Tubemeister 18 combo weird sound on the overdrive channels

Bought a Tubemeister 18 1x12 combo. Enjoying the cleans of this amp. However, I get this weird "low feedbackish" sound (even without any guitars hooked up) on the overdrive channels at high volumes. It's really annoying so I keep my levels down. Anyone have this issue?

Are you using 4CM (4 cable method)? That can cause ground loops - and high gain howling/filtering is one of the more unusual symptoms.

Also, one of the cheap Chinese preamp 12AX7 could be microphonic. Microphonic tubes are susceptible to vibration - which is more likely in a combo. 12AX7 are cheap online, or you could by one locally and play musical chairs with it in V1-V3 in your amp until you find the problem.

Ughh, I just noticed the date on this post - hope you figured it out already...

namklak wrote:Are you using 4CM (4 cable method)?  That can cause ground loops - and high gain howling/filtering is one of the more unusual symptoms.

Also, one of the cheap Chinese preamp 12AX7 could be microphonic.  Microphonic tubes are susceptible to vibration - which is more likely in a combo.  12AX7 are cheap online, or you could by one locally and play musical chairs with it in V1-V3 in your amp until you find the problem.

Ughh, I just noticed the date on this post - hope you figured it out already...

no 4 cable method. the feedback sound is created even without anything hooked up to the amp.

any videos or directions to change out the 12ax7 tubes? not too happy with this since my amp is less than 9mos. I don't feel like sending this to service.

I'm having the same problem. Nothing plugged in and the amp produces this terrible humming breathy sound. I actually contacted Hughes and kettner and they had me send the amp to yorkville to be looked at and they sent it back saying there was nothing wrong with it. I sent it again and again they said there is nothing wrong with it. I would be interested in sharing contact info and maybe send a couple videos back and forth to see if you are having the exact same issue. It sucks because the sound would be top notch if it wasn't doing this.

Im planning to trade in my hughes at my music store for a marshall. this is bs

I also dont like that I have to use the overdrive channel for working with over drive and distortion pedals. Not impressed.

This is not a reported problem by anyone that I have come across.  Mind you, all high gain amps have issues with noise and microphony at very high gain levels.  It's the nature of the job and they deal with it as best they can.

legacygt777 wrote:I also don't like that I have to use the overdrive channel for working with over drive and distortion pedals.

Not sure what you mean by this Legacy.  Can you explain a bit more? All of the channels should accept pedal work.

Are you saying you are using distortion pedals with the amp on Lead and set with ultra high gain?  If so that's a bit of a square wave generator isn't it?  

JimmyAnthony or Legacy, the idea of posting a couple of short clips of this sound would be useful if you could. If you could also give an idea of the amp settings when it is happening it would also give us some info to consider.

bordonbert wrote:This is not a reported problem by anyone that I have come across.  Mind you, all high gain amps have issues with noise and microphony at very high gain levels.  It's the nature of the job and they deal with it as best they can.

legacygt777 wrote:I also don't like that I have to use the overdrive channel for working with over drive and distortion pedals.

Not sure what you mean by this Legacy.  Can you explain a bit more?  All of the channels should accept pedal work.

Are you saying you are using distortion pedals with the amp on Lead and set with ultra high gain?  If so that's a bit of a square wave generator isn't it?  

When using an overdrive or distortion pedal in the clean channel, it sounds very fuzzy and lacks any warmth in tone. To solve most of this problem, you have use a bit of gain on the overdrive channels with the pedals.

bordonbert wrote:JimmyAnthony or Legacy, the idea of posting a couple of short clips of this sound would be useful if you could.  If you could also give an idea of the amp settings when it is happening it would also give us some info to consider.

At everything dialed in about the middle on the overdrive/lead channels, there is a feedback type sound. It gets worse when you increase the volume. You can even have this issue without hooking up a guitar.

This is not an issue with the clean channel.


I'm not impressed with this amp. I'll try and upload some of the sounds.

The most likely problem is the one suggested by Namklak, a microphonic valve.  Try to swap over the two preamp valves and see if the problem changes in nature.  It may not go away with this test but it should change significantly as the noisy valve is put into a different role.

It is a piece of cake to access the valves in the TM18 head and in all honesty that is the only situation I have any experience of.  Someone else must be able to help with this question of the combo. Guys?

Has the amp done this as long as you have had it?  Did it do this when you tried it out before you bought it or has it just started to do it?  You state that it is only 9 months old but if you have just got it you have no real idea of how it was treated before you bought it.  There may have been a reason the guy before you sold it and that may be he has worn out or damaged the valves and can't diagnose it. Those valves may have had a really hard time and been bumped around a lot, particularly in a combo rather than a little light head which is in its padded carry case.  Valves are not cast iron, they are quite delicate inside.  For a valve to go microphonic may just be a sign of regular heavy handling.

Re your pedal problem.  Are you aware that the TM18 actually has a solid state buffer built into its input to lift the signal to a working level for the valve stages?  This is set up to prevent serious input overload (3.3Vish peak) and to act as a pseudo Tube Screamer type distortion pedal in its own right.  It is quite sensitive to the level you put into it, in a good way, it has sensitivity.  Dial back a little on your guitar volume and the buffer is absolutely clean and featureless, (no, despite what "they" will tell you you can't hear any signs of a well designed clean buffer. That's the definition of 'clean'.)  Turn your high output shredding pups up, or first put them through anything like a clean boost (or another distortion pedal with gain) and things change.  The buffer gets driven into distortion mode and gives you first assymetric clipping then, when driven even higher, double sided clipping.

By all means use a pedal in front of it but make sure you have the pedal gain up to get your distortion as you want it to sound, but its output level down so as to not kick in the TM's own TS distortion otherwise you are effectively running two distortion pedals in series.  Would you do that with discrete pedals?  This is before the 'Lead Gain' control so that can always be used to get back any volume you are frightened of losing by throttling back before the amp. The Clean channel is much simpler in its layout and is not really there to be used for distortion tones. The Clean chimey clean tones are usually considered one of the amps best features. I would seriously consider why yu want to distort the Clean channel, just use the Lead channel and play with lower settings of the pedal output and the amp Gain control. It's just a learning curve.

This is a quite sophisticated amp unlike most of its competitors.  It deliberately has a number of variables which you can play off against each other to get a wide range of sounds.  You either have to accept that and figure it out a little or decide now that you just don't like it and step off the ride.  I suspect that with an open mind, a little understanding and experience it will give a lot more than you are hearing at the moment.  We see a lot of people here who just turn it on, whack up the Gain control, whack up the guitar volume, kick in their favourite boutique 'two-diode' pedal with maximum drive and output and wonder why it doesn't sound like Satriani.  If only it were that simple.  

[quote="bordonbert"]

"Has the amp done this as long as you have had it?  Did it do this when you tried it out before you bought it or has it just started to do it?  You state that it is only 9 months old but if you have just got it you have no real idea of how it was treated before you bought it."

I bought it new online. It's always had this issue. I've learned to deal with this problem. When I'm playing a show, the "sound" gets drowned out. When I'm not playing, I'll switch to the clean channel. Apparently I'm not the only that has this issue.


"Are you aware that the TM18 actually has a solid state buffer built into its input to lift the signal to a working level for the valve stages?"
I'm aware of this setup. But I've owned some solid state amps before and have been able to work through it.



"By all means use a pedal in front of it but make sure you have the pedal gain up to get your distortion as you want it to sound, but its output level down so as to not kick in the TM's own TS distortion otherwise you are effectively running two distortion pedals in series.  Would you do that with discrete pedals?  This is before the 'Lead Gain' control so that can always be used to get back any volume you are frightened of losing by throttling back before the amp.  The Clean channel is much simpler in its layout and is not really there to be used for distortion tones.  The Clean chimey clean tones are usually considered one of the amps best features.  I would seriously consider why yu want to distort the Clean channel, just use the Lead channel and play with lower settings of the pedal output and the amp Gain control.  It's just a learning curve."

There are a lot of amps I've own that have great sounds that you can distort the clean channel. I also have a lot of experience with different amps that also have a learning curve. I don't have an issue with my sound for cleans, although it's a bit bright that I have to tame. I don't have an issue with distortion pedals and my overdrive on the dirty channel either, although I'm able to get a warmer tone on my marshalls. But I didn't know that I had to only use the dirty channel to get the warm distorted sound i'm looking for. THat's extra pedal pressing on a complex rig I run which (I wasn't aware that I couldn't use the clean channel).


"This is a quite sophisticated amp unlike most of its competitors.  It deliberately has a number of variables which you can play off against each other to get a wide range of sounds.  You either have to accept that and figure it out a little or decide now that you just don't like it and step off the ride.  I suspect that with an open mind, a little understanding and experience it will give a lot more than you are hearing at the moment.  We see a lot of people here who just turn it on, whack up the Gain control, whack up the guitar volume, kick in their favourite boutique 'two-diode' pedal with maximum drive and output and wonder why it doesn't sound like Satriani.  If only it were that simple.  "

I'm not an amp tech pro. But I now how to setup a rig and maximize the potentiality of an amp with my guitars. I've spent many hours on the HK combo and have read and studied this forum and other online and youtube sources. My main big amps, are the JCM2000 TSL, DSL's and TWIN. The TSL is actually more difficult to dial in than the Hughes. I appreciate your feedback.

I have a video ready on YouTube. But the forum is telling me I can't post an external link for seven days. So I will post as soon as I can. Unless anyone knows a way I can post before then.

Jimmyanthony60 wrote:I have a video ready on YouTube. But the forum is telling me I can't post an external link for seven days. So I will post as soon as I can.  Unless anyone knows a way I can post before then.

I opened the amp and changed the preamp tubes (12ax7?).  It's still making that feedback microphonic sounds.  Can the poweramps be the issue and be causing the noise?

So I completely changed both the power and preamp tubes and everything is good.

I'm still debating to trade this amp. I tried out the bassbreaker by fender today. that amp has killer tone. I'm thinking of changing the HK speaker to a more fenderish tone like a Jensen speaker. For now, it sounds really good.

My gut feeling is that it isn't a power amp problem. Without hearing the sound you are both talking about it is very difficult to give you any better advice. You describe it as a "feedback" type of sound and that is "hummy and breathy" but that could mean quite a lot of things and that sort of description is always subjective. What you would describe as feedbacky may sound like hum to someone else.

Is there any way that either of you can post a soundclip on Dropbox or something similar and just give us a link to it in a post? I would just put your link with some sort of edits in it to make it plain text and then tell us what the edit is if necessary so we can convert back to a legitimate link. For example "www dot google dot com".

youtu [dot] be [slash] 84LWuAEySvU

Here is the link to my video. Replace the dot and slash.

This is on 18 watts but it does it on all settings except for direct. If you have any insight on this I'd really appreciate it because I love the amp. It's just not usable this way.

Thanks.

For anyone else the vid is here: TM18 Combo Fault Sound

I have to say Jimmy that that seems very much as though something is faulty. I've never heard one do anything remotely like that. Mind you, running it with the Gain full up is a bit extreme and all amps will be noisy under those settings but it shouldn't do that. It sounds like something mechanical and my money would have been on a microphonic valve in the first instance but you've replaced them all I believe.

What does the TSC show on the back panel? Are the LEDs lit or extinguished both in normal use and when this is happening? And what does it show when you fit a plectrum in the slot and give it a push?

We can see in the vid that you have other amps available so try the following. Take the H&K 'Effects Send' out into the 'Effects Return' of another amp. That will tell you whether it is isolated in the H&K preamp or not. If that stops it from happening then do the same in reverse, the other amp's 'Effects Send' into the H&K 'Effects Return'. A really good test would be to use the internal amp with only a remote speaker cabinet. I don't know whether the TM18 Combo has that facility. If it does then try that too.

I would also say that if you can you should try the Redbox out into something where you can hear the signal, even just a pair of phones. This is a straight takeoff of the output signal to the speaker/power soak, but it could also be used with the amp on silent to see whether it is definitely a vibrational issue or not.

Next, do any of the other controls affect it in any way? In particular the tone controls may change the character of the sound. Does that happen? It would seem to be obvious but does the Boost switch make it worse?

Try getting it to do this then very slowly turn down the Gain. Does it gradually become quieter or is there a point when it suddenly collapses and stops doing it completely? And does it start again once you go just above this point or do you need to turn the Gain up near full to start it again?

Now these are all questions that could help if we had clear answers so please do all of those simple tests and describe what you find clearly. You have no idea how many times we give advice here and we just get a hash of random badly worded info which doesn't actually answer any of the questions we asked.

If it were me there are a couple of things I would do. First I would go to the H&K Facebook page and ask there posting the link to your video so they can actually have a listen. Just do a Facebook search for "Hughes & Kettner" and choose the one which shows up with "Products/Service" underneath. I would also take it back to the supplier and insist on demonstrating this to them then and there in the shop, I would NOT just leave it with them to investigate. If you can do it in front of other customers then that's even better! They are then under pressure to show themselves as being supportive of you or risk losing new sales.

Give us the answers to the questions above and we'll see if that helps.

So the TSC LEDs are extinguished in normal use and when this is happening.  When I fit a pick in the slot, both LEDs flash.

We can see in the vid that you have other amps available so try the following. Take the H&K 'Effects Send' out into the 'Effects Return' of another amp. That will tell you whether it is isolated in the H&K preamp or not. If that stops it from happening then do the same in reverse, the other amp's 'Effects Send' into the H&K 'Effects Return'. A really good test would be to use the internal amp with only a remote speaker cabinet. I don't know whether the TM18 Combo has that facility. If it does then try that too.

With the H&K effects send out into the effects return on my Jet City JCA2212C, I plugged into the H&K and it seems to be a clean signal on the JCA while the H&K remained producing the strange sound.  The guitar signal is there, but the weird noise overpowers it.  The other way around with the effects send on the JCA into the effects return on the H&K, guitar plugged into the JCA, clean signal on the JCA, the signal is sent to the H&K and I can hear it, but the weird sound is there right alongside it.



The Rebox is interesting.  I ran the redbox out into my presonus audio interface and recorded tracks with all 4 power soak settings.  The only time I get a clean signal is when the power soak is all the way down (speaker off).  And the noise is louder on 18 than 5 and 5 is louder than 1.



The controls seem to have no effect on the sound.  Bass, mid, treble do nothing.  Gain all the way up, or gain all the way down the sound is the same.  Volume as well.  It's almost like its there no matter what you change.  Once it "warms up", its there at the same volume.  And I say "warm up" just because it takes a couple of minutes to reach its peak annoyingness.

I'm going to post the video on Facebook and I may take it to guitar center when I can get up there and see if they can help me.  When I originally took it there, they were not very helpful and told me to contact H&K.  And like I said before H&K had me send it out to Yorkville and they sent it back saying nothing was wrong with it and I got discouraged and sick of sending it back and forth, so sadly it sat for a while.  But now i would love to be able to use it properly.  It think they probably ran some diagnostics and they come back ok, but you can't deny that there is something wrong.  I'm even willing to pay to have it be at 100 percent.

Thank you for your time, and if you need any clarification on anything please let me know.

Excellent work JA!  Good tests and good result reporting.  There is info there that is very interesting.

The TSC leds are all as normal so there would appear to be nothing wrong with the output valves in the sense of their bias setting.

The clean signal on your JC tells us that the problem is not in the preamp.  The signal after that is giving you a clean problem free sound with a different power amp hence it is working as it should.  In reverse the clean signal from the JC is being crocked by the power amp of the H&K.  The fact that none of the controls in the preamp have any effect on the noise is also an indicator that the preamp is problem free.  It seems the problem is after the effects loop in the power amp section.

The Redbox tests seem to show that there is also a power level related part to this issue.  My first instinct as I read your results was that it was beginning to point to the output transformer as a mechanical type of sound from a partially mechanical component, but with the noise changing in that way as you change the power soak setting it is odd.  The Tx remains loaded to the same extent no matter what the setting is so the character of the sound should be roughly the same.  Mind you, with lower powers the Tx loading has less speaker reactive elements, (the power soak resistors become more significant), which is always easier for it to handle.  It seems odd but it is almost as though the less the speaker is involved in the transaction the less you have the problem.

The combo has a speaker out socket on the back which means it is an easy thing to check.  Do you have an alternative speaker so you can test the whole H&K setup right up to the output?  Anything from 8-16ohms will be fine and it doesn't have to be a single 10" either of course, asny type will tell you what you need to know.

If you look back you will see that at the start of this thread Namklak recommended testing for microphonic valves.  That's a real hot possibility for this sort of problem.  I had assumed that you had replaced yours to check it out and it had made no difference. Now that I've done a review of the posts I can see you haven't of course, it was Legacy777 who had ruled out all of his his valves.  Do you have a different pair of EL84s which you could put in there to try this?  You could maybe even borrow them from another amp just for the test.  That is another definite thing you could rule out.

I would also try this, change the two 12AX7s around and do the test with the JC out into the TM in again. That would rule out the 12AX7 acting as the power amp phase splitter from the problem.

bordonbert wrote:Excellent work JA!  Good tests and good result reporting.  There is info there that is very interesting.

The TSC leds are all as normal so there would appear to be nothing wrong with the output valves in the sense of their bias setting.

The clean signal on your JC tells us that the problem is not in the preamp.  The signal after that is giving you a clean problem free sound with a different power amp hence it is working as it should.  In reverse the clean signal from the JC is being crocked by the power amp of the H&K.  The fact that none of the controls in the preamp have any effect on the noise is also an indicator that the preamp is problem free.  It seems the problem is after the effects loop in the power amp section.

The Redbox tests seem to show that there is also a power level related part to this issue.  My first instinct as I read your results was that it was beginning to point to the output transformer as a mechanical type of sound from a partially mechanical component, but with the noise changing in that way as you change the power soak setting it is odd.  The Tx remains loaded to the same extent no matter what the setting is so the character of the sound should be roughly the same.  Mind you, with lower powers the Tx loading has less speaker reactive elements, (the power soak resistors become more significant), which is always easier for it to handle.  It seems odd but it is almost as though the less the speaker is involved in the transaction the less you have the problem.

The combo has a speaker out socket on the back which means it is an easy thing to check.  Do you have an alternative speaker so you can test the whole H&K setup right up to the output?  Anything from 8-16ohms will be fine and it doesn't have to be a single 10" either of course, asny type will tell you what you need to know.

If you look back you will see that at the start of this thread Namklak recommended testing for microphonic valves.  That's a real hot possibility for this sort of problem.  I had assumed that you had replaced yours to check it out and it had made no difference. Now that I've done a review of the posts I can see you haven't of course, it was Legacy777 who had ruled out all of his his valves.  Do you have a different pair of EL84s which you could put in there to try this?  You could maybe even borrow them from another amp just for the test.  That is another definite thing you could rule out.

I would also try this, change the two 12AX7s around and do the test with the JC out into the TM in again.  That would rule out the 12AX7 acting as the power amp phase splitter from the problem.

My issues with feedback are now gone replacing all my tubes (both power and preamp).

I was still not exactly happy with the sound. I'll be honest, I bought this amp with only youtube for reference. You can't really find these amps at stores to test out.

Anyway, I replaced the stock speaker with a Warehouse Speaker and the amp sounds so much better. Much warmer cleans and dirty sounds and having a different character. The stock form of this amp is not my taste at all. Too much brightness on the cleans and too much fuzzy or buzz metal on the dirty channels for me. It also lacks some overall creamy tone sounds.


If you play this stock vs a marshall dsl15, bluesbreaker or ac15, it doesn't sound as good. But changing all the tubes and speaker has given this amp some character and warmth so I'm going to keep it. THe mods also make this amp not so hot so you can get more speaker breakage and dynamics.

In my amp, it came with some cheap generic chinese stock tubes. I suggest to everyone on here to change them.

I like this amp now.

Good news Legacy. Glad it's sorted it.

Yes, like you I'm not a fan of buying things based on YT vids, they never give you a true picture. What you seem to have found is exactly what most of us older members here have found, this amp is not suited to classic rock sounds, it's too high gain. We are getting a lot more members now who are using it for modern metal and who reckon it sounds great for that type of material. I'm sure it does, I wouldn't really know. One thing I do notice with the YT vids is how all of the reviews simply show you a clean twinkly sound with a bit of fingerpicking which the H&Ks do really well, then they launch off into high gain head rocking tub thumping metal sounds. No one can show you how these amps can play Free/Bad Company/Thin Lizzy/Humble Pie genre. The answer has to be, as far as I am concerned, they can't!

Changing the valves will have a subtle effect on the overall sound, it's never anywhere near the "ground breaking life changing improvement which lifts a poor amp to the realms of a top flight boutique model" as most people seem to want to hear. Don't be conned, the effects are subtle! An interesting test would be to swap the valves back to the originals one by one, trying to locate and eliminate the microphonic one, and see how you think the sound changes now you have your improved speaker choice in place. Changing two aspects together is not a test of either of them individually. This is something people do alll the time. They change their valves for some overpriced pieces of cold war junk and their speakers for something they know and claim that both changes are magnificent upgrades. How can you possible know that? You can't say whether either makes any real difference or how the factors are shared between them. Try the new valves with the original speaker if you can. I'm sure there will be some improvement in the top end fizziness, we all noticed that, but there is not that much difference in the underlying character of the sound. There is a great really long thread on valves swapping in the GM36 forum which applies to the TM as well. (Look in there for advice on NOT using 12AT7/12AU7/12AY7 alternatives, they aren't. They alter too many other factors than stage gain which is what people are usually trying to reduce. Look for the 5751 which is much closer to the original 12AX7/ECC83 valve and really works in my experience.)

Speakers however are a different beast. If you want to trim your sound my honest advice based on what I've had to do with my TM36 and GM36 is to work on the speaker choice. That can make a huge difference. Going from V12s (which many people love - metal?) to G12M Greenbacks was a huyge improvement.

bordonbert wrote:Good news Legacy.  Glad it's sorted it.

 An interesting test would be to swap the valves back to the originals one by one, trying to locate and eliminate the microphonic one, and see how you think the sound changes now you have your improved speaker choice in place.  Changing two aspects together is not a test of either of them individually.  This is something people do alll the time.  They change their valves for some overpriced pieces of cold war junk and their speakers for something they know  and claim that both changes are magnificent upgrades.  How can you possible know that?  You can't say whether either makes any real difference or how the factors are shared between them.  Try the new valves with the original speaker if you can.  

I tried using the original tubes and compared them with the stock speaker to new tubes. The new preamp tubes did make a difference but it wasn't drastic. When I changed the power tubes, I was getting better breakup with the speaker and solved my microphonic issue. But still the overall sound wasn't that drastic. But changing the speaker and tubes totally changed the amp into a different beast. Thanks.

So I finally got back to working on this issue. The first thing I decided to do was just go get 4 new tubes and start there. Instead of replacing them all at the same time I first only replaced the preamp tubes. That did nothing in terms of the crazy motor sound the amp was producing. So then I opened it back up and replaced the EL84s and that seems to have done the trick. I gave it a couple of days before i posted the results to make sure I wasn't jumping the gun. I fired it up for 5 consecutive days and played for different amounts of time on different channels, settings, volumes, and power soak settings and it hasn't gone back to making the crazy noise since the power tube replacement.

So for now I'm pretty happy. I bought the amp for the modern high gain so from my perspective the sound is killer.

Thank you bordonbert for all of the help and insight!

It was actually Namklak who was the first to point you at the valves Jimmy, he's a pretty switched on type from a sound engineering background like me so any advice from him will be worth listening to. I would have bet it was the power section. And well done for changing them in stages to check that out, not too many people see the point of doing that but now you know you have a usable set of spare preamp valves.

And for high gain stuff you couldn't have a better amp. Enjoy!!!