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Project27 adding reverb and overdrive/distortion

Started by bbmf, January 30, 2017, 10:33:41 AM

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I am building guitar amplifier Project27 from RodElliott. Preamp is ready and currently I work on the power amp.


I want to add reverb to it, I was thinking about Equinox  II digital reverb


Also I want to add overdrive, something like Tubescreamer 808.

The question is where to put this in, before preamp or after and in which order? Do I need to bypass preamp or not? Any suggestion or thoughts about this are welcomed.

Also if you prefer other overdrive/distortion or think that would work better in this setup please shared it with me. I know this is subjective but let me know what you prefer.



Speaking from experience;
Keep the amp build as basic as possible and it will give you years of trouble free service.
Once you start adding built in FX you then need switching circuitry and in a lot of amplifiers I've repaired it's often the added circuitry that fails while the amplifier itself is still intact and working fine.

(yes I once wanted an all in one amplifier,,, oh boy what a disaster that was) :loco :duh :lmao:
They are called pedals which are External devices and as such can be used into any amplifier. :tu:


I want it all!!!

You have to admit "all in one" sounds good  :)

But you are right I will keep it simple and after that I will build all the pedals I need.

I will also put 3 way switch and put some silicon, germanium and leds for the "soft" clipping and test it. If I like the result I will put it on the box. Also I will experiment with the bright switch a little.

Thanks for sharing your experience.


just my opinion

Why not build the power amp and use the tubescreamer as preamp first. hehehe  8)

Also ive guild my amp using a 12au7 for preamp into and equinox reverb then into a General guitar Gadgets TDA20x0 power amp.

I have pictures here https://www.ssguitar.com/index.php?topic=4180.0

i also added an effects loop and a Turn on continuity delay circuit (for speaker) to eliminate the turn on pop


I also had the idea of an aux send & return to run a delay/reverb unit. Rod's advice was to take a feed from the output of U1b (pin 7) via a cap, trimpot and 100 ohm resistor, the latter being to stop oscillation induced by shielded cables. The return feed could be re-inserted via a buffer with the output decoupled via a cap and 2.2k summing resistor with another 2.2k summing resistor in the output of U2a before the master volume.

There is also a method of patching in the Tremolo circuit - Project 29.