12AX7 dual triode "Signal Enhancer/Conditioner"

[sampleaccurate]

Here are pics of my new 12AX7 based "subtle distortion generator". It's simply a stereo two stage preamp that uses cascaded triode stages with the signal inverted between the first and second stage. All stages are op-amp buffered so there is no interaction between the stages and the output impedance is less than 50 ohms to drive long cables or even headphones if desired.

The purpose of the device is to "condition" recorded instrument tracks that were tracked on purely SS and digital systems that are devoid of the non-linearities that older tube consoles provided that added desirable coloration to the sound. Instead of using a VST digital plug-in to simulate tube saturation I decided the real thing would be nice to have.

It sounds great. At nominal volume there is no perceptible effect and it sounds absolutely clean even though it's not. Cranking the levels up brings out the harmonics. There is a maximum point where "enhancement" stops and ugly distortion begins, but it basically does what it's supposed to, and it seems to do it well. There is a slight hum at high gains but overall the noise floor is below what I expected.

It's mostly PCB with all traces tinned and all components surface mounted. I see no reason to drill holes in order to mount components on the opposite side of the board. I started surface mounting discrete parts and DIPs in the 70's. So far no failures due to the construction technique which saves a lot of time IMHO.

[richardburak]

Just couldn't wait 2 and a bit weeks before you posted? Could you

[sampleaccurate]

Originally Posted by richardburak

Just couldn't wait 2 and a bit weeks before you posted? Could you

?