BossAreaForum

I decided to start picking up particular (affordable) circuit variants of Boss drive pedals. I figure this might make a good sticky for reference at some point.

To the best of my knowledge, the significant variants are:
Boss OD-1 - 14-pin vs. 8-pin op amp, at least 3 different 8-pin op amps were used. There is also the 40th Anniversary version.
Boss SD-1 - There are at least 2 different op amps were used. All later ones were JRC4558DD. There are also SMT and Waza versions.
Boss DS-1 - There are 5 versions including the 40th Anniversary. There are also SMT and Waza versions.
Boss DS-2 - There are germanium diode and silicone diode versions + SMT.
Boss MT-2 - There are 3 versions of the op amp combinations. There are also SMT and Waza versions.
Boss BD-2 - There is a significant difference in the JFET behavior on the pre-ROHS vs. post-ROHS versions. There are also SMT, Waza, and JB-2 versions.
Boss TR-2 - There are at least 5 different variations + SMT.
Boss DM-2 - There are MN3005 and MN3205 chip versions + Waza.
Boss CH-1 - There are analog and digital versions.
Boss CE-5 - There are analog and digital versions.
Boss DD-3 - There are 4-5 versions + the DD-3T.
Boss PH-1 - Original + 40th Anniversary
Boss SP-1 - Original + 40th Anniversary

Are there any others that should be added to this list?

a few more,

SD-2 had a notable revision on only the lead channel circuit I think
CS-3 dbx/THAT chip
PS-2 actually had a revision I think the originals technically had something wrong with the noise reduction in the compander on the delay line

I'm assuming basically all of the analog pedals have had some changes in equivalent opamp chips, and then if they are still in production you probably assume theyre going to be SMD at some point

Thanks for these. I was entirely unaware of all of them. I know the MIJ CS-3 and early black label MIT sound a lot better to me than anything in the PSA era.

The SD-2 is one of my favorites but I have only owned 3 total and never had more than one at a time and my 3 all sounded quite similar. Makes me curious to A/B it with others.

Good to know about the PS-2 as well as I have only had 1 of those.

The early PS-2 models have a very noisy sound. Nothing great to hunt down an early model. My unit suffered from it and it sounds so much better after the official modification that is described in the service manual. Here are pictures of my PS-2:

www.instagram.com/p/CQFtGpNn6wd/
www.instagram.com/p/CQFuFSeH814/

Pepe wrote: ↑

Thu Sep 21, 2023 11:59 pm

The early PS-2 models have a very noisy sound. Nothing great to hunt down an early model. My unit suffered from it and it sounds so much better after the official modification that is described in the service manual. Here are pictures of my PS-2:

www.instagram.com/p/CQFtGpNn6wd/
www.instagram.com/p/CQFuFSeH814/

Do you know the approx. serial or year they changed Pepe? Despite it being sat in my draw I consider the PS-2 one of the best (subjectively) delay made by BOSS! I'm not exactly sure if mine is a "noisy" one of not though lol.

Oh, the information is in the service manual:

"The change (A) must be done with the units numbered prior to 845800."

Are there any documented notes on the SD-2 changes somewhere?

zentropa wrote: ↑

Fri Sep 29, 2023 3:41 pm

Are there any documented notes on the SD-2 changes somewhere?

I don't have any documentation, but I did open up my two SD2s and noticed that the boards did have some variations. One is from 06/1993 and has been modded a bit, the other is stock and from 11/1994. From what I understand, the SD2 started production in 04/1993 and was done by 1998/1999. Therefore, one variation happened early on, well before 1995.
The first thing that jumped out was that the older one has a R100 component location not found on the other. When I turned them over and looked at the trace side, there were a couple small differences, too.
I showed some pics on this thread: viewtopic.php?f=6&t=635&start=10