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Old Guild amp - what have I got?

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  • Old Guild amp - what have I got?

    No pictures, I'll get some upp if I can.

    Says Guild MAster AMp, but doesn't come close to the schemo at Schematic Heaven by that name.

    2x12 Jensen alnicos

    The thing is pristine. Literally owned by an old lady who had it in a closet for 40 years. THing appears to be from 1955 or so. Two tone cab. Upper half is a blond coarse fabric. I'd call it tweed except that isn't the pattern of it. The pattern is tiny little "V" shapes in alternating darker and lighter tan. It is beautiful. Imagine looking at the surface of a coarse wood rasp, but purty colors.

    Lower half is fake wood grain - for all the world, shelf paper. I'd think someone covered it, but the job is extremely neat and includes the rear panel

    CHrome panel is perfect, biggish pointer knobs. FOur inputs. One is accordian/mic, while 2,3,4 are instruments, 3 and 4 labelled recording. VOlume control for 1 and one for 2,3,4. Bass and treble and two knobs for trem controls. Rotary power switch for standby and on, like old Gobsons, but the third position is "tweeters off". The thing has tweeters!

    Under the hood there are a couple 12AX7s, but the most noticable feature is the row of SIX 50L6 output tubes. There appears to be two separate sets of speakers, but a common OT. There is no power transformer. A couple largish selenium rectifiers work right off the mains.

    Nice brown canvas cover is fleece lined. Reminds me of old Hammond organ cover material, same stuff for Leslie covers. This amp cover even has a large zipper down the center of one end to make it easier to put on.

    WHat is this thing?
    Education is what you're left with after you have forgotten what you have learned.

  • #2
    Enzo,

    I think this may be the 1-12 version - cool!



    Couldn't find a print, though. SIX 50L6's?! That's gotta be the most powerful guitar amp available at that time.

    Ray

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    • #3
      I have one with a worn-out chassis......the speakers sound pretty good (had to have them reconed as the cones were rotted, and I use it as a cabinet for an Epiphone Valve Junior head......never have connected the tweeters.

      Comment


      • #4
        also, be careful using it; with no power tranformer, it uses wall-voltage for the output tubes and the chassis a potential shock hazard....and those selenium diodes should be replaced.....

        Comment


        • #5
          Ray, yes that is exactly what it looks like, but a 2x12 - and two little tweeters. The ipper tweed ib your photo is a sort of basket weave pattern, which is a different detail. But that is what it looks like.

          TD, thanks, yes I am quite aware of the safety issues. There are two large selenium bridges, and a small one. Don't know what for yet, I'd be guessing bias, but who knows.

          AC power cord is stiff and cracked. The seleniums need to go.

          If you have ever smelled a burnt selenium rectifier, it is an aroma you will remember all you life. These days they are antiques, but when I was a kid learning, they were the cool replacements for recto tubes. Still have a box of them somewhere. Smells sorta like burning rotten cabbage. Sorta.
          Education is what you're left with after you have forgotten what you have learned.

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          • #6
            Not a big fan of power direct. Usually tube filiaments in some series order.

            I would install a power tranny an reconfigure the tubes.

            Probably no massive distortion during those days

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            • #7
              An iso transformer would be a good idea, but I am restoring it with vintage value in mind. The guy already has serious money offers for it. SO I want to keep it as close to stock as possible.
              Education is what you're left with after you have forgotten what you have learned.

              Comment


              • #8
                Enzo,

                Maybe not for this amp, but I had an idea for making these kinds of amps a bit less hazardous in most cases; replacing the stock AC plug (if unpolarized) with a polarized one, neutral to chassis. It would only be as "safe" as the outlet it was used with, but it should still be way safer than the stock '50/50 luck-of-the-draw' deal.

                Ray

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                • #9
                  wow, somebody is offering big $$ for that thing? No doubt the jensens are the reason. I had the one rotted-cone one reconed by Weber to BlueDog specs....

                  Might be good as a jazz amp.

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                  • #10
                    I'd have to think the fact that it is 50 years old, in great shape, and certainly not common might be a large part of it beyond the speakers.
                    Education is what you're left with after you have forgotten what you have learned.

                    Comment


                    • #11
                      Originally posted by Enzo
                      An iso transformer would be a good idea, but I am restoring it with vintage value in mind. The guy already has serious money offers for it. SO I want to keep it as close to stock as possible.
                      Enzo- Do they make isolating transformers that would plug in between the wall and the amp? If not you could make one in a metal box and sell it to the customer.

                      Just a thought

                      Steve Ahola
                      The Blue Guitar
                      www.blueguitar.org
                      Some recordings:
                      https://soundcloud.com/sssteeve/sets...e-blue-guitar/
                      .

                      Comment


                      • #12
                        Yes, of course they do.

                        For example at MOuser:
                        546-171B
                        802-GIS-150
                        Education is what you're left with after you have forgotten what you have learned.

                        Comment


                        • #13
                          iso transformer

                          Steve,
                          Ebay has al kinds of interesting transformers coming in from china. I bought a 1000W step up for somethinglike $50 including shipping, last spring. Mouser is great if you want to spend more $$.....

                          Marc
                          Originally posted by Steve A. View Post
                          Enzo- Do they make isolating transformers that would plug in between the wall and the amp? If not you could make one in a metal box and sell it to the customer.

                          Just a thought

                          Steve Ahola

                          Comment


                          • #14
                            Careful, Marc, not all step ups are iso. We need an iso for this type situation, not a voltage change.
                            Education is what you're left with after you have forgotten what you have learned.

                            Comment


                            • #15
                              Well, by golly it is working. Haven't tried the trem yet, suspect it needs some help yet. But I have been tracing out the circuit, and the trem is like nothing I've seen. The two input channels are conventional, 150k plate load and 3k under the cathode.

                              From each triode there is a wire from the plate and from the cathode to a DPDT switch. It is the trem assign. The trem tube is a triode, and through this selector switch, the plate is wired directly to the preamp tube plate. The cathode of the trem tube has a 150k load resistor (with a bypass cap), the bottom of which is wired through the switch to the preamp tube cathode.

                              In essence, the trem tube is wired as a variable resistor in parallel with the preamp tube. I've never seen that arrangement.
                              Education is what you're left with after you have forgotten what you have learned.

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