Soul food diodes

jpfamps

handsomerik said: you mean silicon surely Your are obviously not a Minder or Only Fools And Horses fan.....

Or even Charles Dickens.

ecc83

jpfamps said:

ecc83 said:

The 1N34a diodes are point contact types just like OA90/91s so I doubt there will be any audible difference.

Other types you can play with are LEDs and Shottky diodes. 

Just to be an early morning pedantic? SiliCONE is a complex compound. SiliCON is an element and is what semiconductors are made from.

Dave.

Forward voltage drop of geranium diodes is lower than silicone diodes so you will notice a difference.

As you are generating a square (ish) wave with higher harmonics I suspect stray capacitance may also have an effect.

Err,the 1N34a's ARE Germanium point contact?

Dave.

ecc83

jonnyburgo said:

ecc83 said:

"Just to be an early morning pedantic"

Did you mean "Just to be an early morning pedant"?

No, I just let everyone else insert "twat"!

Just remembered! It is a bit of a minefield. "We" had to go from conventional LEDs to SM jobbies and they made a tiny difference (so I was told! Mutton you know)

Dave.

suspiciousminds

I'm going to have a go at modding this today with a on/off/on dpdt switch.
My plan is to desolder both diode ends on the left side in this pic and resolder onto two outer pins on the dpdt switch.
Then connect the two oa90's together and connect them to the two pins on the opposite side of the switch.
Then solder some wire to the two remaining centre pins on the switch and solder both wires back into the board where the 1n4148's were.
Would this work ok?


This is the other side of the pcb, the diodes are by the r17

Gassage

I've dropped a note to a mate of mine that's very good on pedal innards.

His name's Mason- he'll be back shortly when he's finished his legal cases.

ICBM

The diodes are in parallel - essentially a single circuit element - so you only need a SPDT switch not DPDT, if that's useful in order to save space and simplify the wiring.

suspiciousminds

Do you mean similar to this ICBM?

ICBM

Yes, exactly.

suspiciousminds

Cool,
Great stuff! Cheers!

suspiciousminds

All small update - ended up putting sockets into holes for the diodes on the board, as i was worried about damaging it - its quite compact inside and theres a few surface mounted components quite close.
Without any diodes it sounds quite a rough overdrive, not bad though.
So far i've tried new 1n4148's which sound quite smooth, OA47's which sound great, and the OA90's - not really noticably different to the OA47's.
Switch to go in next.
Now on the net i can see "meat" mod which is an additional pot which seems to add bass to the sound, unfortunately i cant find any schematics for that so i'll put that on hold.

suspiciousminds

Heres a pic now its housed back up:

Thanks for everyones advice - much appreciated.
Now i've had a play, the IN4148 is the quietest setting, the off is very loud but quite rough sounding almost distortion like, the OA47's sound great - again quite loud but smooth and not fizzy like the IN4148.
The only real issue i had was rehousing it up - for some reason every time i tightened down the nuts on the vol/treble/drive pots the signal switched off so i had to place washers between the pots and the case - possibly an earthing issue due to the mod?
Anyways, well worth doing IMO.

ICBM

I would guess there's something shorting against the casing when the PCB is pulled up tight. The washers will give just enough clearance to stop it.