EL34 in Cary CAD120S bias info needed

I have the CAD 120's. What preamp are you running? I had EL34's in a V12R, I love the sound with the stock KT88's. What are you trying to do soundwise? You have a fantastic amp. Good luck.

I have a Parasound Halo P3 Preamp. The connections to the amp are by balanced lines. Inexpensive ones but I do not recall where I got them.

In my initial setup there were three different amp hums. I have learned to ignore the really low level transformer hum. Cable placement changed the second hum. The third hum required getting a HumX by Ebtech to isolate the ground.

Like you, I was very pleased with the sound of the KT-88's and still think that it is wonderful.

The EL34's I imagine have the biggest difference in sound of any of the available tubes and that is why I went to these just for fun. The bias will not get to 140. It is just a guess but the 6L6 requires 0.9 amps for the heater and the EL34 requires 1.5 amps. Maybe that is why the resistor needs to be bypassed. I would like to hear from someone who knows this stuff to comment on why the resistor needs to be bypassed.

To answer your question about what I am trying to do soundwise: I am still figuring that out. Why does my wife get new dishes when the old ones look perfect?

The sound is intoxicating. There are so many ways in that it falls short of the KT-88's but I am not rushing to go back. The good thing is that having the jumper connections outside the amp make it easy to switch back and forth. Paradoxically for me that makes me less likely to switch back. The disease is AudioMasochism.

Hi,

I've been new to the audiophile hobby but I guess I've picked it up fast because I'm a very experienced RF engineer with good knowledge about transistor amplifier theories.

Anyway enough about me so you won't get bored. I happened to own a few months old CAD 120S MkII with Clarity caps upgrade and a good used SLP-98P. I've upgraded the Clarity caps to Vcap CuFT reference ones and Mundorf S-G-O for the SLP98. They've been broken in properly close to 300 hours for the Vcaps and 70 hours for the S-G-O ones. They really sound wonderfully crystal clear and wide soundstage with deep accurate image for the Maggies 3.7i speakers.

I also own many NOS and NIB tubes ranging from Psvane TII, Svetlana/SED Winged-C in Petersburg, Tungsol, EH gold pin for EL34, KT88/120 and 6550 for the 120S MkII. I biased all except the EL34 at 135mA. The EL34 is maxed out at 110mA or a few less when fully warmed up for two matched quads. The other two quads were maxed out at 100mA. However I could not tell the sonic differences between them. And all EL34s sounded just as wonderful as the KTs or 6550, even more and tighter bass from the EL34s with better midrange as they are known for. Another plus is they draw less current therefore the amp runs cooler noticeably by at least 300-400mA lower. That said I don't think you have to bias to 140mA for better sound as they are required so. Remember with 10% recommended limit and a typical 120-130mA for these low power tubes 110mA sound just about right.

I've not opened up the boxes of Psvane TII 6CA7/EL34

The 6SN7s as driver are EH GP and Psvane TII as front end. They are Sylvania JAN WGTA or CHS V231 which have not been rolled in yet but soon for the SLP-98, which also got the Psvane as driver. And for the phono input they are Telefunken or Amphoronics? or something by England.

If you got some extra cash around try the MEL 6SN7, they sound excellent! Probably the best.