hi all, i've just made my first electronics project; an audio optical compressor, i'm pleased with the sound from this, but i have to put my guitar through a mixer and push up the gain before it goes into the compressor as it won't drive the circuit.
can anyone suggest a simple but quality preamp circuit i can put on the input, i'd like it to be as low noise as possible. i have a few spare lt1028 opamps i could use?
cheers
Try searching the forum here, but use Google's advanced search and limit the domain to electro-tech-online.com search for low noise pre-amp, your post will show up but I'm pretty sure Audioguru has posted schematics for some simple low noise pre-amps before.
yeh, thanks for that, 500 results for audio pre-amp on this forum, many, many more from my old friend google, all combine to confuse the noob!
i pulled this from the lt1028 data sheet (attached). which one would suit my requirements best do you reckon & why? i'd like to learn a little as i go along if anyone fancies sharing a bit of knowledge. cheers
The LT1028 opamp produces extremely low noise when the source impedance is very low, the example has only 7.5 ohms. Its input resistance is also very low.
It is noisy when its source resistance is high.
A guitar pickup should feed a high impedance of about 3M ohms so an LT1028 opamp should not be used.
An OPA134 FET-input opamp produces very low noise when its source resistance is high. It would make an excellent guitar pickup preamp.