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Old 9th August 2013, 11:34 AM   #561
SY is offline SY  United States
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They're passed through different sections in the same envelope. This compromises separation at megahertz frequencies, which is not terribly worrisome. At audio frequencies, the weakest link is usually the volume control or the selector switch.

To put things into perspective, a good phono cartridge might have 20dB of separation. A preamp will be 100-10,000 times better than that.
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Old 9th August 2013, 11:41 AM   #562
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Originally Posted by 6L6 View Post
Jack, BDP thanks for the info, that clears some things up.

Jack - Just to verify, the CCS Fets don't have to have their legs crossed on this version of the PCB?
the new version is minus the contorted legs. i think i must've been thinking of lateral mosfets. they did, however, remind me of the girls in my grade school class taking "step dancing" lessons. (even the those of italian descent had to take step.)
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Old 10th August 2013, 12:31 PM   #563
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Thanks a lot for the explanation
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Old 20th August 2013, 10:37 PM   #564
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Look at post #454. That's what I did to mine. Still my favorite preamp. Every once in a while I will swap in another, but that doesn't last long.
This. I have moved into a small condo and have considered letting mine go out on loan for a bit, assuming I could get nice packaging for it... perhaps there is interest in this?
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Old 20th August 2013, 10:38 PM   #565
SY is offline SY  United States
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Are you in AA yet?
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Old 20th August 2013, 11:17 PM   #566
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Indeed. Didnt miss the Texas heat one bit this summer.
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Old 29th August 2013, 09:44 PM   #567
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I've been reading through this thread but just ran out of time at work, so apologies if this has already been answered.

The original Impasse specified a 650 VCT 40mA 6.3 VCT 2A mains transformer.

What are the upper and lower limits of these supplies. I expect the 6.3V to be about 2A but can the HT be say 620V or 640V as the American transformers are expensive here in the UK.
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Old 29th August 2013, 09:57 PM   #568
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Yes, the regulator will take up that slack. If the raw DC is too low for the regulator to cope with, you can set the regulator output a bit lower without much issue.
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Old 29th August 2013, 10:04 PM   #569
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SY, as the Impasse is now a few years old, were there any significant improvements to the original design ?
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Old 29th August 2013, 10:07 PM   #570
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Personally, I would like to build the Impasse without the input transformers. My source is very close the pre-amp so input leads are not a problem.

They can always be added later but at $60 each here in the UK, and an added source of "loss of fidelity", I'll try it without them first.
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