H&K TM18 Vibration Noise?

NIN8185

Member
Messages
22
Hi first post here! recently my Hughes & Kettner Tubemeister 18 head has started to produce a vibrating sound that is amplified through the audio signal when playing certain notes.(Its only noticeable when a particular note is drawn out long like when tuning or playing some dark ominous open drop D bits lol so it is livable for now) Could one of my tubes or its springs be getting loose and/or old or could there be a bigger issue at hand? the amps handy TCS says the tubes are running as they should be. When I take the head off the cab the amplified vibration goes away mostly, so obviously the cab is causing the vibration but the amp is producing the unwanted noise when mounted on top. I noticed the vibration noise awhile ago but wasn't sure where it was coming from but now its gotten louder and I can defiantly tell its coming from the Tubemeister. Should I have some one tighten things up and/or replace the tubes? I have had the amp with it stock tubes for over a year now 3-6 hours of usage each week and is still under warranty but H&K doesn't have a service center finder on their page, just says a authorized H&K dealer.

Edit: In the mean time I made my self I isolation mat from some foam and a thin piece plywood I had laying around and has reduced the noise to just about nothing (Cab<foam<plywood<head), but would still would like to know what was causing the noise in the first place!

Thanks any help!
 
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DaveKS

Member
Messages
16,704
Well fact you isolate and it diminishes is good. More than likely a tube going bad, only way to know is switch out for a good set. You might be able to find which tube by lightly tapping ea. tube with pencil or chopstick and listening as you tap ea. one. If you hear a tink sound that tube is microphonic. Also internals of tube can rattle, if so it needs replaced. With the cheap Chinese glass those ship with I wouldn't be surprised if one of your tubes is going. You should have a complete set as a backup anyway. You'll probably get nice tone improvement also over those cheap tubes.

Can also just be tube needs reseating and cleaned/conditioned, arcing from vibrations can cause that type of sound. Also could be a bad solder joint rearing it ugly head.

Get you a new set tubes and a Deoxit tube survival kit. Replace 1 preamp at time, then test, then if not a improvement swap in new pair of el84 and clean up/condition ea. tube sockets as you go. This is something you should be able to handle if your even remotely handy. PM if you need more detailed info.

But be warned there are lethal voltages inside a amp. If you are in anyway uncomfortable, take it to someone who is. Fact that it under warranty would make this even a better idea. But if you are going to own a tube amp you should at least be able to replace tubes on your own. It is really a simple thing to do. Most manufactures only warranty tubes for 90 days anyway.
 

NIN8185

Member
Messages
22
I have not replaced tubes myself yet so I would be bringing it into a local shop and see if the mind if they go through it with me. Also H&K states that if you open the amp yourself it voids the amps 3 year warranty. though on Youtube someone has a guide how to open it with out voiding the warranty which i'm sure i will need to tell the gear repair man. Basically the bottom four screws need to stay in the amp when taking its top off or else it will break a warranty seal kind of like a cellphone has a water marker. Waiting for H&K to respond back to see if i can take it to the shop of my liking but don't see why not if its just a tube change. I will more then likely replace all the tubes to replace the cheap china ones but it makes sense to go through each one by one so I can get to the route of the problem.

Also will it be safe to use the amp till i can get an appointment? the TSC on the amp is still running smoothly and i've read that it will cut out the tube before the tube goes completely bad so it wont hurt the amp.

Thanks
 
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