Double Bass Talking Ohms Here...

[bkberwanger]

Without getting too over the top with the technical jargon my question is this...

I have a Full Circle P/U on my upright. I run through a Fishman Pro Platinum Bass EQ. I am about to order the new Acoustic Image Clarus SL amp. After reading about the two inputs, High & Low, I'm good with the High having more impedance for the Full Circle- it is 10 Mohm. If I skipped the Pro Platinum I'd go direct into the High input. Now, here's where I get confused. If I go through the Pro Platinum first, which already has the 10 Mohm impedance, do I still use the High input? Or, is that overkill?

Sorry if that was rambling. I'm not too hip on all the frequencies and ohm stuff. I just play the bass you know

 

[klem.gote]

Great question!! I've often wondered about plugging into a piece of gear that has some of the same features as the amp I'm going into. For instance plugging into an Fdeck, then into an amp that has a high pass filter, or if using the Platinum pro into an amp, which tone controls take precedence?

 

[DoubleMIDI]

The high input impedance is only needed directly following the passive piezo.

Any impedance buffer (separately or as part of a preamp) needs some power to transfer the low input current into a higher loadable output current. So the output is much lower in impedance than the piezo. Typically around 10 KOhms. That should be low enough even for the 'low' input of the amp. But the only thing you loose using the 'high' input is a higher sensitivity for electrical noise which would be unnoticeable using shorter cable lengths.

The cable between preamp and 'high' input of the amp can be more sensitive to cable microphonics (vibrational noise like an impact on the cable gets amplified), but often enough this does not happen if the preamp has an output volume control (which keeps the impedance low from the output side).

So basically, it doesn't matter in practical application.

 

[seamonkey]

Pre-amps have High impedance inputs and low impedance outputs