6V6 line preamp

[stajo]

Well, here is the monster, with the scrap I had at home over the weekend.

An externally hosted image should be here but it was not working when we last tested it.

Foilcoated plank, pre-war caps, trafo and a 5Z3 for now. I made dual filters for trying out dual AZ1 or such later. Got 2,3 k in the filters plus chokes now, had 335 V B+.

Behold the beauty
Staffan

 

[Salas]

Cool test preamp. Is it the gain version (common cathode) CCT? What make of tubes, and what heaters power scheme?

P.S. You already wrote AC for heaters, OK.

 

[stajo]

Yes, gain version. Were there a cathode follower to? Didnt see that. Tubes is old RCAs testing fair. Regular electrolytics as cathode resistor bypass, 1uF MKP output caps, resistors what I found around. Other then that, fairly as the schematic I found in this thread.

Heaters power scheme? Regular AC 2 lines 6,3 VAC from the trafo. It has 5 V to. From an old radio.

Staffan

 

[Salas]

RCAs are great. Black anode? Yes there was a bootstrapped cathode follower also shown for those who want a buffer. Repeating for quick reference:

 

[buzzforb]

Salas,
you ever tried Susy tube linestage? In the back of my mind, i am thinking that if this goes as well as expected, it might be cool to do dual mono version like john mcclaens balanced B1 or even simple Susy.

 

[Salas]

Susy, no. I have a single ended wired system anyway. So no opinion on that question.

 

[buzzforb]

FWIW, musicians friend is having sale om matched TungSol 6V6 for $35.

 

[Salas]

New from Saratov, or American NOS?

 

[buzzforb]

Unsure. Jusr got the notice.

 

[stajo]

Black anode. Cool, maybe I'll re-bread it to buffer while waiting for regulator stuff. Gonna tune and "compactisize" the filterlines to and work it out for two 340/360 lines, for with and without SSHV2. I have two old output trafos from old radios at about 11 H each that I think will take the current.

 

[Salas]

Unsure. Jusr got the notice.

Just visited and checked. They are the new Russian ones I found good. 5 stars there from all 4 guitarists customers reviews also.

 

[Salas]

Black anode. Cool, maybe I'll re-bread it to buffer while waiting for regulator stuff. Gonna tune and "compactisize" the filterlines to and work it out for two 340/360 lines, for with and without SSHV2. I have two old output trafos from old radios at about 11 H each that I think will take the current.

Use FT3 0.1uF Teflon input cap if you can for the CF, it makes a difference in my experience in this circuit.

SSHV2 plays very good on #26 feedback says. Its a new reg, take caution you will be the first to apply, don't know behavior on the higher B+ and mA for double 6V6 yet. SSHV1 works in Gregory's though.

 

[buzzforb]

Salas,
how detrimental will the 170 be to the sshv2 i have tons of them and no 117gr.

 

[Salas]

More drift, a bit less bandwidth. Fine to make a test.

 

[stajo]

don't know behavior on the higher B+ and mA for double 6V6 yet. SSHV1 works in Gregory's though.

Ok, I'll use 1/channel then and tune up the voltage for testing when Im there. And let you know if it blows

 

[Salas]

Keep the last filter cap near to the reg's input. I don't mean to jinx you, but I had to remind there is no SSHV2 test on that pre yet, to be typical. Let us know and good luck.

 

[buzzforb]

Salas,
I think i read that you ended up with Mundorf Supreme on output. I have heard hypass this with MKP1837 can improve the sound. Dunno, but cheap experiment.

 

[Salas]

That's in speakers by the dutch guy with the series crossovers on tweeters test I think. Different levels and applications but I have such capacitors and I can try too.

 

[Salas]

Ooops, 160VDC are the 1837, forget it.

 

[buzzforb]

Your right. Was just checking. Might be worth trying with MKP10 if you got one. They can handle the voltage. I have obbligato Film in Oil tha i will start with, bt i think the Supremes is where i will end up. My brother has them throughout his Ming DA integrated and loved the improvement.