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Old 02-22-2017, 09:54 AM
Dan of SC Dan of SC is offline
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Default powered mixer

I have a Yamaha powered mixer. Our trio uses 3 microphones and 2 instrument plug-ins. One instrument has an active pickup and one is passive. For the passive one we use a separate preamp. It seems each of the microphone inputs contain a preamp. Could the passive pickup be somehow plugged into a microphone jack, eliminating the need for a separate preamp? Thanks, Danny Gray
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Old 02-22-2017, 11:05 AM
RustyAxe RustyAxe is offline
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Quote:
Originally Posted by Dan of SC View Post
I have a Yamaha powered mixer. Our trio uses 3 microphones and 2 instrument plug-ins. One instrument has an active pickup and one is passive. For the passive one we use a separate preamp. It seems each of the microphone inputs contain a preamp. Could the passive pickup be somehow plugged into a microphone jack, eliminating the need for a separate preamp? Thanks, Danny Gray
Sure ... run it through a DI ... anything from a simple transformer (like the Whirlwind IMP-2) to an all out EQ/preamp/modeling DI ... and everything in between. Not knowing what your instrument/pickup is, I can't recommend anything specific.
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Old 02-22-2017, 11:09 AM
jomaynor jomaynor is offline
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The short answer is yes, you can plug the passive pickup directly into the PA.

Although it probably won't sound as full this way as it would if the passive pickup were first going through a decent preamp/DI box. But, yes, plugging a passive pickup straight into the PA will work, sure.
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Old 02-22-2017, 01:36 PM
pipedwho pipedwho is offline
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Mixer input impedances are always too low for passive pickups to sound their best. The mic preamps are incredibly low impedance (on the order of a few kOhms) and are designed for low impedance dynamic mics, or buffered condenser mics (that require phantom power). The 'line inputs' are higher, but still far too low (on the order of 10s of kOhms). Even using a DI is usually not enough (also 10s of kOhms into a mic pre input), as most DIs aren't designed for high impedance piezo inputs unless it's a special purpose DI that also has a built in preamp.

Your best bet is to keep using the preamp with the passive pickup, as the purpose of the preamp (assuming it is the correct one for the job) is to provide an ideal input impedance for the pickup in question (piezos work best with input impedances on the order of 1000s of kOhms).

The effect of going direct to the desk without using a preamp, and therefore loading down your pickup depends on the pickup type. With a passive magnet sound hole pickup, you'll lose a lot of treble and the sparkle will disappear. This is usually not desirable from a magnetic pickup unless you're going for really subdued jazz tones. If the pickup is a piezo (most likely if this is an acoustic instrument), then the effect will cause a significant loss of bass and low mids, and probably also a small loss of sparkle/presence, making the pickup sound tinny and anaemic.

I have a Radial Stagebug SB-4 DI/Preamp that I keep in my 'box of tricks' for people that turn up with passive instruments and no preamp. It has a very high impedance input (5000 kOhms) that is designed specifically for passive piezo pickups. It requires phantom power, but it's small and easy to keep around just in case I need it. Your existing preamp should do a similar job.
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