I bought Marantz PM44SE (second hand for 50 Euro). Looking at circuit board of PM66 on pictures posted here i cant notice differences with PM44, probably the only difference is PS voltage, maybe output trans also.
I've changed caps (the small ones of 100uF) with Silmic's, the amp sounds much better. I also increased a bias current to 150mA per transistor, highs are more clear, but there was no improvements in imaging. Maybe separate trafo's and PS per chanell will be worth to try. Also small trafo and regulated PS for AN7062. I did this before on Marantz PM62MKII, great soundstage, deep and wide. Im highly recomending separated power suppllies for power outputs and regulated one for AN7062.
I've changed caps (the small ones of 100uF) with Silmic's, the amp sounds much better. I also increased a bias current to 150mA per transistor, highs are more clear, but there was no improvements in imaging. Maybe separate trafo's and PS per chanell will be worth to try. Also small trafo and regulated PS for AN7062. I did this before on Marantz PM62MKII, great soundstage, deep and wide. Im highly recomending separated power suppllies for power outputs and regulated one for AN7062.
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@TC: Oh no, sorry to hear it's broken again. Your post wasn't visible when I replied - just your previous one where you said it was working.
btw I think I might've actually found a supplier for a toroid, so I may not have to buy an entire amp after all.
Latest pic
Here's the latest pic of my amp. IEC is now a basic Furutech inlet. Since my last pic, all electrolytic caps on main board and phono stage have now been replaced with Black Gates.
I realize BGs aren't always worth it, and may not be the best choice anyway, and it could all just be a trick of the brain, etc., etc. but I'm sort of addicted to putting them in, spurred on by the urgency of the fact that stocks are almost gone.
Anyway, the phono stage is one place where the Black Gates, albeit up-rated ones, have made a huge improvement. Records sound amazing now. I'm looking suspiciously at the op-amp now though since I recently upgraded my CD player's op-amps to LM4562HA. Not sure what I'd replace it with; I'm tempted to go the other way and try a discrete one.
Here's the latest pic of my amp. IEC is now a basic Furutech inlet. Since my last pic, all electrolytic caps on main board and phono stage have now been replaced with Black Gates.
I realize BGs aren't always worth it, and may not be the best choice anyway, and it could all just be a trick of the brain, etc., etc. but I'm sort of addicted to putting them in, spurred on by the urgency of the fact that stocks are almost gone.
Anyway, the phono stage is one place where the Black Gates, albeit up-rated ones, have made a huge improvement. Records sound amazing now. I'm looking suspiciously at the op-amp now though since I recently upgraded my CD player's op-amps to LM4562HA. Not sure what I'd replace it with; I'm tempted to go the other way and try a discrete one.
An externally hosted image should be here but it was not working when we last tested it.
Anyway, the phono stage is one place where the Black Gates, albeit up-rated ones, have made a huge improvement. Records sound amazing now. I'm looking suspiciously at the op-amp now though since I recently upgraded my CD player's op-amps to LM4562HA. Not sure what I'd replace it with; I'm tempted to go the other way and try a discrete one.
Looking good. The HAs are normally pretty special in phono stages. You could also run that pcb off a dedicated psu with say a 15Va toroid from RS and a nice little psu.
Also bypassing the ribbon cables for the signal path is a good idea. Input pcb --> pot --> power pcb
Brent
Thanks guys!
@tc: I changed ALL electrolytic caps on main board and phono for the highest rated Black Gates I could get. From memory they're mostly FK, and the very small values are PK. I also did the 1% silver micas listed by Brent, except the 150pf, which I bought but can't find on the PCB!
@Brent: OK, I'll keep a lookout on eBay for another HA at a reasonable price. Nice idea about the dedicated PSU. Yep, I already did the source direct bypass as per your recommendation with Kimber TCSS red/black twist.
Still no luck on the transformer front. Signals won't get back to me after initially saying they had the part, but I think they got it mixed up with the standard SE frame. I've also e-mailed Nuvotem.
@tc: I changed ALL electrolytic caps on main board and phono for the highest rated Black Gates I could get. From memory they're mostly FK, and the very small values are PK. I also did the 1% silver micas listed by Brent, except the 150pf, which I bought but can't find on the PCB!
@Brent: OK, I'll keep a lookout on eBay for another HA at a reasonable price. Nice idea about the dedicated PSU. Yep, I already did the source direct bypass as per your recommendation with Kimber TCSS red/black twist.
Still no luck on the transformer front. Signals won't get back to me after initially saying they had the part, but I think they got it mixed up with the standard SE frame. I've also e-mailed Nuvotem.
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...
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.
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.
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.
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.
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.
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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