Small Stone mod to sound like Phase 90??

[changes]

Hello Hello

Is there an existing mod out there or idea on how to make a small stone sound like a phase 90? Something like matching the sweeping frequencies of phase 90 with some part changes?

[Mark Hammer]

Having made several of each, I think the biggest immediately audible difference is that the P90 seems to sweep in a lower range.  So maybe increase the value of the caps in each phase shift stage.  If they are .0068uf (6n8), try .01uf (10n).

[StephenGiles]

Which version of Smallstone - CA3094, LM13600 or SSM2164?

I wonder why you would want to make a Smallstone, which has its own unique sound, have the characteristics of a Phase 90's sound?

[Mark Hammer]

There's a Smallstone issue that uses an SSM2164?

[StephenGiles]

Just testing !!

[Mark Hammer]

I'll cut you some slack because you're currently a shut-in, Mr. Giles.  But don't scare me like that! 

[changes]

Having made several of each, I think the biggest immediately audible difference is that the P90 seems to sweep in a lower range.  So maybe increase the value of the caps in each phase shift stage.  If they are .0068uf (6n8), try .01uf (10n).

Which version of Smallstone - CA3094, LM13600 or SSM2164?

I wonder why you would want to make a Smallstone, which has its own unique sound, have the characteristics of a Phase 90's sound?

Thank you Mark and Stephen

It's a clone of 13600 version and I just want to have best of both worlds 

[Mark Hammer]

Looking at the schematic I have of the LM13600 version, the caps in each phase-shift stage are 3300pf, just like the Ross phaser.  I imagine if you tacked on a small ceramic 1000pf disc in parallel with each of those 3300pf caps, on the copper side of the board, you could test out whether that does what you want.

I'm afraid I'm not well-versed enough in the rest of the circuit to prescribe some mod to the modulation subcircuit that might nudge the sweep range a little lower in the spectrum.

Here's the schematic, courtesy of "Uncle Boko". 

[changes]

Thanks again Mark !

I'll try altering the value on those 3300pf caps asap

[StephenGiles]

Here's that circuit without photobucket!!

[changes]

Here's that circuit without photobucket!!


Thank you Steven!

I see there are versions with 6n8 instead of 3n3 caps. Could those sound closer to phase 90?

[Mark Hammer]

No,the cap-value choice is a function of the surrounding component values.  EHX picked 3300pf to sound as close to the earlier issue using 6800pf as possible.

There may be a difference in the shape of the sweep and degree of feedback in the two Color switch positions.

[changes]

Thank you Mark!
I'll be back witht the result as soon as I'll have time to work on the cap values mod.