I've Been On An Amp Building Bender!!

Discussion in 'Building the Classics' started by danfrank, Jul 7, 2017.

  1. danfrank

    danfrank Well-Known Member

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    Hi all. I've been building amps like crazy these last couple of weeks. First up is my attempt at an SLO clone. I bought the preamp PCB from C3 and the rest of the parts are from stuff I had in storage.
    I bought a couple of Peavey Windsor heads a few years ago because they were dirt cheap. Didn't like the amp much so I gutted them both and used the chassis and cab for builds. One of these I used for the SLO build:
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    This was a complicated build compared to the Plexi style amps I usually build, mainly because I had to look at pictures on the internet on all the stuff that goes into this build that is not incorporated on the PCB. I guess I did it right because it plays and considering how much gain this amp has, it is relatively hum free.
    Personally, I would change the location of the "normal/overdrive" switch. If I could do it over, I think I would put that switch between and under both "gain" controls and have the toggle switch from left for "normal" to right for "overdrive". The other two switches seem to only work in "normal" mode. As you can tell, I've never played around with one of these amps, so I kind of went blindly into this project.
    For the PT, I used a RCA transformer from a vacuum tube type RCA television. These old TV transformers make great PTs for tube amps; they are beefy transformers. I used the Windsor OT for the time being but I will probably switch it out for something a lot better quality when I have more disposable funds.
    The choke is rated at 7H @ 70ma. I don't know why they spec a 200ma choke for these amps because the most current that will go through the choke is around 60ma as long as 6L6 type tubes are used. With EL34s current through the choke will be about double. Most of the other parts are what I had lying around; everything else is to spec on the schematic even though it may not look like it on this build.
    The face plate is a work in progress. I need to print out all the names for each control. I put the effects loop on the front panel since that is where the 2 jacks were for the Windsor.
    By the way, does anyone have one extra Peavey Windsor knob that they are willing to part with? I need one more knob for this amp. I am willing to pay for the knob plus shipping if anyone can help me out.
     
    Last edited: Jul 8, 2017
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  2. danfrank

    danfrank Well-Known Member

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    Here's another amp I built recently; another 100 watt "PIG". Here's the build thread for the first one I built several months ago:

    http://www.marshallforum.com/threads/marshall-200-i-mean-marshall-100-build-pig-0-5.94239/

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    Compared to the SLO, this is an easy build; but then again I've built many of these so it's kind of old hat. There's been a lot of interest in these, I even had some press about this amp in Italy. LOL! It is a good sounding amp.
    I did do one mod on this amp compared to the original... The knob on the back panel right next to the speaker impedance selector is a control that varies the amount of negative feedback that goes to the PI. All the way counterclockwise the negative feedback is stock, and fully clockwise the amp has about 1/4 the amount of feedback that the stock amp has. This makes the amp very dirty when this knob is turned clockwise. A big difference from stock!
     
    Last edited: Nov 17, 2017
  3. jensvonbustenskjol

    jensvonbustenskjol Active Member

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    Neat!
    Very nice and clean build :)
     
  4. danfrank

    danfrank Well-Known Member

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    OK here's what I did with the other Peavey Windsor head I have; I turned it into a "Blonde" Fender Showman Clone!!! 6G14-A

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    Last edited: Sep 29, 2017
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  5. danfrank

    danfrank Well-Known Member

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    This is the amp with the "Harmonic Vibrato". I had finished this months ago but there was a problem with the "vibrato" channel; it was too dark sounding. All bass, no treble. The oscillator worked like it should but the sound was very boomy. SO I opened it up and retraced my work against the schematic. Oooops! I soldered the 250pf cap to the wrong side of the 220K resistor by the mixer tube. All the treble frequencies were being drowned out. Easy fix once I found it.
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    For the vibrato circuit this design uses 2 1/2 12AX7s. I'm not into wasting 1/2 a tube in a build so I subbed a 6AV6 for the 1/2 12AX7 tube and it works like it should. The 6AV6 is one triode of a 12AX7 in a 7 pin tube. It's the bright one in the back.
    I used old USA stock 5881 power tubes like the original Fender did. They are a great sounding tube that overdrives very smoothly. I don't know how the reissue Tung-Sol 5881s sound compared to the originals, but the new ones do look nice.
     
    Last edited: Jul 27, 2017
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  6. MarshallDog

    MarshallDog Well-Known Member

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  7. danfrank

    danfrank Well-Known Member

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    Hi! Yes I have had Sourmash build me a couple of cabs so far... I think his work is top notch and he is reasonably priced. Very sturdy cabinets, and look great also.
    As for the amps I build, I enjoy building them... I like finding things that nobody wants and then turning them into something else... I'm still trying to find out if that "something else" is in demand or not! LOL!
    I like building the "classics" to see what all the hype is about... Fender and early Marshall really hit on something with their classic amps. Besides being functional, there's a reason why the originals have become iconic. They sound wonderful.
    I guess the amps I build would be good for someone on a budget that would like to gig with one of these classic sounding amps but not have to worry about the liability of actually using an original in a live/touring setting.
     
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  8. soundboy57

    soundboy57 Well-Known Member

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    Very nice work. :)
     
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  9. danfrank

    danfrank Well-Known Member

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    Thanks!
     
  10. MarshallDog

    MarshallDog Well-Known Member

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    Wow, some ones been a busy Beaver LOL! Nice work! I have always thought I would like to build an amp but just not sure what one and do I want to go for it?! Maybe an old Marshall style Blues Breaker or JTM in a combo style. I could have SourMash build me the cab...just a thought but something old school, one channel and simple to start with.
     
  11. danfrank

    danfrank Well-Known Member

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    If you like Fender, a Deluxe or Princeton are nice to start with, or like you said a JTM Bluesbreaker. The nice thing about the 2 Fenders I mentioned is that they're loud but not obnoxiously so.
    But then you would have to decide which version... Tweed, Brown or Blackface!

    Edit: I'm not affiliated with this guy, but I was on Ebay and saw he has a bunch of stuff listed to make one...

    https://www.ebay.com/sch/jaxax999/m...0gcAAOSwek1ZeQZT&rt=nc&_trksid=p2047675.l2562
     
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  12. ibmorjamn

    ibmorjamn Well-Known Member

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    Very cool !
     
  13. Pappy58

    Pappy58 Member

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    Very nice work! I would love to try something like the SLO but at this point need to stay with the simple designs, and I am a sucker for tweed era pre-amps. I have built a 5E7 Bandmaster that is my #1 for most gigs, but even at 30watts it's too loud for many rooms. I'm just starting on a 5E3 Deluxe to address that issue. Once I finish the Deluxe I have a JTM45 kit I'm going to start. This will be my first Marshall type kit, but the circuit doesn't seem to differ much from the 5E7. I might change gears on that and go 1987x on that one. Thanks for posting your results, knowledge is good! :cheers:
     
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  14. danfrank

    danfrank Well-Known Member

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    Hi,
    And thanks for the reply. I think it's great that so many are getting into amp building. It's fun, educational and you get to enjoy the end results. It's a win win... Or would that be a win - win - win!
     
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  15. DeathAdder

    DeathAdder Active Member

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    Let's see some pictures of your SLO. I built two of them. If you think that's hard, try my newest project - a Hiwatt DR103.

    I'm kind of on a bender myself, trying to keep up with my normal load of clients.

    Best of luck, Dave
     
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  16. danfrank

    danfrank Well-Known Member

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    Thanks. Pictures of the SLO build are in post #1. It was a Peavey Windor originally, that I gutted and used the chassis and headshell from.

    Funny that you mention Hiwatt, that's probably gonna be my next build... Thinking about a DR201, the six EL34 version, as I have all the iron for it already. I really like amps that have the split B+ supplies for plate a screen. 650-700 volts for the plates and 350-400 volts on the screens, depending on the output tube type used. The tubes seem to like this setup also, as they don't blow as often as they do in a 500v B+ Marshall. The only drawback is that the output tubes don't last a long time with 700 volts; they just wear out quickly at that voltage.
     
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  17. DeathAdder

    DeathAdder Active Member

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    And of course you only use quality components. That makes a huge difference. Wow, I'd love to try a DR201. This amp has got me 'wired'. It's so neatly done that while building it I whisper to myself, "I don't have to make it that neat, right? I mean this guy that Revees hired just went overboard, right?". Then I come to my senses and tell myself it is a challenge to be taken. After this amp it should be all downhill.

    I know what you mean about the voltage. On another thread, I have a picture of the top side of the amp so take a look. They are the biggest trannys I have ever worked with. Much bigger than the Heyboers on my SLOs. i was reading a post on another site where a guy bought a vintage DR103 from England. It weighed in at 23 kilos. My kit came from East Asia, without cabinet, and weighed in at 22 kilos. Take away the chassis and a couple of pounds of parts and the rest was tranny weight. Check it out.

    About your build. If you have a 10 watt 470ohm resistor (or whichever) feeding the screens, make it 25 watts just to be safe. And watch the grounding. Hiwatt was infamous for the ground bus tucked under the main turret board, again just for neatness. This caused noise problems with many original units. Bring your grounds .... well you know, just don't do it their way.

    Cheers, Dave
     
  18. danfrank

    danfrank Well-Known Member

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    Thanks for the suggestions on grounding.
    As to the work of Harry Joyce, being as neat as he was is no simple task. But the other thing to consider is that certain wires on a build can't be around certain other wires or problems will ensue. So, it's not only the neatness that is hard, it's also knowing the best way to layout the wiring so there are no noise or instability problems with the amp.
     
    Last edited: Nov 17, 2017
  19. danfrank

    danfrank Well-Known Member

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    Here's a pic of the completed "PIG" amp from post #2 of this thread. The faceplate is mirrored silver with blue lettering. The head cab is Navy tolex with silver piping. It's in a "small box" JTM45 type cab.

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  20. DeathAdder

    DeathAdder Active Member

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    Are you ever right on that one. This amp will take twice the time it took me to build my SLO 100. I read the suggestions on the wiring issues such as the grounding that could have been improved. Picture will be posted when it doesn't look like a ratsnest (which is does now). Ceriatone makes some good kits ans the trannys he sent me are way bigger than even the custom Heyboers I used in my SLO.
     

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