Supro Identification

[01redcobra]

I need a bit of help here in identifying an early 50's Supro. Apparently has 2-6V6 tubes, but I'm not sure of the rest. Thanks in advance!

[EFK]

That's one version of the "Supreme" circuit, 10" speaker. There were approx. 3 or 4 versions of that circuit over the years, you'll have to go through the tube lineup and match it to one of the schematics. The earliest version had only a volume, no tone, and the last version w/ 6973 output did not utilize a field coil or octal preamp as yours does. By the later 50s octal version they had also done away with the grid cap tube and were 6SQ7 into 6SC7, so your is 1948-1954 or 55 era probably, iirc 6J7 into 6SC7 just off the top of my head? All versions of these are great sounding little amps, they really are.

Oops - had to edit, meant to write 'Supreme' as that's what it is. Model 1600B. I've got a schematic for that one exactly, have to figure out how to post it.

[soundguruman]

Valco Chicago made these amps for Supro. This looks like Model 51 Valco. But I can't really see the model number...
It has a field coil speaker (the speaker has high voltage so don't shock yourself)
It is very similar to an amp called: "Oahu." Also made by Valco, and sold in Hawaii.
(the Oahu amp has a different grill, with a Palm Tree Logo, but basically the same amp)

You will notice that these amps had several different grill designs...and several types of grill cloth...
But they are the same amp chassis, with different names attached to the grill...

One more of these was sold by "NATIONAL."
but it's still the same amp...Valco...Supro...National...all made in the same place - and sold by different companies with different names attached to it.

Here is the schematic that matches it:
valco51.pdf

These amps were primarily intended for electric lap steel guitars...or a microphone.

You will NOTE: that the input jacks say "instruments," and not "microphone."
Technically it's a guitar amp. In fact, one of the first guitar amps.

Hawaiian music used to be the most popular in the world.
These companies cashed in on it, by manufacturing a matching amp and Lap Steel Guitar, as a set.
So, this amp was originally paired with a matching lap steel guitar, probably.

But what you are looking at is the dawn of guitar amps. One of the first guitar amps, that predates Leo Fender's amps.
This makes the amp pretty collectable. It has major Mojo, extremely cool.

Leo Fender did not invent the guitar amp. Although many people say that he did...that's not really correct.
Guitar amp probably first invented by Rickenbacker, Valco popped up shortly afterwords.
Then came Fender a few years later...

And it's from the early 1940's probably. The field coil speaker was used in amps during the late 1930s and early 1940s.
The field coil is helpful in finding the approximate age.

These amps sound really great when they are working. They have a really distinct tone.
A lot of that because of the field coil speaker.
They are great for Blues Harp...sought after by harmonica players.

The 6J7 pentode preamp tube grinds like a chainsaw. 6J7 has a really nice gritty overdrive sound, and lots of gain.
That's a big plus for a Blues harp amp....

So, as far as fixing it or rebuilding it, you should keep it as original as possible.
Try to preserve the original parts. Avoid mass replacements...

I really love these amps. Some of my favorites for sure. Really great tone.
One of the very best and coolest of all guitar amps, according to ME.

I have restored a few of them, but they are rare. Most of them are all torn up.
This one appears to be in very good condition. A KEEPER for sure!

[EFK]

Here's the schem for the version that you have. The 1600B was the version immediately prior to yours with just a volume, then a tone control was added which is what you have. And I will definitely echo what soundguruman posted above, other than standard service type stuff i.e. add a grounded AC cord and address the filter caps and any cap that's badly leaking, it's best to leave it as original as possible. It'll sound the best that way anyway!

[soundguruman]

I need a bit of help here in identifying an early 50's Supro. Apparently has 2-6V6 tubes, but I'm not sure of the rest. Thanks in advance!

[ATTACH=CONFIG]27662[/ATTACH][ATTACH=CONFIG]27663[/ATTACH]

It's 1940s NOT 50s. I am guessing early 1940s based on others I have worked on.
AND the field coil speaker pegs it to early 1940s also.
Also, metal 6J7 tube, joint Army Navy Issue (JAN), is pre-1950s.

Inexperienced people tend to tear these amps up...
they try to replace all the parts...bad idea.
Overhauling the coupling caps and resistors makes the sound crappy.
Keep as many parts as possible original as possible.

Don't change the speaker or try to convert it to a modern speaker.

Power supply filter capacitors - will need to be changed usually...but the rest of the parts will function, a lot of times...OK.
That's why you should keep the old parts.

Even the power supply caps still work OK in several of these. YUP it might be OK still yet.
I have seen 2 of these, where the caps still worked OK.

Grounded power cord - OK well I give you that much. Probably a good idea.

[EFK]

Hey not trying to argue with you too much but these particular amps did not incorporate tone controls until the very late 1940s, I think around 1947-48 at the earliest. The power transformer dates it to the 7th week of 1951 (in 1941 they were not 166--- coded) and the X serial number on the amp is early 1950s. Those 550-3 (the 550 code means Valco Mfg., the 3 is the internal code for the speaker) coded Rola speakers with field coils were used as late as 53-54, possibly a bit later. I just sold a National version of this last month which was 1953 with exactly the same speaker, although mine did away with the 6J7 for the 6SQ7. Once they did away with the field coil, they still maintained the same 550-3 code for the 10" Rola speakers up until the point Valco went to Jensens around 1962.

Interestingly enough, there were Gretsch branded versions of these which used a 6SJ7 strapped as a triode after Valco did away with the 6J7 but before the 6SQ7 was subbed. However, I have never ever seen a Supro or National or any of the other brands with that intermediate tube between the two versions. Very odd.

[01redcobra]

Thanks for all the info. The amp belongs to a customer of mine and I have yet to actually see it. He's bringing it in because he says it won't power up and we've already agree to keep it as original as possible. I'll keep you updated once it arrives and I find out what's going on.

[AndyMarshall]

I have 3 of these exact amps, and they are, without a doubt, built in 1950 and 1951. I love them.

[HaroldBrooks]

I need a bit of help here in identifying an early 50's Supro. Apparently has 2-6V6 tubes, but I'm not sure of the rest. Thanks in advance!

[ATTACH=CONFIG]27662[/ATTACH][ATTACH=CONFIG]27663[/ATTACH]

I also have three of those amps, the older version with no tone control, the ancient early 1940's version, and one other with a tone control from 1955, but that last one it uses a 6SQ7 tube and bigger coupling caps after the phase inverter. Sound fantastic, all Three of them !

Those are my Favorite Valco amps of all time, and in my top 10 of all amps in the universe.

Here's one screaming on Youtube ! :

And another :

And another (this one is a bit "Far out" but shows some of the versatility !) :

[Old tubes 56]

Wow. I am new to this forum and I have learned alot already. I have what I believe is late 30s to early 40s Supro. It only has two inputs, one volume, round cabinet oak, round speaker. I have pictures but I can't figure out how to post them on here yet. I inherited it from my Dad who said he brought it home from the Hawaiian Islands after serving in the US Army.