Supro 1624T build

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I built a 1624T a few weeks ago and wanted to share some info and pics.

I used one of my last Dirty Dawg chassis, 16x6. Musical Power Supplies PT275.2 and ClassicTone 40-18063 OT.
This OT is quite small and is advertised as a clone of the original OTs that Mag Comp used to make for Valco way back when.
The PT has 115VAC and 120VAC taps. I used the 120 taps with SS rectifier and got 350V plates.

Before building the scratch amp, I put the circuit into a Bogen PA test bed, and liked it enough to build this one. They both sound very similar. The Bogen may actually sound a bit sweeter. Its OT was slightly larger, built PTP with a mix of caps. The scratch build was all 6PS caps, and I added an extra stage of filtering, as the originals ran 4 stages off one node. I very well may change that back to spec.

Here's some clips. I honestly can't remember which is which, but the mic placement is providing the biggest variance here, as they were recorded days apart .
https://soundcloud.com/jeremyslemenda/jpa2
https://soundcloud.com/jeremyslemenda/jpa6

I ran with 3 inputs instead of four. Hi/Lo grid leak and Hi cathode biased. Jumpering sounds good.
I also recently added a "pull dark" switch on the grid leak volume, and am fiddling with bright caps there.
Lots of good tweaks to be had in this amp.

I've included the faceplate .svg file for those running Inkscape. It of course could be changed to suit any amp. Maybe that will help someone just starting with designing faceplates. If anyone needs other file types let me know.
The faceplate is plastic with a brushed aluminum finish, and looks pretty damn good, from my local engraving shop.

The board layout is pretty close to what I ended up with, but I did move a couple things around...the 15K cathode on the vibrato stage comes to mind. The chassis layout is about 2/3 done, but should suit, and the grounding is what I used and works well. I used a 1M pot for the "speed" control, with 500K across it, as that was all I had with a spst switch.

There is a lot of great info from Eric K.(not sure if he is a forum member) here : http://www.dirtygirlamplification.com/A ... 1624T.html
He has done his homework! The 1690T scheme has some great ideas too.

Happy building!

Jeremy

[Structo]

Cool!

Does it do the Led Zep thing?

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more pics

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files :

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Ahh the .svg file won't attach. PM if you'd like it - J

[xtian]

That is really nice looking work, in a compact chassis, with inexpensive iron. My kind of build! Thanks for sharing.

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Thanks! T'was a fun one too!

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Cool!

Does it do the Led Zep thing?

I think it does it allright, seems to actually do ZepIV a little better. It's pretty crunchy. Cleans are really present and pretty , too.

[dorrisant]

Nice looking build Jeremy.

Sounds right too!

Tony

[Blackburn]

Sweet build! Very clean. Digging the tone too. What speaker?

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Thanks guys. Speaker is WGS ET65, one of their higher powered greenback interpretations. I ordered a Green Beret(25W) to go in the combo but haven't put it all together yet.

[jelle]

Looks really good. What are the gray resistors?

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Thanks Jelle. You mean the little light blue ones? Honestly I can't remember but they are modern.

I was planning on keeping the amp when I built it, but someone came along and had to have it . He plays in a kinda cosmic cowboy band with an SG through it.

[jelle]

Gotcha, sounds like it found a good home.