Building the Meat Sphere

[lulu_joe13]

I have a question about the grounding of this. On the drawing Taylor has in the pdf all the audio connectors are grounded to the same point. Is that the same ground as the ground pad on the board? Should I connect all the grounds to the neg side of the power? Thanks.

[Taylor]

Yes, connect all the grounds including the board ground together. Most people do it at the input jack because it's got a bigger tab onto which to solder than the power jack.

[lulu_joe13]

Taylor thanks. Learning lots from this one. The Gristleizer worked like a snap, so I didn't need to learn about troubleshooting and tracing until now!  OK. So, I have now determined that the vactrols aren't lighting. When I measure the change of resistance across the vactrol resistor posts I see none until I briefly touch the positive side of the vactrol LED post with +9VDC. Then the resistance changes and the visual LED lights as well. Any suggestions what I should look at? Thank-you. Joe.

[DrKoester]

I replaced the colour pot with a different B100k.  The one that came off tests fine when it is disconnected.  This replacement is doing the same thing...essentially it goes 0-60k through the first 80% or so of its motion and over the last 20% it comes back down to 55k. 

Is there something going on elsewhere in the circuit that could cause this?

Thanks, Tom

[Taylor]

Taylor thanks. Learning lots from this one. The Gristleizer worked like a snap, so I didn't need to learn about troubleshooting and tracing until now!  OK. So, I have now determined that the vactrols aren't lighting. When I measure the change of resistance across the vactrol resistor posts I see none until I briefly touch the positive side of the vactrol LED post with +9VDC. Then the resistance changes and the visual LED lights as well. Any suggestions what I should look at? Thank-you. Joe.

Seems your envelope follower is not working. Check the dual opamp and its surrounding circuitry for shorts. Also, the opamp here is critical. You need the part listed in the PDF (don't remember it offhand) and some people have experienced some units of that opamp not working as well as others. Try swapping it out for another.

[Taylor]

I replaced the colour pot with a different B100k.  The one that came off tests fine when it is disconnected.  This replacement is doing the same thing...essentially it goes 0-60k through the first 80% or so of its motion and over the last 20% it comes back down to 55k. 

Is there something going on elsewhere in the circuit that could cause this?

Thanks, Tom

Often resistances read strangely while in circuit because f series and parallel resistances from other components. I wouldn't worry so much about that. It sounds to me like you have the same problem as lulu joe regarding the envelope follower, but in your case I suspect something is shorting out in your enclosure. Try taking it back out and seeing if it works. If so you know it's shorting and you can figure out a way to better isolate the board from the box.

[DrKoester]

Thanks Taylor!  Looks like you were right about the short....the thing works fine out of the enclosure.  Back to the funk!  Bittersweet however as this is supposed to be a b-day gift for my bass-playing older brother.  I have a feeling as soon as I hand it off to him I will be back to building my own.

[lulu_joe13]

Well. I did an audio trace. The audio signal seemed very weak on the side of the 220k resistor that is farthest away from pin 1 of the dual op amp. So, I changed the resistor. The signal also seemed weak on the decay pot. So, I reflowed the solder joints. In fact I reflowed most of the solder joints on the board just to be sure. I changed all the electrolitic caps in case they were damaged when I connected power backwards early on.
I replaced both theTL074 and LM1458 with new ones.
So, now I think it's working. I can get a triggered wah effect and so forth.
I read the resistance at the vactrol legs and it changed from 220k down to very small when I strummed a note. And, didn't change when I turned the trigger to off.
========>I STILL can't get the visual LED to flash? RLED is 4k7. Somewhere in the thread I thought I read that value is what it should be. Would changing that value make it light? If I can get this damn LED to light, I'll consider it done.
As always thanks for reading this.

[lulu_joe13]

One last thing about the vactrol LED and visual LED. I only read about 1.6 volts on the positive leg. Thanks again.

[lulu_joe13]

Hooray. Debugged and working! I call mine the Funky Meat! Thanks for the help.

[DrKoester]

Greeting again.  I can't get the FX loop working.  I've looked over the wiring diagram and I believe I have it wired correctly.  Here's how I have it:

[lulu_joe13]

Do you have a VOM? Check the diagram one MORE time and the use the VOM to check continuity. Does it you could be getting a short on the enclosure.

[DrKoester]

lulu..sure enough checking over the diagram resolved it.  I had the tip of the send connected to the tip of the return.  Fixed it and I have a fully functioning meatsphere!

Thanks all!

[Nicofromfrance]

Can someone please tell me what are the exact dimensions of the Meat Sphere pcb? I'd like to know if it will fit in an enclosure that I already have. Thanks a lot!

[lulu_joe13]

It measures 4-15/16 x 2-6/16.

[Nicofromfrance]

Thanks, I appreciate that! 

[Rmanen]

Has anyone got sound samples of this pedal on bass guitar? 

[lulu_joe13]

I don't have sound samples, but if the question really is, "Does it sound good with bass?", then the answer is, yes. I use mine with a fuzz in the effects loop and it sounds awesome. Hugh Hopper, Soft Machine like. I also use it with the bass alone to get a funky clave sound.

[kwijibo]

I'm not getting a triggered effect. I get clean output when turning the blend all the way to the clean side, so the first TL074 appears to work. The LED will light depending on the positions of the attack, decay and intensity knobs but doesn't seem to change at all with the input signal. The sensitivity knob doesn't seem to have any affect. Pulling the LM1458 stops the LED from lighting under any conditions. I've traced through the circuit from the input and continuity seems to be correct, just that the envelope detector doesn't seem to work.

Any ideas? Are there any common opamps I could try and substitute with? My LM1458s have the National logo and came from Tayda.

[kwijibo]

I went through a couple of sheets of conductive foam covered in ICs and found an LM358 and now it appears to work. The LED follows the input and I get a huge filter sweep