The Boost 'n' Buff is designed to fulfill three distinct applications.

1. In bypass mode , it's an ultra high input impedance buffer.
2. In the lower volume range, the frequency response is flat for use as a simple volume booster for solos.
3. In the upper volume range, the Boost 'n' Buff becomes more like a treble booster for driving a valve amp into overdrive without getting loose and fuzzy.

The Circuit

The circuit is a rather elegant design based around one ultra low noise transistor. By not utilizing a large number of active devices, I was able to keep the noise level of the booster down to an almost imperceptible level. This is a very important factor in applications where a booster is going to be used before a gain device, like a dirt pedal, or an overdrive channel of an amp.

The way that the volume control on the Boost 'n' Buff works is also quite interesting. Most transistor based booster designs have a fixed gain, and the volume control simply limits the input or output volume.

Flat Booster

In the first half of the volume sweep, the frequency response of the Boost 'n' Buff is flat. This provides you with about 15db of flat boost before the frequency response of the pedal starts to become more treble booster-like. This is perfect for solo volume boosts. The one thing to note is that if you're going to use digital effects in your signal path, I'd suggest putting the Boost 'n' Buff after the digital effects to avoid overloading the A/D converters.

Another interesting application is using the Boost 'n' Buff in the FX loop of an amp to act as a secondary volume control. Since it has ample headroom, line level signals are not a problem. So even if your FX loop is line level, you can still get quite a bit of boost using the Boost 'n' Buff. This way, your FX loops can also double as a solo volume booster as well as a standard FX loop. By putting the Boost 'n' Buff in the FX loop, you can use it to boost the volume of an overdrive channel. If you're using the overdrive channel of your amp, then putting any booster between the guitar and amp will just increase the amount of distortion as opposed to increasing volume. By putting it AFTER the preamp (in the FX loop), you can achieve volume boosting without affecting preamp tone.

Treble Booster

Once past the half way point, the mid and high frequencies start to climb faster than the low frequencies. At maximum gain, not only do you have an amazing amount of boost (approximately 35db), but the frequency response is perfectly tailored to driving a valve amp. It's literally like hot-rodding your amp with an extra tube stage. Also, with the 18V headroom, your sound will be 'cleaner' going into the amp, so that there's less colouring from the transistor.

Other Features

• LED status indicator
• Mechanical switching for buffer/booster mode selection
• Heavy duty die-cast aluminium enclosure, professionally powder coated and silk-screened
• Large pointer knob for easy manipulation of the volume control

Picture of the MI Audio Boost 'n' Buff