Supro push pull point to point diagram

[Johnnydoright]

Hello. i have a Supro that I am trying to locate a schematic for.  I'm not sure what year it is. what I do know is there is a serial number plate in the cabinet T34155.
The wiring is point to point.
The speaker is a 1500 ohm field coil speaker
The tube compiment is 12AX7 x 3, 6973 power tubes x2, with a 5Y3 rectifier
The amp has 2 channels, marked channel 1 and 2. 2 inputs each. One marked "TREBLE" and one marked "REGULAR".
Channel 2 is a  TREMOLO channel, with INTENSITY and SPEED controls. The speed control has an on/off switch
As it has 12AX7 preamp tubes, i am guessing it was constructed after 1946, which about the time that tube was introduced.
The amp has no output, but powers up and does not blow fuses. I plugged it into a current limiter, and there is a glow from the 150 watt bulb in it, so i don't think there is anything shorted.
i have found a wire not connected that connects to pin 9 on the first 6973, but am not sure where the other end should connect.
Any information would be most appreciated. Thanks so much.
John

[scstill]

Might be made by Valco
this has the tubes but not field coil
https://el34world.com/charts/Schematics/files/Valco/Supro_s6424.pdf
Looks like Pin 9 connects plate to OT. Sure wouldn't get output without that connected. :-)

Can you post some pictures?

BTW - Google says 12ax7 was released in Dec 7 '48 (7yrs after Pearl Harbor) so shouldn't be older than that

[Johnnydoright]

Sorry, still trying to a climate to the site. I will try again later.  Been scouring the files too long and I am cooked. Thanks.

[Johnnydoright]

Here are a couple more pictures of the Super. Anyone that has any ideas about what model it is.  The tubes are the same as the S6424 I believe, but I find nothing with a field coil speaker.

[Johnnydoright]

Trying to add a front picture

[sluckey]

Since you only have one tone control I would think the circuit is the 1624T rather than the two tone circuit of the 6424. However, the field coil speaker does not fit the time frame of the amp. Neither does that cab. I wonder if someone has created a one of a kind oddball?

     https://el34world.com/charts/Schematics/files/Supro/Supro_1624t_schematic_263.pdf

[Johnnydoright]

Thanks Steve! That is my thought exactly. I would like to get the amp working, but the 12AX7s and field coil speaker really don't belong in the same amp. Also, the fact that it is point to point makes it somewhat tedious to follow, for someone like me with limited experience.  I spent most of the day yesterday looking through the library, but did not find anything that is like this. The chassis is clearly marked for the correct tubes, and the cabinet looks like a Supro cabinet, but there are quite a few inconsistencies. I will take another look at the 1624. Were the early Valco amps point to point wired?  I know the company was founded early on ( 1930 something) , but its a lot tougher to find information on their older amps. I mean, I am used to the old Fender stuff, where you type in the model and 30 hits pop up😊.
That said, I am not going to give up on this little amp. I do have a Magnavox 8 ohm speaker, so I suppose I could get an O/T and see about converting it, I just worry that I might be messing up a really classic vintage amp.
Thanks for your input, I enjoyed your Supro build, and would not have probably seen bit if not for this little amp.
John

[sluckey]

Those Valco/Supro amps were P2P wiring. I really think the chassis is a 1624T that has a slight mod to power that field coil speaker. BTW, not sure, but I doubt Valco would have used a Magnavox speaker. The 1624T was a late '50s or early '60s era and field coils were a thing of the past at that time. The OT would have been mounted on the speaker frame for a 1624T. Look closely at the terminal strip where the wires from the speaker assemble connect to the amp. Does the wiring/soldering look original or is there evidence of later soldering? If the soldering all looks original, you may just have a real one of a kind Supro. I sure can't find any evidence of such an amp on the net.

[Johnnydoright]

Nor can I find a trace of information. It looks like there has been some work done, the soldering is not the cleanest i have seen, so  I suspect the amp is modified, for what reason i do not know...all the 1624t models I found on the internet look just like this chassis, so i am going to say you are most likely correct on that.  i saw a 1959 1624t that looked very much like this amp. I wish I knew more about this stuff.  I have been building for a couple years, so do not consider myself very  experienced. I will press on and try to sort it out. Thanks so much for the input. you have been a lot of help.
John

[scstill]

Here is a Reverb listed 1624
https://reverb.com/item/54615884-1963-supro-valco-model-1624t-combo-amp
The control panel of this 1624 looks different than the one you posted here.
There are three controls with large knobs in your middle cannot read what they are marked.

Did you connect Pin 9 to the OT?

[sluckey]

I found some decent pics of a 1960 Supro 1624T. Chassis sure looks like your chassis. Take a look...

     https://trcrandall.com/products/1960-supro-1624t

I would like for you to set up your amp for a couple more hi-rez well-lit pics. Try to duplicate the inside chassis view of the amp above. Use plenty of lighting. I want to do a side by side comparison.

[sluckey]

I found your amp!

https://reverb.com/item/307297-1959-supro-1624t-dual-tone-vintage-valco-usa-1x12-tube-amplifier-rola-jimmy-page

[scstill]

Nice, Love these old Supros. Recall I am scratch building a 1696TN
Where would they have placed the model number on this one?
And why is it so different than the 1624 link I posted earlier (also on reverb)?

[sluckey]

Nice, Love these old Supros. Recall I am scratch building a 1696TN
Where would they have placed the model number on this one?
And why is it so different than the 1624 link I posted earlier (also on reverb)?

No clue about the 1696TN

The last 1624T I posted was a 1959 model. They did a big cosmetic change in 1960.

[Johnnydoright]

Steve. I did connect the output transformer wires. Also located another wire at the speaker that was not soldered and repaired it. Its a miracle! It actually works. I have been sweating bullets for the last 3 days because this is not my amp. It belongs to the keyboard player in my band. He told me he had an old amp, that hasn't worked since he got it, and like the idiot that I am I told him I would take a look. I replaced the cap can, because they were shot, and to do that I had to pull the chassis out of the cabinet. Also tested the preamp tubes (my little 5F2 clone is good for that) they were good. When I initially got the amp going today, I was elated. I have had it apart for a few days and was starting to wonder.  Anyway, once it made some sound, and the current limiter was not blinding me I figured I deserve to play a few minutes through it. I plugged in a guitar, but the output seemed poor. Thin, and no real drive. Since I had ordered a new matched set of tubes, I figured I might as well.plug them in.. That's when I discovered the switch is not working correctly. I have told my friend that I would prefer to install a grounded cord, but he was reluctant. Well if he lets me replace the switch, he's getting the grounded cord too.. Anyway the amp is operational, and sounds pretty good. There is a little hum, I suspect from the field coil speaker, but it sounds very much like the guitar does on the first led well pin album. I'm marking this as a success. Many thanks for all your help with this. Doug has created a great forum here.. I have to go check out the amp you found, 1959 1624t? That was the closest I came on my search .

[bmccowan]

One of my goals is to sell one of my Valco amps without mentioning Jimmy Page.
Cool amp - I have a Vega V70 labelled Valco that has a larger version of that style cab and chassis - same knobs too - its 2x6L6/7027 with a 15" speaker. Pretty much identical to a Supro 1695T.
Given that your amp did not originally come with a field coil speaker - I would proceed carefully. I would also return it to its original spec. Vintage Rola speakers are pretty easy to find, but a Weber would sound great in that amp. Hammond or Musical Power will have an OT that would work.
That amp is not far away from being a valuable amp. Jimmy Page or not.

[PRR]

....6973....

6973 appeared 12.Aug.1957. (Or 6CZ5 05.Nov.1956)

I could almost accept 12AX7 with a field coil in a factory amp, but not a 6973 from 1957 in a wall-power amp. (Car radios "could" have FC even later, in trailing-edge products.)