View Single Post
  #6   Report Post  
truegridtz
 
Posts: n/a
Default


"Lawrence" wrote in message
.42...
Some people told me that a "good" and "no-so-good" 12AX7 and 12AU7 really
make a big difference to the pre-amp and power-amp.

I look at some Chinese 12AX7A which cost about US$12.00 a piece, and a
piece of Tesla ECC803S cost about US$50.00; similar goes to the 12AU7!

I wouldn't mind to pay for the difference, but I want to know if it is
worth paying that?

Can anyone ever tried that can be kind enough to share their experience?

Thanks in advance!

Lawrence


L: I clicked on an ebay link on the radio-phono NG about someone selling
silcion o-rings for tube dampers. Eventually I ended up on a website that
sells HALO tube dampers, looks like a good idea.

Anyhow, somewhere along the line I encountered an article about what you are
interested in. It may have been in the HALO site.

This guy gave an excellent explanation of why some tubes sound better than
others in a particular circuit. As I recall the bias is one factor. This
was an excellent article. If you can find it you will be glad you did.

He explains in a believable and logical way why there is no particular best
tube. Simply try them and use what you like in a particular circuit.

You can get Sovteks cheap from Parts Express, both WA and WB. They have the
one with the special low hum filament, too. They are supposed to have
different sounds. This would be an affordable place to start. I would be
cautious of anything from China.

I have also read that there are counterfeit tubes from foreign countries
that are marked to look like what they aren't.

I am not fortunate enough to own hi-fi tube audio, only vintage 50s record
players, so I don't know why people don't really like JAN (military) and the
similar 5xxx and 6xxx industrials. I have found that the manuf tolerances
in them are much more precise and their gain and gm is much better than
commercial grade.

The commercial grade will probably have a much wider tolerance range. Thus,
one may sound better than another due to better gain. This is a big factor
in RIAA equalizers. The 12ax7s must have full gain to really reproduce the
curve.

Someone gave me an old torn up muddy junker preamp awhile back. It had two
perfectly good Telefunken X7s in it. Old consoles are often full of good
USA 6BQ5s, and X7s. RCA sometimes used Amperex from Holland, as did
Magnavox. The late 50s is when they got good. Keep an eye out for junk.
Good Luck, Mark