Is the Tubemister 36 noisy through gain stages

Hello friends,
I have recently bought a tubemister 36 combo, watched great reviews and really enjoy the options available with this amp.  One came up at a great price so bought it without testing on line.

I have a couple of questions, is this amp really noisy? As in overly noisy when you add any gain... Sounding like The hum you get from a cranked gain channel with single coils,  on the crunch channel with low gain I can't go past 9 o'clock. With the lead channel almost uncontrollable.

If not and I'm guessing not, has anyone had this issue previously? How did you fix it??

I'm guessing it's the valves, there blinking 14 times when tested which I think is over the preferred.

Thanks guys/girls my first post so look forward to reading all your past posts also

Hi there Snaggs.  Congrats on your find.  A TM36 is a pretty awesome beast to own and play through.  Here is a long diatribe of advice on aspects of noise with your TM36.  Please be patient, some of it will be relevant to you.

Noisy?  Well that really can be a subjective thing.  My own GM36 is certainly not noisy - to my ears, but then I don't play high gain metal.  All guitar amps will exhibit some noise and it isn't always the amp which causes it.  The whole guitar electronic generating process is "tiny signals at very high impedances".  That is an absolute recipe for disaster noisewise.  I have known guitarists who expect their rig to be as quiet as a high quality hifi.  That's an unrealistic unachievable aim.  The best I ever expect is that the noise should not intrude while I am playing with a band.  For recording there would need to be a higher level of noise immunity than that, but there is always a limit as to what is achievable.  Then we go to noise gates, of which there is a good one on the GM!  Unfortunately I have just noticed you have a TM36 which doesn't have that feature.  The possibility does exist that you could get a noise gate pedal if this remains a problem for you.  I would consider that if you have not already.

The noise level on Clean will be very very different to the noise level on high gain Lead of course.  But you describe your problem very clearly and I would say that is not how things should be.  So what can be done?  First let's consider the info you have given.  The output valves are pretty much ok according to the TSC count of 14.  The manual, (available online for download if you don't have it), shows 14 flashes to be in the middle of the acceptable range.  Are they all matched at or very near 14?  They should be matched pairs as the outside two LEDs the same and the inside two LEDs the same.  Make sure the two valves in each of those two pairs are within four flashes of each other.  The difference between the pairs is not as important.  However, that may be interesting but being the output valves it should not cause too much of a problem with your noise situation.

Is your guitar and cable ok in other amps?  It may just be poor grounding on your guitar.  Shielding with copper sheet does nothing for hum, that's down to the Physics and can't be denied, and it improves high frequency buzz only a limited amount.  Industry spends millions trying ultra complex solutions to remove noise in its sensitive electronics but guitarists can do it with a bit of tacky copper foil?  Naaaaah, it doesn't work like that in the real world of Physics!  Check that ground leads in your guitar are clean and good.  The leads connecting the pot covers and the output socket are all good.  The output socket must be soldered cleanly and its terminals must be clean.  The wire through the body which usually connects the bridge or tailpiece to the pots is sometimes just pinched under the metalwork.  This must be clean on both surfaces to make a good contact.  A good test is to stand the guitar away from all electrical kit and yourself.  Does it hum?  Then pick it up and put it on and don't touch anything metal.  Has the hum increased?  It should!  Touch the strings and the hum should drop noticeably.  That is all normal.  You yourself reradiate noise which your body picks up when you are surrounding your guitar with your body and the guitar picks it up.  When you touch the strings the guitar grounds you and you stop radiating.  That is a sign all is well with your guitar grounds.

Really poor noise levels usually comes from the preamp valves and in particular the first input stage.  That is the ECC83/12AX7 on the right as you look into the front which should be covered by the aluminium can.  That can is important as it is there to prevent pickup in the first sensitive stage which is then amplified by every following stage in the amp.  It has by far the most effect on noise levels.  Is the can there?  If not then get one pdq.  Assuming it is then try the following.

If you have access to a spare 12AX7 which you know to be good then swap it for V1, the covered right hand valve.  Even if you don't have a spare you can swap V1 with V2, that's the covered 12AX7 on the right with the middle one.  (If you swap V1 and V2 remember to swap them back afterwards as it is better to keep valves in the slots they were originally chosen for.  Sometimes a valve can be chosen for specific characteristics such as lowest noise for an input valve or balanced action for a Phase Inverter.)  If your first valve is noisy then the noise level should drop noticeably when you swap it for a better one.  In the case of the V1 and V2 swap the noise has not gone away, it is simply not going through as many gain stages now in the V2 slot so should be quieter.

Failing that, if you don't know the history of the valves then it may just be the right time for a swap of the preamp 12AX7s anyway.  Guitarists frequently dump their oldest rattiest valves into an amp they are selling, particularly if the sale is online.  Preamp valves in well designed stages last a ridiculously long length of time but do gradually fade and need replaced someday.  Replacing preamp valves every 18 months or earlier as a matter of course is STUPID and wastes money!  It's the equivalent of changing your car's clutch every 20,000 miles just in case it is wearing.  If it 'aint broke don't fix it dummy!  They should give you many years of use as they are not stressed in any way in use.  They all work with low bias currents and signal currents which are even lower, and their anode voltages are well inside their design capabilities (in good amps).  They do not "wear out" in use.  They are killed by such things as incorrectly designed Standby circuits or by use in circuitry which was not designed for that particular valve.

Here's a handy hint from an old engineer: Swapping for 12AT7, 12AU7, 12AW7 or 12AY7 is dumb!  The whole stage design goes up the swanny and every parameter changes unpredictably, sometimes even dangerously.  There is no "family" of 12A*7 valves which are all equivalents, they are all totally different and have been designed to perform totally different jobs.  It's like saying your Porsche Boxer and your Honda Civic only differ in their top speed, just like these valves only differ to the layman's mind in their "gain" which doesn't exist as a concept for valves anyway.  The only valve to consider if you must valve roll is a 5751 which has a lower Amplification Factor, (definitely NOT the same thing as gain), but is so close in its other parameters to the 12AX7 that they actually can be considered as high and low gain equivalents.  Many valve stages are designed so the external components, the resistors and capacitors, control the stage gain and response anyway and the valves' parameter differences are actually nullified by the stage design.

The H&K Standby is special and doesn't exhibit any problems but others in some mainstream amps like some Marshalls and Fenders should not really be used, at least for extended times.  They actually kill the valves they control, usually just the output valves and maybe the PI, by cathode poisoning (Google it) if they remove the HT but leave the valve heated with no way to remove the electrons emitted.  I do not understand why just turning down the Master Volume is not acceptable, it achieves the same effect with no detriment to the valves.  No, remember, I said they don't "wear out" in normal use, as in when they are idling with no signal.  The H&K Standby works by controlling the output valves' standing current via semiconductors in the cathode circuit.  These play no part in the signal amplification.  The Standby cuts these down to a low steady current which prevents the problem of cathode poisoning.  It does leave the amp with a very low just audible signal level when played and this irritates some guitarists.  But why the heck are they trying to play the damned guitar when the amp is on Standby?

I also recommend you do not spend loads of time researching the valves which gurus reckon will give you the best tone.  In truth the whole idea that valves of the same type from different manufacturers have different tones is a laughable one and can easily be demonstrated to be incorrect despite what most guitarists insist on believing.  That concept defeats the whole electronics industry's aim of producing components to fit within the same quoted spec from all manufacturers.  They all have exactly the same frequency response through the audio spectrum and up into radio frequencies and that is flat.  When they are used outside of that design spec area, as in when they are overdriven by us, they can overload differently so the character of distortion can be a little different but this is at best a subtle thing.  It is the cork sniffers who will tell you there is a world of difference between a JJ and a Mullard NOS.  There is, but it's only the price and bragging rights!  In the years I have been on this site I can tell you there have been and still are a few valve aficionados hanging around but the vast majority of people buy simple JJs or similar, or they simply put in what they have to hand.  They then make no noise about it so stay quietly satisfied with their amps.  If you have £70 NOS types then by all means use them but please don't shout out to everyone you are getting "a couple of tantric levels above the normal" sound because your valves are old and ridiculously pricey.  The guys who work in electronics at anything like a high level laugh up their sleeves when they see stuff like that.  The guys who sell those valves piss themselves all the way to the bank.

Ok, recap.  Is your guitar and cable up to spec?  Is there a can fitted on V1?  Is it fitted properly so it is correctly earthed to the chassis?  Can you swap out V1 for a known good spare?  If not, can you swap V1 with V2 using the proper procedure for opening up the amp, (if you don't know it let me know and I'll post it here)?  Give us the answer to those questions and you may find your noise level drops to sensible levels.

Thank you for your in depth response, fantastic!

Im a little unsure how to open correctly following procedure.
Cables are good (I believe) new koltz cable. Guitars grounded I'm using Jeff beck signature and ibanez AT however I have not tried my Les Paul yet as its in my brothers studio.

Good info there. If this is the same with two different guitars that should rule them out as a cause.

The opening procedure is not essential for the safety of your amp but it does preserve the anti-tamper setup inside which allows H&K to see the amp has been opened.  That would invalidate the warranty.  Of course that might not matter in the case of an older amp but it also makes the whole process quick and easy.

Remove the top two screws from both end cheeks fully.  Remove the middle rear screw leaving the front one alone, it only holds the silver handle on.  Loosen the two bottom screws only a few turns so the end cheeks flop outwards allowing you to lift the metal lid off.  Take care to not disturb the thin LED PCB if you can, there should be clips to hold it in place, and make sure to steer clear of the cable feeding that PCB on the front right of the amp.  When you refit the top make sure you have the PCB correctly fitted and the cable back in place.

You can easily remove the valves with the top off.  Just make sure to not wiggle them too much as you pull up as the pins can bend if you go too far sideways.  There are no special procedures in handling valves other than don't eat lovely greasy fish and chips immediately before you do.  Gloves and special cleaning are not necessary at all, that's another stupid internet myth.  It helps to keep them clean but solvent spotless is rank overkill and tap dancing around not touching them with your fingers is ridiculous.  They have been handled by everyone who uses them since the 1930s without any problems.  They are not the same as halogen bulbs for your car which must not be touched at all, they are just plain glass envelopes with printing on them.  You can also safely run the amp with the top off for short periods of time.  There is no need to refit the top to test after every change.

Give the valve swaps a go if you can, that is a skill every guitarist who plays through valve gear should have.  One last thing.  If you replace your valves don't ditch the old ones.  Put them in the boxes your new valves came in and LABEL THE BOXES!  Write on what date you swapped them out and maybe which slot they were in.  That will let you know when you build up a couple of spares which may be the better one without spending hours plugging them in one by one and trying to compare, (which can't be done accurately if you have to switch off and on and warm up each time).

One other tip I can give.  The hardest working most highly stressed valve in your amp and in many others with this type of design is the Direct Coupled Cathode Follower.  This is often used as a driver for the tonestack and usually comes last in line in the preamp and just before the loop and PI valve.  The design of that DCCF stage means the valve is put under enormous over voltage at switch on until the valves warm up and start to conduct current.  If any valve is going to age early it will be that one.  I've experienced this in my Marshalls as they also use DCCF stages and they do start to sound a little grainy when the DCCF valve goes bad.  That means in your case with a TM36 V2 might be the valve which needs replaced a little more frequently than V1.  It is often claimed that Chinese valves take that stress better than others seem to.  I have used a Chinese valve in that slot without any change to the sound at all.  The DCCF circuit has a gain of just under 1x, it's a "follower" not an amplifier, so the valve's "gain" isn't really a feature for this stage and it doesn't get overdriven in the standard gain stage way at all in use so the differences in valve makes make no difference to it.

If you are really fussy you can specify extra testing from some sellers for a pound or two more.  V1 can be a "selected for low noise" type.  V2 can be a standard Chinese type for hardiness as the DCCF.  V3 can be a "balanced" type for the PI.  Worth thinking about.  Other than that it's up an' at 'em!

Again fantastic in depth reply!
Thank you for your time explaining.

I will hopefully be home at a reasonable time this evening to try the above... If not it will be tomorrow i get the time to follow your response, I will keep you updated on findings so you can possibly advise further.

I have looked on line at replacement valves, I had missed the 13:00 cut off for Saturday delivery other wise I might have just gone for full replacement so I knew exactly the age and use of the valves.

So I was able to test new valves in the amp, there is a 1000% difference V1 is the culprit massive releaf that it's the valves causing the problem and not a faulty amp.

I have noticed this doesn't seem like any amp I have used previously while dialing in my clean, crunch and lead tones. I like to clean my tone using my volume pots (Jeff beck style) so clean on edge of break with volume pot dimed, crunch that cleans up, and a lead that sings but not metal is what I'm now searching for

Haha!  Great news Snaggs.  Glad it's up and running and it was such a simple problem to fix.  Please don't get paranoid about the valves in there after this.  With new ones as you have put in you can expect to get years of use without needing to swap them out again.  The output valves may need renewing a little sooner but remember, preamp valves are under no stress in use under any sort of drive in our amps.  Overdrive in our sense is not abusing the valves in any way. In guitar overdrive either, the valve has run out of voltage and is close to having 0V across it with a normal level standing current well within its limits or, it has the full HT line voltage across it but no current at all.  The DCCF I talked about IS stressed but only at switch on for the time it takes for the valves to warm up and start conducting current.  There is nothing you can do about that without getting a soldering iron and modding to fit a couple of additional components and you don't want to do that.

The gain structure of the H&K amps is very much more variable and controllable than the general type.  I really recommend you have a read of posts like this one I put up to get people used to the idea. Understanding and using the H&K Input Buffer  It's for the GM36 really but the GM40D and the TM36 will both be similar, the TM18 certainly is and the 36 will just follow the family line there.  Your TM is simpler than the GM series but it seems basically similar in its basic audio design so the info there should help in setting up the amp and extracting the tones you want.  If you can get your head around this and trust the info there long enough to genuinely try it, it will make your search for your own tones a much easier one.  By the way, I'm absolutely with you in your preference for the way you set you levels.  That tonal approach seems very like my own idea of what I want from an amp.  The last thing I ever do is to dime any amp and then search for a way to make it sound rich and responsive with the amp rasping out a desperate croak for mercy.  That's not good amp management in my book.

Now you have the amp performing correctly, make sure to consider the difference that speaker choices will make.  That is a very significant factor which you can tweak to your hearts content to real advantage.  These amps seem to be very sensitive to speaker types.  They don't take any notice of things like "Such and such speakers are always a bit mellow and laid back".  I have always found that they really have their own way of interacting with speakers so try try try any that you can if your current ones sound a bit hard or toppy.  That is much more useful than fiddling with different valves as I said above.  The H&K upper sharpness is a common complaint in all of this class of their amps so don't be surprised if you experience that and need to tame it a little.

Incidentally, here is a link to another info post I made for those who took on board the DCCF startup issue.  A Mod: Direct Coupled Cathode Follower, fix to prevent switch on stress.

(And this is easiest to implement on a TM36 believe it or not. )

Again thank you for your extensive knowledge, you sir are a tonal wizard!

I have read you linked post and have tried to absorb the information it contains, it sounds as if my preference on how I like to play my amps is really beneficial to this kind of circuitry.
I truly hope I can find that Jeff beck kind of sound through my volume pot, I had tried his preferred amps to no avail. As he is constantly manipulating his volume and tone pots.

Thank you so much for all your help out of curiosity how do you set up your amp on clean, crunch & lead
I understand if you don't want to share, but thought it might be a good starting point

Hahaha!  You do me too much credit.  There are many on the internet who insist I know nothing about REAL tone as I am just an engineer.  I put my trust in things I can measure and which comply with the laws of Physics.  Most guitar internet "common knowledge" does not!  My ears then tell me if I like it or not but they certainly don't give any reliable indication of anything technical, they are too easily fooled.

Your own TM36 has a different channel structure to my GM36 with separate Gain and Volume controls for each of the channels.  My amp uses the digital control setup and they share Gain and Volume controls with each setting remembered for that channel when selected and with a separate common Master Volume to set overall level.  The process should be very similar though if we ignore the digipot side of things. For myself, I use a GM36 to play only classic pre-high gain rock, 60s/70s/early 80s, (the real rock stuff   ).  I found early on I never use the Ultra channel, it is too hard sounding for me, though any channel can be a useful voice with its gain dropped right down as they are all voiced differently.  Nor do I feel any need for the H&K Boost function.  It also alters the channel voicing slightly when it is applied.

Anyway, I limit myself to the Clean, Crunch and Lead channels with no internal amp Boost under normal circumstances.  The Boost function increases the gain and adjusts tonal balance slightly in a few of the stages and I prefer not to change things inside the amp's circuitry.  I use no external pedals other than an absolutely clean Boost of my own design to simply lift the input signal a touch on a couple of occasions when needed.  That allows me to use the GM36's own effects (rarely) and to hit the Tubescreamer type input stage of the amp itself a little harder just to give an edge.  The extremely varied range of distortion sounds (so they say) from the thousands of boutique (= overpriced) pedals out there does nothing for me.  The character of a clipped diode type or a clipping solid state stage type is pretty much the same and the filtering which does give some pedals a bit of their own character is usually lost in the sound of a full band playing on stage.  That H&K input stage is a really good piece of design when the guitarist learns how to use it and it is exactly what I've seen inside s huge number of overdrive distortion pedals selling for silly amounts. It is capable of giving a very usable overdrive sound once you get to grips with it.  Very few owners ever do!  I work to find and use a good general live sound, I'm not a bedroom aficionado or a recording tone junkie.

Other than that the way I approach it is to keep as much of the overdrive in the valve stages themselves, power amp included.  The Power Soak comes into this of course and you should adjust that to give you the tone contribution you want from the power amp.  Set it on as low a value as you can to get more output valve distortion, i.e. the power amp is driven harder because the PS is wasting some of the output power, or set it on a higher level to get lower output stage distortion.

Set up the Clean channel first starting with its Gain to get its basic character and adjusting the guitar volume to introduce some input buffer distortion if you need that.  You will need to play one off against the other until it sounds best to your ears.  Then adjust the Clean Volume to as high as required in order to get the level of this lowest gain channel up as you want.  It is easier to turn down the higher gain channels accurately to match a high volume Clean than a low volume Clean where all of the Volume controls will be working over a very restricted range at their lower ends.  This way the Clean channel is my reference.

Then each of the other channels can be dialled in in the same way finishing with their Volume controls to set their overall level to balance the Clean as you prefer.  This is a starting point for me.  I can then select any channel and use the guitar volume to tweak the amount of overdrive/distortion I achieve.  If you get this right there is actually less difference between the volume of a nice crunch level and a harder driven lead level in the same channel when you touch nothing but the guitar volume.

Fantastic information yet again!

There is to much mythology used within the search of the perfect tone! I came up against its in there fingers many times, however if I hit a open note I would expect a very close sound to whoevers tone I'm trying to recreate.... But artist A will always sound like artist A because of his rhythmic feel and phrasing yet the underlying tone will change with the changes in their gear. Ie beck going from the Rat to clon to an archer pedal, but he still sounds like beck in his playing where his tone for me has become more refined.

I used to be that player who always had my guitar at 10, until my love for beck and Andy timmons grew so set my guitar and amp with my volume rolled way down adding gain through the volume pot allows so much more control.

This was ever present with my keely mod blues driver, a friend plugged in to try my new pedal and cranked his guitar the sound that came out he looked at me with disgust and commented glad I didn't waste my money on one of them.... "roll your volume down to 3-4" and there it was the beautiful tone heard in electric gypsy.

On setting this amp I think I need to sit with it and really learn the character. And this added TS style boost at the front end.
I usually have a TS 9 on my board drive around 3 and then the volume cranked up to 8 for the SRV kind of sound.