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Old 11th August 2010, 08:15 PM   #1
pjanda1 is offline pjanda1  United States
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Default My Opus II

I just tossed together an Opus II, and I figured I'd show it off briefly (excuse the ugly pics, its been a busy summer). I liked the idea of the 8741, as I'd rather not mess with an extra output stage if I don't need to. I traded a pair of speakers for the brand new Opus and spdif boards in addition to a completed (parts soldered) power supply. Most everything else is from the parts bin. I find that not only is it more challenging to build that way, but it helps keep my junk inventory lower.

The chassis is made from two slim enclosures, some AL mesh from an old R2R and the front and back panels (front panel cut down) of an old phono pre. The two power transformers are from wallwarts. I like the idea of using IE cores for digital circuits to help filter what gets back to the line. And I had them. So, I cut them out of their boxes with a hacksaw and removed the PCB's with the rectifiers and caps. I then modified the remains of one of the plastic enclosures, glued and zip tied both transformers in, and bolted the whole mess to the chassis. I'm running the DAC unbalanced. Rather than use the nice Silmic caps that were included, I bolted in a matching pair of little old motor runs.

I am very pleased with the sound. It is very resolving and tonally richer than what I'm used to. Not a hint of grunge or nastiness. I'm getting plenty of gain driving short ICs into a 33K load. Someday I plan to switch all my digital playback to a PC based solution. When, I do, I'll swap out the spdif receiver for USB. I'm also curious about running it balanced into transformers. Until then, I'll be enjoying it!

Paul
Wild Burro Audio Labs - DIY Full Range Speakers
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Old 12th August 2010, 01:04 AM   #2
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Thats a nice build! Good work. I am very glad your enjoying it. That after all is the whole point. I also very much enjoy re-purposing old stuff.
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Old 12th August 2010, 01:48 AM   #3
pjanda1 is offline pjanda1  United States
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Russ,

You've probably covered this elsewhere, but I haven't stumbled upon it. What is your feeling about the influence of spdif cables? Right now I soldered some cheap RCAs and 75 ohm coax. Currently, I'm stuck with the RCA's but I could covert the DAC end (transport end would be a pain). I know soldering isn't the best thing, so I'm thinking of getting a Blue Jeans Cable digital cable. I don't have proper crimping equipment, nor do I think it would make a great investment.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers
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Old 12th August 2010, 01:58 AM   #4
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Honestly my personal experience (and I won't think any less of anyone who feels differently) is that 75 ohms cable does not have to be anything fancy. Cheap Belkin cable works as well as anything else I have tried.

I would use BNC if its practical, if it is not, then don't sweat it. use RCA and be happy.

BTW, I am looking at your speaker projects. Very very cool. I am currently trying out a pair of Tang Band full range in a sealed enclosure.

Cheers!
Russ
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Old 2nd September 2010, 03:01 PM   #5
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cool - nice to see that it's completed.

Unfortunately, the other half of that trade is still sitting in boxes waiting to be put to use. Hopefully over the winter.....
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