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"ART" MP 12AX7 tube microphonium preamp:




 
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Author Topic: "ART" MP 12AX7 tube microphonium preamp:  (Read 20470 times)
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Vortex Joe - N3IBX
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« Reply #25 on: August 14, 2008, 12:49:24 AM »

Hello All,
           The ART MP 12AX7A tube microphinium speech amp is alive and well! I connected it to my ART-13 earlier this evening for some preliminary testing to make sure the one I got this time is in working condition, and fortunately it is. I noticed that they (Musicians' Friend) did not send me my old one albeit "repaired", but another new one from their inventory. The one I received today has a 10/07 production date, whereas my old one had a production date of a few months earlier.

I ran it with the +20db button off, and the liniter/compressor on during my initial testing with a crystal head D-104. I specifically chose the aforementioned mic due to it's inherit gain. I had to run both the input and output gain quite high (with the +20db button off) and am very pleased with what I heard in my station monitor. Unfortunately, time didn't permit any A-B type responses from other stations, but I do plan to get to get some on the air critiques.

I would think that what I heard in my station monitor was the result of the op amp(s) inside of the processor itself, and very little, if any gain or compression is related to the single 12AX7A tube. I was delighted to hear quite a bit of enhanced bass response and "warmth" from my audio, with a different presence rise. It seems that this is done without any sacrifice in midrange or higher frequency audio products, which is ideal in my opinion.

Unfortunately, I wasn't able to test other mics in my stable, including a RCA 74B "velocitium ribbonium microphonium" that I suspect will give me the best low end response down to 100hz or so, next to the Behringer B-1 condensor mic that excels in the low frequency production arena. I plan on doing so as time and frequency space permits. Remember that this is a mic preamp only, and doesn't include a EQ. Any change in frequency response, etc is solely due to the microphone and the anomolies within the processor itself.

I'm very pleased overall in lieu of my negative initial experience with getting a new product that wasn't functioning. For a cheapo microphone preamp; at $29.95 it's hard to beat, and has a real vacuum tube in it for effect or whatever you care to describe it. I suspect it has enough audio hutzpah (+60db of gain) to run a broadcast transmitter with the +20db button in, and will be testing it in that area as well.

For the times that we've all had in searching for a mic preamp around the shack to plug into a specific modulator to use on the air with something we've slapped together; it really shines for the money. It's diminuitive size doesn't take up much room, and it seems to do what a mic preamp is supposed to do, for a small investment.

Regarding the altered or enhanced frequency response curves, I'll be finding out more as time goes on and other people give me their opinions.

Many thanks to all respondents with this thread and hope to "Mod-U-Later" with a tube enhanced speech amp!

Joe Cro N3IBX
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Joe Cro N3IBX

Anything that is Breadboarded,Black Crackle, or that squeals when you tune it gives me MAJOR WOOD!
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