For anyone working on the Harmonic Perculator (update!)

[mattpocket]

Hey Guys,

I posted the main body of this post in one of the other HP threads yesterday, but I think we're moving on a bit now with finalising the circuit...

I posted the follwing yesterday but I remembered I missed a few things off so I put an update at the bottom, here goes:

Yesterdays post:
Hey guys,

I breadboarded this today and got it working, sounds pretty good... a really good distortion actually, the best I've built so far... I am going to play around with the clipping and a few different amp/guitar setups, I will probably add a tone stack of some description too... I am currently playing it with my PRS Singlecut with humbucking P90, and my Marshall MG100DFX (no jokes  icon_redface) and it sounds good even through that amp! I will give it a go through my valve head and cab tomorrow when I can be arsed to lug the cab upstairs...

Has anyone else had a go yet? I used the schem from above to do my breadboarding, rather than using the layout, so I cant verify it yet... and I dont want to re-breadboard until I have tweaked some more...

Can anyone give me any info on the biasing... I currently have all the resistors apart from the one in the clipping diodes wired up as trimpots... which trimpots should I alter to change the bias, and where do I put my multimeter?

Thanks for the help with this circuit guys...

Matt


Today's update:
So yeah, I forgot to tell you a few things yesterday. Firstly, my main issues were with the 47uF tant cap. I couldnt find them at smallbear so I brought a 47uF electro and tried that. It just kept farting out and making weird sci-fi noises... I then tried two 22uF tants in parallel and series, with no good results... I also tried a standard film cap of 47uF which was also no good... I then settled on the 22uf tant on its own as this for now is producing good results... Although my farting problems could be to do with the biasing of the circuit at present. Read on.

I also noticed that the ge diodes I was using, two variations one workalike of 1n34a's and another couple, but done quote me on those... These were also adding to the farting out, so I switched them out for 1n4148 si which seem ok...

I havent done anything with biasing yet, because I've not done any before and really dont know where to start. I am guessing R2 on the schem is going to be the place to look.. (I've reposted the schem below for convenience)

Any help with the biasing would be much appreciated, and also if you guys can give us all updates of what you've been finding...

FYI, I've used trimpots for all resistors apart from the clipping resistor, and set them to the values specified on the schem (I am scared of messing with them). I used 2n404a (hfe 50) for the pnp and 2n3565 for the npn.

Hope you can get something out of all that, all my work has been a bit of a hash so far...

http://www.geocities.com/george_giblet/effects/percolator_later_rev1_1.png

Matt

[mattpocket]

Hi,

I saw another perc thread that doug_h posted that his brick/speculator could get the weird harmonic feedback like in the gearwire albini vid.

Has anyone managed to acheive this with any other designs, particularly the one a lot of us have been working on from the alphonso hermida schem?

Matt