6V6 line preamp

[iko]

Nope, my 26 has a ixcp10m90s gyrator load and cap output. No cash for a good output transformer.

 

[Salas]

I am sure it measures much better that way.

 

[stajo]

Well sqarewaves are squarewaves and music is music. Squarewaves are good for tracking problems, not so good for judging the goods or bads in a music machine. No news for anyone here I guess.

Vgeorge, I wouldnt be surpriced is the 25 mA iron is on the edge of saturating, and that might be what we are looking at.

There is lots of line trafos that leaves unnoticable footprints on squarewaves, I think its more of an implementation thing.

 

[Salas]

Still the wiggle was no accident, it denoted resonance that manifested in excess microphony. Choke load takes double the Ip spec and a snubber it seems so to be judged correctly. It owes to bring less THD and more gain to the plate but in a behaving manner.

 

[stajo]

Amen to that. I merely ment that one shouldnt diss iron as a concept based on a single implementation.

 

[vgeorge]

Correct Stajo. I don't dismiss iron, in fact I try to use it most possible. Just this iron in this implementation did not work out. In fact in my power amp I m using now have some nice Hashimotos!
Even if I solved the slight ringing on the scope, I should take extreme measures to avoid microphonies.

 

[vgeorge]

Nope, my 26 has a ixcp10m90s gyrator load and cap output. No cash for a good output transformer.

If your power amp has a highish input impedance that' s fine!

 

[vgeorge]

I found some Mills 6,8K resistors and put them in.
Plays beautifully now! Excellent sound, I m thrilled!
I will get a stronger subchassis for the parts and rearrange things a bit in the future, now that I do not use the chokes.

 

[iko]

Seriously, the two resistors made a difference in sound?

 

[vgeorge]

They were better suited to this circuit compared with the chokes I used. Maybe other chokes would perform better. Resistors were less prone to pick up vibrations mainly, that resulted in clearer sound. Still need work t do on the chassis as I said.

 

[Salas]

6k8 are near 7k5 I suggest when having B+ around 300V. So its a good op point for Rload too.

 

[vgeorge]

B+ 295V now, at 16,5 mA.
Iko, you should try this pre, if you haven' t yet.

 

[Salas]

This version which stays on the roadmap of the original 6V6 pre concept must be much more economical to make than your splendid #26 build with TVC and OPT? I wonder how closely it fares to the premium preamp in the system. If its a poor man's special pre at all.

 

[vgeorge]

Well, first, when I decided to go for #26 pre, I knew I was not aiming for the ultimate fidelity, but for a nice tone and liquid mids. And it has these qualities. This is more truthful to the source and more dynamic with bigger stereo size, depth and resolution.
I' m tempted to take the TVC from the other pre and put it here now that I have the space......

 

[Salas]

More "monitor" but less "tone"?

 

[vgeorge]

Compared to a 26, yes.

 

[buzzforb]

vgeorge,
has its signature changed using different power amps. What have you paired it with?

 

[vgeorge]

TSSA and Baby Huey. Brings the best out of them.
Have not listened much yet, but the sonic signature is more or less the same.
I think it would be ideal for F5 though, or other low gain amps with highish input impedance.

 

[buzzforb]

Didnt like it with F5 at all. BA3, completely different story. I know. It sounds stupid. THank goodness its just an opinion. BA3 seems to get out of the way more, as crazy as that sounds. I have parts for TSSA coming.

 

[vgeorge]

Built a few F5, not my favored amp, liked an Aleph J, I still have, more. But the two I mentioned before are my favorites.
I think that for the people who like the F5 it should be considered.