|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
24.184.41.88
In Reply to: RE: Looking for some help posted by David Smith on December 08, 2014 at 13:24:07
6V6s in triode sonics vary a lot depending upon the manufacture. I never found one I liked beyond the old Sylvania 6V6G 'coke bottle' glass and the old Sylvania 7C5 with the small oval plate (VT type mil spec tube).
IMO, less risk would be using a true triode driver. CCS in the tail of the phase splitter preforms well. The 6V6 bottom tube grid is not connected.
Follow Ups:
I am a bit surprised at the negative comments about the 6v6's based on what I've read in the past, but I'll take that into consideration. Yes I should have finished drawing the driver circuit before posting, I have since fixed that but thanks.
Dave
The 6V6 in triode has great plate curves- drew me into building a PPP triode connected 6V6 amp years ago. Problem was the large stash of NOS RCA metal 6V6 I had sounded awful. Finally, the 7C5 bailed me out as finding 8x 6V6 Sylvania G glass did elude me. I did borrow four Sylvania 6V6G glass for testing in one amp. (I built monoblocks).In your case for a driver you have more options. I found the 6SN7 sounds better than a 6BX7 or 6BL7. Not all 6SN7s worked for me either. The Sylvania 6SN7GTA with the plates on an angle sounded most clear.
Granted the 6BX7 or 6BL7 has more drive capacity, but the 6SN7 provides enough drive. I would use a Tung Sol round plate 6SL7 as the preamp tube. find more magic with a high gain preamp tubes and the 6SL7 has less miller capacitance issues vs a 12AX7.
Use a coupling cap from 6SL7 to 6SN7 and place a CCS on the 6SN7 cathode. Then, you can ground that bottom grid. That means no capacitor in the grid to ground. The TT phase splitter will be very accurate & accurate phase splitters is the trick for PP amps to sound about as good as SET amps in the midrange plus PP are more dynamic without a loose coupled SET audio transformer.
200 volts plate at 14ma or 250 volts at 9ma per 6SN7 plate is in a good part of the 6SN7 plate curves.
My 2 cents worth.
Edits: 12/10/14
"The Sylvania 6SN7GTA with the plates on an angle sounded most clear."
Interesting you say that, I absolutely agree. I had a chance to buy a good number of the Sylvania 12SN7 chrome tops last year at a really good price. They were marked Zenith, and that apparently put most buyers off. What I found though is that the sections in each envelope were much more closely matched than identical 12SN7s marked Sylvania. I can only assume that Sylvania screened them for this before printing the Zenith name on them. All of these are a world better than RCAs from the same era, frequently so mismatched in the same bottle that I can't use them.
--------------------------
Buy Chinese. Bury freedom.
Why the 6SL7 over 6J5? I think I should get enough gain with the 6J5, but perhaps I'm wrong. Is it a sound thing or you think I need the gain?
Save
The 6J5 (1/2 of a 6SN7) does have way enough gain for the application. The operating point on the plate curves is good. The right brand of 6J5 should sound excellent.My notes over the years have shown higher gain front-ends of amps sound better with the right high gain tubes. I am not opposed to cross over to the 'sinful dark side' using a pentode preamp tube either. The stellar performing H&K Citation II and Marantz 8B that use pentode preamp tubes come to mind.
I like the Tung Sol 6SL7 round plate as a preamp tube is all. Nothing wrong with a 6J5 tube as seen on the paper specs. Being the 6J5 is 1/2 of a 6SN7 and I do not like the sound of many 6SN7s, simply choose a great sounding 6J5. Perhaps a Sylvania 6J5GT with that same plate as my favorite Sylvania 6SN7GTA exists.
Bottom line is IMO the brand of tubes make or break an amp.
Edit- I remember using a Sylvania 6J5GT with a metal base and black round plate. That is a good sounding tube!
Edits: 12/10/14
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: