Demeter Fat control *mini*

[Zanius]

Also verified :)

[sharaynishi]

Unverify this.

Just made it and all i get is a non-stop "beating" sound no actual gtr signal going thru.
Or am I just missing smth here?

[fx-fidden]

I didin't build it not compare it with the schematic, but it says verified.
Anyway, pay attention with this layout. To make it "mini" it has some unusually cut track between holes and an holes shared between a lead of the cap and a jumper.
Did you check every components and cut track... and all the rest?

[sharaynishi]

Yes, Sir. did the tracks (genius way of cutting it to save space imo) checked it all

[fx-fidden]

Ok. Keep to check your built, I'm going to compare this layout with the schematic and the bigger layout
in case there's something wrong. Maybe the author built it succesfully but he posted a wrong version.

[fx-fidden]

Ok, I think I found at least a mistake.
Did you see that cut track line next the 10nF? Jumper it, because that 10nF should go in the VB right in that stripe, instead now is isolated. But I think that is not enough to make the circuit mute, it controls just the high end cut.
I can't find anything else to make this layout failed. Anyway, fix that and test it.
If it still doesn't work... I'll write here the usual thing to check, just in case:
Position of the components, position of the wires, orientation of the caps, orientation of the diode, check if the pot works, check the jack connection, caps value, resistors value (compare the bands color with the resistors you have in stock).

If you want write the votages of the IC (is it a LF442?), and maybe you can post some pictures of the circuit.

Are you testing the board or is everything into the box?

[sharaynishi]

Hey!

Out of the "not wantingness" (I know that's not a word lol) of building another one (since I rly enjoy the non mini version of this in one of my guitars) I decided to give it a try by probing it and the mistake was just at the very beginning (47n Cap was placed 1 space off). Well, I should next time do my work properly rather than spew nonsense.
So, sorry about that.

Now it works well and I am looking forward to putting this into my 2nd instrument now.
Thanks for the help!

[fx-fidden]

Great! Thanks for the update.
Did you jumpered the cut track next the 10nF cap I mentioned some message above?

[sharaynishi]

no, mate. the jumpering wasn't necesarry

[Alamondm]

I may give this one a go. When I do I will leave that cut out. Makes sense.

[golcs]

Hi!

I built the fat control, it works, but doesn't seem to cut the high. It works now as a booster instead. Can it be the cut next to 10pF?

[fx-fidden]

You mean 10nF, I guess, not 10pF.
I really think that cap should cut high end, so if you made the cut put a drop of solder on it and let us to know if you can solve the issue.

[golcs]

Yes!
That solved the problem.
My other question is, i found some info about the Tyler midboost variation which replaces the 10n and the 100n to 220n.
Can you help me which caps effect which cutoff frequencies, and at what frequencies?
Thanks a lot!

[fx-fidden]

I found this information about 10n and the 100n caps replaced by 220n cap, I'm not sure about that mod, and I really like to get the Tyler mid boost real schematic.

If you change the 10nF with a 220nF I think you will get an extremely muffled sound. You can try it, and hear what sounds you really get.
While, change the 100nF with a 220nF should add low end.

Now some speculation.
I found some images of the original PCB with just one electrolytic cap (the one in the PSU, I suppose), three 220k cap (220nF) one more then stock Fat Control pedal, and two greenie caps.
We can assume those are the 47nF input cap and the cap across the VB (10nF in the stock pedal).

This could mean the 1uF electrolytic cap is one of the cap replaced by the 220nF. This has effect just when the boost pot is lower, and it gives more low end (if there's no other mods!). I can't understand totally this thing.
I'm not sure about the value of the two greenie cap.
The input cap could be 47nF: there's no difference if you change it with 22nF or 100nF. I'm not sure about the other greenie cap, it seems a bit bigger than a 10nF.

A thing that me confused is another version of the PCB with a fat red box wima style cap, I'm not sure that could be a small value like the 10nF cap or just a bit more than it.

Here's you can find some circuit image:
https://reverb.com/it/item/13109056-james-tyler-mid-boost-circuit
https://reverb.com/item/28173931-james-tyler-demeter-midboost-and-buffer-combo-pedal-red

And here's there a picture of a schematic drawn, but not so clear, unfortunately.
Page: https://studiogream.blog.fc2.com/blog-entry-126.html
Schematic: https://blog-imgs-55.fc2.com/s/t/u/studiogream/DSC08835.jpg

There is where I see the 1uF replace from a 224 bipolar cap. And even the resistor before that cap: 2.2k instead 1.8k.
The 100nF in VB seems to be, indeed, 220nF.
I can't tell if the 10nF cap is a 10nF.

That's it.