Supro S-6424 final report

[Planobilly]

Hi guys,

The EL84 version of the Supro S-6424 that Steve was kind enough to draw up is running without issue. Thanks to everyone for the help.

The tremolo issue was a bit of a problem to solve. It turned out to be a bad cap.

The amp sounds very much like what I was hoping for. It is currently hooked up to a vintage 12" Celestion speaker. The amp has a very rock mid-1960 tone at reasonable volume levels.
I have a vintage 15" Supro speaker coming to test out also...we will see.

In talking to a few friends in the tube business, they did not think there would be a huge difference with the EL84s.

Again, thanks to Steve and others for help with the Cliff jacks and the schematics.

This is a good amp to have if you are a Blues/Rock guitar player. It sounds good through both Fender and Tom Anderson Strat-style guitars. I will post some sound clips at some point.

Billy

[bmccowan]

Congrats on the successful build.
Funny, I have done the opposite a few times. An 18W TMB, and an AC15 based preamp with 6973 power tubes. I mostly use old RCA 6CZ5 tubes which I find identical except for pinout (and price!) to the RCA 6973. Agree - compared to EL84 not a huge difference in tone. EL84s have more chime which a lot of people like. 6973/6CZ5 in a similar circuit have a more solid bass - more like a 6V6. For a time, Valco made the same circuit with 6V6 or 6973.
Curious - you say a Supro 15" is coming your way. Valco never made speakers AFAIK - they used Jensen C-15s in the Thunderbolt and Harmony 420. Really nice sounding speakers IMO.
BTW, I am in the same boat as you; 70, fishing, flying, motorcycles, tube amps: High on a Mountain, standing all alone, wondering where the years of my life have flown, as the Del MeCoury song goes.

[Planobilly]

Thanks. I may, at some point, experiment with the 6973 tubes. I am having a bit of vision difficulty. I had eye surgery which turned out very well except for near vision. All that added to the stress of trying to figure out things. I am pushing 80 pretty hard. Getting old has its drawbacks...lol

Here is a photo of the speaker I found used. It has been moving around in the USPS system for the last two weeks. I only assume it will arrive at some point.


As I think about this build, I think I will build the amp and speaker in two separate cases. I am getting too lazy to carry this heavy stuff around. In fact, I use Guitar Rig software as much as anything to play through. I miss the analog world and playing on stage with a Super Reverb cranked up on 14...lol Well, that ship sailed a long time ago. More and more pro players are going to solid-state amps.

I assume there are enough young kids who have an interest in tube equipment to keep that older technology alive. People tell me that it has become more difficult by the year to find people to repair tube amps. The issue is not just a knowledge base problem but the high cost of having a brick-and-mortar store.

I talk to the people at Eurotubes out in Portland, Oregon, from time to time. They tell me that lots of Boutique amps are being built. Those people who start out life in the tube world are all getting pretty old.

Well...at any rate, I got up on the right side of the dirt today. Who knows what the future will be like.

Cheers,


Billy

[bmccowan]

Sorry to hear your eye surgery didn't go perfectly - I am on tap for that this winter.
It hadn't occurred to me that it would be a newer Supro item - should sound great. I have an original Valco 6973 amp that is Gretsch labelled. It has 2x10 Rola speakers. That combo also works well.
My builds also are heads - and often stay bare chassis for quite a while as I get anxious to start a new tube chassis and put off the table saw work. Its madness really. I have a Fender Brownface Concert 4x10. I can barely lift it these days. I joke that my vintage Fender and Valco amps are serial number 401K. But I need to start selling some. Separation anxiety gets in the way. Instead I do the opposite - just bought a 1940s Masco and a Univox U45B that I plan to modify as a Goodsell Unibox.
 

[labb]

Not to hijack the thread but on getting up there in age. I am in the process of building a version of the Fender Bassman. Nothing new I have built it before. I tore down on old amp that was not being used to salvage some parts. The build and parts recovery is kicking my butt. I don’t see out of one eye so depth is  issue. Can’t tell where the soldering iron tip is. At times I shake if my arms are not supported on something so the iron tip may go anywhere. Mentally I second guess my self a lot. This will probably be my last build. It has been along good run. I have loved every minute of it. The good and the bad. I turn 81 next month.

[PRR]

There's no shame in building-up a wrist-rest. A stack of 2x4s just taller than your chassis(stand). There's a pad in the garden store you can cut up for the top.
https://www.amazon.com/Kneeling-Pad-Comfort-Gardening-Exercise/dp/B0734KSZKS
https://www.amazon.com/Fiskars-94216974J-Ultralight-Kneeling-Cushion/dp/B0002YTVJA

One-eye aiming.... usually we want large uniform lighting on the work for all-around light with minimal shadows. But in your case you could try a single light at an odd high angle so you can tell by the shadow of the tip where it is to/fro. If your color discrimination is still good (not welder-burned) then one color for the spot light and another for a fill-light. Maybe only "Warm" vs "Cool" if your discrimination is excellent. Maybe a headlight--- waggle your head to see how the shadow falls.

When I had my cataracts out, I had been losing accommodation for a decade and realized the stock lens would only work for one distance. I had always been near sighted and wore glasses to drive. I got fixed for far-vision and now own a collection of "reading glasses", just like my friends (pick up the menu, drop it and go back to the car for specs). I have 1.5 for 24" (PC monitor), 2.0 for 19" (fine print), 3.5 for 12" (soldering and small stuff).

[labb]

Thanks for the tips. I’ll give them a try

[Platefire]

I use an automobile trouble light with a pretty hot bulb when I'm soldering. It has a clamp so you can attach it to a back of a chair close by and focus it in to the intended area. Like ya'll have had cataract surgery with the standard lens that Medicare allows. Far foresightedness was greatly improved but nearsightedness is better but still need help for small stuff. The optometrist said wait three months after surgery to give eyes time to adjust before ordering new glasses, so it's time now. Right now I'm down to two pair of glasses that I'm using for small stuff and a magnifying glass for super small. Not perfect but overall a lot better!!!!!

Congratulations Planobilly on the success of your amp! It's worth going through all the tweaking,
twist and tangles when you finally get it sounding and responding like your want

[Planobilly]

Large florescent overhead and a bright LED light under the cabinet.



What I have to put on. To much black writing on black plastic down in a black hole...lol



The doctor who owns the place and did the eye surgery wears reading glasses.

I think with cataract surgery it may not be possible to fix both near vision and far vision.

I got the 15" Supro speaker but I like the sound of my 12" pre Rola Celestian Greenback better.
 

[sluckey]

I think with cataract surgery it may not be possible to fix both near vision and far vision.

You can do mono vision. That's one eye for distance, one eye for close up. My wife has been doing that for about 20 years. So does my eye doctor. Sounds like it would drive me crazy. My wife and eye doctor seem sane enough and they both like it.

I had my cataract surgery last fall. I opted for distance vision and the more expensive lens that also correct astigmatism. Been pleased.

[PRR]

> may not be possible to fix both near vision and far vision.

Unless there is something I missed, the distance difference is just focus. First get a fair fix for "infinity", including astig if you need it and can afford it. Then figure what distance you want to work at (for seeing-size and alowing for arm length, soldering iron clearance, etc). Figure what focal length lens(es) to buy, remembering that eye-guys do meters and inverse fractions so normal folks are befuddled.

Either the surgeon or the eyeglass guy can help you with this, IF you know your working distances.

Dollar Tree used to sell cheap but functional reading glasses at... a dollar. They seem to have gone up a bit since supply chain crisis, but still a screaming deal. (Yes, they are decent optical quality; no frills and frames may not live long.)

[Loomer]

Have read through your recent threads with interest as I've been really enjoying every demo/sounclip of a few Supro amps, above all the Dual Tone and Coronado and, without wanting to get ahead of myself, I'm liking the idea of trying this out as a second build.

Out of curiosity, what's the headroom like on your build? A lot of demos focus on the cranked sound, but I think these seem to sound fantastic clean and right on the edge of breakup, with Fender worthy clean characteristics but a MUCH nicer breakup (I guess I'm just not a fan of Fender amps breaking up...!). Would I be right in thinking these give off a pretty clean sound up to at least halfway up the volume?