Project files: New gainclones

What is it?
These are the board files for the gainclone amp and PCBs posted here. They (sort of) supercede the original files from this post – at least the PSU.

How big are the boards?

  • Amp: 2.4″x1.5″ (app. 61×38 mm)
  • PSU: 3.925″x1.95″ (app. 100×50 mm)
  • Bridge: 2.55″x1.6″ (app. 65×41 mm)

What is the status of the boards?
The boards are in version 1.0 or higher. They have all been built and tested.

Does it use any special/expensive/hard-to-find parts?
Not really. You can do what I did and splash out on 0.1% resistors and audiograde caps, but it definitely isn’t necessary.

Anything else I need to know?

  • The LED on the amp board is connected rail-to-rail which means that in a typical application it will drop around 70V, so it should be rated 1W.
  • If you use film caps thicker than 3mm for the bridge board, you may have problems mousing the diodes completely straight (as I had on the one I built)

Download design files here

Related information:
Note: Always read the “intro post” for additional important information about my designs.

You can find additional information about the LM3875 gainclone in the LM3875 build guide over at



10 Responses to Project files: New gainclones

  1. Walker says:

    One of my guitar amps uses an LM3886. Honestly I wouldn’t be surprised if I yanked out the power amp board and replaced it with a gainclone design like yours and it sounded /better/. Peavey’s “trans-tube” technology that is supposed to make solid state sound like tubes would be better named “horrendous over-engineering”.

  2. theslowdiyer says:

    I am not too familiar with musical instrument amps, but I seem to recall that much of the “special sound” seem to come from a very high output impedance (low damping factor). Even manufacturers that were using low-impedance class D amps for space/cost reasons would then raise the output impedance to ridiculous levels (up to 50 ohms or more for a power amp). If this is the case here, then substituting a “real” GC would definitely change the sound – whether you like it or not is a different matter though.


  3. Greg says:

    Can you comment how the TPA3116 sounds relative to the gainclone? I have a non inverting GC running with 24VAC 300VA trans with some cheapy carbon film and metal film resistors, with 2200uF panasonic FC caps. In short I am very happy with it… I’m curious where the TPA3116 compares to it in terms of depth, clarity, soundstage, and lastly if it can match up to the GC in terms of power handling.


    • theslowdiyer says:

      Hi Greg,

      I haven’t done any detailed comparisons, but I think (subjectively) the GC is ahead on most parameters. The TPA3116 sounds very good for what it is, but I believe overall the GC sounds more natural. Note that there might be more performance to be squeezed out of the TPA chip itself by using better components etc. and I didn’t get that far yet. However, as a basic comparison you can get an assembled TPA board off ebay for about the same as two LM38xx ICs, so trying for yourself might be the best option 🙂


  4. Rupert says:

    Hi theslowdiyer,

    Thanks for the article, but it appears the Design File download is corrupt.



    • theslowdiyer says:

      Hi Rupert,

      I works for me, but if you are still having problems then send me a message through the contact form (on the “about me” page) and I’ll email you the files instead 🙂


  5. Pingback: J-Mo buffer/headphone amp | theslowdiyer

  6. Pingback: Cloning a classic… | theslowdiyer

  7. Pingback: A Smaller Gainclone… | theslowdiyer

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: