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.
Anyone?
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 8)
Don't bother removing the tone control. Just change C2 to .0047u, and leave the tone control at 12 noon (no cut or boost).
Thanks very much guys. I appreciate the advice.
Quote from: jplaudio1. 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!!! :D :D
Finished with the mod. Gonna A-B it with my OD-1 at rehearsal tomorrow.
let us know how it sounds 8)
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.
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
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
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.
Quote from: jplaudio
2. Remove C4 and replace with a 10k
Could someone please clarify this instruction? Everything else makes sense to me.
Quote from: jplaudioQuote from: palthegiraffeQuote from: jplaudio
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:
[/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]
Quote from: G Kresge
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.
Right, Thats that quad opamp, MartyMart! Those are the models I prefer.
Regan
In that case, does anyone know how to date Boss pedals based on their serial numbers? I'd love to locate one of those that you're talking about with the quad opamp!
And does anyone here have a schematic for the OD-1? The link in the schematics section of this website to that pedal goes to a nonexistent page.
HI,
The older OD1s with the quad op amp were MUCH better sounding. You can get 90% of their tone on the newer OD1s with the following mod:
C1 C6 and C7 .047 -> .1
C2 .0047 -> .047
I have also removed the dual opamp and installed a quad but VERY difficult as they are in upside down and several traces need to be redone, and several bias resistors need to be removed or changed to run the op amp. The chip change did not help as much as the cap change.
have fun!
Okay, if the .01 is the less bright sounding of the two resistors that were suggested, what about metering the equivalent resistor in an OD1 and then placing a resistor of that value where the .01 is now in the modded SD1? If this would work, which resistor should I be metering in the OD1?
Analogmike: are your cap changes for the Od1, or for the modded SD1?
Thanks!
Also, I have a couple of different downloaded OD1 schematics, but I really don't know how to read them beyond recognizing what the parts are - no idea as to what the parts do or how they work together. If this would help out anyone that can make any suggestions about the mod, I could e-mail the schems.
Thanks again.
Quote from: G Kresge
Analogmike: are your cap changes for the Od1, or for the modded SD1?
Thanks!
Sorry I was unclear, the mod changes a later (8 pin chip) OD-1 to sound like the earlier (14 pin) OD1. But SD1 could be very similar to the later OD1, I have not compared them.
Thanks Mike,
I might try that if I don't end up finding an older model with the quad opamp, good to know I'm not nuts in thinking they are much better:)
Regan
Thanks for clarifying, Mike.
If the .01 is the less bright sounding of the two resistors that were suggested, what about metering the equivalent resistor in an OD1 and then placing a resistor of that value where the .01 is now in the modded SD1? If this would work, which resistor should I be metering in the OD1?
Boss SD-1 schematic link (http://fuzzcentral.tripod.com/sd1/SD1.gif)
Boss OD-1 schematic link (http://membres.lycos.fr/youngilaboungi/od1.gif) (4558C version with switching omitted from the diagram)
Call me cuckoo, but the only differences between the SD-1 and OD-1 according to the two schematics linked above are:
SD-1 to OD-1:
R1 >> 1K
C2 >> 0.0047uF
C6 >> 0.018uF
C4 >> 10K resistor (see below)
This last weird cap to resistor change requires a bit of extra trickery. If you look at the second opamp stage of both pedals, you can see that:
In the SD-1:
R7 is connected to pin 3, and 4.5volts is also connected to pin 3 via the capacitor C4.
In the OD-1:
R7 is connected to pin 2, leaving 4.5volts connected to pin 3 by itself via a 10K resistor.
I'm guessing you could solve this problem by doing this:
1. lift the end of R7 from its hole
2. desolder the wire from lug 3 of the tone pot
3. solder this wire to the lifted leg of the R7 resistor
4. swap C4 for a 10K resistor
Just make sure you're lifting the resistor leg that was leading towards C4 and pin 3 (maybe someone can confirm which side leg this is?)
(http://users.bigpond.net.au/styrowfoam/mod.gif)
Hopefully that trick should work. Finish it off by desoldering the other two wires from the tone pot and put tape on the ends or something so they won't short out against anything.
I'm just going on the differences I can see in the two schematics and don't want to kill your pedal. Perhaps some other forumites can confirm that this will actually work first?
I'll give that a try on another SD1 over the weekend. Thanks for the tips. I'll report back once I A/B that one!
I think the end of R7 you've gotta lift is the leg pointing up towards the top of the board if I remember correctly.
I sure hope this works :twisted:
QuoteQuote from: MartyMartQuote from: G Kresge
The .01 should give a lower cutoff on the high pass (more bass) than the .0047.
There may be other variables including the opamp.
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]
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.
How similar (if at all) are the PCB layouts between the quad and dual opamp versions???
Quote from: G Kresge
How similar (if at all) are the PCB layouts between the quad and dual opamp versions???
Those versions of the OD-1 are quite similar except as I mentioned above the quad opamp and dual opamp traces need to be shuffled, and a few other traces for the bias resistors are different. I used 4 jumpers on the chip to make the 14 pin opamp work.
Damn it! I wish I could make a PCB from the schematic and just build one myself. I'm sitting here staring at it trying to draw it out, but I haven't got any idea what the hell I'm doing.
Quote from: G KresgeDamn it! I wish I could make a PCB from the schematic and just build one myself. I'm sitting here staring at it trying to draw it out, but I haven't got any idea what the hell I'm doing.
If you can borrow a vintage OD1, the "raised" solder traces should be easy to "trace" onto grease proof paper,( like we did as kids ) then stick a coresponding piece on top and "copy" in the components, from the top side.
You could then "tack" those onto a nice exact size piece of perfboard !
What do you think, possible ?
Or have a PCB made from it.
I know it can be done also on a scanner, scan both sides and print to see through plastic sheets, which you can stick to each other :)
Just an idea.
Marty. 8)
Well, what I originally intended to do was very similar to that. Before a couple of days ago - and finding out about the quad opamp version of the OD1 - I had scanned and meticulously "traced" the OD1's PCB with that exact intention. If anyone out there that has the quad version could send me a scan of the PCB (top and bottom) I would be incredibly grateful.
Quote from: G KresgeWell, what I originally intended to do was very similar to that. Before a couple of days ago - and finding out about the quad opamp version of the OD1 - I had scanned and meticulously "traced" the OD1's PCB with that exact intention. If anyone out there that has the quad version could send me a scan of the PCB (top and bottom) I would be incredibly grateful.
On its way to you soon sir !!
Marty. 8)
Mike,
A few questions,
Is there enough room for a small daughter board with the quad chip?
Which quads did you try?
Hmmmm, is it a matter of paralleling the opamps? I wonder if piggybacking two duals would work fine.
I'll have to take a look when I'm less tired.
Regan
Quote from: ReganMike,
A few questions,
Is there enough room for a small daughter board with the quad chip?
Which quads did you try?
Hmmmm, is it a matter of paralleling the opamps? I wonder if piggybacking two duals would work fine.
I'll have to take a look when I'm less tired.
Regan
IN this case it's easier to cut traces and run jumpers than a daughter board. But you just gave me an idea... tack 1/2" wire leads onto the quad op amp chip. Use a 1" lead on pin 4. Then you can move 3 of the legs down one slot (4 5 and 6) and pin 7 can go to pin 4, saving cutting of any traces.
I also forgot to mention that you have to bend leg 2 and attach to leg 1 on the chip and leg 13 to 14 (leave holes empty on new pin 2 and 13).
It's not so easy to describe but you can figure it out, that's why it's called DIY 8)
This is an ancient subject but I'd like to comment about the coupling capacitor values. If you look at the schematics for the 14-pin and 8-pin versions you will see that the resistors to analog ground following the capacitors are also different. They scale accordingly.
The high pass filter before the input buffer C1 and R2 are 47n and 100k for the dual op amp version vs 100n and 220k for the quad. Both set the high pass corner at 7.2Hz. Similarly this is the case for the 47n and 1M vs 100n and 470k feeding the output buffer. Is is also the case for the 4.7n-100k combination vs 47n-10k combination which feeds the clipping stage. The corner frequencies are the same despite the sizes of capacitors used.
I'm comparing the schematic dated April 1, 1978 with one dated December 26, 1980.
I've modified an SD-1 to match that of the dual op-amp OD-1 and am satisfied with the results, but I think a higher fidelity op amp for the clipping circuit and low pass filter is necessary to get the clarity of the original OD-1.
Am I missing something?
Given the circuit I find it astonishing a different opamp can give clarity or the opposite.
Only a really big signal (let's say the output of another pedal) gets you most of the time in opamp clipping area.
But with guitar at the input you need a guitar with let's say at least 2V output.
It's a simple circuit. The NPN input and output buffers have been standard in Boss pedals for decades. I don't believe they contribute to the midrange congestion. Save for the chip used for clipping and tone control circuits there really isn't anything left.
Quote from: bobbletrox on January 06, 2005, 07:44:23 PM
Boss SD-1 schematic link (http://fuzzcentral.tripod.com/sd1/SD1.gif)
Boss OD-1 schematic link (http://membres.lycos.fr/youngilaboungi/od1.gif) (4558C version with switching omitted from the diagram)
Call me cuckoo, but the only differences between the SD-1 and OD-1 according to the two schematics linked above are:
SD-1 to OD-1:
R1 >> 1K
C2 >> 0.0047uF
C6 >> 0.018uF
C4 >> 10K resistor (see below)
This last weird cap to resistor change requires a bit of extra trickery. If you look at the second opamp stage of both pedals, you can see that:
In the SD-1:
R7 is connected to pin 3, and 4.5volts is also connected to pin 3 via the capacitor C4.
In the OD-1:
R7 is connected to pin 2, leaving 4.5volts connected to pin 3 by itself via a 10K resistor.
I'm guessing you could solve this problem by doing this:
1. lift the end of R7 from its hole
2. desolder the wire from lug 3 of the tone pot
3. solder this wire to the lifted leg of the R7 resistor
4. swap C4 for a 10K resistor
Just make sure you're lifting the resistor leg that was leading towards C4 and pin 3 (maybe someone can confirm which side leg this is?)
(http://users.bigpond.net.au/styrowfoam/mod.gif)
Hopefully that trick should work. Finish it off by desoldering the other two wires from the tone pot and put tape on the ends or something so they won't short out against anything.
I'm just going on the differences I can see in the two schematics and don't want to kill your pedal. Perhaps some other forumites can confirm that this will actually work first?
This is a far easier solution that is functionally equivalent:
-Remove C5
-Remove the wire that connects pin 3 of the tone pot to the hole on the board labeled 8
-Put a short across C4
-Change C2 from 18nF to 4.7nF