Woodward-Schumacher specs

[Colossal]

Does anyone have or know if there is a collection of specifications for 1960s era Woodward-Schumacher OTs and PTs somewhere?? I called them yesterday and although the person relaying their response to me said they had a guy on staff that knew exactly what I was asking for (I explained I was a guitar amp geek tracking down some specs on an old OEM part), they said they did not have the information on hand and instead gave me numbers to Advance and Phillips Lighting to call with no other explanation. I gave up waiting on hold with Phillips and didn't get a hold of Advance.

I want to find out the secondary voltages on a particular PT and primaries on a particular OT.

Thanks for any leads on this.

[Richie]

do you have the transformer numbers?

[Colossal]

Thanks for the reply Richie.

Yes, these were made for Magnatone.

Pieces start with 606 (Schumacher's EIA number), then the date code (YWEEK e.g. 921 = 1959 21st week)

PT
#6206
OT
#6107
#6217

[Phil_S]

Call them back and see if you can pry loose an email address for someone who might care enough about what you are doing to reply.

I once got a reply from another manufacturer on an old Heath PT. I was fairly amazed. The guy wanted to scan and email all the specs and whatnot that he managed to find in the archive, but I managed to dampen his enthusiasm enough to get him to just write down the winding specs -- voltage and mA and wire color -- which he gladly did.

[Richie]

the trubador or model 213 tonemaster used a couple of those.
I'll have to find the 6217.
but the others, and i would also say more like 15 to 18 watts..
but this should give you a clue. the magnatone group may have info on them.
Or look up the amp models schem, which should show voltages etc, which could be helpful. The tonemaster is highly sought after for being a rocking little amp.
Sometimes also old transformers had cross ref. And you could maybe find another company that had similar specs that crossed or used as replacement.
Power Tubes
•2 x 6V6GT
Power Output
•20 Watts
Preamp Tubes
•3 x 12AX7
•1 x 12AU7
Rectifier•5V4-G Tube
Transformers
•Power Transformer
Woodward-Schumacher 606 934
# 6206
•Output Transformer
Woodward-Schumacher 606 918
# 6107

[Colossal]

Yes, that's what I'm researching right now, the Troubador family. Unfortunately, none of the available schematics show the actual PT secondary voltages but there are some clues...

2x6V6
370V plates
330V screens
21V cathode (250R/20uF 25V bias)
5Y3 rectified

On the OT, I have seen one with 5k and another with 6k5 primaries. I think the correct/more prevalent one would be 6k5.

[Prairie Dawg]

There are some good old replacement transformer catalogs on the bunker of doom website. I use them often. Not Schumacher but I suspect what you have there are OEM type iron. You're pretty close to having it figured out.

This'll help:

http://www.hammondmfg.com/pdf/5c007.pdf

http://www.bunkerofdoom.com/xfm/index.html

[Richie]

The Estey 413, [same amp] shows the schem voltages on the amp.

That amp has the 6av6 and uses the 5y3. And the PT shows a 117v transformer. So in todays world it would be putting out a few more volts than the schem is showing.

Also that amp, as i'm sure you know is the Evil Robot PhilX thing copy.
Some other models sub in a different tube. The one that uses the 6av6 is the one that is he uses.
http://www.youtube.com/watch?v=NRnXiHGQBSs

[Chad]

http://www.bunkerofdoom.com/xfm/index.html

I looked at the website for a little while and it seems like a cool site. I have bookmarked it. Thanks Dawg, Chad

[Colossal]

The Estey 413, [same amp] shows the schem voltages on the amp.

That's where I derived the voltages from

So in todays world it would be putting out a few more volts than the schem is showing.

That's the trick. That amp would have been running on 110V and with a 5Y3 to arrive at 370V on the plates. So yeah, to just use a clone PT would result in voltages that are way to high across the board. Usually 5Y3s sag a good bit of voltage, almost 1:1 or 1.03:1 IIRC.

Also that amp, as i'm sure you know is the Evil Robot PhilX thing copy.
Some other models sub in a different tube. The one that uses the 6av6 is the one that is he uses.
http://www.youtube.com/watch?v=NRnXiHGQBSs

haha, yes, love the PhilX stuff! There's magic in that amp and plenty in his hands too.

Check out this load line. This is based on 285V screens so the current has not been extrapolated for the 214/413's 330V screens but I'll call that close enough. This is for a 6k5 load which I think that OT-in-question is. I get 8.9Wrms per tube before clipping so that is right on par with the amp's output of 18-20W. Tube is smokin' though...

Does this seem reasonable?? The load was figured 400/(6500/4)= 246mA, then the line was fit through the idle point at the known plate voltage of 370V. Looks like some of the later Champs that ran 330-0-330.

The amp has a cathodyne PI biased to just -4V. I get 1.5mA max plate current for it.

EDIT: Load line removed.

[martin manning]

Yes, that's what I'm researching right now, the Troubador family. Unfortunately, none of the available schematics show the actual PT secondary voltages but there are some clues...

2x6V6
370V plates
330V screens
21V cathode (250R/20uF 25V bias)
5Y3 rectified

On the OT, I have seen one with 5k and another with 6k5 primaries. I think the correct/more prevalent one would be 6k5.

If I start from the voltages above, my first question is with the cathode resistor and voltage. With 21V across 250R you have 84mA, which seems way to high for a pait of 6V6's.

If I accept the Vk of 21V and Va of 370V, that means Va-k is 349V. A reasonable bias point for cathode bias might be as high as 85% of the 12W max plate dissipation, which would say Ia should be (0.85 x 12)/349 = !a, or Ia = 29mA. Rk should really be more like 21/(2 x 0.029) = 360R. Throwing in another 5% for screen current would take it down to 345R. The (GE) data sheet isn't much help here because the plate curves are shown for 250V screen voltage and the mutual characteristics are shown for 250V plate v0ltage.

Going with that and the 6k5 primary impedance, plus assuming a 60V drop for the 5Y3, I think the PT should be 320-0-320 @ 150mA, and at least 3A for the 6.3VAC, and 2A for the 5VAC.

A Hammond 290BX (Deluxe Reverb replacement) should work, although it's 330-0-330.
http://www.tubesandmore.com/sites/defau ... b290bx.pdf
Deluxe Reverb OT, at 6k6, would seem to be fine for this too.

[Colossal]

Yes, that's what I'm researching right now, the Troubador family. Unfortunately, none of the available schematics show the actual PT secondary voltages but there are some clues...

2x6V6
370V plates
330V screens
21V cathode (250R/20uF 25V bias)
5Y3 rectified

On the OT, I have seen one with 5k and another with 6k5 primaries. I think the correct/more prevalent one would be 6k5.

If I start from the voltages above, my first question is with the cathode resistor and voltage. With 21V across 250R you have 84mA, which seems way to high for a pait of 6V6's.

I know, it's crazy. Those are the published values. I've seen outlandish data on some of these old schematics which, when fitted to a load line, make you scratch your head and question whether you made a mistake or not. Makes you think there's either a typo or they had bulletproof tubes or just did things willy-nilly and somehow got by with it.

If I accept the Vk of 21V and Va of 370V, that means Va-k is 349V. A reasonable bias point for cathode bias might be as high as 85% of the 12W max plate dissipation, which would say Ia should be (0.85 x 12)/349 = !a, or Ia = 29mA. Rk should really be more like 21/(2 x 0.029) = 360R. Throwing in another 5% for screen current would take it down to 345R. The (GE) data sheet isn't much help here because the plate curves are shown for 250V screen voltage and the mutual characteristics are shown for 250V plate v0ltage.

Pretty much every 2x6V6 power amp in that family of amps all have 250R as the published value for Rk. I ran into some similar confusion in trying to suss out some information on Champs, same thing. You see these ridiculously high voltages on some of these amps that by the math should be melting glass.

Going with that and the 6k5 primary impedance, plus assuming a 60V drop for the 5Y3, I think the PT should be 320-0-320 @ 150mA, and at least 3A for the 6.3VAC, and 2A for the 5VAC.

Thanks for the sanity check Martin. That's what it looks like to me, like a push-pull Champ power section. I read that those Magnatones were supposed to be running in Class A P/P but under the conditions above and my crude estimates that it's running Class AB. Plus, if it's really putting out 18-20W, then it's not running Class A. If the cathode resistor is really 250R and the load 6k5, then I'm wondering if the PT is running much lower and those values of 370V plates and 330V screens are a typo.

Of course, I don't have one of these to take voltages from That's why I wanted to find out what the secondaries were for Schumacher #6206.

[martin manning]

Go here: http://support.fender.com/schematics/gu ... ematic.pdf

The '57 Deluxe is running ~370V on the plates, and 320V on the screens, and it has a 250R cathode resistor. Cathode voltage is listed at 21.2. So, Fender is really doing that with new production tubes. The load might be either 6k6 or 8K, but that doesn't matter for the idle point. With this hot bias it runs in class A up to about half-power.

BTW when you plot the load lines, the class B load line goes from Va-k at zero current to Ia = Va-k/(Zaa/4) at Va-k = 0. Then the class A load line has half the slope (Zaa/2 since both sides are conducting) and passes through the idle point at (Va-k, Ia).

[surfsup]

Philips lighting??? I work in their building...

[Colossal]

Philips lighting??? I work in their building...

Dude! Gather some intel!

Seriously, I have no idea why Schumacher would send me to Philips unless they somehow have their old records. Half the fun in researching these old amps are the snipe hunts