Meatball / McMeat Layouts with on-board switches

[phoganuci]

jota.ventura... Never done my own pcb before.  What hole size should I use?  Different for rotaries than other components?  Thanks!

[jota.ventura]

For most components 0,8mm should be ok. The rotary switches need a little more, about 1mm or 1,2mm, I don't remember. Can't you just measure the pins?

[ChanchoPancho]

Hey everyone, I would like to say that my layout is ok to those who where asking. Altought there are a couple of problems i've found and read about the original design:

1. Mix of phase inverted signals in the blend pot.
The filter inverts signals phase in every opamp stage. This causes a problem in mixing the wet and dry signal in the blend pot. The only mode that works properly is the band pass, in low and high pass mode this problem is noticable.
The solution is to put an signal inverter in each low and high pass mode before the switch.

2. Use of distortion and blend pot.
The other issue i've found is that if you're going to use distortion you hace to place it in the effect loop. This causes 2 problems. First, you can't use the distortion unless the meatball isn't in bypass mode. The 2nd problem is that if you blend the distorted and filtered signal with the one at the input, it will mix a clean and distorted one which in my opinion sounds awful. To correct both issues i think of various mods:
    a. Input is now the return.
    b. Add a amp stage in the new input so now it is buffered (so you can plug your guitar directly)
    c. Previous Input is now trigger. This is just to control the filter response.
    d. in the trigger input replace the opamp stage with one that can amplify and contains the sens pot.
        (now the input can be more sensitive). One thing you should add is a trigger output so you can connect
       directly your guitar there and trigger output to other effects.
    e. Change the first pin of blend pot to the opamp of new input's output.

3. Up & Down mode assimetry.
The filter response is very different in up and down mode. I put and example of how it should work: Suppose the filter is in up mode and the center frequency is in 500Hz. If you play the guitar it should sweep to 700hz and now go down again to 500hz. In the down mode it should be in 500hz at first too, sweep down to 300hz an the go back to 500 again. The problem is that in the down mode frequencies are very low. it think it would be 200-100-200 for the given example.
To correct this issue i think one should put a trimmer in both Sw2A and Sw2C in up/down mode switch. Both trimmer shoul be connected between GND and V+ and the middle lugs to the switch.

Later i'll post a schematic of this changes

[ChanchoPancho]

Later i'll post a schematic of this changes

So here it is. This should give you an example of the mods. I havent asign values to new components yet.

[MAK]

hello, help me please. The problem with "IC2" set at TL072 signal comes on PIN2, of PIN1  no longer published, a map voltage giving.

IC2(TL072)
1 8.92
2 3.15
3 0.57
4 0.00
5 8.50
6 6.60
7 6.60
8 9.50

[MAK]

hello, help me please. The problem with "IC2" set at TL072 signal comes on PIN2, of PIN1  no signal, a map voltage giving.

IC2(TL072)
1 8.92
2 3.15
3 0.57
4 0.00
5 8.50
6 6.60
7 6.60
8 9.50

[MAK]

Del please &  Reply #144

[Strategy]

I'm finally getting around to etching, using the ChanchoPancho layout. is there a final parts layout diagram updated to reflect the corrections & comments accumulated in this thread?

cheers to all who contributed, i'll see if I can make sense of it with a build attempt.

- Strategy

[DavidM]

Hi all,

I am noticing many of you have created the PCB just mimicking exactly the original, including all connections.

However, if I am not wrong, the schematic you guys are working on is the one by Joep, which is thought as a True Bypass scheme.

Could you enlighten me if you are using a true bypass or a buffered bypass scheme, since the original Meatball is buffered bypass?

Thanks,

David

[ringworm]

The schematic was really only used for reference, when I built mine I had it wired the same as the original, buffered bypass.

[DavidM]

Thanks, Ringworm.

Is there any shcematic for the buffered bypass? I take it people copying the original PCB are using it as well? Since I can not find any reference to the buffered bypass in the thread.

Thanks

David

[ringworm]

No schematic but I had this wiring diagram posted in this thread somewhere. You could maybe figure it out from that, I just copied from gutshots of the pedal.

[DavidM]

Thanks a lot, Ringworm.

I am kinda sucking info from this topic since I am building my Meatball on a PCB I etched myself but hope no one gets offense

EDIT (that was intended for the Meatsphere thread, sorry)

I am wondering about Pedals 1 and 2 and their connection points...

D

[ringworm]

With regard to the jacks, I just made reference to the gutshots posted earlier in the thread. Word of warning, I don't own an expression pedal, so never tested 'pedals 1 & 2', the send/return worked fine though. I had knocked up a smaller layout but never built it and made the jack wiring a little clearer. Again, use with caution, as it's untested.
http://dl.dropbox.com/u/11183663/meatwire.pdf

[DavidM]

Thanks again, ringworm. WIll keep you posted.

D

[DavidM]

Hi everybody,

Finally assembling my McMeat.

I have a question: why are R17 and R21 different values? In the Mu-Tron III, they are both 220K.

Any ideas?

thnkx

D

[DavidM]

Just for the fun of it, here are two clips of my ultra modded McMeat.

I have added an LFO, independent outputs for Dry and the 3 filter options, a buffer to the Return, an inverter for HP and LP so as to avoid phase issues, a Full Wave rectifier and a manual Cutoff knob.

http://snd.sc/MFvgko
http://snd.sc/MFvfgc

Best,

Dave

[giappui]

UP!!

no one tested the ringworm's layout?

for layot with pot on board where can i  take the schematic? is that on mcmeat pdf?

sorry for my english i'm italian

thank you all 

[ch1naski]

Here is a schematic, I I don't know if it's for the onboard pots..... http://www.experimentalistsanonymous.com/diy/Schematics/Filters%20Wahs%20and%20VCFs/Lovetone%20Meatball%20McMeat.pdf

[Govmnt_Lacky]

Necro-bump...

HAs anyone verified any of the layouts on this thread?

I am interested in doing a 1-for-1 PCB clone of the original Meatball and this is the closest I have seen. Can anyone verify that ANY of these layouts are good to go?