DIY Amp Making & PCB's

Discussion in 'Shock Brother's DIY Amps' started by kleydejong, Jan 26, 2020.

  1. kleydejong

    kleydejong Tele-Holic

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    Context

    I've been doing a deep dive into pedals for the past several months. One interesting observation I see is the dominant prevalence of PCB's as the construction method. It makes sense. Lots of advantages. More efficient use of space. Easy to work with in a paint by numbers approach. PCB mounted pots are super nice to hold the board securely.

    But it isn't just that PCB's are commonly used in pedals - but I'm shocked at how vast the library is. There are a handful of different vendors selling PCB's for just about any pedal you may have or haven't heard of. They sell the PCB and you source the other parts.

    Next enlightenment is that one can readily download software to draw schematics and then transfer that into creating a Board layout. The software will perform some design checks to ensure the board is within construction tolerances at a real life factory. Then you can send that file to a variety of factories in China that will make you a PCB and mail it to you. For like $20 for a set of 5.

    So I'll get to my question - why aren't PCB's used in the DIY amp making world hardly at all? Almost all builds I see are Eyelets or Turrets just like Leo and Jim used to do it. Some PTP-ish work from time to time.

    You see PCB's commonly used in amps made at scale in factories. But I would also state that there are a number of higher end builders that use PCB's in their amps. So I don't think you can argue that a PCB can't make a good amp.

    The Argument Against

    On the other hand I can see why they aren't used as much. In amps you don't have as much premium on space conservation as you do in pedals. Even with a PCB you still have a fair bit of off board wiring to do. I would say that amp building is more advanced than pedal building. It requires more safety, more knowledge in construction techniques, more expensive components. There are probably more people building pedals than amps. Pedal guys can build up a stash of parts and basically order a PCB on a whim and build it from their reserve without a lot of problem.

    One element that I waffle on is the aesthetics. Some of you guys make works of art - and the use of a PCB may detract from that.

    From a design perspective I can see some negatives. You need more care in thinking about ground planes, trace routing, and component locations with amps compared to pedals. Pedals are also easier to prototype.

    The Argument For

    All that said, I don't really think there is a good reason why we in the DIY amp building community don't use PCB's more. I think it could be a great asset for the newbie. Take a PCB and combine it with thorough instructions and it really makes it a straightforward paint by numbers approach. If you could find a way to mount tube sockets directly to the board and handle filaments too - without noise or other design issues - it would be VERY beginner friendly in my estimation.

    Next it could give a more aspiring builder some nice options. Thinking about if there was a web store like some of these pedal pcb stores that offer a pretty wide variety of PCB's and then you source your parts around it. Not as a kit, but just the PCB and the rest is on you. Many guys in this forum would easily be able to tackle some pretty advanced circuits if enabled by PCB.

    Next I wonder if this is simply an area where we are simply stagnating. This isn't the first time guitar players have exhibited some ludditism. I say this to myself as much as anyone else.

    Conclusion

    So I would love to hear some feedback. Have any of you guys messed around with PCB's in the DIY amp world? Are there reasons I'm not contemplating?
     
  2. edvard

    edvard Tele-Afflicted

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    I think this says about half of it. The other half (in my humble opinion) is split between bad experiences with early PCB tube amps, and the association of PCBs with Solid State amps. Us guitar players are not only stubborn, but we have a long memory...
    I think there's also a small slice in the middle that favors P2P wiring for ease of repair; it's much nicer to simply clip out a bad part and solder a new one in, than to disassemble the whole damn thing, remove and replace some fiddly part out of a fully populated board without lifting the traces, and re-assembling the whole mess again. Trust me, I used to make side money repairing pedals for a local used gear shop. PCBs are bad enough in a 3" x 5" metal container with 1-4 pots to deal with. I don't need 5 times that mess to deal with.
     
  3. LightningPhil

    LightningPhil Tele-Meister

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    You should try fixing a recording desk without a manual. Only done once, and luck would have it that it was a duff cap, which was the go-to first thing to inspect.

    On the PCB front, good PCBs are great. But jumbled messes of PCB fragments and spaghetti wiring is horrid. I'm looking at you Fender Bassbreaker 15...

    Thus far, I've only built and modded PCB based amps. But for a change, the next one shall be turret based.

    Have you tried building a pedal dead-bug style with only components and nothing else to hold them in place. Quite fun and can look neat with patience.
     
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  4. elpico

    elpico Tele-Holic

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    Card mounted sockets are very much a thing, and they very much suck. The pins in tube sockets were meant to have some give so they can align themselves with the never-perfectly-straight tube pins. Even when they can move it can take a lot of force to get a tube into/out of a socket, lock them in place and you have to push even harder. PCBs don't want to be flexed by you trying to the get the tubes in and out. Amp makers usually try to stabilize the PCB near the socket with two little stand offs, but you're always still transferring some force to the pcb that wiggles and flexes the solder joints, traces and components. You absolutely can make great amps with a PCB, but even in a PCB amp chassis mounted sockets are where it's at.

    Sooner or later you'll run into one of these pain in the asses:

    [​IMG]
     
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  5. edvard

    edvard Tele-Afflicted

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    Yep. Some bargain-basement brand 16 track. Each track board had something different wrong with it, and the shop said never mind fixing it, recycle it if I could salvage some parts. I got about 20+ JRC4558 op-amps out of it, 1/3 of them were burnt. The rest of it was almost-useless plastic parts and odd value pots.

    Once. Wait. Twice. First one was a silicon Fuzz Face. Most of the parts in that can mount right off the pot lugs. Second one was a simple FET buffer mounted inside a bass guitar with a weak pickup. Neither of them looked neat :oops:
     
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  6. LowCaster

    LowCaster Tele-Holic

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    I don’t like pcbs. I mean, they are necessary and practical from an industrial point of view, but I don’t like to work on them. I’m a noob in electronics and my soldering skill do no allow me to remove a component without burning the track...

    This Gretsch 5222 had a broken input jack socket. I went trough the trouble to figure out the (simple) wiring and replace the small board with good old school components. I’m much happier and confident that it won’t fail again, or that it will be easier to replace.

    A306ACEC-6B03-4FBC-B68B-51230A2C9621.jpeg

    69A525DA-16DD-4842-B42A-E7DDF69439B2.jpeg

    CC9C4C0B-3ABF-4F75-8347-0887C34D842E.jpeg

    Now look at the first picture, you see that the board is crippled with wires and connectors. Find a picture of an original 1953 fender « 600 » with the parts soldered to the chassis, isn’t it nicer?

    For the same reasons (simplicity, sturdiness, serviceability and aesthetics) the four pedals I built so far (from kit) are eyelet bord based. What amazes me is that there are not more of these on the market...

    It’s a preamp by GMR spares:
    [​IMG]

    But sure I wont’t try to do that for a more complicated circuit like this Ehx memory boy. I wouldn’t play with the PCB either.

    9DFB19CF-BDF7-4562-AB42-C4EEF395FED9.jpeg
     
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  7. shortcircuit

    shortcircuit Tele-Meister

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    I built PCB based headphone amps and pedals before getting into tube amps. Even etched my own boards. At least for me, it's much more fun doing a turret/tag board/tag strip/point-to-point than stuffing a PCB.
     
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  8. LowCaster

    LowCaster Tele-Holic

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    Getting back to your question, I would like to point out that most amp kits are replicating the vintage tube amps. People don’t want to pay for a vintage amp (with all the drawbacks of used gear), but they want to get as close as possible to how they used to be made. If a guitar player wants a modern PCB based amp or a solid state amp, he can already buy that for cheap. Very few people will open a Blues Junior and say « I want to build that » be it with PCB or turret board (boards?)...
     
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  9. Wally

    Wally Telefied Ad Free Member

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    Back in the ‘90’s I had a EE friend who built extremely high dollar solid state monobloc power amps which sold to recording studios and high end private users....$30k a pair. He got interested in guitar amps and built 7 ‘tweed’ circuits in about a month and a half. He used the same process for his tube amps as he did those SS monoblocs...he etched his PCB boards from copper sheets. Those amps were merely exercises for him, but they were very good amps.

    https://www.instructables.com/id/How-to-Etch-a-PCB/
     
  10. jvin248

    jvin248 Poster Extraordinaire

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    PCBs are not used for the same reason premium guitars don't have plywood bodies nor ceramic magnets ... all the cheap stuff was made with plywood, ceramic, and PCBs and if you're a "real" player you can't have any of that if you expect good tone.

    On the guitar side .. most players who bought plywood ceramic guitars back in the 60s and 70s because they were inexpensive and a cheap guitar was better than no guitar, struggled with the wonky fretwork and poor setups which made those guitars bad not the materials used in their construction, but teens can't see fretwork and setups so they blamed what they could see was different between their guitar and the top end guitars. Didn't help there has been this Tone Wood marketing myth in every magazine review. I've rescued quite a few trashy player guitars with fret leveling and setups that sounded awesome after the work was done.

    PCB amps can be much higher quality, more manufacturing repeatable, by using that board. But boards have historically only been used in the cheapest amps sold for the lowest prices with sketchy parts on those boards (like the plastic jacks noted above) and so players have come to associate hand soldered point to point circuits as 'the best!' and PCB as 'the worst!'.

    Look into the Peavey Bandit ... all solid state PCB that was once hated (because it was an inexpensive amp kids played when kids still had a lot of learning) but now that the Internet channels found them, they have seen a resurgence. Used market for them has effectively doubled in the last five years. Most of them are surprisingly durable and one factor they are loved.

    The other thing to ask the fancy hand wired amp players ... how big is their pedal board full of PCB panels? They are effectively running a modular PCB amp.

    .
     
  11. Lowerleftcoast

    Lowerleftcoast Tele-Meister

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    I don't think a proper PCB is a problem at all. The problem with PCB design in a guitar amp is the quality of the PCB board and the layout. The rigors a guitar amp has to endure do not mix with PCB mounted tube sockets. I am not a fan of input jacks, pots, speaker jacks and the like mounted to the PCB either. In a pedal, the stress put on the board is small and problems seldom arise. That is not the case in guitar amps.

    I don't know why guitarists spend as much money on a new DRRI when a much more reliable DR is available for the same price. Well, maybe it's the new car smell.

    One more thing. I find it extremely difficult to twist the PCB for AC heater supply.o_O
     
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  12. Digital Larry

    Digital Larry Tele-Afflicted Gold Supporter

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    Since many people (as already noted) are (re-)building some of the simplest tube amp designs of yesteryear (Fenders, Hammonds) and many of those are documented not only by schematic but a physical layout (terminal strips/turrets), there's no need to interpret anything, and one feels a better sense of replicating the original. Especially if you don't really have an electronics background and are painting by numbers so to speak.
     
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  13. Zipslack

    Zipslack Tele-Meister

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    I'll also throw out that size and cost are an issue. You need a large piece of copper-clad, a large container, and a lot of etchant- preferably a heated setup with aeration/circulation. Then you have the chemicals and wastes to deal with. In the end, you will have something that will stand less abuse because of the heat and vibration, but will also be more difficult to repair over time (lifted traces).
     
  14. muchxs

    muchxs Doctor of Teleocity

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    Read the hundreds of threads PCB vs. tag board.

    Around 30 years ago I tackled an ex- Rolling Stones SVT, part of the Piero's Music stash of broken amps Lou hooked me up with back in the '80s. Thanks, Lou! There was some really, really good stuff in that pile.

    And... if you've ever tried to repair an expensive amp that has holes burned through its board where its screen grid resistors burned through...

    Same with the Marshall- esque Univox I got from Lou. Broken PC board.

    Tag boards and turret boards are far less troublesome.
     
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  15. LowCaster

    LowCaster Tele-Holic

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    This is an interesting comparison. I’m good at painting, so painting by numbers is of no interest to me. I’m no good at electronics, but if I build something I want to learn something and understand what I’m doing, ready-made PCBs are more like painting by numbers, I don’t think they help the learning process.

    Making your own PCB may be interesting for the more advanced, but for me it just adds some unnecessary complexity for the smaller projects.

    Once again I’m not bashing PCB, it’s the path to more complex builds, mass production and miniaturisation. While most use PCB as a way to produce things cheaper, I heard that some amps used high quality PCB as a way of improving quality. I looked inside my Peavey Bandit 65 too and the PCB in there is huge, with lots of free space and the conductive tracks are as large and thick as possible, that’s the kind of PCB I could see myself using.
     
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  16. Axis29

    Axis29 Poster Extraordinaire Ad Free Member

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    I love my PCB-built amp. But, I don't love working on it. It's a true PITA to get any small components off and replaced when it goes bad. I've ruined one amp PCB already. Don't like the idea fo doing it again.

    But, the other issue is... What if I design the PCB incorrectly? A little off and there's hum, or I send a wire the wrong way and it fries my brand new transformer? I am not an EE. Don't know diddly about designing PCBs. Chances are, I'll get it wrong.

    When it comes to hand-wiring, the parts and wires are bigger, easier to chase down, etc.


    But, the other part of it is the hand-crafted-ness of it all. It feels more like creating something when I've soldered every piece in place. Even if I'm doing a kit, or following an age-old design. It's like making a belt at summer camp, it might have not been the prettiest thing, but you wore it with pride because you had made it. I always felt more accomplished if you handed me a block of wood, and said carve a neckerchief slide... As opposed to handing me a pre-carved piece and said, paint it pretty colors.
     
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  17. moosie

    moosie Doctor of Teleocity Ad Free Member

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    Ease of maintenance. Robustness. End of story.
     
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  18. KT89

    KT89 Tele-Meister

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    Strongly disagree. PCBs aren't used because you can't go out and make one. Single sided PCBs at home are limited to what your printer can do which is usually too small to be useful. Professionally made PCBs are expensive in the size that tube amps require. Much cheaper to do a turret or eyelet board DIY but a well-made PCB will be both lower noise and more robust than your DIY turret solution. Don't even compare true quality circuit boards to the cheap junk found in most commercial amps; the good stuff is not cheap.
     
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  19. moosie

    moosie Doctor of Teleocity Ad Free Member

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    Sorry, I should have said "ease of maintenance, robustness, end of story FOR ME".

    To suggest I use a well-built PCB is to suggest a fix for a problem I don't have. Personal taste, I guess. Just don't need 'em.
     
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  20. sds1

    sds1 Tele-Afflicted

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    Been wanting to start a PCB thread for a while... I love love love PCB and have generally abandoned turret boards and P2P in favor of them. Here's why:

    1) The design-time advantages of PCB are HUGE over traditional methods. With PCB CAD software you get both electrical rules and design rules checking as well as built-in validations to ensure your board matches the schematic. With DIYLC for example there is no way to validate a layout against the schematic diagram.

    2) PCB design forces you to create a BOM before fabrication and deal with real-world component dimensions, ensuring that your board layout matches up with the components you actually use.

    3) PCB minimizes assembly errors (less human assembly).

    4) PCB can be more compact.

    5) PCB can achieve lower noise floor over traditional assemblies.

    6) PCB is very inexpensive to fabricate

    I've found that many arguments against PCB are unfounded, or easily overcome via design choices.

    1) PCB is just FR4 + copper, the idea that the same exact circuit/components on PCB will inherently sound worse is silly!

    2) PCB can be just as maintainable as traditional construction if you design it to be.

    3) PCB material can be extremely high quality if you choose -- up to .125" FR4 and as much copper as you want.

    4) Hardware like jacks, sockets, pots, can be mounted off-board and attached to circuit via hookup wires, as is tradition. Physical forces combined with crappy quality boards/solder have historically led to high failure rates where these components are mounted on-board. I avoid this completely, my boards come out looking quite traditional despite being PCB:

    [​IMG]

    All that being said though, PCB may get a little bit impractical in the DIY world for one-off building. I would not attempt doing my own chemical etching at home, I've heard that doesn't always go so well and you're then dealing with a single-sided board. That's limiting! You can fabricate small boards in China for practically nothing (think relay boards, power supply boards, an add-on reverb circuit, etc.) but to do an entire amp with minimum order of 5 boards, I can see where folks would think twice about the practicality of that.
     
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