50s Stancor - Anyone have any info on these amps?

[MCK]

Saw this on eBay while looking for Stancor OTs for an express and bought it on impulse. The recorded video sounds good to me so I am quite ok to use it as is but also interested in modding it to use its bits in a future wreck-inspired build perhaps. Now waiting for delivery.

Anyone have any insight into these amps? I know this is like fishing in the ocean so thanks in advance if you have anything to share.
Appreciate your help.

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0423875081

[David Root]

I bet the iron is good. What are the power tubes? That seems a lot for one of these old PA amps, but I'm not up to date on these, this type of amp used to go for $50.00 or so a few years back.

A lot of these amps had the schematic pasted on the inside somewhere. You might get lucky. If not you can always draw it up youreslf. Stancor did have catalogs on their amps, I saw a 1941 Stancor amp catalog for sale on vacuumtubes.com.

[MCK]

David, thanks for your kind reply. Will post photos & diagram when I receive it. I agree price went a little over what I wanted to pay. I wasn't even shopping for this. I saw a Stancor 3801 which I was trying to get for a future express build, couldn't get the 3801 and at the same time got tempted into this one. I'm sure it'll be good fun to play with it and learn along the way.

[MCK]

Ok. Amp received and is working well. Very loud for its size and runs real hot. Great tones as it is though. I decided to add a VVR on it using Dana's kits but first I need to analyze it so I know which type to order. Don't care so much for original looks but as luck would have it there are two volume pots in the faceplate (1 x mix + 1 x phono) so the one not doing a thing for me while playing the guitar can take the VVR... Also considering putting in an express like preamp in there and push it over the edge.

Just want to see what happens if a total noob starts mixing it up. Life insurance, check. In I go!!!

[MCK]

I bet the iron is good. What are the power tubes?

It has

2 x 6SL7GT (Sylvania) Preamp Tubes
2 x 6V6GT Power Tubes
1 x 5Y3GT (RCA) Rectifier Tube

Power tubes don't have a brand on them but a print that says when needed replace with Emerson tubes bla bla. Black top tubes.

Here are some photos of the innards. The OT is marked Stancor but no code I could see so far. PT is marked FREED 14698, Brooklyn NY, USA

Caps don't seem to have any leaks and no sign of abuse anywhere. Looks like the genuine deal.

Next starts the schematic prep work but in all honesty looking at the guts of this guy I am wondering if its a good idea touching it. Such cramped P2P installation can only work if you do it everyday.

What do you think? Can I make this thing interesting while keeping its basic design intact? I would get rid of all the phono input junk and associated stuff so that would clear the circuit up a bit. Thoughts?

[MCK]

Wow. Certainly is a pack of noodles in there. Just to document it I might end up damaging a lot. Wondering if this was a bad idea...

[Structo]

That is a pretty clean amp, looks all original.

The first thing I would do is install a three prong cord for safety.

Did you find a schematic for it?

[jaysg]

The schematic should have been glued to the bottom plate...that was the typical method at the time. Has it been removed...does it look like the amplifier has been modified? It seems like the tones on the video clip are unlikely for a phonograph amp, even on the MIC input.

[MCK]

Structo, JaySG,

Thanks for your replies. The bottom plate has a yellow paper talking about licenses in how this amp can be used etc but does not have the schematic. I was not lucky I suppose.

Pretty sure all is original. The only thing that looks perhaps out of place is the 1/4 input jack. The metal color is very new and does not match the rest of the set but other than that all is standard.

I agree the tone on the video is unlikely to come out of the amp in an un modified state. I asked the seller the question again and he claims he did not have any overdrive etc on the line at the time of the shoot. He claims the amp was turned way up and recorded like that with a camera which has built in compression. Be that as it may, I maxed volume and still couldn't get it to distort so well with my LP using humbuckers. Since the video had a Strat I would imagine the chances of that level of distortion to be lower. Oh well. It distorts but not quite like that on the video.

I tried looking up the Mesa V-Twin preamp I have to this guy and the results were quite good actually. So if preamp section is bumped up then there might still be some good times left in this old girl.

I could also simply implement the 3 wire for safety & VVR for sanity at home and then keep it as is and drive it with an OD pedal when required. Not sure yet how much appetite I have to dig into this one. It might be easier to simply build something ground up and leave this as a clean sound amp.

I could not see any bias pot on the circuit so I'm thinking this is a cathode biased unit. Do you agree?

[MCK]

I dug up this old amp I had in storage and brought back this zombie thread!

Its a nice 6V6 push pull platform. Its working as is but with the original caps I doubt it will keep going for much longer. Option to keep circuit as is and make safe with a 3 prong vs gut it out and make something more interesting...

What would you build with a 2 x octal pre + 2 x 6V6 + 1 x 5Y3 rectifier recipe?

Not expecting to turn this into a miracle amp. Simply looking for ideas on what to build in order to continue learning and improve my understanding of circuit design etc. Thanks for your help.

[Cliff Schecht]

MCK the 5B3 I just finished was made from a 50's Arkay A-12 hi-fi unit. It looks nearly identical to what you have (mine might be smaller, I only have 4 octal holes in the front not 5). But still I found enough room to fit in a turret board and wire the thing up in a cleaner fashion than they did in the 50's. If you plan everything out well enough then you can easily fit in a Deluxe tweed type amp or even a BF with octals (what I was going to do but the PT wouldn't give enough B+).

I'll post some pics later, it might help you decide what you want to do layout-wise yourself. FWIW as I warned in the other thread you have to be extra careful with lead dress with the 6S*7 types of tubes. They don't have humbucking filaments and are more prone to microphonics and noise. You might have to sort through a batch to find a good one or just use adapters to fit in 9-pin sockets.

[xtian]

I recently finished a similar build. A 5e3 "Deluxe" 15 watt amp. See my thread: https://tubeamparchive.com/viewtopic.php?t=16996

[MCK]

I'll post some pics later, it might help you decide what you want to do layout-wise yourself.

Super. Thank you so very much! Right now I am inclined towards taking out the PtP stuff and going turretboard as well. Your layout would be of great help. Appreciate your posting the photos.

I recently finished a similar build. A 5e3 "Deluxe" 15 watt amp. See my thread: https://tubeamparchive.com/viewtopic.php?t=16996

Going there right now. Thanks much for the idea and link.

[MCK]

Just fired it as it is one more time to see how it is doing... Still works. Old caps and all, still works. Very low noise. Not too bad sounding either especially when dimed! Still, I want to gut it and redo it from ground up. Maybe I'll regret it but hey...

[MCK]

Oh and I measured 315V at the plates with my CompuBias. It showed 10.5 to 11.5 watts on the tubes which is a little hot for 6V6. In terms of making a decision for the PT where does this put me? 5B3 or 5E3 still ok?