super od clip type

edo

edo

Power User
Vendor
Just curious to know why the super od (boss sd1 model) defaults to Silicon clipping type as opposed to 4558 (which should be the stock chip in it). Does anybody know?
 
I believe the SuperOD uses diodes for the clipping. The op-amp is just for pushing the signal through. (Although it probably also does contribute some clipping of its own when pushed.)
 
edo said:
Just curious to know why the super od (boss sd1 model) defaults to Silicon clipping type as opposed to 4558 (which should be the stock chip in it). Does anybody know?
Click to expand...

"There are 3 silicon diodes in the negative feedback path of the op-amp. Two diodes are in one direction and only one in the other. This arrangement produces asymmetrical soft clipping -- one side of the waveform is clipped more severely than the other."

upload_2017-4-4_9-58-37.png

D3-D8: 1S2473 (switching diodes)

http://www.hobby-hour.com/electronics/s/sd1-super-overdrive.php
 
Pwrmac7600 said:
Curious what one would need to do in order to replicate the Keeley modded sd-1?
Click to expand...

Found this, but I'm not familiar with the Keeley mod. so I can't verify it's accuracy or authenticity.

http://diyguitaramp.tistory.com/358

[Edit]

This part seems to be correct;

"Here is the tricky part of our mod, take a germanium (Ge) transistor and use the Base-Emitter junction (legs) of the device and use it in place of D6."

based on this;

"A Germanium transistor in the clipping section serves two purposes..."

http://www.robertkeeley.com/manuals/sd_1_5_star_w_diode_switch.pdf
 
Toopy14 said:
Found this, but I'm not familiar with the Keeley mod. so I can't verify it's accuracy or authenticity.

http://diyguitaramp.tistory.com/358

[Edit]

This part seems to be correct;

"Here is the tricky part of our mod, take a germanium (Ge) transistor and use the Base-Emitter junction (legs) of the device and use it in place of D6."

based on this;

"A Germanium transistor in the clipping section serves two purposes..."

http://www.robertkeeley.com/manuals/sd_1_5_star_w_diode_switch.pdf
Click to expand...
Yes I normally do switch it to germanium. But I know it is voiced differently as well, just not sure where the high and low cut off points would be.
 
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