Supro 24 with ppimv?

[ALBATROS1234]

Pretty self explanatory, I am about to  build a 6424 clone and thought maybe I could do a type 3 post p.i. master volume. I googled it and read an old thread and a few posters seemed to think it would be a bad idea and would change the tone of the amp. I don't get why so I thought I would pose the question here to get some trusted input. Thanks

[shooter]

did you read this thread;

http://el34world.com/Forum/index.php?topic=3496.0
it has it all 

[sluckey]

Aha! I knew it. Look here...

     http://sluckeyamps.com/supro/supro.htm

[shooter]

I had to look twice 
now I can go back to the race 

[ALBATROS1234]

Thanks guys eating an Italian sausage poboy with my 90yr grandma right now but I will check out the thread in a bit

[ALBATROS1234]

so if i understand correctly if i use the cross phase ppimv also known elsewhere as a #3 ppimv which uses the output from each leg of the phase inverter with a 1 meg pot to cancel out volume using the opposite phases. this type at volume on 10 it does not effect tone substantially and it is basically out of the circuit thus the amp will behave as if it wasnt there. with master down i can crank my pre amp and get low volume crunch at the sacrifice of some tone? if so thats what i am looking for.

sluckey i am using you 1 input with a 3 position switch to select either or both channels. i just thought the amp may be too loud for home without a mv and needed a few trusted opinions before taking the leap.

[sluckey]

I'll be surprised if you like the cross-line MV, but it is so simple and easy to try that you should try it first. Heck, you can just use a couple gator clip test leads and not even have to solder anything to try it.

Did you see the MV in the link I provided?

[ALBATROS1234]

Yes I did, thank you. I just don't have a dual gang pot on me. So I will try the cross type and see if it's acceptable if not order a dual gang. I am also skipping the tremolo.and using a 6ca4 with upsized filters since I have a 32/32 can

[ALBATROS1234]

I guess the tone may be a bit stiffer with the 6ca4 and 32/32/10 filters but I got this pt out of a Sony 500 r2r and it's ideal for the most part. I get 326-0-326 measured ac at line level voltages. One other thing I have been debating is this pt has 4, 6.3v windings. They are 1.5a ,1.5a, 1a, and.6a. The .6 I will use for the jewel light. A 1.5 a will be the rectifier. And I am not sure if I should try to put 2 12ax7 and 2 6973 on one 1.5 and leave the other just sit or do I put the 6973s on the 1.5a and the 12ax7s on the 1a. If I add up filament current I get exactly 1.5a so it should be fine but I have wondered if I should split the pre and power tubes to 2 Sep windings just cuz they are there? Actually none if the 6.3 windings have c.t so I will have to do artificial type with 100 ohm resistors. Do you guys have any advice on my course of action?

[sluckey]

Either way will work fine. Putting all 4 tubes on the same winding will simplify wiring and only require one pair of 100Ωs.

[ALBATROS1234]

That's what I'm thinking now . At first I was thinking I got the windings may as well use them but like you said then you gotta make 2 virtual c.t and extra wiring. It's going in a chassis from an unknown stereo push pull amp. I took off one ot and the pt ht didn't have a ct , had been wanting to do the supro and this chassis already had a perfect 7.2k to 4/8/16 plus all 9 pin good quality sockets. I drilled out the control panel last night all I gotta do is wire it up

[PRR]

> if I should split the pre and power tubes to 2 Sep windings... with 100 ohm resistors.

Only the preamp tubes really need CT power. The Power tubes are normally fine if you just ground one side of the 6V.

[ALBATROS1234]

That makes sense prr.  I was thinking that and wondering how much would it really matter. I guess since I have a 1.5a winding and the 4 tubes add up exactly to 1.5a I will just go with it and tape off the other 6.3v winding. It's good to know that though for future reference

[dude]

Hey, Sluckey you said you used an AO-43 chassis for your Supro build you posted above. I see you used a brushed plate over the front, rear and top of that AO-43 but I don't see a plate over the inside of the chassis?  Either I can't see as well as any more or you're the magic man and made the holes inside disappear...? 

[sluckey]

Hey, Sluckey you said you used an AO-43 chassis for your Supro build you posted above.

I did not!

[tubenit]

Just a personal preference thang, but I have the crossline master volume to consistently sound awful.  Very unmusical buzzy sounding in my experience.  I've tried it on a few amps and never liked it.

With respect, Tubenit

[davidwpack]

I tried it and thought it sounded so aweful that I thought I had hooked it up wrong.

[ALBATROS1234]

I will try it because that's what I have on hand but if need be I will get a dual gang 1meg pot and try it another way.though crossing thru my head,and I 68k uh I guess it would be retarded to have 2 separate master  vol knobs one for each tube or phase as opposed to dual gang.

[dude]

Hey, Sluckey you said you used an AO-43 chassis for your Supro build you posted above.

I did not!

Here: http://sluckeyamps.com/supro/supro.htm

[sluckey]

That's not what I said. This is what I said...   

"I used a Hammond AO-43 amp as the donor for the Supro."

If you read between the pictures you'll see what I said about the chassis I used. But surely, just looking at the pics it's clear that I used a brand new aluminum chassis.

[dude]

OK, the iron, my bad. Hey, you do wonders with your builds, that chassis kind of looks like an AO-43, you're good but not that good. 

[sluckey]

I've got two AO-43 chassis in my junk pile.

[ALBATROS1234]

I do have to concur sluckey builds some sweet looking amps. Wiring is way neater than my builds. Plus most of my stuff is still just a donor chassis sitting on top if a speaker cab. Which I have 3 speaker cabs I use one is an old combo with the chassis removed which has 2 8" cheapy celestions. And 2 1930s/40s record player boxes I got from a local picker. I clamped and glued the lids to the boxes and cut circle holes and stood them up. They are wood not plywood and sound damn decent one gas a 1954 12" Magnavox that sounds like a vintage Jensen and the other has a 50s 10" Wright speaker which sounds damn good and low fi vintage vibe . So I try all my build with each one, some sound better with one or the other but the Magnavox 12" is a damn good speaker.