boss sd1 mods op amp

[gringo699c]

i have been trying to change some of the things inside my sd1.
I want to try different op amps. I know the one in the pedal  has 8 pins.
I have zero experience with electronics. I dont know squat.
 I heard the brown burr chip is nice but when i look on the net there are many many kinds.
 My question is what am I looking for in a replacement besides the number of pins on it.
 Where is the best place to buy them?
 Any help here would be so nice.
Thanks
chris

[phillip]

I got my SD1 mod chips from Digikey.  I've tested the original JRC4558DD, the Texas Instruments RC4558P, the Burr Brown OPA2604AP and the Burr Brown OPA2134PA.

Out of all of those, I liked the OPA2134PA the best, they're about $2.50 each, but the 2134 is part of the "Sound Plus" line of Burr Brown chips, which are designed specifically for audio applications.   It's a very high quality, high fidelity, low noise chip.

Also, be sure to get an 8-pin IC socket so you can experiment with different chips.

Phillip

[gringo699c]

This helps alot. I went to digikey and was overwelmed with the number of chips that were there since I have no experience.
Im going to learn though!
Chris

[Mike Nichting]

where do you get the Burr Brown chips??

Mike N.

[gringo699c]

this place has some
www.digikey.com

[Fret Wire]

Digikey's shipping is reasonable: I just ordered 50 1uf caps, $1.29 S&H. I wish I saw this post yesturday, I would have ordered a few of those to try.

[mstoppini]

Has anyone tried a fet input op amp for the modded SD-1? LF353 or TL072 for example. I think I'm gonna try it one of these days but I was wondering if you have  already installed these chips.
Thanks,
M.

[brett]

The TL072 sounds fine in any of the tubescreamers, if that helps.  I like the NE5532 for most applications.  Quiet and smooth.

[smoguzbenjamin]

Socket! Put a socket where the DS1's opamps were and then you can see which sound best!

[Fret Wire]

The latest Taiwan models use an inline chip. Apparently, there is a JRC sub that sounds better. Will have to check that out. Wonder if there is a NE5532 equivalent too?

[WGTP]

A number of people recommend those op amps.  I've been experimenting with over a dozen different ones and the old stand by 4558 isn't bad, but the others you mentioned sound good too.  I would say slight differences can be heard.

To get samples, go to TI.com and register.  Then check out the ones you want.  They include the Burr Browns and other models you mentioned.  I might suggest a TLC2272 cmos to try as well.  

[LH]

The latest Taiwan models use an inline chip. Apparently, there is a JRC sub that sounds better. Will have to check that out. Wonder if there is a NE5532 equivalent too?

Are you talking about the DS-1 or the SD-1?

[Fret Wire]

ops! I was talking about the DS-1. I'm following a bunch of ds-1 and sd-1 posts, wrong reply on the wrong post. Thanks for catching that, my bad.

[Mark Hammer]

If, by your own admission, you aren't that well-versed in this sort of stuff, then I'd suggest NOT removing the existing op-amp since chip desoldering is tricky even under the best of circumstances, and this board is a tight fit anyways.  The risk of a novice overheating and fracturing traces is just too great.

If you are itching to mod the damn thing, then I'd suggest something a little more foolproof, and that we know will produce an audible (and to some ears desirable) difference first time out, and which is easily turned into a variable control.

The SD-1 is essentially the same thing as a TS-9/808 but uses 3 diodes in the feedback loop of the clipping stage rather than 2.  If you can identify the 2 diodes of those 3 that are in series with each other, and simply shunt one of them, you will have, in effect, transformed it into a TS-9.  make that shunt a simple SPST toggle switch mounted on the chassis, and you can have your choice of TS-9 or stock SD-1.

Difference between chips are the sort of thing that can easily disappear once the volume gets turned up or the treble turned down.  The switch between symmetrical and asymmetrical clipping, however, is something that tends to be easily audible in spite of other changes, particularly with respect to picking dynamics.  Switching to 2 diodes will yield a more compressed, and somewhat lower volume sound.

[WGTP]

I definitely agree with Mark.  Different diode combos are way easier to hear than op amp differneces.