What Other People Think

Below are reviews, tests, modifications and opinions by others. I'm providing space for these articles to create a site that contains as much useful information about PreSonus microphone preamplifiers as possible. Hopefully current and potential users of PreSonus products will find this site to be a valuable resource.

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Best of luck!

John L Rice

Changing OpAmps By Francisco Lobato

Well, first off, my MP20 was shipped with the newer generic transformers, so thanks to John Rice for his great site on how to perform the transformer swap.

First I emailed PreSonus to tell them my disappointment in the fact that the manual clearly stated that I had a unit with Jensen transformers... Not! But, Rick Naqvi from PreSonus was really helpful and explained to me that some of the units that shipped with generic transformers mistakenly had the old manuals which state that the transformers are Jensen.

Secondly I asked PreSonus if they would ship me two of the famous Jensen transformers, which, they did at no cost to me and fast too! I think the length of time from the moment I talked to Rick Naqvi to when I received the transformers was less than 5 days.

Sooo... not having ever held a soldering iron or toyed with a circuit board, I went to Radio Shack and bought the necessary soldering and desoldering equipment. The whole thing set me back only $40 which is pretty good for a soldering iron, a desoldering vacuum and some solder.

There's a site called the The Basic Soldering Guide by Alan Winstanley with pictures which is cool if you've never done this before. Also before doing the operation on the MP20 I practiced on a old portable TV set I had which has a small circuit board.

Anywho. . . I did the transformer swap and I must say the Jensen transformers do sound better than the generic transformers in the MP20, but nothing overly dramatic, just a bit richer and darker.

Next off, John Rice, Rick Naqvi and others had talked to me about trying out different opamps for the preamp. Now, changing the opamps in this unit is very easy since the opamps are socketed, not soldered.

I received my Burr-Brown opa627ap opamps and tried them out ( btw, it takes 4 opamps, two opamps per channel, for the MP20 ) WOW! Night and day on this one, the generic opamps sound thin and almost out of phase, ( I don't know how else to describe the deference and yes the mic was in phase both times ), compared to the Burr-Brown opamps which give a much more rounder tone and sound more like reality. Now this was not a very scientific test, I simply left the generic opamps in the second channel and put the Burr-Brown's in the first channel.

Recording chain : AT4060 mic to MP20, MP20 balanced out to Lexicon MPX 500, MPX 500 out via 24 bit / 48khz SPDIF, ( dry signal only ), to Layla 24 bit / 48khz SPDIF digital in. I recorded about 15 seconds of vocal on each channel consecutively. I know it's not perfect but the deference between the 2 is very obvious. Listen to the two takes ( these WAV files are 1,379 KB each ) :

Conclusion : I've worked with high end pre's, ( Avalon, Focusrite, Drawmer, Manley, etc... ), and not so high end mic pre's. Now in my project studio, for recording demos or low budget albums or voice overs, with the Jensen transformer switch and the Burr-Brown opamp switch, this preamp sounds pretty decent to me. For the price I say it sounds darn good to me. It's a nice, clean, no frills
mic preamp.

Hope you find this useful! :)

Franky B