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Digital Pots......Help!

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9/3/1998 2:05 PM

Digital Pots......Help!

Hello,

Has anyone here had any experience using digital pots for controlling EQ, drive, gain, etc., etc. on there amp. I'm considering using some method to store presets and have midi program changes and such. I'm currently looking into a part that Dallas Semiconductor sells, (digital Audio pot). I'm really concerned about it screwing up my tone and such and wondered if anyone had tried this method of control.

Thanks,
Brian

9/4/1998 12:11 AM

Been dare. Dun Dat. I have heaps of info on digital pots kicking around. I considered putting in some form of MIDI control to a real tube amp, not like the voltage staved ADA and such. These pots are designed to work with semi-conductor amps and will not easily be fitted into an amp with tubes. The resistances are nowhere near high enough. There are motorized pots but again not in the right resistances although Xicon said they will build custom ones for me upon request. I can see the motors causing havoc though, so I havent given it more thought.

It is possible to use both, but it would be difficult. I'm looking into using fets to create variable resistances, but it's really on the backburner for now. If you come up with something, let me know.

GVB

9/4/1998 7:25 AM

Vishay/Dale, Rohm, and CTS used to make (and probably still do make) R-2R resistor ladder networks that would form the heart of a DAC. Controlling the FETs (jFETs?) is going to be the trick - getting them turned good and ON or good and OFF as required. I'm assuming you're going to have some kind of CPU in the thing, so you can use that to convert from your control's need to be logarithmic to the DACs linear response.

Hey, maybe they make LOGDAC resistor nets...

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