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My "ah-ha" moment with NOS tubes...

I was just about to give up on a recent tube amp purchase (Conrad Johnson Premier 140).

First I started with new Tungsol 6550's, Sovtek 6H30's & a NOS Amperex Orange label 6922 input tube. The sound was "ok" but not as good as my previous McIntosh MC275 MKV.

Next I tried changing the 6922 signal tube to a Telefunken labeled Siemens. The highs opened up, albeit glassy and bright and the bass was lacking.

Next I replaced the Tungsol 6550's with SED 6550's. Changes, yes, but not necessarily better or worse... just different.

The "AH-HA!" moment came when I put in a Amperex PQ 7308 signal tube. Gone were the bright, glassy highs. The sound was full bodied, liquid and smooth with robust bass & mids.

I'm happy... lesson learned!
128x128pdreher
jea48
4,259 posts
 
You might want to try a Amperex USA made white label PQ 6922.

Another great tube is early 60s Siemens CCa.
nonoise's avatar
nonoise
10,540 posts
 
Another 6922 choice is a '70s Mazda RTC from Brent Jessee.
samhar
1,048 posts
 
Glad your happy with the amp!!! Which 7308 do you have US or Holland? Have you tried different 6H30Pi tubes to hear if the sound is effected. You could try EH 6H30Pi, they're reasonable in cost, I hated their sound in my CJ Act preamp, and might let you hear if these tube alter the amp's sound. If they do, I had excellent results with Reflector 6H30P-DR pre '90 NOS in the CJ, a difference similar to moving from a Sovtek 6922 to an Amperex 6922 PQ in the quality of sound with an improvement in dynamics.
larryken
537 posts
 
I found the white label Amperex PQ 7308 to be the best also....military strength build also.
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