Anyone ever build an amp by just copying an original?

Discussion in 'Shock Brother's DIY Amps' started by islandjimmy, May 20, 2020.

  1. islandjimmy

    islandjimmy TDPRI Member

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    Hi All,

    Has anyone out there built an amp without a schematic or outline, but rather by just copying an existing amp? For instance, I have a 1974 Fender Princeton Reverb (which I love), if I remove the chassis, make note of all the parts, order a set of each part, and then just solder it together just like the original? All the parts are available out there, and there would be an already built model to follow. Just curious if this is common practice, or if most of you out there build from layouts and kits. What would be interesting is to copy the original amp as exactly as possible and then compare the sound.

    Thanks!

    Jim
     
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  2. SonicMustang

    SonicMustang TDPRI Member

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    Sounds like a great idea to me. I would really love to find out how close it sounds. Of coarse i'm sure the speaker will be different and the cab could be different material.
     
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  3. LOSTVENTURE

    LOSTVENTURE Tele-Afflicted

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    I've done it, back in the 60's, but having the schematic always helps.
     
  4. islandjimmy

    islandjimmy TDPRI Member

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    I make my own cabinets so I was thinking of making everything, even the wood choice, as close to original as possible. You're right about the speaker but I'm sure with all the great speaker manufacturers out there, you could find one voiced very similar to the original?
     
  5. SonicMustang

    SonicMustang TDPRI Member

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    sounds super plausible to me!
     
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  6. sds1

    sds1 Tele-Afflicted

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    Typically a schematic is available...

    Comparing what you have to existing schematics, noting deviations, seems like a great use of your time if you are trying to clone an exact build you have.
     
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  7. islandjimmy

    islandjimmy TDPRI Member

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    Yes, I would definitely have a schematic on hand in case I couldn't see the values on the components.
     
  8. schmee

    schmee Doctor of Teleocity Silver Supporter

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    Sure you can, but for 95% of it just follow the layout. Easier
    No two vintage amps sound exactly alike, so... I have 4 DR's about 2007 -08. I compared them all. They of course were very similar but not 100%.
     
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  9. Preacher

    Preacher Friend of Leo's

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    Not the schematic as there have been a few improvements on the old 5E3. But I did take the measurements on the cabinet and tried to stay true to how Leo built them.
     

    Attached Files:

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  10. King Fan

    King Fan Poster Extraordinaire

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    Your basic idea is what I try to do when I build an amp. A big goal is to hear what somebody heard when they played one in 1957, or 1965, or whatever. To be fair, that's what a lot of kits and home builds want to do also.

    The devil is in all the little details. You don't want to change the sound but you also *don't* want to copy outdated safety and function items. A few examples:
    • Building a cab just like Fender did is great, but you really want the 60s-style pine cab with removable baffle, not any later 70s version.
    • You definitely don't want to copy the 2-prong cord, death cap, ground switch, etc.
    • Adjustable bias is easy and super useful, and also it can only help to use an upgraded 3W resistor and 100V cap on the bias board.
    • You really kinda want upgraded (2-3W) dropping resistors.
    • You don't really want to solder to the chassis, which is hard to do well and less secure than keps nuts on bolted solder lugs or chassis anchors.
    • And you really don't want to copy Fender's random grounds to a brass plate, which even if you can solder like they did, is prone to corrosion.
    Now this last point is where you could start to go your own way. Some modern kits and builders do use the brass plate. If you really want to, and you have a *big* iron and the experience to use it effectively, hey, it's your amp.

    But the important part, cloning the bits that do alter the sound, also gets tricky. Sure, you want to use carbon comp resistors where Fender did, but are you gonna use modern production versions or NOS Allen-Bradleys, which are well-loved but have sometimes drifted in value? Which modern caps do you think sound like the originals? (Let's hope for your sanity and budget you tilt a bit toward the 'caps-is-caps' camp -- and hope you're definitely not in the 'must use ancient caps' fringe). And the speaker, as noted, is huge -- you may actually want to shop for a vintage speaker, but *which* vintage PR speaker is a whole 'nuther opera.

    For a PR, luckily, there wasn't much change other than cab and parts/build quality between BF and SF. I can think of one '70s item you may actually want to copy, the upgraded Schumacher 010020 PT, with 100mA available and 3A on rectifier heaters. In any case, if you want a sonic copy of the original, don't be tempted by bigger beefier modern iron.

    Finally, some slightly good news. If you can figure out what must or should be changed for safety and function, and use the schematic for nominal resistance and capacitance, as well as for build testing and tracing, you get the best of both worlds -- an amp that sounds as close as possible to the originals but works even better. And why would you want that? Because otherwise it'd be a heck of a lot easier and probably about as cheap to go buy another '70s SF to 'clone' the one you already have. :)
     
    Last edited: May 20, 2020
  11. jhundt

    jhundt Doctor of Teleocity

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    if you already have an amp, why would you build another one just like it?
     
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  12. fenderchamp

    fenderchamp Tele-Afflicted Silver Supporter

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    /me blinks and stares
     
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  13. ClashCityTele

    ClashCityTele Tele-Afflicted

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    Yeah, Jim Marshall did it!!!;)
     
  14. Cysquatch

    Cysquatch Tele-Holic

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    Beat me to the punch. Nicely done.
     
  15. Area51

    Area51 Tele-Holic

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    I made Champ going on 30 years ago well before building your own was a thing. I still have it and use it. Doesn't look anything special. The cabinet is just wood, I put a metal handle from a hardware store on top and rubber feet. The chassis is bud box! Sounds great! My only regret is I went with a 10" speaker. Wish I did an 8" so it would break up sooner. I read others like the 10" because it doesn't break up...

    It came out so well that I followed up that build by making a SR head. This time I bought an old blown cabinet and put some Webber speakers in it. I sold it for a decent price. I love SRs, but they're a little loud or me.

    It was fun tweaking them too!

    Back then some of the parts were hard to find. I remember even calling Fender and talking to an engineer who helped me procure an output transformer.

    Honestly, some are very high quality and I believe they're probably more cost effective way to build your own. That's the route I would go if I was to build one again.
     
  16. lowatter

    lowatter Tele-Meister

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    Methinks the OP may be shooting for one original amp of fairly high vintage value to keep at the house and one to gig with or beat up a bit without remorse. JMHOYMMV
     
  17. islandjimmy

    islandjimmy TDPRI Member

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    These are the gritty details I was wondering about. Thank you for your detailed explanation. I will definitely follow your advice. Basically it will be a modern version of a classic. I agree with you on the grounding to the chassis bit. Seems like you would need an industrial strength soldering iron to do that properly. And a 2 prong cord is out of the question. Good advice thank you!
     
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  18. islandjimmy

    islandjimmy TDPRI Member

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    Just to know how to build one and repair the original over time. One that can be used for gigs and one in the studio. Just to do it really.
     
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  19. Lowerleftcoast

    Lowerleftcoast Tele-Afflicted

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    I wouldn't say it is commonplace. Seems here on TDPRI there is a lot of kit building going on.
    Sounds like as good a reason as any to build one.

    Modern parts and technique can make a quieter version. Safer too. I would not build a strict clone.

    You won't be able to make a perfect clone anyway. The resistors alone can not be duplicated and NOS will not be the same due to degradation over the years. (Don't use NOS resistors). You can make a very nice sounding amp though.
     
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  20. Engine Swap

    Engine Swap Tele-Meister

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    I'm getting ready to do this.

    I have a 1965 Fender Deluxe Reverb that I modded the crap out of. Back in the 80's, when I did this, it was just an old amp. I love it in it's modded state, but feel like I should restore it back to stock.

    My plan is to document the current configuration, and then build a clone to match as close as possible. Once that is done, I restore the old amp.

    When I'm done, I'll have a modded amp and a stock amp. Best of both worlds.
     
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