SD-1 diode swapping.

[holio cornolio]

Not about an SD-1 but an OD-1...

Many years ago I built a quad-opamp OD-1 with all new components. A new JRC3403 opamp, and 1N4148 diodes. I laid out my own circuit board, with no reference to the vintage Boss layout or lead-dress.

The clip comparing it to a vintage pedal is here:
https://www.youtube.com/watch?v=upFJytwqTCo

The objective was to see if the tone came from the design/schematic, or from the vintage components, or both. You can maybe hear a subtle difference. But it isn't much.

My conclusion is that the majority of the tone comes from the schematic.

Impressive stuff. I'm only listening on my phone speaker right now but I can't hear a difference between the 2 pedals. I have an od-1 clone that I built from a byoc kit. It has the 3403 chip and 1n914 diodes I think (could be 1n4148, I don't recall). It's my favourite overdrive. I've heard it said that the sd-1 is an od-1 with a tone control but even with my shitty ears I don't believe they sound alike. Even the 4558 od-1s have an edge and an openness that isn't present in even the best sd-1.

[Old_Iron]

Not about an SD-1 but an OD-1...

Many years ago I built a quad-opamp OD-1 with all new components. A new JRC3403 opamp, and 1N4148 diodes. I laid out my own circuit board, with no reference to the vintage Boss layout or lead-dress.

The clip comparing it to a vintage pedal is here:
https://www.youtube.com/watch?v=upFJytwqTCo

The objective was to see if the tone came from the design/schematic, or from the vintage components, or both. You can maybe hear a subtle difference. But it isn't much.

My conclusion is that the majority of the tone comes from the schematic.

Really impressive that you could match a vintage OD-1 sound with new components!

The test was made with all the knobs at maximum, which makes more difficult to hear differences, but still is impressive.

[holio cornolio]

I agree that parts tolerance, or parts value drifting over time, is a considerable factor when you compare different pedals, but it is more pronounced when you compare new pedals with vintage ones. Like in a made in Japan vs made in Taiwan comparison.

When you compare a vintage MIJ with another vintage MIJ, same model, that is less important.

Believe me, when you play with those 3 different variants that I mentioned, you can hear the (subtle) difference.

P.S.: Another relevant detail, I have also MIJ OD-1s and DS-1s with those diode combinations, and when compared that same result comes up.

So I had a small change of plan. Given that my mij and MIT units sound very similar, I decided to use the MIJ as a kind of aural benchmark and a/b it against the unmodded MIT pedal. Having got a decent aural memory of the comparison, I then swapped the 1n4148 in the MIT pedal for 1n1588. I then a/b'd again. Well, I can hear a difference. I surprised myself. The 1n1588 seem to give a very slightly more open and less compressed sound. I hear a touch more high end in the clipping (I don't even know if that makes sense, I don't have the right words to explain what I mean) To use your foam analogy, this is a less tight and more airy foam than it was with the 1n4148. Unfortunately the subtlety really isn't picked up by the microphone on my phone so I will have to invest some extra time in a proper recording when I get a chance. Obviously not scientific by any standard but I am surprised to say that I did hear a difference because I wasn't expecting to. I think I prefer the 1n1588. Which is great because I can't be arsed to switch back

[laurie]

Hmm... 1N1588 is a Zener

[holio cornolio]

Hmm... 1N1588 is a Zener

Sorry 1s1588

[Old_Iron]

So I had a small change of plan. Given that my mij and MIT units sound very similar, I decided to use the MIJ as a kind of aural benchmark and a/b it against the unmodded MIT pedal. Having got a decent aural memory of the comparison, I then swapped the 1n4148 in the MIT pedal for 1n1588. I then a/b'd again. Well, I can hear a difference. I surprised myself. The 1n1588 seem to give a very slightly more open and less compressed sound. I hear a touch more high end in the clipping (I don't even know if that makes sense, I don't have the right words to explain what I mean) To use your foam analogy, this is a less tight and more airy foam than it was with the 1n4148. Unfortunately the subtlety really isn't picked up by the microphone on my phone so I will have to invest some extra time in a proper recording when I get a chance. Obviously not scientific by any standard but I am surprised to say that I did hear a difference because I wasn't expecting to. I think I prefer the 1n1588. Which is great because I can't be arsed to switch back

Maybe you heard a "touch more high end" because you compared to the 1n4148, if you compare to the 1S2473 (the yellow band) you will hear the 1S1588 a bit more round and mellow.

There are many videos on youtube talking about clipping diodes and how they work. You can even "predict" before hand how they will affect the sound just by looking the datasheet for the forward voltage of a given diode.

There is a Wampler's video where he was debunking the magical opamps, and in it he admits that the clipping diode do make an audible difference in overdrive pedals.

Edit: That's the video, he talks about it from about 17:30.
https://www.youtube.com/watch?v=PH2uj9bWfM4

But remember to compare diodes with the gain knob in a lower position, if you crank the gain everything will sound alike.

These two videos are interesting to watch:

https://www.youtube.com/watch?v=kjizpsTv4kg

https://www.youtube.com/watch?v=bb_gmhgzLaA (corrected)

[holio cornolio]

So I had a small change of plan. Given that my mij and MIT units sound very similar, I decided to use the MIJ as a kind of aural benchmark and a/b it against the unmodded MIT pedal. Having got a decent aural memory of the comparison, I then swapped the 1n4148 in the MIT pedal for 1n1588. I then a/b'd again. Well, I can hear a difference. I surprised myself. The 1n1588 seem to give a very slightly more open and less compressed sound. I hear a touch more high end in the clipping (I don't even know if that makes sense, I don't have the right words to explain what I mean) To use your foam analogy, this is a less tight and more airy foam than it was with the 1n4148. Unfortunately the subtlety really isn't picked up by the microphone on my phone so I will have to invest some extra time in a proper recording when I get a chance. Obviously not scientific by any standard but I am surprised to say that I did hear a difference because I wasn't expecting to. I think I prefer the 1n1588. Which is great because I can't be arsed to switch back

Maybe you heard a "touch more high end" because you compared to the 1n4148, if you compare to the 1S2473 (the yellow band) you will hear the 1S1588 a bit more round and mellow.

There are many videos on youtube talking about clipping diodes and how they work. You can even "predict" before hand how they will affect the sound just by looking the datasheet for the forward voltage of a given diode.

There is a Wampler's video where he was debunking the magical opamps, and in it he admits that the clipping diode do make an audible difference in overdrive pedals.

But remember to compare diodes with the gain knob in a lower position, if you crank the gain everything will sound alike.

These two videos are interesting to watch:

https://www.youtube.com/watch?v=kjizpsTv4kg

https://www.youtube.com/watch?v=bb_gmhgzLaA (corrected)

Now you've got me checking eBay and reverb listings for a 1s2473 sd-1.

[Old_Iron]

I just learn something about the SD-1, it's a side note about it, didn't know where to post it so I am posting here.

When exactly the production moved from Japan to Taiwan?

Well, last made in Japan = 87XXXX February 1988, obviously first made in Taiwan 88XXXX March 1988.

I have a MIJ 874581 and there is one for sale on ebay MIT 881377.

Mine




For sale on ebay

[chromandre]

welp I'm ordering some 1s1588! I have just a generic SD-1 produced in the past 10 years

[holio cornolio]

I just learn something about the SD-1, it's a side note about it, didn't know where to post it so I am posting here.

When exactly the production moved from Japan to Taiwan?

Well, last made in Japan = 87XXXX February 1988, obviously first made in Taiwan 88XXXX March 1988.

I have a MIJ 874581 and there is one for sale on ebay MIT 88137

Great info. I had my eye on that one on eBay. The orange caps interested me. But now my attention is turned to finding a 1s2473 variant instead.