Price $56

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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 diffferent 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 Powerjack. (Click here for info on the Pure Preamp).

POWERJACK MINIATURE ENDPIN PREAMP

The Powerjack, made by Fishman, is as small and unobtrusive as a preamp can be, making it suitable for mounting on or in an instrument. It takes the form of a cylinder, 3 7/8" long and 5/8" in diameter at its widest – taking up not much more space than the normal passive output jack, which it replaces. The package includes a battery clip for separate mounting of a standard 9-volt battery. The Powerjack is designed as an endpin jack for acoustic guitar, but it can be used with any instrument that you'd want to put a pickup on. While the endpin mounting is standard, the Powerjack's small size and unobtrusive shape make it easy to come up with ways to mount it on your particular instrument.

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 preamp in the signal path as close as possible to the pickup. The preamp 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 Fishman Powerjack's very high input impedance of 10 mega Ohms makes it ideal for this purpose. The Powerjack is also good for most magnetic pickups. It is not suitable for low-impedance microphones.

To install the Fishman Powerjack you'll need to make two solder connections, attach the battery clip to the instrument, and arrange for mounting the Powerjack itself. (The included spec sheet details the standard end-pin mounting. For non-standard applications, it'll be up to you to come up with a mounting system.) The Powerjack does not include volume or tone controls (the spec sheet, however, contains wiring diagrams for adding them). The gain is a modest 3dB, reflecting the fact that the Powerjack is not designed to function as a powerful preamplifier, but rather to provide high impedance pickups – piezos in particular – with the buffering and impedance-lowering they need for improved performance.

Further details: Battery life: 12,000 hours (!). Input impedance 10 mega Ohms; output impedance: less than 5k Ohms. Signal to noise ratio 94 dB. For applications involving two sources on the same instrument (e.g., pickup and internal microphone), the Powerjack has extra solder terminals that allow the option of running the signal from the second source through the Powerjack (bypassing the preamp) and out through a stereo cable.

• Price $56 Item #120

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

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 will do fine with magnetic (electric guitar-type) pickups. It is not suitable for low impedance sources such as most microphones.
• The K&K Pure Preamp will do fine with magnetic (electric guitar-type) pickups. 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 unobturusive 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 is 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.

Amplifiying 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 then 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