Tube Amp Archive

Oh I get it... a voltage regulator!

Doesn't it take all sorts of calculations to figure what resistors to palce on either side to get to value?

also - could I just use a little 117x 6.3 volt tranny to run the HT's?

How would I wire that up? Just splice it into the power cord and ground?

Hate to show my total ignorance but what an LM317

It's from a 50 Watt SD 84-50

I have a black output tranny from a 50 watt amp with the following numbers and writing on it:

OIN - TRAN 3011
30 - 8815


Any way to ID it?

Yeah - but it's not that simple because those filaments start out life at 25V not 12. It's been suggested that I get new appropriate iron from mosse. Guess that's what I'll have to do. Any ideas what this crazy SD PT might work for project wise?

I did find out that this is a 50 watt tranny too

Also - I have only two IN 4007's on hand, but also 4 IN4005's. Could I use the 4007's with the 4005's and get aways with it? Can you even intermix diodes like that? If not, can I just use all IN 4005's? I think they are rated to 600V.

Okay guys, I think I have a tranny that will work perfectly if I can just figure out what the HT voltage is. But I don't have the tranny specs, just a schematic of the circuit it came out of that I will attach here for you all to see. The filaments are shown as + and - 12V. But thats after going thr...

I'm not a guru by any means but I remember Mr. Weber saying that the 5E3 is bad humming waiting to happen. It's an oscillation nightmare that sits on the edge of hum all the time. I just can't remember what he said to do about it, but I have the book he wrote that in and will try and find the excerp...

Actually, the larger question now becomes completely different than my original one. Looking at the schematic I attached, that winding isn't 12volts at all. It ends up being 12 volts after running through diodes and resistors right? What I really need to know is what the actual voltage is right now ...

Here's the rectification for the SD 84-50 what's weird is you can see it's got IN4004 diodes for the filaments full wave rectifier, but going down the page you can see there are IN4007 diodes for the primary's. And it's not full wave - right? Isn't that drawing depicting just two IN4007's? Yes-it is...

and if the plate voltages were 100volt higher on the SD 84-50, how do I get rid of that voltage? Can I change resistor value to get there? What else could I do? Yes, the SDwas harsh and it's OD channels unuseable in my mind.

So if I follow you right, then disconnect the Ht wires I would normally put into pin 9 of the 12ax7's and put them into pin 4, then leave the EL84's as normal.

I'm planning on trying to pull iron out of an old seymour duncan 84-50 head for a Liverpool clone. But the PT has a 12Volt winding instead of the 6 volt or 6.3 volt winding for the lamp and tubes. Is there a way to setp that voltage down with a resisitor? I know this is probably a stupid question an...