Originally Posted By: justanoldmuso
simon.
1.as always spot on.
nice to meet a kindred refurb spirit.
cant beat them.
2.re dda. mic pre's.
its fun to try and build ones own mic pre's.
(on gearslutz is geekslutz forum. )
lots of vintage schems on net .
i just stay away from tubes cos they scare me lol.
for fun google the 5 dollar mic pre schematic.
then go to gearslutz, put in 5 dollar mic pre in search.
hilarious thread where it fooled some engrs in tests
against expensive pre's.
3. usb4. yup good points.

best.
oldmuso.



The DDA mic pre uses nearly the same chip as the 5-dollar mic pre (I think the INA217 or similar), just with a bit more filtering and a good power supply (the PSU is in my rack and does all the AC-DC conversion so the board doesn't have any 60hz AC anywhere near it).

I actually built a handful of the 5-dollar mic preamps (with the SSM2019 chip rather than the INA217, but similar enough), but rather than running from a stack of 9v batteries I built some beefy +-15v power supplies and added a switchable pad and high pass - then built them into a couple shielded enclosures (shielded with foil tape on the inside - added nearly 20db noise reduction), and eventually rackmounted a stereo pair with a fat toroidal power transformer.

We put the 4 of them up against everything we had in the studio (which included a pair of API 512C, an LA-610 MKii, an Avalon 737, a Drawmer 1960, a TL Audio CL-1, and the preamps in an SSL Duality) and - there was no winner. They were all equally good. Popular vote were that my slightly-more-than-five-dollar preamps were the most similar to the Avalon, interestingly enough!

Attached a pic of my "5-dollar" preamps.

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