Pure Compact Preamp from K&K Sound Systems

We sell two models of compact preamps, the Fishman Powerjack and the Pure Preamp from K&K. Both are well suited to the needs Experimental Musical Instruments people are likely to have, but they have very different features. To help you decide which is best for your purposes, there's a comparison chart at the bottom of this page. The rest of this page is about the Pure Preamp. (Click here for info on the PowerJack.)

THE PURE PREAMP

The Pure Preamp made by K&K Sound Systems will enhance the performance of magnetic pickups, piezo contact pickups, high-impedance microphones, and other high impedance, low-level sources. (It can work with low-impedance microphones too, but not optimally).

The Pure Preamp is practically noise-free and the fidelity of the output signal is excellent. It’s compact – just 2.5" x 3.5" x 1.25" (including the knobs). It comes with a belt clip, so you can wear it when you play, keeping cable lengths from the pickup to the pre-amp to a minimum. Or perhaps, if this works for your instrument, you’ll devise some simple way to mount it directly on the instrument. There is no additional wiring or soldering required; nor is it necessary to make any modifications to your instrument. You just plug in the cables from the pickup and to the power amp, and play. It has easily accessible volume, bass, midrange and treble control knobs – almost like having controls on the instrument itself. In addition, there’s a gain-control located inside the unit that allows you to adjust the input signal strength as needed to prevent overloading.

High-impedance signals, particularly the ultra-high impedance signals coming from piezo contact pickups, tend to lose both fidelity and signal strength when they pass through cable runs of more than a few feet. The solution to this problem is to include a pre-amp in the signal path as close as possible to the pickup. The pre-amp will boost the signal, making it more immune to unwanted noise pickup, and it will convert it to a lower impedance, allowing for longer cable runs without loss of fidelity or signal strength. The K&K Pure Pre-amp is excellent for this purpose.

Further details:

The Pure Preamp has standard quarter-inch jacks for input and output.

Volume and tone controls readily accessible, plus a special input level control on the inside
Unplugging the input works like an off switch to prevent battery drain.
It uses a standard 9-volt battery; battery life up to 180 hours playing time.
Frequency range: 10 – 30,000Hz.
Input impedance: 1 mega Ohm
Output impedance: 10K Ohm.
Comes with a one-year warranty.

For more information on different types of pickups, their uses, and the pre-amp question, click here.

EMI item #115

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K&K Pure Preamp vs. Fishman Powerjack: COMPARISON

To aid in your buying decision, here is a comparison of the features of the two models of compact pre-amps that we sell.

USE WITH PIEZOS:

The Fishman Powerjack's very high input impedance makes it ideal for use with piezos.

The K&K Pure Preamp will also handle piezos. Its somewhat lower input impedance means it is not technically ideal, but the difference in this case between the ideal impedance match and the less than ideal one is scarcely noticeable.

USE WITH OTHER SOURCES:

The Fishman Powerjack is made primarily for piezos, and although it will work with magnetic (electric guitar-type) pickups, it's usually not needed in this application except in special cases. (Magnetic pickups don't need it for impedence lowering, and it doesn't add a significant boost to the signal). It is not suitable for low impedance sources such as most microphones.

The K&K Pure Preamp is well suited for magnetic (electric guitar-type)pickups and will provide a useful signal boost. It is not ideal for low-impedance microphones, but it will still do a good job with them.

MOUNTING ON THE INSTRUMENT

The Fishman Powerjack is designed as an onboard preamp – it's made to be mounted on the instrument. Specifically, it's made to be mounted where the endpin of an acoustic guitar would go, but its small size and unobtrusive shape mean that it can be mounted in other ways on any number of different instrument types. It's not well suited to being used offboard.

The K&K Pure Preamp designed as an offboard pre-amp. You can set it on a table or mount it on a mic stand nearby, or use the belt clip it's provided with. It is small enough that you might be able to find a way to mount it on the instrument, but not as conveniently or inobtrusively as the Powerjack.

CONTROLS:

The K&K Pure Preamp has volume and tone controls readily accessible, and a special input level control on the inside.

The Fishman Powerjack does not have controls.

AMPLIFYING THE SIGNAL

The K&K Pure Preamp can substantially boost the signal level, and with excellent clarity and fidelity.

The Fishman Powerjack is not designed primarily to boost signal strength, but rather to provide high impedance pickups – piezos in particular – with the buffering and impedance-lowering they need for improved performance. Accordingly, the Powerjack provides only a very modest boost in signal strength.

SOLDERING OR MODIFICATIONS TO THE INSTRUMENT REQUIRED?

The K&K Pure Preamp requires no soldering or modifications to the instrument, assuming that whatever you want to plug into it has a cable and a standard 1/4" with a plug.

The Fishman Powerjack is intended for permanent onboard installation rather than off-board plugging and unplugging. It requires soldering of the two wires from the pickup. It also requires mounting of the pre-amp on the instrument and attaching the battery clip.

PRICE:

K&K Pure Preamp: $96

Fishman Powerjack: $56

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