No more 60 Hz hum in a PL2000 preamp.
- Thread starter George S.
- Start date
Listening to digital files with the Acurus L10. First "line level preamp" I've heard. This will remain stock and be used for comparative testing with the PL2000. Then probably go into the garage system to replace a Marantz 3200 that's currently commanding ridiculous money on that auction site.
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Nice Work George
now my not so well thought out question is have you tried to remove those output caps completely
correct me if I’m wrong but they are there to prevent DC output. And as a result effects output signal
running DCP protection this can get stopped down stream Right
just asking , may be dumb idea or brilliant
now my not so well thought out question is have you tried to remove those output caps completely
correct me if I’m wrong but they are there to prevent DC output. And as a result effects output signal
running DCP protection this can get stopped down stream Right
just asking , may be dumb idea or brilliant
Glenn, that's a question I have thought about a lot.I really don't have a answer, but, I'm going to find out. I really don't understand how output capacitance affects frequency response. Did some reading, but it was too technical for me to understand.
Got four 50 ohm cables built. Was using 75 ohm Monoprice cables.
Got four 50 ohm cables built. Was using 75 ohm Monoprice cables.
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Agree.
I have observed postings on other sites that people have placed a wire across the caps to A/B/A any subjective audio improvements before or after eliminating output caps. The benifit does not seam to outweigh the potential of the power amp amplifying DC offset.
But also may depend on if your amp has input caps as well...
I have observed postings on other sites that people have placed a wire across the caps to A/B/A any subjective audio improvements before or after eliminating output caps. The benifit does not seam to outweigh the potential of the power amp amplifying DC offset.
But also may depend on if your amp has input caps as well...
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Got sidetracked today with a coolant leak on the wife's Buick Encore 1.4 Turbo. Plastic coolant manifold seeping and dripping coolant onto transmission. All fixed now.
Well, measuring the Acurus this morning was a eye opener before I got sidetracked. Now have the PL2000 on the right channel, and Acurus on the left channel of the QA400. Very easy to compare them. Going to run through the testing.
Well, measuring the Acurus this morning was a eye opener before I got sidetracked. Now have the PL2000 on the right channel, and Acurus on the left channel of the QA400. Very easy to compare them. Going to run through the testing.
Al, good while back I think it was "Kevin" maybe who upgraded Lee's Acurus. Last year or two I copied all the photos from that thread. Lee got a next size larger Triad standard replacement transformer. Haven't seen anything about a toroid in a Acurus. But this one will get no changes. It'll stay stock as a piece of "test equipment".
I might have gotten that transformer type wrong - I also saved the pics for one of those "maybe" projects. Maybe not.
The L10 I bought is working very nicely with the Acurus A250 I got from a friend several years ago. It was a new-in-box "spare" for a customer's home theater that was dismantled. People with big money amaze me when they decide to scrap things.
The L10 I bought is working very nicely with the Acurus A250 I got from a friend several years ago. It was a new-in-box "spare" for a customer's home theater that was dismantled. People with big money amaze me when they decide to scrap things.
O.K., progress. The Frequency Response issue is solved. I had "A Weighting" engaged. There is a flat spectrum response with it off.
But, the PL does have a noise issue. THD is very close between the two units. But THD+N is way high on the PL, and readily visible on the RTA. The Acurus does have a safety cap between chassis and cord ground. The PL has no connection to the IEC socket ground,
Mark L. recommended the Vishay X440 safety caps a while back, I do have some. these are rated X1 and Y2, pretty damn cool that one cap can do both. So I'll install one between Line and Neutral as the X cap, and another between Line and chassis ground as a Y cap. Then retest for noise.
If you look at the screenshots, FFT is at maximum resolution, the fundamental is balanced between the two units and as close to 0 dB as I can get it without clipping the QA400, and averaging is set at 10 to reduce jitter.
The Acurus is the Yellow trace, PL2000 the red trace. Lots of noise between the harmonics. Oh, and the PL is on the right channel of the QA400.
But, the PL does have a noise issue. THD is very close between the two units. But THD+N is way high on the PL, and readily visible on the RTA. The Acurus does have a safety cap between chassis and cord ground. The PL has no connection to the IEC socket ground,
Mark L. recommended the Vishay X440 safety caps a while back, I do have some. these are rated X1 and Y2, pretty damn cool that one cap can do both. So I'll install one between Line and Neutral as the X cap, and another between Line and chassis ground as a Y cap. Then retest for noise.
If you look at the screenshots, FFT is at maximum resolution, the fundamental is balanced between the two units and as close to 0 dB as I can get it without clipping the QA400, and averaging is set at 10 to reduce jitter.
The Acurus is the Yellow trace, PL2000 the red trace. Lots of noise between the harmonics. Oh, and the PL is on the right channel of the QA400.
