Alamo Paragon amp O.T. wiring

[Gtr_tech]

Silvertone and Valco used grid leak input stages on some models too. I can't stand it myself....but thats just me. Breaks up too early with a hot input and sounds kinda nasty when it does. You'll see this type of input stage used alot on old tube PA amps for the mic inputs.

[Mars Amp Repair]

Ahhh cool...and I have the bloody RCA Receiving tube manual to boot!

Grid leak bias must be used exclusively when the cathode goes to ground...only reason I can think they'd do this is to save on components or just a cheap way to design a hi gain low signal-in input stage. There also would have to be a coupling cap the way they describe it to provide a charge to build up the bias voltage from the input AC signal.

The true 'grid-leak' (not bias) resistor as I described it will be seen in a ckt with cathode bias & a high impedance input. You can also see the 1meg resistor to ground on the control grid of interstages that as I recall helps to keep the plate voltage from the previous stage from charging up the coupling cap & causing unwanted bias on the control grid.

I'm just recalling from my tube training back at RCA Institute of Electronics in NYC from about 1973!! Thanx for the info....g

[hasserl]

Reduction in parts is not the only reason, tone is also. Gtr tech may not like it, but plenty of other people do. It is a subjective value and individual preference is the only thing that matters.

Re the Paragon Bass, it's a great sounding amp IMO. I recall one evening here in my garage I had a fellow guitar player buddy over and we were just playing thru a bunch of amps, making a lot of noise and generally having a really great time at it. At one point we connected my Super Reverb and my Paragon Bass amp up thru an AB pedal and we sat and spent a lot of time just switching between the two amps, and we both ended up preferring the Paragon Bass. Everyone knows how good a Super Reverb is, great amps for sure. But in that situation, at that time and place, the Paragon Bass was the better amp. Better cleans, better overdrive, more interesting tones, more easily controlled with the guitar volume, just better overall. And that was with an old amp in need of service and new caps, 3 prong cord, etc.

[LowBassDub]

I worked on one of those a while back. If I remember correctly, it had Ultralinear taps on the OT. Is that one like that too? I actually drew up a schematic at the time. I'll see if I can find it again. Is that cab 2 12 inch speakers or 2 15's?

I wouldn't say no to you posting a schematic. I've got one of these, or something very similar, it's an Alamo, no model name, similar guts and tube complement. It's suffering from the dreaded red plating, on just one of the power tubes. I'm about to recap it, as the caps look original.

[gui_tarzan]

Does anyone have a copy of this schematic? It doesn't appear to be accessible anymore.

[gui_tarzan]

bump

[Theaxeman]

Mars Amp Repair

Alamo Paragon amp O.T. wiring
Well,
Look at this wiring diagram drawn from an originally wired Paragon amp. It kinda makes sense & then again...BUT it does work.

If you connect your load the 'rear jack', you'll need to measure output with a dual trace scope in the add mode, owing to the fact that both + and - speaker leads have signal on them.

The 6L6 cath resistor connected to the black (hot) side of the output transformer is rather perplexing. It is also the negative feedback tap, too. the cath resist is not bypassed & I guess as this is set up, it really couldn't be as it would shunt the output transformer secondary. I suppose if someone were to do a network analysis on this it might make more sense.

this information just FYI for anyone who might encounter one of these amps, as there doesn't seem to be a schematic to be had for this amp anywhere.
the rest of the amp is pretty much just a tube amp you can find your way through like any other.
the issue with this one was leaky coupling caps to the outputs as well as a few in the preamp that as the amp got hotter, would leak more & cause distortion.

Pardon my rough drawing. I have to use Excel & convert it to a PDF.
glen

Sorry about resurrecting an old thread, but I spoke with Mars Amp Repair just now about the Alamo Paragon wiring diagram that is in post #1 above.

He said he had sold his business and all the wiring diagrams etc. were sold with the business. He did suggest that I ask here on the forum, and someone probably downloaded it and would be willing to share it again.

If any of you have any wiring diagrams or schematics for the Alamo Paragon Amp, would you please upload it and share it again?

[gui_tarzan]

Ditto, I still need a copy of it.

[Theaxeman]

Ditto, I still need a copy of it.

I contacted Mars Amp Repair and even though he has since sold his business, he looked in his archives and sent it to me via email. His was in pdf format, so I opened it on my computer and took a picture of the screen.

I'll attempt to post it to the forum.

[g1]

Please zip the pdf file and post as zip attachment.

[Theaxeman]

Please zip the pdf file and post as zip attachment.

Will this forum allow me to upload directly as a zip file and post it?

If so, I'll be happy to do that.

[Theaxeman]

Paragon - OT wiring.zip

I think that might have done it.

Hope it works!!