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Old 9th March 2005, 06:08 AM   #1
akunec is offline akunec  Canada
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Default Has anyone used linkwitz 3886 design?

I was just wondering if anyone has used linkwitz's design for the Lm3886 and power supply (www.linkwitzlab.com)?

He uses a standard 25A bridge rectifier in his power supply, so I was wondering why everyone seems to be going with discreet diodes. Linkwitz is a very highly regarded audiophile and EE (at least in my books) and I'm just surprised that more ppl haven't used his designs.

Alex
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Old 9th March 2005, 07:26 AM   #2
llmobll is offline llmobll  United States
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2 Reasons....


1. BrainGT's kits come with discrete components.

2. A small discussion is seen here on the other why:
http://www.decdun.fsnet.co.uk/gaincloneFAQ.html
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Old 9th March 2005, 07:56 AM   #3
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I think that you will finde that a lot of people use a large bridge rectifier like mr. Linkwitz. They just don't seems to feel the need for so many threads, since it works fine.

I use LM3886's in a set-up very similar to Mr. Linkwitz and it works fine.

Have fun

Thomas
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Old 9th March 2005, 07:57 AM   #4
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Answer is easy : avalanche of rubbish as is normal in all hifi .
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Old 9th March 2005, 08:48 AM   #5
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Default Re: Has anyone used linkwitz 3886 design?

Quote:
Originally posted by akunec
He uses a standard 25A bridge rectifier in his power supply, so I was wondering why everyone seems to be going with discreet diodes.
Discrete rectifier bridge is a fashion here at the moment. I think that's simple reason and soon we will be using body diodes in mosfets as the next fashion! Don't forget that it looks a lot cooler with a discrete rectifier bridge. The coolness is an important factor and we should not neglect it and I mean it!
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Old 9th March 2005, 09:01 AM   #6
MBK is offline MBK  Singapore
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I built my PSU and the 3886 circuits exactly as Linkwitz says (except for separate transformers for L and R, since my amps sit inside the open baffle speaker).

Works like a charm, and I'm happy with the sound too.

Additional decoupling caps after the main caps were initially 10 uF and now 470 uF. I tried CarlosFM's "snubber" as well, it did seem to change the sound for more clarity back when I had 10 uF at chip ins only, but I haven't taken it off since I added the 470 uF caps. So I can't say if it is really necessary. Doesn't hurt though.

You'll notice that the PSU schematic already has those 0.1 uF caps on the AC secondary which were hotly discussed as a grand discovery, lately, here on the forums.

You'll also notice a smart cap network around the 3886 chips:

- a bypass cap for the feedback resistor to limit bandwidth

- a cap between -in and +in of the 3886, working with the feedback cap, to prevent back emf and HF from feeding through from the output to the diff inputs. None of the chip amps here have that AFAIK. As a consequence, he omits the output inductor as well.

- input RF filter

Also, note low resistor values (20 k feeback cap) for lower noise and lower HF pickup than many chip networks presented here.

My only mistake was to build 8 of those point-to-point as SL suggests. It was very tedious and I have some fears for long term reliability.
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Old 9th March 2005, 09:06 AM   #7
steenoe is offline steenoe  Denmark
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No problems with generic bridges, whatsoever. Used those on several occasions for chipamps. Being able to use excotic circuits and/or parts is part of the game for many DIY'ers though. Why shouldn't it be? Afterall, if one finds it worthwile and cool too; why not go ahead and do it? This is just one of the advantages of DIY. Oneself, and noone else, make the decisions

Steen.

BTW where on his page has Linkwitz hidden the LM3886?
Prob. just me gone blind
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Old 9th March 2005, 09:42 AM   #8
sunil is offline sunil  India
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Ditto, the bridge rectifiers sound as good as the discrete diodes. I have tried both & can't hear any difference. They both sound great, only thing is the discrete's cost more, a lot more.

Cheers,
sunil
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Old 9th March 2005, 09:54 AM   #9
Alcaid is offline Alcaid  Norway
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Making the diode bridge is part of the DIY spirit, why buy one already made when you can DIY?
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Old 9th March 2005, 10:02 AM   #10
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Talks about sound of rectifier's diodes ? What do you will bring in the next time ? " Positive consequence of cooling of electrons " ?
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