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Visiting at my friends house yesterday I happened to notice this somewhat decayed but beautiful amp in the corner. Turns out a lady he knows husband had been playing it for years but past away and asked my friend to try sell it. Anyhow my friend suggested I offer her R1000 for it since its in pretty bad shape and currently not working.

I've been wanting a retro kinda low wattage amp and have been wanting to learn my way round some amp circuitry. But being that I'm quite new to working on electronics would this be a worth while investment for experience and a fun low watter to jam at home? The circuit looks extremely simple so i think i could manage.

my main worries is that the transformers and speaker might be shot if you look at the pics you'll see some major rust spots.








    Awesome find , i love that look ..

    Old vintage amps are usually easy to repair as everything is point to point wiring and no pc boards ,

    but take it to an experienced tube amp person to restore ,

    if you in jhb i recommend jp le roux , hes a genius with old gear and not expensive , and also fairly quick ..... And yes i talk from experience as h restored an old vintage amp for me and to date not a niggle or comeback

    if you in jhb ...private message me and i'll send you his number

    but awesome find
      What a find!

      I doubt there will be anything wrong with the transformer. If the speaker is indeed damaged you could get it repaired, although the better option would probably just be to replace it. You have some funky Grey tiger caps in there as well.

      Best idea would probably be to just get it working first. Replace dead tubes etc. and then decide whether you need to swop the speaker or recap it. I see one of those old power chords, so I think a priority would be to make sure you have a safe power supply so do you don't hurt yourself. Sometimes these old amps need new caps, so check if there are any that are leaking. The values should be on the caps and you can order from one of the online vendors.

      Keep us posted on how this goes ?
        Nice find. Some people wait a lifetime for such a find.

        Some tips: Take care not to power it up in the state it is in now. It is quite easy to check the transformers and speaker without powering the unit up. Those capacitors looks like they've crossed over a while ago ???

        Yeah, off to the tech is the only way to protect your investment. If you want to learn, ask the tech if you can watch him/her work. Most tech's hate it when someone looks over their shoulder when they work, but it is a sure way to learn the basics. Then you can ask questions on the forums, and get some answers.

        May she play again. :yup:
          Wonderful find. Don't rush it and there's no reason it won't sing like an angel in short order.
            Wow that is so cool! ? ? ?

            I hope you do not restore the looks, it is too awesome!
              Wow must be the quickest replies I've gotten on this forum ? . Ok now I'm more excited than ever. I'll definitely take it to a tech. I live in PE so it can be quite hard finding anything but luckily I know a really cool oom who's always got his hands digging around in some amp or building guitars winding pick-ups etc. Last time I went there he played me his AC30 clone he made and it sounded awesome so I trust him ?

              In terms of usability should I expect much from this amp? I'd like to use it at church and maybe some small gigs as well. But from what I've read guys say they are typically quite low output in there worn down vintage state. They were rated 12-14watt when released (which sounds like enough). And also I seriously dislike using a delay or reverb without an fx loop if the amp is overdriven which this one does best and only really gets much volume at a ballsy overdrive. But then it would be ridiculous to not run this thing overdriven!

              Has anyone ever modded a vintage amp for an fx send and return or would this be defeating the point of a vintage amp?

              In terms of how it looks i wouldn't wana touch a thing maybe just glue down the lifting tolex so it doesn't tare off. But if i see a rapid deterioration i think i'll remove all the guts and build an identical cab and maybe keep the old one as a nice show piece around the house ? I'd hate to ruin the way it looks now

              saw this vid last night and cant stop thinking bout the tone:
              =
                aja wrote: Wow that is so cool! ? ? ?

                I hope you do not restore the looks, it is too awesome!
                +1
                Awesome looking amp. Hopefully it'll be sounding awesome some time too.
                Rob Brown wrote:
                In terms of how it looks i wouldn't wana touch a thing maybe just glue down the lifting tolex so it doesn't tare off.
                That's the way.
                  That's awesome! You've got to love a good bargain..

                  edit: regarding advice on fixing it up:

                  -I would first remove all of the tubes, then check if the power cable is 3 core and that the earth is connected to the chassis and the earth pin on the plug - if not, rewire it so that it is.
                  -Then I would plug it in with all the tubes removed, switch it on, and measure the voltages across the power transformer windings with the multimeter set on AC.
                  >you should measure around about 500-700V between the two rectifier HT pins (pins 4 and 6, there should be numbers on the socket. if not, here's what the arrangement looks like:

                  >you should measure around 5V across the heater pins {2 and 8}
                  >you should measure around 6.3V across the heater pins of a power tube {2 and 7}

                  if you don't measure any voltages, it might be the switch or fuse - either that or your power transformer is probably stuffed.
                  -then you can check for continuity all the way along your 6.3V heater line pair (on each of the power tube and pre-tube sockets).
                  -after that you can measure the output transformer primaries and secondaries (primary is the side that sees the tubes, secondary sees the speaker). you should see resistance on both, probably between 1 and a couple of hundred ohms, higher resistance on the primary side.
                  -then measure the resistance across the speaker, should be around 7 ohms
                  (these resistances need to be measured with the leads disconnected from the circuit, to avoid parallel misreads).

                  if all of those check in reasonably, then (and be VERY careful from here on. you should have been careful up there ^, but from here on you can die harder):

                  -plug in the rectifier, switch on again, watch for smoke and things. if all seems fine, measure the voltage across the chassis and the rectifier heater pins. you should see high DC to the order of around 300V.
                  -measure the voltage between each power supply node (the positive terminals of the big electrolytic speaker capacitors) and the chassis. you should see between the high DC you measured before and probably around 100V on each of the nodes.

                  if all of that checks:

                  -turn off, plug in the rest of the tubes and turn it on. watch for smoke or anything strange again.
                  -if all seems well, plug in an instrument and measure the voltage across the strings and the chassis. you should have 0V here.

                  if thats all good, strum away and see what happens ?

                  -if nothing happens, you should probably start by rolling some tubes or testing yours in another amp that is known to be working, and replacing caps. if you get no joy out of that, then you can start debugging the circuit, starting at the input.

                  here's a schem:

                  http://www.gibson.com/Files/schematics/ga-20.gif

                  bear in mind that all of the above attaches EXTREMELY stringent safety warnings. unless you really know what you're doing, do not touch ANYTHING inside the amp when it is plugged in with anything other than a long stick of wood or other non-conductive material. also bear in mind that after turned off, the power supply capacitors store charge at the same potential as the DC HT, which can and will not hesitate to remove your soul from your body. you need to make a discharge contraption for these before you can safely touch anything with the amp off - which consists of an insulated resistor and wire that you can connect across the capacitors and the chassis without having to touch any metal parts yourself.

                  google safety and tube amps before touching anything. any terms you don't understand, google them, or ask here. there is LOADs of info on this tube stuff on the net, so google is your friend.

                  another thing, those 6SL7's are probably one of the best kept secrets of the vintage glowy bottle world ?.

                  oh, and in the odd case that you decide you don't want it anymore, let me know ?

                  let us know how it goes!
                    Please. For pity's sake don't mod it for an effects loop. If the amp doesn't suit what you're doing, rather sell it to someone who really appreciates what these vintage amps are for and use the money to buy some modern thing with 6 channels, 60 knobs, that's 50 watts that you never turn up past 2. Seriously.

                    A 10 to 14 Watt amp is more than fine. (a) it won't be quiet, and (b) if you need more volume, mic it up. You'll be pleased you did when you can still hear past 45.
                      singemonkey wrote: Please. For pity's sake don't mod it for an effects loop. If the amp doesn't suit what you're doing, rather sell it to someone who really appreciates what these vintage amps are for and use the money to buy some modern thing with 6 channels, 60 knobs, that's 50 watts that you never turn up past 2. Seriously.

                      A 10 to 14 Watt amp is more than fine. (a) it won't be quiet, and (b) if you need more volume, mic it up. You'll be pleased you did when you can still hear past 45.
                      +100
                        ez wrote:
                        singemonkey wrote: Please. For pity's sake don't mod it for an effects loop. If the amp doesn't suit what you're doing, rather sell it to someone who really appreciates what these vintage amps are for and use the money to buy some modern thing with 6 channels, 60 knobs, that's 50 watts that you never turn up past 2. Seriously.

                        A 10 to 14 Watt amp is more than fine. (a) it won't be quiet, and (b) if you need more volume, mic it up. You'll be pleased you did when you can still hear past 45.
                        +100
                        +100000

                        Modding something this old and awesome is nothing short of insulting to both the amp and those that love old stuff like this.

                        You'll probably find that effects will do fine going into the inputs anyway.
                          There is one massive reason why an effects loop is a waste on this amp (and other amps like it).

                          Power Tube Distortion.


                          An effects loop is located after an amp's preamp. In modern amps, most of your overdrive comes from the preamp so effects loops are a way of getting reverb and delays and other modulation effects onto that distorted sound without the effects becoming distorted too. This is hunky dory.

                          This amp and others (Marshall 1974x, Fender 5E3, Plexi, Deluxe Reverb) derives almost all of their overdrive from the phase inverter and or power tubes. Installing an effects loop in front of this (only place for it to go) will still result in your effects being overdriven, unless you run the amp at low enough volumes to be clean, in which case you may as well run them into the front of the amp, as the result will be the same.

                          I strongly agree with Makepeace and Singemonkey, it would be an absolute crime against humanity to do this to an amp like this. It would be like installing EMGs and a Floyd rose onto a 1950s Les Paul.
                            Haha ok I guys I get the point! ? knew that one would cause a stir! Think I might just do a bit of an AB vibe and use a more modern amp for all the gimicky effects and use this for the sweet ballsy tone maybe with an extra OD and fuzz for variation!

                            Thanks for all the info learning so much from each post! and don't worry there will be no mods unless the speaker falls apart and I need new one in which case I'd get some kinda reissue type.

                            @ez thanks for that knowledge I had no clue the drive came mostly for the power section

                            @Makepeace I will definitely follow that procedure thanks for the detail and effort. Would it be wise to replace all the caps first before starting? it is round almost 60years old sure those guys would be poked by now?
                              Ez, I'm not sure if I agree with your reasoning, or that its a waste of time. Distortion is by no means the only factor in the theory of effects loops.

                              The one thing that stands out is that it or any other function modification would be a sad thing to do to an amp like this. Its just as easy and cheap to build a replica amp that has no sentimental value which you can do whatever you want to.

                              Modding this amp for an effects loop entails reusing one of your dual triode tubes (a whole channel) as a send and return for the loop. That's more than just a small modification, and it will leave you with only one channel.
                              Rob Brown wrote: @Makepeace I will definitely follow that procedure thanks for the detail and effort. Would it be wise to replace all the caps first before starting? it is round almost 60years old sure those guys would be poked by now?
                              Either or. You never know hey, they might be fine. And by looking at those pics they don't look bulgy or charred, which would indicate expansion/combustion caused by failure, although the might also have dried up. An easy first checkpoint test you can do is desolder one lead of the caps (AFTER DISCHARGING) and set your multimeter to around 20k resistance at first and measure across the cap (observing polarity). If the resistance rises with time - it means your multimeter is charging the cap, and it might be ok, but bear in mind this is by no means a comprehensive test. By testing to see what is actually stuffed you don't waste your money. Although - its safe to say that if these caps are fine now, they probably won't last immensely long. So whatever you decide. If it were me in your position, I wouldn't be patient enough to order/go shopping for new caps :roflmao:

                              Oh, and another obvious thing to check often while you're debugging is the fuse. Just measure resistance across it to see if there is continuity.

                              Last thing, as regards the speaker - if its broken, it will most likely be repairable by a speaker mechanic for less than a new speaker would cost, so I'd suggest investigate that route first. You could even strip and re-paint it while you're at it.
                                makepeace wrote: Ez, I'm not sure if I agree with your reasoning, or that its a waste of time. Distortion is by no means the only factor in the theory of effects loops.

                                The one thing that stands out is that it or any other function modification would be a sad thing to do to an amp like this. Its just as easy and cheap to build a replica amp that has no sentimental value which you can do whatever you want to.

                                Modding this amp for an effects loop entails reusing one of your dual triode tubes (a whole channel) as a send and return for the loop. That's more than just a small modification, and it will leave you with only one channel.
                                Haha, shows you how much I know of effects loops (they're for sissies). The main reason most people quote for wanting them is the "I don't want my reverb to be overdriven". I guess there's also the relative volume thing and so on but I'll stand by my reasoning for now. The folly of having one in this amp is only overshadowed by the heritage of the amp and the fact that there are probably not many of them left in original or near-original condition.
                                  ? ? ? ? ? ? ?
                                  Wow! Super cool find Rob 8) Ja, just get her working and enjoy her for what she is. Really nice find.... :goodtimes:




                                    Getting a gem like this for R1000 is pretty awesome! Good luck restoring her!!
                                      singemonkey wrote: Please. For pity's sake don't mod it for an effects loop. If the amp doesn't suit what you're doing, rather sell it to someone who really appreciates what these vintage amps are for and use the money to buy some modern thing with 6 channels, 60 knobs, that's 50 watts that you never turn up past 2. Seriously.

                                      A 10 to 14 Watt amp is more than fine. (a) it won't be quiet, and (b) if you need more volume, mic it up. You'll be pleased you did when you can still hear past 45.
                                      +100 x 10 6

                                      PLEASE ! do not mod or change it in any way.....If you can't find a good AMP tech in PE bring it to CTown.
                                        Cool thanx guys now I've just gotta wait till I got some cash again then I'll get this this little amp up and screaming.

                                        @makepeace as a repairman once said to me fix it nice or fix it twice ? I've got the time to wait for ordered caps so might as well.

                                        Once it's up and running I'll do a lil demo vid and post it back on this site but you'll have to excuse my bad playing ? and listen for the tone.

                                        And just to clarify there will be NO mods done promise! ?