guitar preamp

designed by Igor Shaev
(C) Kaunas, Lithuania 2002


TOMATO is a one tube guitar preamp. 12AX7 (ECC83) tube used. You can plug this preamp directly to the
sound card of your computer to get good enough sound. Of course you can use it as an ordinary guitar
preamp. Just plug it to your favourite tube/transistor power amp and go for that nice *tubey* sound :-)

Preamp goes from clean to overdrive sound. It depends on how 1M pot is set.

The main problem of tube preamps they need high voltage power supply. TOMATOE preamp have voltage
multiplier so only 12V AC power transformer or 12V AC "wall-wart" power supply need. Use transformer
rated at not less than 6W to be safe. You could use diode rectifier for tube heaters.


  • Simple circuit
  • Only 12V AC transformer or power supply need!
  • Drive and Volume control knobs
  • 12V to 120V voltage multiplier
  • Really available parts
  • True tube sound :-)

Schematics updated: 23 November, 2002

Sound samples

Please, pay attention! All samples were recorded directly to the PC soundcard!
No speaker or cabinet simulators were used! 

I had not put the preamp into the metal case so you will hear noise in all sound files. Files were recorded
using Sonic Foundry Sound Forge. You can use Noise Reduction DirectX plugin, all noise will disappear!

I use ECC83 tube and 12V AC power transformer.

My guitar is Stratocaster (made in Korea) with D'Addario strings.

Download sound samples in Windows Media Player wma format above:


Main page is in Russian:

Here is a page with "Tube smilies"! Have fun!