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Old 4th April 2011, 03:21 PM   #371
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Ah, nice of them to at least reply to you though. It looks like I'm back in eBay scavenger mode. Brent, do you know off-hand if any of the larger available Marantz transformers like the "Super O Ring" from the PM17 are likely to be a compatible alternative for a swap rather than doubling up? The listed voltages from the PM66 transformers are very specific, like 28.5V, etc., but presumably there's some tolerance in that due to regulation...
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Old 4th April 2011, 03:28 PM   #372
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Well running 2x 66KI tx lifted the DC to 44V which is the same as the PM17KI iirc so yes you should be fine with that tx. Fitment maybe a bigger issue though.

Brent
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Old 26th May 2011, 05:44 PM   #373
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Hi guys,

After two years of looking, I've finally managed to get hold of a broken amp with a working PSU! My brother took delivery of it and did the operation to extract it on the weekend, so I should receive it in a week or two.

Some LM4662HA op-amps went up on eBay today at a reasonable price (7.99) so I've ordered one for my phono stage - link if you're interested: IC LM4562HA NSC TO-99 | eBay UK

One of the 10ohm output resistors got shorted and burnt during an early botched mod, so I replaced them with 20w Mundorf M-Resist Supreme. Turns out they are freaking huge and I had real trouble getting them in. Still, they're in.

I've also recently upgraded my trusty old B&W 601 S2 speakers to 805S, which I'm pleased to say this amp drives beautifully. I can't believe how much detail I've been missing. The bass response is so good on the 805s that I got rid of my sub because I felt it was no longer necessary. I've been reading for years on the forums about how the 805s need huge clean watts delivered from massive monoblocks or else your ears and tweeters will explode and God will kill a kitten, but seriously, they sound amazing on this amp.
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Old 26th May 2011, 10:02 PM   #374
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Quote:
Originally Posted by Ben Hanke View Post
Some LM4662HA op-amps went up on eBay today at a reasonable price...
A forum member has kindly indicated to me in private that the above impulse purchase may have benefited from some more critical thinking on my part.
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Old 26th May 2011, 10:04 PM   #375
SimontY is offline SimontY  United Kingdom
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Hmm, I take it you mean they could be fakes? That is very cheap for HA op-amps.
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Old 26th May 2011, 10:25 PM   #376
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I hope the ones in my CD63KI are genuine. They were a lot more expensive, but I'm not sure that's good reason to be reassured :-/
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Old 27th May 2011, 07:32 AM   #377
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They look 100% fake to me. As far as I am aware the HA are only in LME49720HA guise.

They don't print the text onto the body either, the top should have the print on in small text. The print should ahve the Ti logo a batch number and then the LME 49720HA on it.

Brent
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Old 27th May 2011, 08:07 AM   #378
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I've ordered 3x LM4562HA from Newark (NATIONAL SEMICONDUCTOR|LM4562HA/NOPB|IC, AUDIO OP-AMP, 55MHZ, TO-99 | Newark.com), as the ones I put in my CD player are also from eBay and also have the lettering on the side. Who knows what their specs are really? This should make for an interesting comparison anyway. The ingenuity of counterfeiters amazes me. I'm just so glad I had the sense to get all my Black Gates from Michael Percy rather than take my chances on eBay.
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Old 31st May 2011, 03:51 PM   #379
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Default The plot thickens

Those three LM4562HA/NOBP arrived from Newark yesterday, who are an approved supplier linked directly from National Semiconductor's website. Both are labeled "LM4562HA", two on the top and one on the side.
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Old 10th June 2011, 05:09 AM   #380
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Hi guys,

It's been an exciting week for mods. I started by swapping an LM4562HA into my phono stage (already benefiting from being fully decked out with uprated Black Gate caps) and the resolution of high frequencies and the tightness of the bass increased dramatically (relatively speaking). I'm mostly buying vinyl these days, and I was so happy with that level of performance that I was starting to think that I'd probably done enough for a while, but then after two years of scouring eBay for a dead amp and enlisting my brother in the UK for salvage duties, my second transformer arrived and I just had to take the risk to fit it. It was a pretty hairy process combining the wires; the connectors were getting knackered, the solder wouldn't stick and the sleeves were melting. Anyway, it worked in the end, and... wow. Brent, you weren't kidding when you said "more of everything". This amp is serious business now. I'm glad I made all the subtle, incremental improvements first, because the extra transformer - the power it gives - is not subtle at all. Holy bass, Batman.

Things left to do... Well, I'd sort of like to upgrade the RCA inputs and binding posts to fancy ones, but I'm holding fire on that for a while because I rather suspect that their effects are mostly cosmetic and placebo and I've got plenty real improvements to enjoy right now. Also, I've still not touched the bridge.
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