Conrad Johnson GAT Owner Problems?

[Rayooo]

I did have a couple sets of tubes over the ages that were EXTREMELY micro phonic. a very slight tap on the case, or even the rack that that GAT was on, came through the speakers. Changing volume, one could here the relays "tingling" in the speakers. Most tubes I've had are dead quiet. The GAT's tube socket boards are isolated (as on the ET5 also) so that helps a little. All tubes have some, 'just a matter of if it causes a real problem. i.e. speaker feedback.

Originally Posted by Sunnyboy1956

Jazzhead
True but do all GAT owners experience the same microphonics?
Lloyd , our GAT owner friend from London says he gets zilch all sound when he taps on the top plate or even tube cage. Lloyd is into analog.
Curious...

[Coppy]

Originally Posted by Sunnyboy1956

Jazzhead
True but do all GAT owners experience the same microphonics?
Lloyd , our GAT owner friend from London says he gets zilch all sound when he taps on the top plate or even tube cage. Lloyd is into analog.
Curious...

My guess is that this is your first tube preamp. The tubes are a bit microphonic... not an unusual issue at all. Tubes can become microphonic with age (and shipping). Even new tubes can be somewhat microphonic and most will be noisy if you gently tap the tube itself; which you should not do. Preventing vibration from entering the sound is what those nice red rubber rings are about. Sounds like it's time to replace the tubes, a normal maintenance issue. Suggest you get a new set from c-j or one of the suggested suppliers mentioned in the forum here. In the mean time, as the Dr. says... don't tap on the chassis.

You haven't mentioned it yet but doesn't your GAT sound wonderful?

Enjoy the music.

[Joe Appierto]

Tony, welcome.

Pradeep, the microphonics could be a function of the tubes being used and also whether the O-rings are in place, or not.

[turntable]

Originally Posted by Joe Appierto

I think there are more than a couple of GAT owners on this forum. Just out of curiosity, has any one else experienced any problems?

I have had no mechanical issues.
I am less impressed with the number of hours I get on the 6922's before they become noisy and have to be replaced. A lot less than the prem16 and ART.

[Joe Appierto]

Originally Posted by turntable

I have had no mechanical issues.
I am less impressed with the number of hours I get on the 6922's before they become noisy and have to be replaced. A lot less than the prem16 and ART.

It's difficult to tell, I guess, whether the earlier tube mortality is due to the GAT itself perhaps driving the tubes hard or whether the preamp is so resolving that tube aging is more apparent.

[Sunnyboy1956]

Coppy
...."My guess is that this is your first tube preamp. The tubes are a bit microphonic... not an unusual issue at all. Tubes can become microphonic with age (and shipping). Even new tubes can be somewhat microphonic and most will be noisy if you gently tap the tube itself; which you should not do. Preventing vibration from entering the sound is what those nice red rubber rings are about. Sounds like it's time to replace the tubes, a normal maintenance issue. Suggest you get a new set from c-j or one of the suggested suppliers mentioned in the forum here. In the mean time, as the Dr. says... don't tap on the chassis..."
Sensible comments but the newbie vibe is a wee bit misplaced. Have owned tube preamps for over a decade. Had a CJ CT 5 for 6 years before the GAT. If you scroll up this thread my comments and praise of the GAT are pretty clear to anyone who cares to read.
Actually, the problem was solved by removing the tubes and reinserting them. Using a pair of NOS Seimens CCa that are IMHO superior to the CJ supplied EH 6922s.

[rlw3]

I have read that the chryo treatment of tubes may in its process releave physical tensions within the tube. Would this reduce or eliminate microphonic problems? Has anyone compared a chryo and non chryo 6922, if so what did you hear??

[Rayooo]

I compared a pair of cyro tubes to a standard working pair. no discernible difference to me, and not necessarily any better sounding..to me.

I did not however try to measure the level of micro phonics with for instance an Oscilloscope, for all I know cryo tubes could be 2db better, but I don't need another science project... just ask the cryo folks, of course cryo tubes are better.

Severely micro-phonic tubes are micro-phonic with or without the rubber bumpers. I suspect the rubber dampers make some kind of difference, but, I've yet to be able to prove this myself. Quiet tubes are quiet with or without the bumpers. Audiophile lore says you need rubber bumpers, so I've got rubber bumpers, I mean tube dampers.

I spent months chasing NOS sound via several pairs of Mullards and Telefunkens. I can safely say after months and $1000 dollars or so, it was a waste. (for me) The tubes sound great for a day, week or maybe a month, but they either get noisy, crackly or are severely micro-phonic right out of the gate.

Yes, I do very lightly tap on new tubes just to see where the fall micro-phonically. Most are dead quiet and show now sign whatsoever of micro-phonics. Some have a tiny amount. Some you could talk-into and hear your voice in the speakers. I draw the line when I lay a remote down on the top of the rack and can hear it in the speakers.

I've since installed a pair of Gold Lions, they, as the stock CJ tubes, sound good and seem to last a long time.

JMHO YMMV

[pstrisik]

I've settled on Gold Lion 6922's in my 17LS. I find them more pleasing than the stock EH's.

[audiojem]

I don't know why CJ does not put better tubes in the GAT, they use the same tube in the base ET-3 a $2500.00 unit.
I know its all about money but a cheap EH tube in a $20,000.00 pre amp come on CJ!