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Simple mods!


Robert Keeley

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Be sure to check out the mods we came up with for the BOSS OD-3 on the Musicians Hotline Magazine. The article is short and sweet and pretty much describes removing parts to improve the tone.

Those are the mods I LIKE!

One pair of cutters and you're off to better tone!

 

Thanks HC brothers and sisters!

Have a great New Years!

Robert

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Originally posted by RossCompress

I read the ceasefire sticky, great advice and well needed for this forum...but I do feel afraid to post almost anything for fear I might be breaking a rule by accident.


hmmmm, hope no one cares about a link to free info.


rk

 

 

I know what you mean. This is what happens when people are employed to mod a forum and know nothing about it's history, foibles and members.

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Originally posted by RossCompress

Be sure to check out the mods we came up with for the BOSS OD-3 on the Musicians Hotline Magazine. The article is short and sweet and pretty much describes removing parts to improve the tone.

Those are the mods I LIKE!

One pair of cutters and you're off to better tone!


Thanks HC brothers and sisters!

Have a great New Years!

Robert

 

any link to this?

 

Although I must admit I REALLY like the stock sound of my OD-3.

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Originally posted by RossCompress

I read the ceasefire sticky, great advice and well needed for this forum...but I do feel afraid to post almost anything for fear I might be breaking a rule by accident.


hmmmm, hope no one cares about a link to free info.


rk



Rules are meant for breaking, surely?:thu:

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hey,
i found this on another forum (i think guitargeek? hell, might've been here). regardless, here it goes:

The Keeley OD-3 Clip Mod
The mod is to remove D6 and D7. You can put them on a switch to toggle this on and off but I think a quick listen will convince you that those can go. These two diodes give a very slight increase in distortion but when removed give you a much livelier and open sound. The reduced gain you'll have is so slight that I think it would only offend those that run this pedal gained to maximum. Really opens up the effect and all you need is wire cutters!!! Thanks to Mr. Keeley...

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Originally posted by rydia_is_hot

hey,

i found this on another forum (i think guitargeek? hell, might've been here). regardless, here it goes:


The Keeley OD-3 Clip Mod

The mod is to remove D6 and D7. You can put them on a switch to toggle this on and off but I think a quick listen will convince you that those can go. These two diodes give a very slight increase in distortion but when removed give you a much livelier and open sound. The reduced gain you'll have is so slight that I think it would only offend those that run this pedal gained to maximum. Really opens up the effect and all you need is wire cutters!!! Thanks to Mr. Keeley...

 

 

Is this basically just cutting out the clipping diodes? Does anybody have a schematic for the OD-3? I'd be interested in seeing what D6 and D7 do.

 

Can't understand how this would actually reduce gain, as a diode is not an amplifier. It would reduce distortion though (and some people do confuse the two terms.

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Originally posted by hoerni



Is this basically just cutting out the clipping diodes? Does anybody have a schematic for the OD-3? I'd be interested in seeing what D6 and D7 do.


Can't understand how this would actually reduce gain, as a diode is not an amplifier. It would reduce distortion though (and some people do confuse the two terms.

 

 

my guess is the original poster just interchanged the two. i just copied and pasted it.

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Originally posted by rydia_is_hot



my guess is the original poster just interchanged the two. i just copied and pasted it.

 

 

Yes, you're probably right. Didn't mean to sound like I was picking on you.

 

Any idea where a schematic is? How does the OD-3 compare to the SD-1 (which is a tubescreamer based design - or so i've heard)

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Originally posted by rydia_is_hot

google image search! haha...i'm pretty horrible at reading schematics, so if you see what this mod does and could explain it in really simple terms, that'd be awesome. thanks!

 

 

Oh, I can read a schematic, but I'm not as well school in discrete transistor designs as I'd like.

 

I'm not really sure just what D6 and D7 are doing. D9 and D12 are pretty obvious, but the D10 and D11 and D6 and D7 are a little harder for me to figure out. I'm not sure why you would have them between the input and output of a single transistor inverting gain stage (I understand how they are used with an op-amp)

 

Hopefully Sir HC will see this thread and jump in.

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Originally posted by shepherdspy

d6 and d7 look like clipping diodes in the feedback of that FET.



They are, but I'm not exactly sure how that works. Come to think of it, I think I need to re-read how they work in op-amp circuits.

That's easy enough though cause in op-amp circuits, they would be in parallel with the resistor that goes from the inverting input to the output. The resistor determines the gain (in conjunction with the input resistor of course) until the voltage difference between the input and output exceeds the voltage drop of the diode. Then the diode conducts and the gain is much lower (basically the interal resistance of the diode divided by the input resistor).

This circuit will clamp the output to one diode voltage drop away from the input, but I'm not sure what else it really does.

I guess what confuses me, is that I don't know why you would have feedback around a FET in the first place. So I don't see what these diodes are doing relative to some baseline textbook circuit.


d10 and d11 are shunt to ground clipping diodes.


now someone smarter than me will come along and tell me I am wrong.
;)



I don't think so.

Q13 and Q14 form a differential amplifier and Q11 is driven off the output of that amplification stage. It looks like some feedback from the output of Q11 is introduced into the base of Q14. The diodes here work with the drive section and effectively short out R38 and the drive control.


D9 and 12 appear to be shunt to ground clipping diodes.

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