Boss OD-1 Clone 14 pin op amp

[roseblood11]

The 3403 version has 47nF/10k in front of the clipping stage. The 4558 version uses 4.7nF/100k.
Why did they change that? The roll off frequency should be the same?

In the 3403 version, r3, r5, c2 and c4 are cutting some treble. All clones with true bypass omit these parts. Has anybody tried, if that makes an audible difference?

[willienillie]

Just for the record, I don't think the OD-1 ever used 1S1588s.  I've seen pics of some with 1S1587s, but most common from the 14-pin era seems to be the 1S2473.

[Mark Hammer]

The 3403 version has 47nF/10k in front of the clipping stage. The 4558 version uses 4.7nF/100k.
Why did they change that? The roll off frequency should be the same?

In the 3403 version, r3, r5, c2 and c4 are cutting some treble. All clones with true bypass omit these parts. Has anybody tried, if that makes an audible difference?

I'm guessing the switch from 10k to 100k is related to the biasing current required for each op-amp type.  Bear in mind the 10k and 100k resistors are tied to Vref.

[roseblood11]

Just for the record, I don't think the OD-1 ever used 1S1588s.  I've seen pics of some with 1S1587s, but most common from the 14-pin era seems to be the 1S2473.

how would that influence the sound?

[willienillie]

how would that influence the sound?

Very slightly.

[roseblood11]

veeery slightly. I had the 47pF in my clone and just cut it out. No audible difference.

[roseblood11]

Mark, which 47nF did you increase to get a fuller sound? Only C5? Wouldn't it make sense to increase C3 as well?

C3 and R4 form a highpass filter at 339Hz, isn't this the cause for the even "boxier" sound of the OD-1 compared to TS808 or SD-1? Both don't have a relevant bass cut before the clipping stage.