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Audio Research CD7's 6H30 tube rolling

The CD7 uses 6H30 tubes - 3 for power supply and 4 for the output stage.

Presently there are only new 6H30 tubes from Sovtek and Electro-Harmonix and NOS 6H30-DR tubes from the Russian military from around 20 years ago.

Some people have commented that the NOS tubes are sweeter sounding and have more "air" extension with their CJ or ARCref3 preamp equipment and others have commented that the latest new tubes (around 2005+?) sound so good that there isn't any difference anymore in sound.

Has anyone done tube rolling for this CD machine with the NOS tubes? And with what results? Would it be better to change the 3 power tubes or the 4 output tubes? Or all 7 tubes perhaps?

Thanks in advance for any comments!
flkin
flkin OP
26 posts
 
I thought that by the nature of what the 6H30 was designed for, tight tolerances were standard and that all 6H30DR tubes manufactured were already matched very tightly.

The tube store where I purchased the NOS 6H30DRs from has a matching service for some extra money. But I don't believe it's necessary for DR tubes.

With that said, it should be noted that the CD7 came with Sovtek tubes marked 1-7 with instructions to place them in their respective sockets marked 1-7. So perhaps there is some selection required in the standard 6H30 tubes.

Reb1208, have you tried 6CG7/6FQ7 tubes in the CD7 or to replace 6h30 tubes in CD players/amp before? During my research for 6H30 background info, I didn't find any mention that there were replacement tubes for the 6H30. Some people in Audiogon wanted to try but there were some comments that they should not be replaced. I forgot with what they wanted to use.

Is it only theoretically possible or is it practically possible? If so, with what results sound wise? Please share your experience.
jafant's avatar
jafant
19,895 posts
 
Any of you guys still using a CD7 in 2016?
oregonpapa's avatar
oregonpapa
4,867 posts
 
I've been using my ARC CD-7 since it was new. I sent it back to the factory several years ago to have it upgraded to the "SE" version that upgraded the power supply. 

Here's how to make an already great sounding CD-7 sound much better: 

1.  Get the "SE" version or send your CD-7 back to the factory for the "SE" upgrade.

2.  Swap out the stock fuses for Synergistic Research Black fuses.

3.  Swap out the stock tube dampeners on all of the 6H30's for Herbie's tube dampeners. 

I am NEVER going to sell my CD-7 SE.  Its not quite what we love about analog, but its darned close. 

That's it.
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