Where to audtion stuff in Los Angeles
I built a control preamp out of some surplus broadcast stuff. It's nice and sounds REALLY GOOD! I used a Broadcast Tools SS 4.1 III switcher for a source selector ("Audio switching via sealed relays utilizing 2-form-C bifurcated - crossbar silver alloy with gold overlay contacts." ), and a modified Broadcast Tools
AHR-1 headphone amplifier (Balanced inputs and DC coupling with servos). The mod involved replacing the three opamps in the unit (I used samples of a new National Semiconductor opamp), building a small power supply inside the box, replacing its 12 volt 3 terminal regulators with 15 volt ones (more headroom) and dealing with some grounding issues.
I'm using it with a modified Sonic Impact T amp (new input caps and reservoir cap) and my Polk RT-600 speakers with full range drivers installed. I cross over to the Polk tweeters above 8 kHz, as the full range begins rolling off.
The sound? It seems to have no particular sound of its own, sounding like a: "wire with gain". It also works great at driving headphones-its original design.
Noise is over110 db down, which I have to remember-If I turn up the volume control too high, I get blasted when I select something! Audio response was measured from below 1 Hz to over 150 kHz.
I didn't have my distortion meter, but the chip specs. THD at .000003%.
This is a NEW opamp-the LME49720-essentially the second generation of the LM 4562.
My question is where can I find a place to audition this thing in Los Angeles? Maybe a listeners group or a Hf Fi emporium that's friendly to this kind of thing. I'd like to hear it against some other preamps.
Anyone?
Oh-here's the links to the Btools stuff:
http://www.broadcasttools.com/view_product.php?pid=36
http://www.broadcasttools.com/view_product.php?pid=144
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