One preamp for passive and active pickups?

[Mr. Paul]

My two guitars equipped with pickups have a passive K&K Western Mini and a Fishman GoldPlus Natural 1 that is powered.

Is there one preamp that can be used with both?

[sdelsolray]

Originally Posted by Mr. Paul

My two guitars equipped with pickups have a passive K&K Western Mini and a Fishman GoldPlus Natural 1 that is powered.

Is there one preamp that can be used with both?

If the normal operating range of the input stage of the preamp (measured in voltage) encompasses the output ranges of the two pickups (measured in voltage), then 'yes'. If not, then 'no' or 'not so well' or 'yes, but with little headroom', etc.

Generally, there are three input voltage ranges for input devices - mic, instrument and line. There is no common set of values for these ranges in studio gear or sound reinforcement gear, except that mic level is the lowest range, instrument the intermediate range and line the highest voltage range.

Many units with input circuitry (e.g., preamps, EQs, compressors, mixing boards, etc.) have more than one of these inputs per channel. For example, a certain mixing board may have mic level and instrument level inputs for some input channel. Other input channels may only be line level. If your preamp only has a mic level input and your output device is an active pickup somewhere between instrument level and line level, connecting the two would not work unless you put a another device in between the two (a stepdown DI).

If you want to be sure before you buy, you just need to acquire the relevant voltage range specs and compare them. Although that sounds simple (and it is), many manufacturers do not publish those specs, so you just have to hope the voltage ranges will overlap properly. They often do.

In your case, the K&K mini's ouput is a rather healthy instrument level and the Fishman is likely a weak line level. Those two are relatively close in voltage.

[pipedwho]

The kind of active preamp that is built into a guitar will usually have a maximum voltage swing of its battery voltage minus a few volts of headroom. This means it is probably very close to unity gain and will output a similar signal level to that of its raw input voltage. It is basically acting as active impedance transformer, maybe with some volume and tone controls to make it more versatile.

A preamp that is designed for passive piezo elements will usually have quite a bit of headroom, as piezos can spike up in voltage quite high. That preamp will also have a high input impedance that is designed not to load down the piezo causing it to sound thin and weak. A high impedance will work fine for both active and passive sources, and a preamp designed for signal levels in this ballpark will have appropriate gain to both attenuate and amplify those signals without being too excessive or too little.

For example, a balanced mic preamp will have a low impedance and much more gain as those signals are not only much smaller than a piezo instrument pickup, but also have a much lower output impedance. This type of preamp is usually found on mixing desks and generally requires a DI box to modify the incoming source signal to a much lower level and stronger drive impedance.

Some examples of preamps that will do what you need:

K&K Dual Channel Pro Preamp
Fire-eye Red-eye Twin
Radial PZ-Pre
Headway EDB-2

[ljguitar]

Originally Posted by Mr. Paul

My two guitars equipped with pickups have a passive K&K Western Mini and a Fishman GoldPlus Natural 1 that is powered.

Is there one preamp that can be used with both?

hi Mr Paul

Any number of external preamps equipped with both Gain and Master volumes will work great. "Gain" is the amount of volume you let into the preamp, and "Master" is the about of volume you send out of it. As long as the output of the Fishman Gold doesn't overload the input of the preamp you are good to go.

One of the reasons I prefer to work with decent external preamps is they have both Gain and Master volumes. I'm trying to think of any of my main working preamps which do not have both…all of my external preamps have both.

As long as your Fishman GoldPlus doesn't overdrive the input of the preamp, you wouldn't even need an accessible Gain control.

[Mr. Paul]

Thank y'all for taking the time to explain this so clearly

[M Hayden]

Don't forget older out-of-production preamps like the Raven Labs products - they have two inputs, the first of which is high-impedence - 10 megohms, I think - and the second at around 1 megohm. I've used it with multi-pickup configs where a passive SBT is in the first channel and a Sunrise is in the second. I think there are other preamps that have this feature - maybe the D-TAR Solstice?

[ljguitar]

Originally Posted by M Hayden

…I think there are other preamps that have this feature - maybe the D-TAR Solstice?

Hi MH

Both ¼ inputs are 10Meg Ohms on my DTAR Solstice.