Wing
Head-Fier
- Joined
- Jun 22, 2001
- Posts
- 80
- Likes
- 10
Hello all,
I've been away for quite some time but I had to come back to report something quite nice. The stock Valve Art (?) EL84s were OK but I felt it had had a touch of cold brightness/brittleness. Doing a little research I found a modern, inexpensive tube that is almost an equivalent to the EL84. This tube is the Svetlana SV83 that the decware.com Zen amp uses. I have been meaning to try out the SV83 for some time now and did recently. Reading some of the caveats from the technical articles in the "hidden" directories on the svetlana website, and looking at the Head schematics it seems the SV83 is a drop in replacement. The only thing I think should be modified in the Head is the addition of 330 ohm grid stop resistors ala the Zen amp, to prevent the possibility of ultra high frequency oscillations due to the video bandwidth capability of the SV83. I did not do this and the amp has not blown up yet.
On to the sound. This tube rocks! It extends bandwidth in both directions, tightens up the bass, is not cold, is neutral, has more palpability and sounds quite alive. I think this is due to its linearity and high transconductance which gives it better current driving capabilities. I recommend it and have already ordered my stash from triodeelectronics.com. Try it, you may like it and for around $10 for a matched pair, it is IMO quite affordable.
As a side note, I plan to use the SV83 in my own tube amp creations. Possibly Zen and Head clones. Incidentally the driver 12ax7 circuit of the Head only has a -0.6v cathode bias. That's about 0.6 ma plate current. It may be a little too low and may be the cause of the scratchy volume potentiometer due to grid leakage. I read that 12ax7s like a -1 to -2 v bias to stop grid leak. I'll report back again when my Head clone is done.
I've been away for quite some time but I had to come back to report something quite nice. The stock Valve Art (?) EL84s were OK but I felt it had had a touch of cold brightness/brittleness. Doing a little research I found a modern, inexpensive tube that is almost an equivalent to the EL84. This tube is the Svetlana SV83 that the decware.com Zen amp uses. I have been meaning to try out the SV83 for some time now and did recently. Reading some of the caveats from the technical articles in the "hidden" directories on the svetlana website, and looking at the Head schematics it seems the SV83 is a drop in replacement. The only thing I think should be modified in the Head is the addition of 330 ohm grid stop resistors ala the Zen amp, to prevent the possibility of ultra high frequency oscillations due to the video bandwidth capability of the SV83. I did not do this and the amp has not blown up yet.
On to the sound. This tube rocks! It extends bandwidth in both directions, tightens up the bass, is not cold, is neutral, has more palpability and sounds quite alive. I think this is due to its linearity and high transconductance which gives it better current driving capabilities. I recommend it and have already ordered my stash from triodeelectronics.com. Try it, you may like it and for around $10 for a matched pair, it is IMO quite affordable.
As a side note, I plan to use the SV83 in my own tube amp creations. Possibly Zen and Head clones. Incidentally the driver 12ax7 circuit of the Head only has a -0.6v cathode bias. That's about 0.6 ma plate current. It may be a little too low and may be the cause of the scratchy volume potentiometer due to grid leakage. I read that 12ax7s like a -1 to -2 v bias to stop grid leak. I'll report back again when my Head clone is done.
