6V6 line preamp

[stajo]

What kind of glue have you used for attaching caps to alu radiator?

None, its Cable ties. But heat glue works fine

Staffan

 

[yagoolar]

None, its Cable ties. But heat glue works fine

Staffan

I have not noticed. Thanks.

 

[Salas]

Hi Staffan, comes out nicely on the box. Did you get any difference in tone with the DC in the filaments nonetheless?

 

[stajo]

DC worked fine and I didnt hear much of a difference so far. Gonna work off B+ ripple tomorrow and then compare to elevated AC.

But overall its a lovely little rat-amp. I will try it on a friends 6C33 OTL some day, which is especially hard driven.

Staffan

 

[tcqanh]

Hi all,

I've just built 6V6 pre for my friend. Here are some pics. Sound is very good on mid, bass and rich tone.

My schema is based on Salas' one, but I use AC filament with hang of 40Vdc. PSU is with 5V4 tube, CLCRCLC for separate chanel. No hum AC, but I have some hizz on one chanel. I think it's tube noise.

 

[buzzforb]

Very nice. Excellent construction

 

[Salas]

Hi all,

I've just built 6V6 pre for my friend. Here are some pics. Sound is very good on mid, bass and rich tone.

My schema is based on Salas' one, but I use AC filament with hang of 40Vdc. PSU is with 5V4 tube, CLCRCLC for separate chanel. No hum AC, but I have some hizz on one chanel. I think it's tube noise.

Good looks. Did you take any anti microphonic measures? Its the common cathode 15dB gain circuit yes?

 

[RCruz]

Hi all,

I've just built 6V6 pre for my friend. Here are some pics. Sound is very good on mid, bass and rich tone.

My schema is based on Salas' one, but I use AC filament with hang of 40Vdc. PSU is with 5V4 tube, CLCRCLC for separate chanel. No hum AC, but I have some hizz on one chanel. I think it's tube noise.

Splendid build

 

[buzzforb]

R Cruz, I assume that you have built this, having listened to the NJfet RIAA.

 

[RCruz]

No.... unfortunately I do not build anything with bulbs for long now... but I will.

I am using a p2p dcb1 with V12r shunts as a reference.

 

[buzzforb]

DCb1 is no slouch by any measure. It is my SS volume control. If you dont need the gain, try the CF. It will be next for me. I will have both versions interchangable, depedning on my mood.

 

[RCruz]

CF?

 

[buzzforb]

cathode follower. It is on first page. Would be good alternative to DCB1 if no gain is needed. Check first page.

 

[RCruz]

Thank you.

I know it is a good contender... that is why I am following.... It will happen soon

 

[Salas]

It pushed the B&W MPA 1 monoblocks I repaired very easily in CF mode today. Those are 30dB gain amps nonetheless. And I liked live voices on the radio too.

 

[stajo]

Nice Salas. I had kids here today so it was more Minecrafting then soldering but I made those:

The hawkeyed can see that it has the same screwhole placement as SSHV2, so I can interchange them. The cap-thingy will become an R-C then.

I also did some quick voltage measurement and I ended up between 245 and 310 V B+ with 2,2-6,6 k as last R. That puts the bias to between 16,6 to 21 V which might put me in a strange little corner on the curves. Maybe a 680 DCR LL1660 would be more suitable.

Then I'm stuck with a strange groundnoice. I rewired stargrounding without results. DC-filaments and more smoothing C dont affect it.

Well, one's got to save some for the day after...

Staffan

 

[Salas]

Is there a possibility something oscillates there? What does the scope show?

 

[stajo]

Is there a possibility something oscillates there? What does the scope show?

Thats possible. Usually that takes us to motorboating but i can easily swap the filterchoke to a resistor and see if it there. I could also rig the scope. Its downhill skiing on the agenda tomorrow so lets see what it brings.

I changed last RC and also second C a couple of times so it shouldnt be there . And its overkill 1 k carbons on the grids. But you never know with chokes and capacitors.

 

[Salas]

Can be some nuisance in the cathode circuit interfacing with the iron beasts.

 

[stajo]

Can be some nuisance in the cathode circuit interfacing with the iron beasts.

Well yes. I could check with a lil resistor network instead of beasts.

Cathode Circuit is currently just the chokes (930 DCR 100+ H), 10 uF output caps decoupled with 10 k to ground.