So, how does it work?
All our products utilize supercapacitors (sometimes called ultracapacitors) as the energy storage elements. To charge the supercapacitor, simply plug-in the Power Charge to the AC outlet and then connect its stereo 1/4 output plug to the instrument’s audio output. After 60 seconds (yes, only one minute!) of charging, your preamp is ready for 8 or 16 hrs (depending on the model) playing time

Is it a rechargeable battery?
No, it’s not a rechargeable battery. A supercapacitor is a huge capacitor, and unlike any rechargeable battery, can be charged very fast.

Will it die after a certain number of charging cycles?
No. It’s an extremely reliable component and the minimum number of charging cycles is at least 50,000 (for your regular Li-Ion cell phone battery this number is about 500). So if you charge it once every day, it will last for more than 137 years… We think it’s probably long enough for most of us, even with the advances in modern medical technology.

What will happen to the sound when the charge of the supercapacitor goes down?
It will sound like in a case of dying battery. You will hear some distortion first on very strong notes. The less charge is left there – the more distortion you will hear. It is not going to die abruptly.

Are you new in the market?
Mi-Si Electronics Design, Inc. was founded in April 2004, backed by many years of experience in the field of acoustic instruments amplification.

Is it a new technology?
Not anymore. The supercapacitors were developed by NASA about 20 years ago and were first used as the computer memory backup in the mid 90′s. There is a much broader spectrum of applications for supercapacitors now. The wireless pagers and the hybrid vehicles are just two examples of their use.

Is your technology patented?
Yes, we were granted a patent allowance by the US Patent and Trademark Office.

Is it passive?
No, all our systems are ACTIVE with all the benefits associated with it. You always get a strong full bandwidth signal no matter what input impedance your amplifier or PA system has. The length and the type of connecting cable also have no effect on the signal quality in the active systems.

How much voltage do you have in your systems?
From 2.5V to 5.4V, depending on the model. We know how to configure input stage in such manner that clipping will NEVER occur even with the high output/high capacitance pickups. Our Kremona-made violin pickup has capacitance of 10-12 nanofarad and it works just fine with the 2.5V supply in our Lil’ Jack preamp.

At the same time we know how to keep the noise level down in all of our products. Our extensive expertise in designing low noise, low power circuits makes this possible.

What is a custom linearization scheme?
Everyone knows about the “quack” associated with the piezo pickups. This characteristic type of distortion is caused by the hysteretic behavior of the piezoelectric materials. The amount of these distortions depends not only on the type of the material used, but also on how the piezo pickup is connected to the amplifier – as a voltage source or as a charge source.

The later case results in much lesser distortion, but to build a charge amplifier with just the right amount of gain and broad bandwidth, the exact capacitance of the pickup must be known. Thus this method is unacceptable for general purpose preamps. We are using L.R. Baggs Element and Kremona pickups in our packages and we know their capacitance. Thus we can produce circuits which exactly match their characteristics. This is what we call by “custom linearization scheme.”

We recommend that you contact us if you are planning to use our preamps with some other pickups. Of course, we can give you 20 or even more MOhms of input impedance and everything will be just fine. But for the best results we would like to know your pickup’s capacitance.

Is it possible to have the Volume and Tone controls with your Simple Jack preamp?
Yes, it is! The Passive volume and Tone controls can easily be wired using the 10 KOhm pots. Please contact us for the schematic. We also can provide you with all the necessary parts.

What soundhole diameters does Acoustic Duo pickup fit?
Acoustic Duo soundhole pickup will fit in soundholes as small as 78 mm or 3.07 inches.

What is your warranty policy?
One year from the date of purchase.

What do I do if I’ve forgotten/lost/misplaced my Power Charger and I need to play a gig?
No sweat. Just go and get your familiar 9V battery and you also will need a regular stereo cord. All our manuals describe in detail how to charge our systems from the 9V battery in case of emergency. We don’t encourage you to do it, though… The batteries are simply not good for our planet. If your Power Charger is lost, you can always order the replacement from us.

Please do not attempt to use some other power supplies – doing so can damage the circuit and will void the warranty.

Is it possible to use other pickups with your preamps?
Absolutely! Please contact us first for the best results.

Can we use your technology for powering other preamps?
No. Our preamps are uniquely designed for low noise/low power consumption operation.

Where are your products manufactured?

Where can I buy your products?
In the USA, you can buy them from Elderly. For other dealers, see Mi-Si Dealers. If you would like to become a dealer in the United States, you can contact Harris-Teller. Please see Mi-Si Distributors for the list of our distributors outside USA. You can also contact us directly at