get those holes drilled accurately! Look forward to those two measurements! Cheeeers

    Hughes & Kettner Hughes & Kettner on November 26, 2014 Reply

    OK, so the feet measuremeants are 1.8mm and 2.2mm (for the bottom and the top bit attached to the head respectively, of course)… good luck 😉

Neville on November 17, 2014 Reply

Haven’t tried it loud for extended periods in the rack yet – going to do so Saturday and assess then whether or not a fan unit will be necessary… 🙂

Can you please tell me the diameter of the feet of the amp?! (Got it in my rack case and don’t want to have to disturb all that cabling to measure them! – I would appreciate the diameter of the bottom of the feet (where they touch ground) and the tops also! (where they meet the amp chassis) as they are (fortunately) slanted (I have a rack tray coming in the post hopefully that the amp will fit on and going to drill 4x holes of a diameter between these two measurements you give me so that the amp feet sit in each of these holes but the chassis of the amp does not actually make contact with the shelf!) ..well that’s the plan anyway!!

    Hughes & Kettner Hughes & Kettner on November 21, 2014 Reply

    Well, the best of luck! The overall dimensions of the amp are 445 x 170 x 150mm, but we’ll have to measure the feet for you. We’ll let you know!

Neville on November 11, 2014 Reply

Just to clarify…

Is it absolutely imperative that I implement an active cooling system into my rack for the GM36? Just trying to save on forking out another £75 ideally! (And also an additional potential source of noise!)

…I’ve got it in my rack case now, and will be using it on every attenuation level (silent / 1w / 5w / 18w …all the way up to 36w)

HOWEVER, the case depth is only 200mm (it’s a shallow-shallow ABS job)

…I have the GM36 on top of a VENTED 19″ metal rack tray (so not only is the GM raised from this shelf because of the amps’ feet but the shelf is also vented for improved airflow…

The next rack above the GM is my TC G System brain – which is very shallow in depth (around 10cm) and has a gap between itself and the ‘heatsink’ chassis of the GM36 of around 1cm…

So there is room for airflow everywhere around the GM!)

What do you think? I could send a picture for clarification?? 🙂

Thanks in advance!

    Hughes & Kettner Hughes & Kettner on November 12, 2014 Reply

    Only you can make that call, Neville, based on what you feel is safe. We’d always recommend cooling, but if you’ve got airflow all round it, it might be OK. How hot does it all get when you’ve cranked it all for a significant amount of time? Much hotter than the GrandMeister would normally get on its own?

    What you could do is post a pic to our Facebook page – you could then ask if anyone on there has another informed opinion… 😉

      Hughes & Kettner Hughes & Kettner on November 12, 2014 Reply

      Oh, and we forgot to say – we found this pretty cool MIDI glossary while searching round for explanations for you, so take a look:

      There’s some cool terms in there. And for any further reading, we’d also recommend the Wikipedia MIDI entry, as it has some pretty good historical background and so on. It’s pretty good for beginner MIDI nerds 😉

Neville on October 28, 2014 Reply

So you’re saying I’d be best of with 1 (or 2) TM212 cabs as opposed to my 8ohm Mesa 2×12 ?? 😉

How many fans might that be? (hope it’s not as long as a piece of string…!) Found a 4x cooling fan unit on ebay for £70 and they are supposedly ‘silent’ – just to check, fans won’t introduce any noise or hum into the rig would they?

And I was literally going to by a 6U ABS rack case and sit the GM36 on the base of it – perhaps tying the handle at each end taut to the rack ‘wings’ using string ??! Then if i want to remove it from the rack all I have to do is cut the strings… Guessing this will be frowned upon though haha!

    Hughes & Kettner Hughes & Kettner on October 30, 2014 Reply

    Well, different people prefer different things, and that’s all we’ll say. There might be some situations where you find certain cabs work better with certain amps, and we certainly don’t begrudge our players if they use Mesas or Engls or whatever. But yes, you’d be best with ours, of course 😉

    What you need for your rack is indeed as long as the prverbial piece of string! Whatever else you’ve got in there that needs cooling will also need to be taken account of. So long as you don’t use said proverbial piece of string to tie your GM36 to the rack, we’ll be fine 😉 As far as hum and extraneous noise goes, it’s unfortunately something you’ll just have to try out. We’ve read all sorts of conflicting reports online about this stuff, so no doubt the results also hinge on the rest of your setup, where you are in relation to power sources/electric lights, etc…

Neville on October 28, 2014 Reply

You guys are my heroes.

So it would appear I have to be careful as to whether the cabs are wired in series or in parallel then (as 2x 8ohm cabs wired in parallel would result in a 4ohm load = not good for the GM, but 2x 8ohm cabs wired in series would result in a 16ohm load = good times for the GM!)

How many fans does the GM need?! Haha, I am based in the UK and didn’t realise they would be so expensive! How would one go about rack ‘mounting’ it? (or does it just sit in a rack, tie it down with string kinda thing? haha)

    Hughes & Kettner Hughes & Kettner on October 28, 2014 Reply

    Ha ha 😉

    Yes, exactly – it all makes a difference to your tone, too. Our impedance expert who wrote the article does maintain that you can get great sounds out of ‘mismatched’ setups, and as long as you’Re careful you won’t do any damage to your kit. But still, certain setups are known as matched for a reason!

    You’ll need as many fans as the amp needs to avoid overheating, and that will differ from setup to setup. Good fans can cost a lot, yes, but it’s better than buying a €10 desktop fan and sticking that in the back! With regards to how you’d mount it, we’re moving out of our ‘expert’ territory here, so we’d advise you to do some Googling to find out more from people who know their stuff 😉 Are you getting a tech to fit it for you, or do you plan on doing it yourself?

Neville on October 27, 2014 Reply

Awesome, I will google! The app is already awesome, just perhaps needs suggestions added to it and NOTHING detracted from it or removed!

Would a cooling unit/fan best be placed aiming at the back of the GM36? Or above (acting on the metal chassis?) I’m guessing keeping the components inside cool is the issue so best situated blowing cool air INTO the amp…

Also, I see that the TM212 cab is 16ohms… Does this mean I could use 2 of these with the GM36?

GM > 1st TM212 > (parallel connection) to 2nd TM212

As this will result in total load of 8ohms, correct?!?

    Hughes & Kettner Hughes & Kettner on October 28, 2014 Reply

    Yep, right – keeping stuff inside cool is paramount, so you would need to adjust the fan accordingly. We were looking around at rack fans yesterday because of you, and Sweetwater in the US seem to have a pretty good overview:–Rack_Fans

    Spot on with connecting the cabs – here’s what the GrandMeister manual says about that:

    1 Speaker:
    GrandMeister 36 offers one speaker output for 8 Ω to 16 Ω cabinets. Connect a speaker cabinet designed for guitar amps to this jack.
    Using a single speaker cord, you can connect any cabinet or combination
    of cabinets whose total impedance ranges between 8 Ω and 16 Ω.

    The formulas below serve to calculate the overall impedance (R) of two cabinets with different impedances (R1 and R2):
    • For cabinets wired in series:
    R = R1 + R2
    Example: If you connect two 8 Ω cabinets, the overall impedance is 16 Ω.

    However, very few modern cabinets are wired in series. Parallel circuits are far more common.

    • For cabinets wired in parallel:
    R = (R1 x R2) / (R1 + R2)

    Here is an example with two 16 Ω cabs:
    R = (16 x 16) / (16 + 16)
    R = 256 / 32 = 8 Ω

Neville on October 27, 2014 Reply

Great thanks for the info. I’m definitely keen on getting it racked so this advice was imperative as I will need a suitable cooling solution – any ideas let me know as I’ve not delved into the rack world before!

Haha, no problem, I’m sure you’d already had the same idea/suitable places it could go – just can’t stress enough how the app is great itself and shouldn’t be changed; just extras ADDED to it (“if it ain’t broke don’t try to fix it” springs to mind!)

    Hughes & Kettner Hughes & Kettner on October 27, 2014 Reply

    No worries. We’ve got a couple of colleagues who play GM36s and use rack stuff, so we’ll around around and will let you know if there are any tips. And Google always helps. Broadly speaking though, guess most people want GrandMeisters so they don’t need a rack any more 😉

    We’Ve had loads of cool little tips from players, so we really should be able to make a kickass app next time round 😉

Neville on October 25, 2014 Reply

Fantastic. When you say the ‘metal housing’ – does this refer to the chassis BETWEEN the ends? or does that include the 2 ends (where the handles are fitted and holds the chassis together)?

Loving the neatness of the app – can I perhaps suggest a ‘Tuner’ to be added to it? (button could be placed next to the attenuation selector and open a new page – similar to the ‘library’ function?)

Many thanks

    Hughes & Kettner Hughes & Kettner on October 27, 2014 Reply

    Hi Neville. We mean the whole thing, including the ends – although it’s the top of the chassis where you’ll feel most of the heat. But it doesn’t hurt to keep the whole thing cool if you can!

    A tuner is a great idea, and one that’s on the wishlist for future versions. Thanks for the tips on where to put it!

Neville on October 20, 2014 Reply

Is it safe (component-wise) to turn the master, channel volume AND gain all the way up on 36watts for practice/gigging scenarios? I had the vol & gain at about 8 the other day and master at half way and it was doing a good job keeping up with drums and a 500w bass amp but will need more oomph when it comes to gigging and want that from the 4×12 (as will likely mic up and send redbox to PA for audience) but want that oomph from behind me as well… Just don’t want to blow anything up, but it’s German engineering so I do have faith…! 😉

    Hughes & Kettner Hughes & Kettner on October 22, 2014 Reply

    Hi Neville. The amp is designed to run at full power: it is tested and certified to do so. As long you don’t cover its metal housing (ventilation is needed, because the metal housing works as a heatsink and therefore it feels hot at full power!) and do not connect a cab with less than 8 ohms, you will always be safe. Like with German cars: they are designed to drive with no speed limit for hours 😉

John on September 19, 2014 Reply

So, the Line Out is after the effects block? I’m guessing that it is also un-affected by the Red Box. If so, then this signal could be run to a DAW and used with cabinet impulse software such as Recabinet. BTW, sorry but I just emailed a question to your support about this then found these comments. Hate to double your workload.

    Hughes & Kettner Hughes & Kettner on September 23, 2014 Reply

    Hi John, and thanks for your question – and no problem about asking twice: so long as we don’t give you two different answers we’ll be OK 😉

    The simple answer to your question is Yes, but the Line Out only sends the signal from the preamp, so you won’t get that sweet power amp situation.

    Here, just for you, is an unofficial tip from an experienced recording engineer on how to get an unfiltered power amp signal: set the Power Soak to 1 Watt and connect the Speaker Out to the Line In of your mixer: 1 Watt is line level. But take care, if you switch to 36 watts by accident, your mixing desk won’t like that at all 😉

    Hope this helps!

Jorge Jimenez on August 14, 2014 Reply


I love this amp, i am still learning to use it, i want to ask, if i use the amp at 0 watts and i want to record in my steinberger interfase ur22(using the redbox), i have to drop down the master volume almost to zero, because if i let the master volume in 5, i can´t have a clean sound. I don´t now what happen if i use 1 watt. Is normal what happen to me?
Thanks for your help.

PD: Please excuse my bad english.

    Hughes & Kettner on August 14, 2014 Reply

    Hi Jorge,

    easy: the Ur22 XLR input is microohone level, the Red Box sends line level. Like explained in the maunal, please use an XLR to 1/4 inch jack adapter and use the line in, then the levels are correct.

    Best regards

Paul Smith on June 17, 2014 Reply

Will the GrandMeister be available in a 12″ Combo?

    Hughes & Kettner Hughes & Kettner on June 20, 2014 Reply

    Hi Paul,

    Thanks for your question. Unfortunately, there are no plans to make a GrandMeister combo at the moment. This is because the GrandMeister head and the separate TM112 cab are easier to carry than a heavier combo, and the GrandMeister is often used even without any cab anyway (with the built-in Red Box).

    Sorry about that, and all the best!

Paul Smith on May 9, 2014 Reply

This is truly an amazing product. I have one of the first TriAmps and the matching 4×12 slant cabinet, and it still has many great tones, but it is also way too much amp for most of my venues. I am hoping you have plans to offer the GrandMeister in a 12″ combo similar to the TubeMeister. The idea of a self-contained amp/speaker with the pure tube tones, onboard effects and programmable versatility of the GrandMeister makes it number one on my wish list. You guys really help the rest of us Rock!!!

Craig Rosen on April 20, 2014 Reply

I have a Boss RC-30 Loop Station that I use to record multiple tracks and a backing drum track for jamming.
Do you have any suggestions on how to hook up the looper to the Grandmeister 36 so that the looper does not take on the characteristics of the FX access from the amp? Currently, any recorded tracks become distorted and altered by the amp’s effects.

    Hughes & Kettner on April 21, 2014 Reply

    Hi Craig,

    all signals that go through the GrandMeister will have added FX if they are in use. The only way to get a signal without FX is to switch the effects off (turn levels to zero).

    Best regards

Robert Hopkins on April 18, 2014 Reply

I have loaded the iPad app and it works and was designed really well. Good stuff.

Suggestion/enhancement for live players: I really like the second line of text we can add in the preset to describe anything we want and it stores 68 characters which is usually enough to describe a songs intro and verse chords to a song. How about creating a notes window that can be turned on and left on even when presets are changed? This way, the player can have all of his notes on how to play the song right in front of him…

    Hughes & Kettner on April 20, 2014 Reply

    Hi Robert,

    thanks for the nice words and your feedback. A lead sheet managemenet will be tricky, but an extension of the text field for more characters sounds reasonable. Let’s put it on the wishlist 🙂

    Wishing you a Rocking Easter!

Neville on April 16, 2014 Reply

I think the GrandMeister 36 is incredibly versatile but is just missing a couple of things for me to purchase one…

I wish they had incorporated wifi (or preferably bluetooth) capability to utilise the iPad app… perhaps this could be introduced in a mk2 version? I would certainly be willing to pay extra for that.

Also, i’m wondering if the redbox can send a D.I. as well as a dirty tone to a DAW simultaneously…

Lastly, also wondering if it is possible to use the iPad app at the same time as ‘locking-in’ to Logic Pro X …It is my understanding they both require MIDI connection but not entirely sure on MIDI’s capabilities…perhaps both can be used using MIDI ‘thru’ ??

    Hughes & Kettner on April 17, 2014 Reply

    Hi Neville,

    thanks for your comments, makes sense 🙂 The good news: wireless MIDI is also on our wishlist, the bad news: the integration of a wireless module inside a tube amp will add significant costs, the certification for that will be a nightmare and tubes just don´t like electrical interference in their neighbourhood. But a prototype of an external interface already exists, we just cannot tell a date, just started to investigate on the options.

    The Red Box itself cannot send an unfiltered D.I. signal, but there is an “unofficial” way to get what to want: set the powersoak to 1 watt, then you can connect the speaker out to the line input of your audio interface and you have the pure signal from the poweramp.

    You can use the iPad and logic in a MIDI loop, but it is tricky to avoid a MIDI feedback. The better way is to control the GrandMeister directly with logic. The only thing to do is to assign the right controller number either in an logic environment or in the hyperdraw editor, then you can even draw an automation to control your GAIN while you play or any other control on the amp. With logic or any other sequencer, you can store the values for any control in the song.

    Hope this helps, best regards