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In Reply to: RE: I especially agree on the part about... posted by stehno on November 10, 2014 at 19:10:44
Hi, stehno,Actually there isn't much that's interesting to see. The chassis, main power transformer and filter caps. are all reclaimed from a Forte' 200W stereo power amp. The orginal circuits boards of the amp were fried and the chassis scratched, so I decided to have the chassis sandblasted and re-anodized (still black), which also removed the original markings of course. I also changed the original red power LED to a subdued deep blue LED, giving a very nice overall stealth amp effect.
Tripath supplied PCB Gerber files from one of their reference designs, which I then sent to a board house for manufacture. The reference design PCBs are typically configured for 2-channel stereo use, but the documentations also showed how the stereo channels of a single PCB could be configured as a balanced H-bridge mono channel, which is what I did. I hand stuffed two such PCBs, including winding the output inductors on powdered iron toroid cores with heavy gauge solid core wire by hand (which I would not choose to do again). The finished PCBs are mounted directly to the exisitng side-panel style heat-sinks, although being class-D, the now 650W@2 ohms capable amp remains eminently cool when powering my 93dB sensitive speakers.
Call me tone deaf, but the sound quality after some seemingly minor passive component changes, such as I've mentioned, is stunningly clear, dynamic, and natural. When I think of all the processing involved, this result seems quite surprising to me. This is, by far, the best sound I've yet obtained from a power amp, including the original Forte' (Insulated-Gate-Bipolar-Transistor) model I cannibalized, and a pair of Audio Research Classic 120 tube monoblocks I owned for several years.
Follow Ups:
Whose IGBTs did you use? I worked for IR for a decade plus and worked in-fab for the technical people for all that time.
Just curious.
Too much is never enough
Pretty cool, Knewton. I can't even solder well.
If you're up for experiments would you consider 2 suggestions?
1) Assuming it's stock, remove the Monster power thing from the mix and tell me what you hear.
2) It looks like your gear's on a concrete slap. If so, and after testing without the Monster power, remove the Monster and the bottom plate. Get some little steel pucks, even 3 or 4 car lug nuts to use as footers between the amp chassis and the floor. Try to put a couple of the lug nuts underneath near the mounting studs of the PCB boards, and put about 50 lbs. of some heft on top of your amp. In the end, it should be metal to metal to concrete.
You should notice some gains right away, but give it a week or so and I'll bet dollars to donuts it will probably change everything you thought you knew of audio.
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