Supro s6424 build

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JoshBernstein
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Supro s6424 build

Post by JoshBernstein »

Hey everyone,
Im just starting a new build which is going to be a supro model 24. Ive got most of the board work done, a few more things to solder. Ive got a couple resistors on the back as i thought it would make the build neater. Ill be building it with a watts chassis/board. More parts coming soon, i hope, as hurricane irma has created quite the delay.

Its going to be in a high powered tweed twin cab, loaded with a celestion blue and g12h30. Im thinking ill make it straight black, tolex, grill cloth, handle and all. I think it'll look good with the steel faceplate and im thinking silver cap Marshall style knobs

As for parts, ive tried to go for the high quality stuff as i want this to be my best build yet.
-classictone pt 300-0-300
-heyboer ot, i believe its 8k
-prp resistors, and a mix of some others for the 2+ watt rated ones
-sozo caps, and some ceramic and a polystyrene here and there
-sprague premium cathode bypass caps
-f&t filters

For tubes ive got an amperex bugle boy for v1, rca grey plates for v2 and v3, and some new production eh 6973 for the outputs. Rca coke bottle 5y4 for the rectifier. Will post more pics as parts start rolling in.

Any feedback/advice welcome!
-Josh
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labb
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Re: Supro s6424 build

Post by labb »

You might enjoy reading through this. Sure Steve would not mind....http://sluckeyamps.com/supro/supro.htm
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WRC34
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Re: Supro s6424 build

Post by WRC34 »

Very cool build, please do keep posting!

Looks like this amp uses a paraphase inverter, am I wrong?
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JoshBernstein
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Re: Supro s6424 build

Post by JoshBernstein »

labb wrote: Fri Sep 15, 2017 12:35 am You might enjoy reading through this. Sure Steve would not mind....http://sluckeyamps.com/supro/supro.htm
Definitely a good read and a beautiful build!
WRC34 wrote: Fri Sep 15, 2017 1:16 am Very cool build, please do keep posting!

Looks like this amp uses a paraphase inverter, am I wrong?
Ill keep posting as i go along! And yes i believe it's a paraphase inverter!
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xtian
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Re: Supro s6424 build

Post by xtian »

Yummy looking board!

Tack those filter caps down with something sticky to avoid having them rattle against the board. Not that I've ever had that problem before...
I build and repair tube amps. http://amps.monkeymatic.com
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JoshBernstein
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Re: Supro s6424 build

Post by JoshBernstein »

Well, i made my first error of the build! I ordered 1meg linear pots for the tone controls and trem speed. Can i just tack a 1 meg resistor across pins 1 and 3? Thanks!
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jjman
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Re: Supro s6424 build

Post by jjman »

For both I would try the 1megs alone 1st. Then add the resistor if it doesn't seem right.
If it says "Vintage" on it, -it isn't.
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JoshBernstein
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Re: Supro s6424 build

Post by JoshBernstein »

Some more parts here today, waiting on the ot and a few other things before i really get the build going. Also got the cabinet ordered, itll be going in an all black high powered tweed twin cab from mojotone. The only modification to the cab i had to have done was to extend the backpannel a bit to accommodate the chassis. Excited to use the rca 5y4!
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JoshBernstein
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Re: Supro s6424 build

Post by JoshBernstein »

Hi all, she's coming together! Progress has been slow since hurricane irma, as my family who lives in the florida keys had stayed with me up at college for a little bit. Getting the g12h30 here was an absolute nightmare, as i sent it to the wrong address and it took a month to get here, but i wont get into that. Cabinet was built by mojotone. Standard size tweed twin cab, only modification needed was a 2" extension of the top backpannel. Otherwise the amp fit like a glove. The tube sockets and pots have yet to be wired and theres loads of excess wire in there, but ill most likely finish her up this weekend. I think this is shaping up to be my best build yet! An comments or advice would be wonderful!
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pompeiisneaks
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Re: Supro s6424 build

Post by pompeiisneaks »

So yeah, looks super cool!

Two things:

1. you've got yummy peaches
2. it's on the exact same plates as we have at home :)

Nothing to see here, move along

~Phil
tUber Nerd!
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JoshBernstein
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Re: Supro s6424 build

Post by JoshBernstein »

Here it is today. Did all the wiring and the amp sounds great. Only trouble is the tremolo. It only works as the amp warms up, and then as the voltages come up it stops. I used a pt with a 300-0-300 secondary as opposed to the 310-0-310 secondary watts' recommends, so voltages are lower than the schematic as expected. Im not sure how to proceed, i figure ill cool off the bias of the preamp tube being modulated and see if that helps. And advice would be wonderful! Thanks!
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RockinRocket
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Re: Supro s6424 build

Post by RockinRocket »

Glad you like it! Got to build one of these and their pretty cheap for a tube amp
Thomas_H
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Re: Supro s6424 build

Post by Thomas_H »

nice one! where do you got that chassis from?

About the tremolo could be a missing ground on a capacitor or resistor in the tremolo circuit.
My guess is that It works while charging and then stops unable to discharge the capacitor to continue oscillating.
sluckey
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Re: Supro s6424 build

Post by sluckey »

That tremolo oscillator needs a strong 12AX7. Sub several tubes into that socket to see if that fixes it. I have voltages listed on my S-6424 schematic, including trem signal AC voltage level at the footswitch jack. Might be helpful...

http://sluckeyamps.com/supro/supro.pdf
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martin manning
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Re: Supro s6424 build

Post by martin manning »

Your schematic link seems to be broken, Steve. I went up to the top level and worked back down through the Supro page; still no good.
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