The OSA's sound great. To keep it simple we compared the three OSA's to a Brent Averill API 312, a modern API 512, and a Brent A 1272 (familiar neutral territory for most...). So to sum up the preamps we had:

OSA MP1-A OSA MP1-C OSA MP1-L Brent A 312 Brent A 1272 API 512

OSA MP1-A: Extended 'airy' top, "flatter" lows...compared to any other preamp used from these six choices it is VERY clear & neutral sounding (it reminds me somewhat of a brighter version of my Great River MP2H [which I love], same clean vibe). Since the tranny in the MP1-A is a Jensen 'type' tranny, the Crimson and Lundahl versions definitely have more obvious character as I expected. The MP1-A fits well on overheads for my tastes. The highs on the MP1-A seem gently 'compressed' in a flattering way, different from the highs on the lundahl version, see below for more on that. The MP1-A, to my ears, sounds a bit like how a good tube preamp handles the highs, similar to a Pendulum or Manley. It's not quite the same, but there is a certain something going on in a positive way in the upper frequencies. I realize those two product brand examples given above are very different from each other, but if you have experienced what a good tube design can often achieve you know exactly what I mean.

OSA MP1-C "Vintage": Not a huge difference between the Brent Averill API 312 (which is an A in my book) & the OSA MP1-C (very close if not the same, maybe the MP1-C is a little clearer in the low mids and tighter in the highs). I love the Brent Averill 312, so the large amount of similarity to the OSA (and vice-versa) demands the same respect here. The MP1-C has SMOOOOTH highs (less crispy than the MP1-A), nice tight low mids, relatively "flat" lows that are a little bigger than the OSA MP1-A to my ears. This could be due to the percieved mid rich, reduced high end from the characteristic "API" type sound, but this is what I have come to expect and love from this sound. The API 312 from Brent & OSA MP1-C seemed just a tad more colored and smooth than the modern API 512 also.

OSA MP1-L w/Lundahl: Natural Lows, extended highs. The highs sound overall more open and 'wider' than the MP1-A (this is not a frequency issue), not as "compressed". So the different characteristics between the highs on the MP1-A and MP1-L is neither for good or bad, because I could see different uses for both sounds (we can't paint a painting with just green, or just red).

The OSA MP1-L has a similar character as the Brent Averill 1272 (big compliment in my book), but the highs are more extended and focused on the OSA MP1-L andaren't nearly as dark as found on the Brent Averill 1272 (The BA 1272 is the darkest preamp I own) making the MP1-L apparently more useful on more sources IME. Usually I wouldn't use the Brent Averill 1272 for room, snare or overheads. It almost exclusively gets reserved for outside kick or guitar amps, sounds that need the 'edge' taken off. The OSA MP1-L provides the same low end frequency vibe, with a bigger/clearer/more open top end enabling it to be used on far more sources than the 1272.

I hope this helps. I greatly enjoyed all three preamps, and from what I have heard they can sit side by side with what I consider the best on the market.
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Best Regards
Nathan Eldred
atlasproaudio.com



The OSA product line is modular and requires a powered rack, OSA makes 2 the Track Pack (8 Space) and the Power Rack (11 Space). When you order a Track Pack or Power Rack, it comes with a oversized remote power supply. What is oversized? Well as most of you know, the more extra power in your power supply, the more headroom you have from your gear. The current standard OSA power supplies can support 16 modules, that's incredible considering the largest rack holds 11 when full! The power supply is remote, which reduces noise and eliminates grounding issues.

Installing the modules:
The mic pre modules connect to the rack easily. There are 8 connections inside in the Track Pack, and 11 connections in the Power Rack. You simply line up your micpre in the slot you want it to go into, and push the micpre card into the connection inside the powered rack. Once it is connected in the rack, you screw 2 screws into the face plate to secure the module in place.

Inputs and Outputs:
The OSA mic pres have DI located on the front of the module. On the back of the Track Pack and Power Rack are 8 and 11 XLR inputs and outputs, respectively. You plug directly into and out of the Track Pack or Power Rack via XLR connectors. More INFO:
VISIT THE OSA FAQ PAGE