KA3x7 vs LM3x7; is there a difference & bargain price - diyAudio
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Old 27th June 2009, 09:22 AM   #1
smiler is offline smiler  United Kingdom
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Default KA3x7 vs LM3x7; is there a difference & bargain price

Hi all,

In searching for replacement regulators for my Cyrus amp, I came across a Farnell bargain!

They have a few hundred non-RoHS compliant KA317 and KA337 Fairchild regulators in stock, which they're flogging at a lower price to get rid of the old stock. This seems like a great deal, and I'm certainly not bothered about RoHS compliance for my amp.

In case you're interested:
Fairchild Semiconductor KA337 19p/ea @ Farnell
Fairchild Semiconductor KA317 21p/ea @ Farnell

However, I just want to check that the KA chips are really equivalent to the LM series. Comparing the datasheets side-by-side, the figures look identical. I just wanted to check before I get tripped up by this. The amp has LM317 and LM337 chips at the moment.

Thanks
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Old 29th June 2009, 02:04 AM   #2
smiler is offline smiler  United Kingdom
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Lots of interest in this then!

Perhaps I would've been better off posting this in the PS forum? Is there a way to get the PS guys' attention without flouting forum rules or annoying people in general?

Sorry to be a pain. Any response greatly appreciated
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Old 29th June 2009, 02:14 AM   #3
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I've used both and I don't believe there is a difference.

Go for it.
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Old 29th June 2009, 07:30 AM   #4
mjf is offline mjf  Austria
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hello.
i use them often - without problems.......
i think the difference is small (compared to lm..........) but - as always - big enough to beginn a high end discussion......
greetings...........
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Old 29th June 2009, 09:29 AM   #5
smiler is offline smiler  United Kingdom
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Quote:
Originally posted by mjf
i think the difference is small (compared to lm..........) but - as always - big enough to beginn a high end discussion......
Haha, I hadn't actually expected a discussion like this, but I guess this is the place! My primary concern was any practical reason that the KAs wouldn't work.

Okay, now we've established that they'll work: what differences do you think there are mjf? Does anyone have some measured results to support an acoustic difference?

On a side note, I found a comment on Head-Fi (via Google) that the Fairchild chips were found to be less reliable than National Semiconductor in a particular project. Should I be concerned about this? I'm not entirely sure how they were being used (as CCS I suspect).
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Old 29th June 2009, 10:13 AM   #6
mjf is offline mjf  Austria
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[QUOTE]Originally posted by smiler

Okay, now we've established that they'll work: what differences do you think there are mjf? Does anyone have some measured results to support an acoustic difference?

hello.
there is a thread in power supply design:
annother look at the lm317.................
by jbau
greetings...............
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Old 30th June 2009, 07:57 PM   #7
dangus is offline dangus  Canada
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Aren't there some regulators from Linear Technology which perform BETTER than the National Semiconductor originals? I don't know if they'd make an audible difference, but it's more likely to be audible than, say, making connections with "silver wire w/natural unbleached cotton tubing" to quote something funny I just read elsewhere.
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Old 1st July 2009, 08:25 AM   #8
smiler is offline smiler  United Kingdom
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Quote:
Originally posted by dangus
Aren't there some regulators from Linear Technology which perform BETTER than the National Semiconductor originals? I don't know if they'd make an audible difference, but it's more likely to be audible than, say, making connections with "silver wire w/natural unbleached cotton tubing" to quote something funny I just read elsewhere.
Never underestimate the power of cotton tubing

How does Fairchild fair then? Is the performance difference accountable to some measured difference (perhaps evident in the data sheets?). For my purposes, I'm satisfied that the KA317/377 is up to the job, especially at only 20p each! I'm interested this discussion though...
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Old 1st July 2009, 06:22 PM   #9
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I won't speculate on the quality of the Linear vs. National vs. Fairchild, but the Linear ones I believe are the LT10xx series, i.e. 1083,1084, etc. Perhaps there are even newer ones with better specs, etc.

Peace,

Dave Gerecke
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