Insanity Box

aron · April 27, 2009, 08:37:27 PM

Volume drop? No, perhaps the MiniBooster at the end (last stage) is not wired correctly.
Time to make an audio probe.

sm3000 · April 27, 2009, 10:32:59 PM

wait a minute! this is the pinout of the fet MPF102 which is the same as the J201

so this layout (that I used for my PCB) uses different fets? http://www.diystompboxes.com/pedals/layouts/inlay.jpg

danielwarner · April 27, 2009, 10:47:57 PM

Your problem is definitely the JFET pinouts, look at the MPF102/J201 pinout and then look at the board pinouts

You'll have to replace them and do some lead rearranging

sm3000 · April 27, 2009, 10:50:52 PM

CORRECT!!! I'll have to wire the J201 fets with the flat sides facing the 1M resistor and D will match, I'll still have to swap the leads for G and S. What's the best way to do that in your opinion? Just make sure the fet leads don't touch and wire them with S and G swapped?

danielwarner · April 27, 2009, 10:58:43 PM

Maybe insulate the leads that cross with some electrical tape or heat shrink, or there is premade tubing for lead insulation, just so they don't short one another

sm3000 · April 27, 2009, 10:59:28 PM

..and about the opamp I think i'm gonna try and use the 4558 all I have to do, according to pinouts and layout, is cut the pins 6 and 7 on the 4558 and wire on the pcb the tracks that connect the pins 6 with 1 and connect 7 with 8.

so that i can have on the 4558 this wiring:
1 /
2 IN-
3 IN+
4 GROUND
5 /
6 OUT (because connected with pin 1 of 4558)
7 V+ (because connected with pin 8 of 4558)
8 /

It doesn't sound very clear but by doing that I think I'd be able to use the 4558 without a problem.

danielwarner · April 27, 2009, 11:00:43 PM

p.s. You don't want the JFET's flat sides facing the resistor, they're fine the way they are, you just have to rearrange the S and G pins

sm3000 · April 27, 2009, 11:06:46 PM

according to this

you're right! let's get some insulation!

sm3000 · April 28, 2009, 12:53:10 AM

AND IT WORKS! now the FET's pins S-G are switched and after I did that mod to the op amp pins I'm running a 4558 no prob! I still have two 1N34, tomorrow I'll see if I can change them for three 1N914.

Bottom line it sounds bigger and after I fixed the FET section I have no volume losses. I'm messing with the trimmers but I don't seem to find a good setting. It sounds more like a fuzz than a the distortion in aron samples, it's clipping but I don't get all those nice natural harmonics!..any suggestions aron? at least we're making progresses!

What are the differences between your insanity proto and the layout? do you have the 100uF cap connected to the 8 and 9 CMOS pins? do you have the bias control before the CMOS?

aron · April 28, 2009, 01:14:29 AM

The trims between stages are the ones you should pay attention to. They control how much signal is pushed into the next stage. First turn them low and then start bringing them up so that you can hear how they affect the pedal sound.

sm3000 · April 28, 2009, 03:44:23 AM

Ok after switching to three 1N914 the tone is definitely better..but yours is still ganier and less fuzzy...do you think is due only to the trimpots? do you mind telling me the differences between your proto to the layout? thanks and sorry for being a little annoying!!!!!

aron · April 28, 2009, 03:55:54 AM

Did you set the CMOS section to the values I listed? I have no idea about the layout, I didn't design that. I made mine on perfboard. Whatever is happening to yours IS probably the values of the trimpots. There should be tons of gain in this circuit.

sm3000 · April 28, 2009, 05:06:26 AM

might it also be the drive pot? I have a linear instead of a log. (and my pot feels lefty)

aron · April 28, 2009, 05:09:35 AM

If it's 1MEG it will work. The op amp alone will generate tons of distortion.

sm3000 · April 30, 2009, 02:44:07 AM

There you go guys here's a sample of my finished (?) Insanity Box! I only tweak the Drive. I play through a GK 250ML clean channel.

http://www.yousendit.com/download/dVlyK0dsSWhtNEpMWEE9PQ

As you can see the bass frequencies are a bit "clogged" maybe I need a bias control?

aron · April 30, 2009, 03:23:51 AM

Hard to tell on my laptop speaker. Actually it sounds pretty cool here. Let me check it out at work tomorrow.

timotet · April 30, 2009, 12:50:05 PM

I think that sounds awesome good job!

sm3000 · April 30, 2009, 06:59:43 PM

thank you! now i need to finish the enclosure!

I was thinking of building the Dr.Boogie as my next pedal...we'll see.

do you hear, when I play the unchained intro that the bass freq is almost gated? I'm gonna try to tweak it around a little bit and see what happens!

aron · April 30, 2009, 07:05:07 PM

Gated? OK, then yes, might be the CD4049 bias.

sm3000 · April 30, 2009, 08:25:26 PM

So do you think it would work if I added a 50K trimpot and wired it up as shown in the layout?
Aron take a look at that 100uf cap. is it really needed? I don't see it on your orig. schematic

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Insanity Box