SD-1 to OD-1???

[G Kresge]

Based on the similarities in the SD-1 and OD-1 circuits, I'm wondering if anyone out there knows how to eliminate the "Tone" control in order to convert the SD-1 to OD-1 specs?

"Why!?" you ask?

I love my OD-1 and don't want to take it out to gig with it and risk the inevitable "beer spilled in the stompbox" accident from the front row.

Thanks.

[G Kresge]

Anyone?

[MartyMart]

Hmmm, I dont know how similar the circuits are ( would have to take a look inside) but I have both and I dont think they sound very "similar" at all ? My OD-1 is from 1979, so that could be a different parts layout !.
Two of my friends have had "vintage" pedals stolen from gigs, during a break or after sound check !!!!  NOT  cool.
There could be more to it than just removing the SD-1 tone control and to be honest, you are better off leaving it there to get the right sound with whatever guitar/amp your using at the time of your gig/session.

Perhaps just connect both and A/B until you like the matched sound, you could always carefully remove the tone pot and measure the value it's reading, then use a fixed resistor in its place ( there's a thread on this somewhere from yesterday?) or just "set" the tone knob with some hot glue, so you dont loose that "sound"  ??

Good luck anyway,
Regards,
Marty

[jplaudio]

[cd]

Don't bother removing the tone control.  Just change C2 to .0047u, and leave the tone control at 12 noon (no cut or boost).

[G Kresge]

Thanks very much guys. I appreciate the advice.

[jplaudio]

[G Kresge]

1. Lift the end of R7 that connects to C4
2. Remove C4 and replace with a 10k
3. remove C6 and replace with C4
4. Disconnect the wires at pads 5, 11 and 8
5.  Connect the free end of R7 to pad 8 with a jumper wire
6.  replace C2 with a .0047 or you can use C6 (.01)

you now have an OD-1

use the left over pot for a warp control

THANK YOU!!!    

[G Kresge]

Finished with the mod. Gonna A-B it with my OD-1 at rehearsal tomorrow.

[jplaudio]

let us know how it sounds

[G Kresge]

Haven't gotten to A-B the two pedals yet. The adapter jack on my old OD-1 broke, so I need to swap it out before I test them back to back. Thanks again for the DIY tip! I'll let you know when I try it out.

[G Kresge]

I have finally had the opportunity to A-B the SD-1 Mod and an orig OD-1 (a later period model) and Although they were inceredibly similar, the SD-1 Mod was a bit brighter sounding with the controls set the same on both pedals.

How much of this could be due to what is done in step 6 below?

6. replace C2 with a .0047 or you can use C6 (.01)

I opted to use the stock cap from C6.

Thanks
G

[Regan]

I'm not sure how much different the early od-1 is from the later model, but they don't sound that much alike from what I recall.
Back in the mid eighties I had an early od-1(1979 I believe) and a friend bought a new one because he liked the sound of mine. AB'd them together and they were quite different, with the older being much nicer.
I know the older one used a different opamp, plus the switching was done different. Maybe that was the difference.
Regan

[G Kresge]

That's what I'm thinking too after thinking about it more... The OD1 that I really like is a 79 or 80 I think. The one I was A-B comparing with the SD1 mod is a later one. I'll check it out again, but I'm fairly sure that the op amps are the same in both of the OD1s that I'm working with. I'll have to do some more extensive shootouts after the holidays.

Thanks.

[palthegiraffe]

2. Remove C4 and replace with a 10k

Could someone please clarify this instruction? Everything else makes sense to me.

[jplaudio]

[jplaudio]

[palthegiraffe]

2. Remove C4 and replace with a 10k

Could someone please clarify this instruction? Everything else makes sense to me.

The OD-1 has a inverting gain stage using the second half of the OA . The 10k references the non-inverting input to the virtual ground. The output of the clipping stage connects to the inverting input through R7.

<palthegiraffe here admitting his ignorance>
I meant that I didn't know the specific part to put in place of C4. A 10K-resistor? A capacitor that's 10,000 nf?

I have severe limitations sometimes. That history degree does me no good when I'm modding pedals.  :roll:

[G Kresge]

[/quote]
The .01 should give a lower cutoff on the high pass (more bass) than the .0047.
There may be other variables including the opamp.[/quote]

Sorry, I'm unclear as to whether you're suggesting that I try using the .0047 to reduce the "brighter sound"? I'm not sure if I'm interpreting your post the right way.

Regarding the opamp(s):

The opamp in the OD1 (serial number 10200) which I really like the most of the OD1s I have is an NEC 4558C. I haven't gotten around to replacing the power adapter jack on this one for A-B purposes.

The opamp in the OD1 (serial number 0200) which I used for A-B purposes has a JRC4558D.

The opamp in the SD1 which I did the mod on is 4558DD. Is there *really* that much difference in the C, D, and DD suffixes? I guess that could be the case, since I don't know much about the subtleties of these things... Any suggestions or recommendations would be appreciated.[/b]

[MartyMart]

The .01 should give a lower cutoff on the high pass (more bass) than the .0047.
There may be other variables including the opamp.[/quote]

Sorry, I'm unclear as to whether you're suggesting that I try using the .0047 to reduce the "brighter sound"? I'm not sure if I'm interpreting your post the right way.

Regarding the opamp(s):

The opamp in the OD1 (serial number 10200) which I really like the most of the OD1s I have is an NEC 4558C. I haven't gotten around to replacing the power adapter jack on this one for A-B purposes.

The opamp in the OD1 (serial number 0200) which I used for A-B purposes has a JRC4558D.

The opamp in the SD1 which I did the mod on is 4558DD. Is there *really* that much difference in the C, D, and DD suffixes? I guess that could be the case, since I don't know much about the subtleties of these things... Any suggestions or recommendations would be appreciated.[/b][/quote]

The "DD" op-amps are apparently the later re-issue version and sound a bit "crap"
They were the ones in my Park G10r amp, which i replaced with Panansonic NE5532's - IMO that made a HUGE difference to the tone and drive of that little amp.
My OD-1 is from 1979 ( 6800 ) and has a 14 pin op-amp RC3403ADB
The board is thick cream coloured, almost looks like "perf" and the traces are all solid "solder" traces, like a vintage Phase 90 board !!
I would suggest the NE5532 or a Ti- RC4559p for a nice "quality" op-amp but for "original" tone maybe the JRC4558D  would be best ?

Marty.