amperex 6922 pinched waist

AlternativeI · 1st April 2012, 05:31 PM

I came across some amperex 6922 pinched waist tubes and I have not been able to find a whole lot of info on them. I have a quad set with date codes 7L3, delta7J made in Holland white paint PQ's. Also have a pair of made in NYC 7L4, *9J white paint PQ's. I do not have access to a tube tester at this time but assuming they test well does anyone have an idea what would be an appropriate asking price for them? Anyone interested?

radiostar · 1st April 2012, 08:18 PM

I'm interested in ... any pics?

AlternativeI · 3rd April 2012, 05:19 PM

Here you go...

AlternativeI · 3rd April 2012, 05:22 PM

...

HollowState · 3rd April 2012, 06:05 PM

I may be wrong but I can't help thinking that these tubes are Amperex rejects. Rejected because of the distorted malformed glass envelope even though they may be electrically good. Were they scooped up out of the reject bin by an in plant worker? I know if I were a QC inspector for Amperex, these would have never made it to distribution. Perhaps that's why you can't find much info on them. I've spent many past years in the surplus tube business and have never come across any of these. And the branding doesn't look quite right, but it could be the bent glass.

AlternativeI · 3rd April 2012, 06:32 PM

From the info I have found the pinched waist was done on purpose to better support the internals of the tube. People say they are some of the best sounding tubes ever... If so then why they did not continue to manufacture them that way is beyond me.

Scroll to '6922', 'how they sound' and quantity/price sections:

6DJ8 Tubes From Brent Jessee Recording

Amperex 6922 Pinched Waist

Pars · 3rd April 2012, 06:37 PM

Pinched waist PQ 6922s are mentioned in Joe's Tube Lore...

HollowState · 3rd April 2012, 06:54 PM

Thanks, an interesting read. But I now wonder how much is fact and how much is subjective opinion.

SILENTSOURCE · 21st April 2012, 05:29 AM

The tubes you have should sound quite good.

You have 6 tubes. Tested and warrantied by a reputable dealer, they would probably sell for $400 to $500 a pair. Untested from an individual is somewhat of a risk.

I will trust yo that they look good and offer you $950 for the lot of 6 shipped.

You can contact me at silentsourceaudiocables@yahoo.com or (972) 757-6887.

Thanks,

Frank

DF96 · 21st April 2012, 09:58 AM

With most 'pinched waist' valves it is obvious that the pinch is deliberate because it is uniform i.e. not a manufacturing defect. I think the idea was to improve resistance to vibration by clamping the micas.

1st April 2012, 05:31 PM	#1
AlternativeI diyAudio Member Join Date: Aug 2010	amperex 6922 pinched waist I came across some amperex 6922 pinched waist tubes and I have not been able to find a whole lot of info on them. I have a quad set with date codes 7L3, delta7J made in Holland white paint PQ's. Also have a pair of made in NYC 7L4, *9J white paint PQ's. I do not have access to a tube tester at this time but assuming they test well does anyone have an idea what would be an appropriate asking price for them? Anyone interested?

1st April 2012, 08:18 PM	#2
radiostar diyAudio Member Join Date: Apr 2009	I'm interested in ... any pics? __________________ tubes.rs facebook.com/tubes.rs

3rd April 2012, 06:05 PM	#5
HollowState diyAudio Member Join Date: Aug 2006 Location: Taxland, New Jersey	I may be wrong but I can't help thinking that these tubes are Amperex rejects. Rejected because of the distorted malformed glass envelope even though they may be electrically good. Were they scooped up out of the reject bin by an in plant worker? I know if I were a QC inspector for Amperex, these would have never made it to distribution. Perhaps that's why you can't find much info on them. I've spent many past years in the surplus tube business and have never come across any of these. And the branding doesn't look quite right, but it could be the bent glass. __________________ "The supercomputer is technologically impossible. It would take all of the water that flows over Niagara Falls to cool the heat generated by the number of vacuum tubes required." ~ Professor of Electrical Engineering, New York University

3rd April 2012, 06:54 PM	#8
HollowState diyAudio Member Join Date: Aug 2006 Location: Taxland, New Jersey	Thanks, an interesting read. But I now wonder how much is fact and how much is subjective opinion. __________________ "The supercomputer is technologically impossible. It would take all of the water that flows over Niagara Falls to cool the heat generated by the number of vacuum tubes required." ~ Professor of Electrical Engineering, New York University

21st April 2012, 05:29 AM	#9
SILENTSOURCE diyAudio Member Join Date: Jun 2010	Amperex The tubes you have should sound quite good. You have 6 tubes. Tested and warrantied by a reputable dealer, they would probably sell for $400 to $500 a pair. Untested from an individual is somewhat of a risk. I will trust yo that they look good and offer you $950 for the lot of 6 shipped. You can contact me at silentsourceaudiocables@yahoo.com or (972) 757-6887. Thanks, Frank


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3rd April 2012, 06:32 PM	#6
AlternativeI diyAudio Member Join Date: Aug 2010	From the info I have found the pinched waist was done on purpose to better support the internals of the tube. People say they are some of the best sounding tubes ever... If so then why they did not continue to manufacture them that way is beyond me. Scroll to '6922', 'how they sound' and quantity/price sections: 6DJ8 Tubes From Brent Jessee Recording Amperex 6922 Pinched Waist

3rd April 2012, 06:37 PM	#7
Pars diyAudio Member Join Date: Jan 2004 Location: Chicago	Pinched waist PQ 6922s are mentioned in Joe's Tube Lore...

21st April 2012, 09:58 AM	#10
DF96 diyAudio Member Join Date: May 2007	With most 'pinched waist' valves it is obvious that the pinch is deliberate because it is uniform i.e. not a manufacturing defect. I think the idea was to improve resistance to vibration by clamping the micas.

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