I have a problem......

heiney9

Typically I don't have microphonic issues with tubes, either I have been lucky or the small signal tubes I use just aren't prone to microphonics. I have had a few issues especially with the longer plate variants but they either were non-recurring or not that special or expensive a tube.

I have (4) 1959 GE 6829 3 mica, long plate tubes. (2) are 5 star black plates; (2) are "JG" military designation with gray plates. They are identical otherwise. These are industrial rated computer tubes that are very similar to the European 7062/E180CC and it's close cousin the American 6414 with the same Mu as a 5965. These are all very similar tubes.

I bought these tubes from 2 different sellers and they are NOS in original boxes and they are all microphonic. I have some older style Herbies dampers that don't quite do the job.

I need ideas, suggestions what methods and products others have used to get rid of microphonics. These are supposed to be sweet tubes, but shortly after power up they get real sensitive.





H9

heiney9

6829:
Yet another industrial tube that is very similar to the 5965. This one has a mu factor of 47 so it is slightly lower than the typical 12AT7. Those I have heard are rich, detailed, warm, and thanks to the lower mu, very quiet and low in microphonics. GE made these in their 5-star and military line so they are a rugged and long lasting tube. Like the E180CC, this tube is about a half-inch taller than the 12AT7, so you need to consider overhead chassis or cabinet space when swapping a 12AT7 with one of these. An excellent audio bargain now, but prices may soon climb as audiophiles discover them!

SCompRacer

If tube dampers and improved gear isolation don't help those tubes, the only other thing you can try is moving that piece of tube gear from between the speakers to a side wall. I have had issues with some tube gear (not my current tube gear) and turntable feedback between the speakers on the South wall setup; that is why I moved the gear to the West wall. I have no issues with any gear between the speakers on the West wall setup. And that South wall problem occurred with plenty of acoustic treatment present in corners/behind the speakers.

george daniel

The only thing that I'm aware of other than tube dampers,,is to wrap some teflon tape around the tube a few times.Good luck.

inspiredsports

I've run into very few small tubes that are microphonic in my (system located dead center between speakers) preamp, and even fewer that didn't straigten out with dampers (I use Herbie's Ti9's).

I've typically been able to work out an exchange or refund with the vendor for tubes with any hint of microphonics. I can also say that all of the trouble I've have has been with long-plate tubes.

I'm thinking the tubes you are having trouble with just may not work out in your system.

I'm curious about the teflon tape tweak and want to hear back if you try it.

heiney9

Thanks for the comments so far, but I'm also looking for user recommendations for really effective tube dampers. Should I double up on dampers? Or is a tube damper a tube damper and if the ones I currently have don't work, then none will work well?

Rich, one thing you and I have talked about is better chassis isolation. It may be time to step that up too.

H9

stuwee

Although it's tedious to do, a few wraps around each pin with teflon tape is sworn by a few of my tube buddys, whether they are microphonic or not, something about better coupling with the plate. It sure can't hurt anything and doesn't cost much, just a PITA!!

headrott

Brock, I have used Herbie's RX-9 tube dampers. They are pretty good at killing microphonics. If they are ultra sensitive, I am not sure if they wil do the job. They are the best I have found at killing microphonics though. They have the 90 day trial persiod as well. So you can send them back if they don't work for you. Just an idea. Here is the link: http://herbiesaudiolab.net/rx.htm

Greg

Dawgfish

+1 on the Herbies RX dampers. I had some 60s vintage JAN Sylvannia 6922s that were slightly microphonic in my pre and the Herbies RXs solved the issue. I have sinced replaced the tubes with both some 6922 Mullard and Amperex's that had no microphonic issues. I still run the Herbies dampers on these tubes. I have listened to them with and without the dampers and to me the tubes have smoother midrange and tighter, more controlled bass with the dampers.

dorokusai

You could try some solid brass, damper sleeves from Mapleshade or Brent Jessee. I haven't heard any difference in the types of Herbies, titanium vs teflon. That doesn't mean there isn't a sonic change since it was mentioned by two solid Polkies. I own both versions but not the sleeves and doubling up on dampers is fine. At this point you should try multiple combinations. If you need some more, I have some that I am not using.

I would not wrap anything around the pins of the tube nor suggest that to anyone. I believe that to be an awful idea and if the plates are not coupling with the tubes properly, you probably need new sockets or your pins are not in alignment.

zingo

When I've used tube dampers in the past, I used a pair for each tube placed around each spacer where it meets the glass. That technique seemed to work pretty well, but it was only on slightly microphonic tubes.

zingo

Another idea:

stuwee

dorokusai wrote: »

You could try some solid brass, damper sleeves from Mapleshade or Brent Jessee. I haven't heard any difference in the types of Herbies, titanium vs teflon. That doesn't mean there isn't a sonic change since it was mentioned by two solid Polkies. I own both versions but not the sleeves and doubling up on dampers is fine. At this point you should try multiple combinations. If you need some more, I have some that I am not using.

I would not wrap anything around the pins of the tube nor suggest that to anyone. I believe that to be an awful idea and if the plates are not coupling with the tubes properly, you probably need new sockets or your pins are not in alignment.

Well, I'd listen to Mark then, and scratch my post, I don't do it with mine, so my friends might be off in lala land on that trick, lot's of folks do crazy stuff, maybe the socket's on their older gear is shot, dunno.

dorokusai

Stuwee - I'm just going with what I know....and that method may very well work, just not my road. I've heard far crazier things when it comes to audio...just look at what's out there you know?

newrival

I've found the best solution to tube related issues is solid state :biggrin:
couldnt resist.

At any rate, Good luck!

stuwee

newrival wrote: »

I've found the best solution to tube related issues is solid state :biggrin:
couldnt resist.

At any rate, Good luck!

That was very naughty newrival...



BrawHaHaHahahaha

Ern Dog

Clean the pins with some Caig Deoxit.

Joe08867

I have heard a difference in my old setup when they were caged and not caged.

Do you have a cage for your amp?

The Teflon suggestion is something I have also heard but never tried.

heiney9

Good ideas so far. Joe, it's a pre-amp so no cage. I'll probably adopt one or more of these ideas as I move forward. I like the sleeve idea as well as the Absorb-Gel. I'll try Deoxit, but in the past I have managed to reduce hiss not microphonics. And Rich and I have discussed vibration damping of the actual components as well.

I just don;t get it, these are 3 mica, thick glass, industrial tubes that are old style well built and they are all microphonic.

H9

headrott

I have found the Caig Deoxit also only helps with hiss, but not microphonics. Those gel dampers seem pretty like a great idea, but they aren't exactly cheap and (according to the Herbie's site) don't work as well as Herbie's dampers. Granted this is put out by Herbie's themselves. But, he has a number of comparisons for you to read. Here is the link: http://herbiesaudiolab.net/compare.htm

Hope this helps.

Greg

Joe08867

what pre are you using? I don't remember.

heiney9

Dared SL2000A

http://www.polkaudio.com/forums/showpost.php?p=1598753&postcount=80

Joe08867

My suggestion would be to isolate that pre as much as you can.

heiney9

Joe08867 wrote: »

My suggestion would be to isolate that pre as much as you can.

Have any tried and true suggestions?

H9

Joe08867

I had my old Tube setup on an granite amp rack floating on spike style isolators.

I used these. They worked quite well.

http://www.vhaudio.com/isoclean-isotip-s1.html

dorokusai

The tube being microphonic is inherent to the tube, not the equipment.

heiney9

dorokusai wrote: »

The tube being microphonic is inherent to the tube, not the equipment.

I agree, but I could use some isolation recommendations as I'm sure they can help. Not looking to go crazy spending a lot of money because there are so few tubes I have issues with.

But as a secondary project I have been looking into cost effective, real working isolation tweaks, if for nothing other than the pre-amp, since there can be some improvements.

H9

dorokusai

Bright Star Audio is where I've been for years. Check out the used market as they come up on Audiogon now and then.

dkg999

If you haven't tried doubling up the tube dampers, I would do that first. One about 1/3 way up from the bottom of the glass, and one about 1/3 of the way down from the top of the glass. Sometimes tubes are just microphonic and there's no fixing it.