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When did DS-2 go to all silicon diodes?

Posted: Fri Nov 25, 2022 10:16 pm
by Ricey
I just took delivery of an MIT DS-2 Turbo Distortion. The Boss s/n decoder estimates it's manufacture date as April 1999. I have read that early production runs used germanium clipping diodes in one of the modes and silicon clipping diodes in the other mode and that production later switched to all silicon diodes for both modes. Would mine be the all silicon diode version? Did the earlier versions use the germanium diodes in the regular mode or the Turbo mode? Can anyone offer a comparison in tone between the germanium and silicon versions? Thinking of doing the germanium diode mod if deemed worth it?

Re: When did DS-2 go to all silicon diodes?

Posted: Sat Nov 26, 2022 4:16 am
by bigtone23
paging @Old_Iron

Re: When did DS-2 go to all silicon diodes?

Posted: Sat Nov 26, 2022 6:31 am
by Old_Iron
Ricey wrote:
Fri Nov 25, 2022 10:16 pm
Would mine be the all silicon diode version?
Yes, one of mine is a MIT 1999 May and it is a silicon diode unit.


Ricey wrote:
Fri Nov 25, 2022 10:16 pm
Did the earlier versions use the germanium diodes in the regular mode or the Turbo mode?
Both, the turbo mode II is a circuit addition to the mode I, so the clipping of the Ge diodes is already there.


Ricey wrote:
Fri Nov 25, 2022 10:16 pm
Can anyone offer a comparison in tone between the germanium and silicon versions? Thinking of doing the germanium diode mod if deemed worth it?

Before to acquire a Ge diode DS-2, I thought to swap the diodes of my first MIT, recent built, DS-2. But after a research over the net, reading forums and listening to comparisons in youtube videos, I gave up because the end result is very close to null.

If you, like myself, enjoy the "mojo" of the vintage gear, I would recommend you to trade your pedal for a MIJ unit, but not because how they sound, since they sound just about the same.

And answering your question about when Boss changed the diodes, I don't know, never saw anything about that.

My latest Ge unit is a 1990, and my earliest silicon is a 1999, too far apart to figure out when the change occurred.

Re: When did DS-2 go to all silicon diodes?

Posted: Sat Nov 26, 2022 4:51 pm
by Old_Iron
Complementing...

The reason that the diode swap is not so noticeable is probably due to the numerous gain stages in it's dense circuit.

In a more simple circuit, like the OD-1, DS-1, etc., the clipping diodes rules the shape of the wave and therefore it is more heard at the end.

But, you know what, do it!

It's a simple task and you can easily revert, if you don't like it.

Better, put a socket and try with many other kind of diodes, including LED.

It is a fun way to spend an afternoon.

The DS-2 schematic:

Image

Re: When did DS-2 go to all silicon diodes?

Posted: Sun Nov 27, 2022 6:12 am
by bigtone23
Ricey wrote:
Fri Nov 25, 2022 10:16 pm
Can anyone offer a comparison in tone between the germanium and silicon versions? Thinking of doing the germanium diode mod if deemed worth it?

Before to acquire a Ge diode DS-2, I thought to swap the diodes of my first MIT, recent built, DS-2. But after a research over the net, reading forums and listening to comparisons in youtube videos, I gave up because the end result is very close to null.

If you, like myself, enjoy the "mojo" of the vintage gear, I would recommend you to trade your pedal for a MIJ unit, but not because how they sound, since they sound just about the same.
This is interesting, and also supporting of my loose theory: most BOSS pedals don't sound radically different after going through a revision. The engineers do seem to design the pedal to maintain it's fundamental tone and function, regardless of the component changes. In my limited experience, my 1986 MIJ vs 1990, 2001 and 2011 MIT DS1 pedals didn't sound much different from each other than what one would find when comparing two from the exact same era.

I wonder, Ge transistors in fuzz pedals are very reactive to the temperature and voltage of the moment. Si transistors are more consistent and stable. Do diodes follow a similar suit?

Re: When did DS-2 go to all silicon diodes?

Posted: Sun Nov 27, 2022 10:10 am
by Old_Iron
bigtone23 wrote:
Sun Nov 27, 2022 6:12 am
This is interesting, and also supporting of my loose theory: most BOSS pedals don't sound radically different after going through a revision. The engineers do seem to design the pedal to maintain it's fundamental tone and function, regardless of the component changes. In my limited experience, my 1986 MIJ vs 1990, 2001 and 2011 MIT DS1 pedals didn't sound much different from each other than what one would find when comparing two from the exact same era.
I think you're right about that, the difference is always subtle.


bigtone23 wrote:
Sun Nov 27, 2022 6:12 am
I wonder, Ge transistors in fuzz pedals are very reactive to the temperature and voltage of the moment. Si transistors are more consistent and stable. Do diodes follow a similar suit?
Yes, Ge transistors, like the ones used in vintage fuzz pedals, are physically made of two diodes, the temperature effect is the same, in clipping diodes if the temperature rises, the forward voltage drops and with that less overdrive/distortion.

Edited.

Re: When did DS-2 go to all silicon diodes?

Posted: Mon Nov 28, 2022 4:59 pm
by bigtone23
Old_Iron wrote:
Sun Nov 27, 2022 10:10 am
bigtone23 wrote:
Sun Nov 27, 2022 6:12 am
This is interesting, and also supporting of my loose theory: most BOSS pedals don't sound radically different after going through a revision. The engineers do seem to design the pedal to maintain it's fundamental tone and function, regardless of the component changes. In my limited experience, my 1986 MIJ vs 1990, 2001 and 2011 MIT DS1 pedals didn't sound much different from each other than what one would find when comparing two from the exact same era.
I think you're right about that, the difference is always subtle.


bigtone23 wrote:
Sun Nov 27, 2022 6:12 am
I wonder, Ge transistors in fuzz pedals are very reactive to the temperature and voltage of the moment. Si transistors are more consistent and stable. Do diodes follow a similar suit?
Yes, transistors are made of two diodes, the effect is the same, in clipping diodes if the temperature rises, the forward voltage also rises and with that less overdrive/distortion.
Yeah, even comparing my DD2/DSD2/Long Chip DD3 and DSD3 to a newer DD3 finds much the same tonality and function despite being a radically different chip and 3.5 decades of age difference.

Didn't know that transitors are made of two diodes! Thank you!

Re: When did DS-2 go to all silicon diodes?

Posted: Wed Nov 30, 2022 4:58 am
by fuzzbuzzfuzz
If the forward voltage/ specs of the two diodes are the same, then sound wise is perhaps not a massive difference. (proportional to component count, more components less likely influence, unlike say a Fuzz Face).

The diode swap in the SD-1 however does sound very different, instantly noticable to my ears. I deduce the diodes are different in spec and influencing the circuit therefore.

Re: When did DS-2 go to all silicon diodes?

Posted: Sat Dec 03, 2022 11:21 pm
by laurie
Old_Iron wrote:
Sun Nov 27, 2022 10:10 am
transistors are made of two diodes, the effect is the same, in clipping diodes if the temperature rises, the forward voltage also rises and with that less overdrive/distortion.
Hmmmm... a few comments here.

A transistor isn't actually "two diodes". It is a separate type of device entirely. It is possible to use a transistor base-emitter junction to emulate a diode, but it isn't a very good one.

In all semiconductors (apart from a few specially engineered cases) the forward voltage drops as the temperature increases.

Re: When did DS-2 go to all silicon diodes?

Posted: Sun Dec 04, 2022 12:52 am
by Old_Iron
laurie wrote:
Sat Dec 03, 2022 11:21 pm
A transistor isn't actually "two diodes". It is a separate type of device entirely. It is possible to use a transistor base-emitter junction to emulate a diode, but it isn't a very good one.
bigtone23 was talking about "Ge transistors in fuzz pedals", I should had being more specific, but I learned that bipolar transistors are two back-to-back diodes, and a PNP is a bipolar junction transistor...

laurie wrote:
Sat Dec 03, 2022 11:21 pm
In all semiconductors (apart from a few specially engineered cases) the forward voltage drops as the temperature increases.
That's my bad, sorry, you're right, it drops, I edited there. Thanks Laurie.