Author Topic: CP70 preamp bypass  (Read 171 times)

Offline EauClaireGuy

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CP70 preamp bypass
« on: August 06, 2018, 06:33:20 PM »
Does anyone have any experience with bypassing the pre-amp of a Yamaha CP70?

Offline OZDOC

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Re: CP70 preamp bypass
« Reply #1 on: August 06, 2018, 09:36:10 PM »
Two thoughts come to mind:
I understand that the output of piezo pickups is not lineal - that loudness goes up exponentially with force. So this may cause some issues and is probably addressed in the input stage of the Yamaha pre-amp.
The patch out jack for accessories comes immediately after the initial pre-amp stage of the circuit. This stage also has the tone controls. So if you wound all the tone controls clockwise so that the filtering of these controls is eliminated and plugged the signal from the patch out jack into your amp you'll get a fair idea of whether it's worth bothering with anything more invasive.
The question is, what do you think you're going to achieve by double guessing Yamaha's engineers?

Offline EauClaireGuy

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Re: CP70 preamp bypass
« Reply #2 on: August 14, 2018, 06:54:05 PM »
OZDOC,
I would love to trust the engineers, however my preamp is currently nonfunctioning and I am trying to find a temporary work around until I get it fixed. That being said I wonder if I could just go through the patch out if that would be before my problem in the pre-amp, otherwise id like to hop bypass altogether until I get it functional.