Analogguru - Pickup-probe
Posted: 20 Sep 2008, 11:02
Ok, here is a project only for the more sophisticated solder-jockey - Analogguru´s Pickup-probe.
As I could see recently on the requests in this forum, there seems to be a demand for built-in preamp for bass and guitar. But why fiddle around in your holy guitar and change always batterries ?
Therefore I will release and old design by be (only) to freestompboxes.org members for their personal use.
At first you can see in the schematic, that it is possible to construct an "phantom-powered" high-impedance preamp with only one screened cable and a low impedance output. This is important cause as lower the output impedance is, as less the cable capacitance will lead to a treble loss o other problems with non-true-bypass pedals.
The "head" could me mounted in the guitar, but what when the rest is stolen or you want to use another guitar ? This can be overcome by building the "head" into the jack which plugs into the guitar.
As you can see in the following pictures, a Neutrik jack has enough room inside for the head and the cable.
The right input cap can be recycled from old RAM-modules as shown.
The gain of the complete systems is about 10 which is approx. 20dB. As can bee seen in the oscilloscope picture, the amp starts clipping at 4,5V pp but very round and smooth as it is typical for a tube.
the complete prototype can be seen in the last picture.
enjoy improving your soldering skills and I don´t want to see any builds of this offered on evilbay or somewhere else,
analogguru
As I could see recently on the requests in this forum, there seems to be a demand for built-in preamp for bass and guitar. But why fiddle around in your holy guitar and change always batterries ?
Therefore I will release and old design by be (only) to freestompboxes.org members for their personal use.
At first you can see in the schematic, that it is possible to construct an "phantom-powered" high-impedance preamp with only one screened cable and a low impedance output. This is important cause as lower the output impedance is, as less the cable capacitance will lead to a treble loss o other problems with non-true-bypass pedals.
The "head" could me mounted in the guitar, but what when the rest is stolen or you want to use another guitar ? This can be overcome by building the "head" into the jack which plugs into the guitar.
As you can see in the following pictures, a Neutrik jack has enough room inside for the head and the cable.
The right input cap can be recycled from old RAM-modules as shown.
The gain of the complete systems is about 10 which is approx. 20dB. As can bee seen in the oscilloscope picture, the amp starts clipping at 4,5V pp but very round and smooth as it is typical for a tube.
the complete prototype can be seen in the last picture.
enjoy improving your soldering skills and I don´t want to see any builds of this offered on evilbay or somewhere else,
analogguru
![[smilie=a_goodjob.gif]](./images/smilies/a_goodjob.gif "Good Job!"){kind=small}
