Pot values for Phase 45 and question about pot markings

Started by PCR, May 30, 2011, 01:23:37 PM

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PCR

I am building a phase 45 using the board available at General Guitar Gadgets.  The spec calls for a 500k reverse log taper pot OR it says a 100k linear pot can also be used.  Can someone explain why such different pot values are both acceptable?

I have Alpha pots that are marked B and the value (B100K for example), and others marked A and the value (A500k) for example.   Do the letters indicate the taper- if so can someone tell me the code?

Thanks

LucifersTrip

Quote from: PCR on May 30, 2011, 01:23:37 PM
I am building a phase 45 using the board available at General Guitar Gadgets.  The spec calls for a 500k reverse log taper pot OR it says a 100k linear pot can also be used.  Can someone explain why such different pot values are both acceptable?

I have Alpha pots that are marked B and the value (B100K for example), and others marked A and the value (A500k) for example.   Do the letters indicate the taper- if so can someone tell me the code?

Thanks

guess would be that the reverse log is really intended, but it is common to say that a linear is also useable, since many builders don't
have the rev logs lying around.

codes:
http://sound.westhost.com/pots.htm#markings
always think outside the box

smallbearelec

Quote from: PCR on May 30, 2011, 01:23:37 PM
phase 45...spec calls for a 500k reverse log taper pot OR it says a 100k linear pot can also be used.  Why...are both acceptable?

They will both work, but the control of speed will "bunch up" at the high end with linear taper. Reverse audio will give you smoother control and much better "feel." See below also.

Quote from: PCR on May 30, 2011, 01:23:37 PM
I have Alpha pots that are marked B and the value (B100K for example)...can someone tell me the code?

A = Audio
B = Linear
C = Reverse Audio
You can find a complete treatment of this subject, and much more, at GEOFEX.com in "The Secret Life Of Pots."


oldschoolanalog

#4
Read the build reports for lots of good & interesting info/ideas about the P45:
http://tonepad.com/project.asp?id=13
Have fun!
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