The Acoustic Preamp DI


Many acoustic/jazz guitarists have said that they wished they could carry their sound in their pocket when touring. In answer to this I sat down and designed a valve front ended preamp that would faithfully reproduce the full range of tones that come from an acoustic/archtop guitar. The valve is a standard ECC83 (12AX7) but connected up in a very different way from normal. This allows a much broader frequency response than the conventional ECC83 circuits. After this valve stage the circuitry is solid state but with a big difference. I have chosen to use components that are normally used in top end HiFi. The blend of the two technologies results in a very open natural sound with all the dynamics that would be expected from a bespoke guitar amp. The output line to the desk is driven with a brand new solid state device that performs very much like a line transformer resulting in a very low noise floor and good common mode rejection of pickup on the cable to the desk. The output does not require a DI box and should only be connected straight to the desk.

The tone circuits (especially the parametric mid) allow the performer to first set up the preferred guitar tone and then compensate for any room acoustic issues. These controls really work!

The effects are generated digitally but are then filtered through analogue circuitry to produce a more natural tone.

The valve is running on about half its normal rated voltage so should last for years without any replacement.

The amp can either be mounted on a side table or sit in the tray shown below. This tray is then attached to a microphone stand.If a Shucko European power adaptor is required please say with order








Accessories available from source - please click on image to follow link


Microphone stand support tray                    115V 2.1mm power supply for USA



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Dennis Marshall