Help replacing diodes MT-2

[goroth]

Hey dudes,

After modding my MT-2 by removing D1 and D2 I came to the conclusion it sounded total rubbish. The legs on the diodes are a bit too small to solder in easily, so I'm looking at putting something else in there.

Schem is here:
http://web.tiscali.it/boxsmt2clone2005h ... mt2_06.jpg

According to the schem they are 1SS133 diodes - high speed switching diodes. Datasheet here
http://www.eicsemi.com/datasheet/1SS133.PDF

I should be fine replacing them with 1n4148 diodes shouldn't I?
http://www.nxp.com/documents/data_sheet ... 1N4448.pdf

Specs look roughly the same - but I don't really know what I'm doing...

Thanks dudes.

[mysteriousj]

Yeah man, they're pretty much the same. They're the clipping diodes so the spec you want to watch out for is Vf(forward voltage drop).

If you've got some handy you could try some Schottky or LEDs or try combinations. The Schottky will give you a more compressed sound while the LEDs less compressed. It will mess with your ouptut level though.

[goroth]

Sweet, thanks dude.

I thought D3 and D4 were the clipping diodes? D1 and D2 are on the right hand side of the schemo, near Q2 and Q3. I'm guessing those to transistors are part of the switching circuit, which is why the clean signal is getting messed up in there somewhere when I desoldered D1 and D2. Maybe? It's taken me a fair bit of staring at the schematic to come to that conclusion.

The goal is to have less clipping, so I might try one led and nothing in D3 and D4, or maybe an ultrabright LED and a regular one. I love the LED clipping in the Elements, and am keen to hear the boss with asymmetric clipping. Might also put a cap in parallel with one of the diodes to try and smooth things out a bit - it's not like the MT-2 lacks high end...

I can add that I was (blindly) following a suggested mod to clip specifically D1 and D2 but that was either a typo or someone had a very different sound goal than me...

[mysteriousj]

Ooops. When I was flicking through the schematic I saw the clipping diodes and didn't check the numbers .

That's weird someone would tell you to clip D1 and D2. Yeah.. they're there to do with the FET switching. If they're not there the gates connected to nothing, so they won't switch. But yeah 4148s will all work the same.

[goroth]

All sorted now!

Thanks for the help!