Which Circuit?

[stanbp64]

So I have started on the 6V6 amp. Gonna use a 6922 as driver. Using a steel plate that i got from work, it was a sign in its first life. I got about 8 of these out of the trash. They are about 9" x 11". They make a good top plate for a smallish amp. Here are a couple of pics of progress, Gotta start work on a wooden base also. Stan

 

[jaymanaa]

I like the No Smoking sentiment.:thmbsp: Looks like you got it goin on. I'm looking forward to hearing what you think about the sound.

 

[stanbp64]

Finished up this little 6V6 SE amp today.( circuit design by Kegger ) Plugged her in, hit the power switch, and voila---music. Still have to make voltage measurements but so far so good. Sounds really good on my crappy shop speakers too--- real test will come later when I bring it inside. Probably won't mess with it tommorrow... I am off to Atlanta with my two sons and nephew for Prog-nation tour concert. Dream Theater yeah!!! I wonder if I am getting too old for this sort of thing. I am just glad my sons, ages 6 and 13, like some of the same music I do. Sorry for changing the subject. Rock on! Stan

 

[tim614]

very nice Stan!

 

[Kegger]

Way to go Stan!

Have a great time at the concert..

 

[gearhound]

Nice looking amp!!
I must be dense and missed something though?
What OPT's did you use for that amp?


Steve

 

[stanbp64]

The OPT's are Edcors...they are painted black. I was going to place them on top of the chassis.

 

[stanbp64]

Took some readings: Is the voltage on the 6v6 plates too much? Attached is p/s scheme.

6922
P1-111v
P2-109v
c1-2.66v
c2-2.57v

6v6's
p1-352v 353v
c1-22v 21.7v

 

[Kegger]

The front end is fine, and the high voltage "would" work as well if the current wasn't
as high as what its in the outputs, your at like 50ma a piece and at that high voltage.

I suspect your power tranny is NOT 300 0 300, but more like 350 0 350, there are 2
ways yu can change this, lowering the voltage or lowering the current in the outputs.

To lower the voltage swap out the 3.3uf cap for a 1.5uf cap, to drop current in your
6V6 tubes swap out the 430ohm resistors for 560ohm or add say 150ohm in series on
the 430ohm you already have. (whatever solution is best for you)

 

[Redboy]

Awesome job, Stan! I really like the sign base. :yes:

I've got a Kegger special in the works too, but it's taking longer than I expected to get the project done. I'm obsessing too much over cosmetics when I should be suckin' solder fumes!

 

[stanbp64]

Thanks guys. Hey I was wondering...before i correct the voltage/current, would the amp be suited for maybe some 6l6's as it is(with the current voltages) ? Just wondering...... Stan

 

[Kegger]

Sure 6L6 "should" be just fine..

When you put um in repost the voltages again so I can compare, Please..

 

[stanbp64]

Ok, put in a couple of 6l6's and took some measurements:


6L6's
p1---335v 335v
c----26.4v 24v

6922

p1---106v
p2---104v
c1---2.49v
c2---2.53v

What do you think? Sounded good with the 6l6's but don't think i could tell much difference from 6v6, although the highs with the 6v6's did sound alittle strained. Not so with 6L6.

 

[Kegger]

Well with the 6V6 you were definatly "pushing" them.

Those 6L6's should be just fine at those operating points.

I'd like to see a closer match between the 2 6L6's but not to bad.

----------

Getting the voltage to near 350v with the 6L6 would get yu a bit more
output and run the 6L6's just a tad better, maybe paralell another 1.5uf
cap on the input with that 3.3uf you have there, check your PT heat to.
(this is just nit picking and something to play with)

 

[stanbp64]

Thanks Kegger for your help. Once again you have come up with a fine circuit. I thought I had a couple of matched 6L6's when i mentioned using them but alas i didn't. Think I will run 6L6 for awhile... they sound good and I like the look. Thanks again. Stan

 

[jaymanaa]

I'll take a 6L6 over a 6V6 any day.:thmbsp: Glad you got it up and running and like it.

 

[Kegger]

Hey STAN!
YU know u can do what I did with my "tube tester" amp.

Run a 5Y3 for 6V6 tubes. (should get u about 305 volts)
(there are a few slow warmup 5Y3 tubes as well)

Use the 5V4G for the 6L6 and 6L6G tubes. (lesser 6L6's)

Then use 5AR4 for some 6L6GC tubes, and if you have the
heater + B+ current you could run EL34 and KT88's in there.
(plenty of other tubes with the same pinout here as well)

That is the nice thing about that rectifier pinout, you can get
a decent amount of different voltages using different rectifiers.
(even more rectifiers if the 5v winding handles 3a on it)......

That drivers pinout can use a bunch of different drivers just as
the output tube pinout can with those socket wirings you have.
(yah a tube rolling nightmare, or blessing however you look it)

After a while you can tweak that first cap in the supply to work
with your rectifier choices to find a happy medium with swapping
out the rectifiers to work well with quite a few output tubes there.

----------

6L6 tubes can have a very nice tone to them, glad you like them..

 

[stanbp64]

Sounds like a plan. Thanks for the advice!!!