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Atma-sphere amps best power tubes

This question has been debated before on A-gon but without a clear onclusion. I wonder, is it worth it, to upgrade from stock Russian or China output tubes (6as7g), to American NOS tubes?

It seems that everyone agrees that upgrading the Atma-sphere driver tubes from stock Russian/Chinese to NOS is well worth it. This is my experience also.

I am wondering about changing the output / power tubes too. I wonder if a change to NOS is well worth it also in the output case.

It seems likely, judging from my other equipment testing.

My Audiotailor Jade OTL headphone amp uses 1 6asg7 and 1 12ax7. No surprise - it sounds better with a good NOS 12ax7 compared to Russian/Chinese stock 12ax7.

More surprisingly, it also sounds clearly better with a NOS 6as7g output tube (General Electric US NOS). The improvement is largest with the driver tube but not so much behind with the output tube. Almost 50 50.

A lot of output tubes are involved - 28 tubes in my MA-1 amps. Changing them all is costly, and so I would like to know some user experience before I go into this.
o_holter

Showing 7 responses by mechans

mechans
3,048 posts
 
How many good roughly matched 6AS7G US made or other NOS tubes can you assemble. I also have a headphone amp which uses the 6080/6AS7G/421A etc. tubes. I can't recall having a large number of special 6AS7gs offered for sale. You can of course find different Soviet era tubes.
I am curious as to why you thought changing the output tube would nothave a big impact on the sound. I have been on a crusade telling any who care to use tube power amps.
My main system didn't have it's magic sound after years of switching and tweaking, until I switched to tube monoblocs.
mechans
3,048 posts
 
Well it's ten days later, has the perceived lack of overall volume and slam come back? Curious myself because I have a headphone amp that can use 6AS7Gs . Right now I am happiest with 5998s in there (so called "Domino" plates). I have use 6080s and preferred the RCAs. I had some 6AS7G variants but no RCA or other U.S. tubes.
mechans
3,048 posts
 
O_Holter, Interesting report. The truth can be painful. I have been a tube hoarder after discovering that changing out the Chinese 6SN7 driver for NOS Sylvania GTBs (not even fancy pants tubes)in my first tube amp made such a positive impact on the sound. That was about 12 or more years ago. Now divorced I have my tube collection but few places to use it.
I have about 75 really good, some quite rare, 6SN7s in arms length at the moment-Feel free to contact me, if the rules allow it.
mechans
3,048 posts
 


Now that you have some nice NOS power tubes.  Why not, try rolling some of the 6SN7s you may be pleasantly surprised.

mechans
3,048 posts
 
Try dome Sylvania Ws note not WGT ,  These have the renowned 'chrome dome'.  They are expensive but are very good.  The short bottle is relatively more common than the talls etc. and have been selling for unusually low prices of late -about $50  or slightly more for ea. .
mechans
3,048 posts
 
It's a very interesting combination of input tubes . Obviously highly amp specific. If you want clean crisp almost SS sound from a 6SN7 try  old stock Hytrons, avoid the CBS Hytron.
mechans
3,048 posts
 
@ bigboltz. Does the UV-1 transmit the character of the 6SN7S  really well when you roll them?
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