BossAreaForum

holio cornolio wrote: ↑

Sat Dec 04, 2021 8:22 am

But now my attention is turned to finding a 1s2473 variant instead.

It is a difficult variant to find, unfortunately. Most likely because is sought-after by guitar players and collectors.

The ones with the NEC c4558c, a tiny bit more "aggressive" in the overdrive and a tiny bit more "trebly", you will find in batches 06XXXX and 07XXXX, mid 1981.

The ones with the JRC4558D, mine is 151300, are from the begin of 1982. I don't know if there are another batches with the 1S2473, probably there are.

With the JRC4558DD, one "popular" batch with the 1S2473 is the 38XXXX JAN 1984, I've seen quite a few of them on ebay.

If you want something "distant" from the SD-1 with the 1S1588 (blue band), I would recommend the ones with the NEC c4558c.

But my favorite SD-1, sound wise, is the one with the JRC4558D and 1S2473, mine is this one: viewtopic.php?f=6&t=440

But let me tell you that it is not guaranteed that those batches comes with the 1S2473, Boss is a baby's butt, you never know what will come out from it, so ask before you buy.

I have the chance to buy a march '84 pedal. No opportunity to see inside it though. What are the chances of it having the 1s2473??

holio cornolio wrote: ↑

Sat Dec 04, 2021 8:35 pm

I have the chance to buy a march '84 pedal. No opportunity to see inside it though. What are the chances of it having the 1s2473??

I would not risk to buy without asking the seller to show the pcb.

The 1S2473 is an exception in MIJ SD-1. The black band diode from the begin in February 1981 up to 1983/84, and then the 1S1588 blue band up until 1988, are the "oficial" MIJ SD-1 diodes.

Usually the 1S2473 appears in one month only, sometimes two in sequence at maximum, never saw more then that.

I know that the 38XXXX have the 1S2473 because I have one and I saw some other units with it, but march is a bit too far to trust without seeing.

But if the price of this pedal is good, you could buy it because a 1984 is already with the 1S1588 blue diode, then you could sell for a good money your Mitsubishi 5218 SD-1 and keep looking for one with the JRC4558D chip and the 1S2473 diode.

Since you already have one with the NEC c4558c chip, you would end up with all 3 "good" SD-1.

Old_Iron wrote: ↑

Sat Dec 04, 2021 11:02 pm

holio cornolio wrote: ↑

Sat Dec 04, 2021 8:35 pm

I have the chance to buy a march '84 pedal. No opportunity to see inside it though. What are the chances of it having the 1s2473??

I would not risk to buy without asking the seller to show the pcb.

The 1S2473 is an exception in MIJ SD-1. The black band diode from the begin in February 1981 up to 1983/84, and then the 1S1588 blue band up until 1988, are the "oficial" MIJ SD-1 diodes.

Usually the 1S2473 appears in one month only, sometimes two in sequence at maximum, never saw more then that.

Anyone any idea what the black band diode part number is? I was looking at a 1981 service manual and it has 1s2473 as the part number for the diodes. Did the 1s2473 only come with yellow bands? I ask because I'm sure I've seen 1s1588 with black bands as well as with blue.

There is no information about the black band diode manufacturer or it's part number, some people say it is the same as the Toshiba 1S1588 blue band, but made by someone else.

I don't think so, doesn't sound exactly the same, but there's no information available about it.

Well, this is an intensely detailed (and interesting) thread. I was entirely ignorant of the parts changes to the design, so I'm curious. (Though fully aware and SD-1 sounds like an SD-1 no matter what )

I actually have (somewhere) 2 x SD-1s MIJ . My spreadsheet tells me they are August 85 (Batch 57####) and July 1983 (Batch 32####). I have never opened the up but I wonder what diodes and chips are in there respective bellies?  

Time to fire up a true bypass loop and burn my lugholes out

fuzzbuzzfuzz wrote: ↑

Mon Dec 06, 2021 2:41 am

Well, this is an intensely detailed (and interesting) thread. I was entirely ignorant of the parts changes to the design, so I'm curious. (Though fully aware and SD-1 sounds like an SD-1 no matter what )

I actually have (somewhere) 2 x SD-1s MIJ . My spreadsheet tells me they are August 85 (Batch 57####) and July 1983 (Batch 32####). I have never opened the up but I wonder what diodes and chips are in there respective bellies?  

Time to fire up a true bypass loop and burn my lugholes out

Awaiting your evaluation with interest.

A slight tangent, I have decided that I'm probably going to return my capacitor modded sd-1 to stock, or close to stock. My mod was loosely based on the Monte allums mod, which focused most of the functional mods on flattening he mid hump and increasing bass. (there was a diode mod and an increased gain mod that I didn't bother with). Having tooled around with it like that, I have found that whilst it's quite nice as an always on effect or as a slightly dirty boost, with the drive control beyond 10 o'clock it loses the magic. Basically as more bass comes through, and the mids are less accentuated, clipping is added more evenly across the frequencies and that makes it sound flatter and less characterful.
So back to stock cap values and in with some 1s2743 when I can find some.
Tinkering is fun, although I have to say, as much as I enjoy doing this, I'm still 90% sure that my enjoyment of the process is orders of magnitude more significant than the actual tonal variations yielded by the component swaps

I see your point. As much as I would like to have a SD1 with more bass and less mids, I probably wouldn't find myself happily & effectively using it--the SD1 is not really my drive tone. The strength of my early SD1 and 4558 equipped OD1 is as an 'edge of drive' boost with an amp that is already cookin' at a medium-gain level. There really are no better pedals for that purpose, for me, and many others.
Plus, in the BOSS world, I have the OS2, OD2 (turbo mode and R62 mod), BD2 (with a bass/phat boost switch-a la Keeley) and my DS1 (with a riff on the Wampler JCM800 mod) to serve as flatter &/or more scoopy &/or bigger low-end---stand alone drives.

This page is very instructive, yet very simple to understand, about clipping diodes in an overdrive pedal circuit:

https://www.guitarpedalx.com/news/news/ ... ing-diodes