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Post by antonio on Jan 9, 2022 3:27:10 GMT
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Post by Deleted on Jan 9, 2022 8:15:25 GMT
Not sure I like the speaker protection, or the use of crimps, but I am being picky.
It looks like a compact build. Although It seems like the case might be a little small, as the heat sinks are one piece.
I am not sure how this will affect the cooling performance.
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Post by firebottle on Jan 9, 2022 9:12:16 GMT
Ample heatsinking on there. lurch, it's your amp. |
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optical
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Post by optical on Jan 9, 2022 9:32:21 GMT
Although It seems like the case might be a little small, as the heat sinks are one piece. I am not sure how this will affect the cooling performance. Case looks enormous compared to the table it's on! |
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Post by Bigman80 on Jan 9, 2022 9:32:33 GMT
Ample heatsinking on there. Lurch, it's your amp. I'd change the wiring on the outputs and the connections. lurch spend those savings 🤣 |
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Post by Bigman80 on Jan 9, 2022 9:33:39 GMT
Although It seems like the case might be a little small, as the heat sinks are one piece. I am not sure how this will affect the cooling performance. Case looks enormous compared to the table it's on! Certainly bigger than ours 😳 |
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Post by brucew268 on Jan 9, 2022 10:44:56 GMT
Dave, I went to this post thinking you had decided to join The Dark Side! Well maybe not.
I'm always concerned about Faston connections as the auto parts store type and usual DIY crimpers often are electrically and audibly inferior on signal wires. It doesn't seem to affect power circuits as much, IME, which is generally where he's using them. Though, doesn't the impedance need to be kept pretty low between the secondaries and rectifiers? But if he uses quality parts and tool that does a professional quality crimp, they could be great.
I'd think a potential buyer should ask the dimensions of the case. If it turns out shorter than the usual Modushop recommendation for those specs, it looks tall enough to make up for that (heat sinks).
I'm not really sure why speaker protection is a usual feature. Acc to Tom C "...reliability of the LM3886 and, thus, the Modulus-686. Odds of failure are very low, but not zero... I'm fine without it." Nor did I see a need. Of course this builder has fitted them rather cleverly in the enclosure. +
For inrush protection, he uses basic thermistors which seem to be fine for high fidelity even if "low-tech", not sure what the small PCB right after that is. I'm also unsure about putting it between the traffos in the middle of their electrical field. For that matter, I've wondered if having the traffos facing each other without any barrier between has any negative effect, with fields interfering with each other. I don't know, just asking.
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Post by karma67 on Jan 9, 2022 10:52:04 GMT
Case looks enormous compared to the table it's on! Certainly bigger than ours 😳 this seller is the same joe that builds all the clas A amps on ebay i believe. |
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Post by Bigman80 on Jan 9, 2022 10:56:48 GMT
Certainly bigger than ours 😳 this seller is the same joe that builds all the clas A amps on ebay i believe. He is. Tidy work |
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Post by phonomac on Jan 9, 2022 11:00:21 GMT
Why you need to know exactly how the speaker protection relay has been wired: www.halfgaar.net/posts/2012-01/relay-arc-dc-speaker.3gpall the time that arc is running it is passing typically between 6 and 10 amps and the voice coil/cone is at full extension with the voice coil essentially uncooled. |
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Post by mrian on Jan 9, 2022 11:03:30 GMT
Case looks to have a nice finish to it. Price looks to be in the right ball park but hifi sales seem slow to me at the minute, especially at this price level. Cheeky offer and some resilience might deliver a good deal
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Post by macca on Jan 9, 2022 11:27:29 GMT
I don't know, in the context of high end amplification the asking price is practically giving it away - assuming Bruce's reservations are unfounded.
You'd have to go second-hand to get an amplifier that's as capable for less.
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Post by Bigman80 on Jan 9, 2022 11:35:54 GMT
Why you need to know exactly how the speaker protection relay has been wired: www.halfgaar.net/posts/2012-01/relay-arc-dc-speaker.3gpall the time that arc is running it is passing typically between 6 and 10 amps and the voice coil/cone is at full extension with the voice coil essentially uncooled. So is that speaker protection on the 686 mentioned here NOT suitable? Don't want Lurch putting his MLs at risk. |
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Post by Bigman80 on Jan 9, 2022 11:39:21 GMT
Dave, I went to this post thinking you had decided to join The Dark Side! Well maybe not. I'm always concerned about Faston connections as the auto parts store type and usual DIY crimpers often are electrically and audibly inferior on signal wires. It doesn't seem to affect power circuits as much, IME, which is generally where he's using them. Though, doesn't the impedance need to be kept pretty low between the secondaries and rectifiers? But if he uses quality parts and tool that does a professional quality crimp, they could be great. I'd think a potential buyer should ask the dimensions of the case. If it turns out shorter than the usual Modushop recommendation for those specs, it looks tall enough to make up for that (heat sinks). I'm not really sure why speaker protection is a usual feature. Acc to Tom C "...reliability of the LM3886 and, thus, the Modulus-686. Odds of failure are very low, but not zero... I'm fine without it." Nor did I see a need. Of course this builder has fitted them rather cleverly in the enclosure. + For inrush protection, he uses basic thermistors which seem to be fine for high fidelity even if "low-tech", not sure what the small PCB right after that is. I'm also unsure about putting it between the traffos in the middle of their electrical field. For that matter, I've wondered if having the traffos facing each other without any barrier between has any negative effect, with fields interfering with each other. I don't know, just asking. Speaker protection is irrelevant......if you can replace them lol Why run the risk? Like you, I'm not 100% convinced about a couple of things but mrian has had his a bit now and that was built by Joe. I am sure it's up to the task, but I'd check that speaker protection out, replace the wiring on the speaker outputs, replace the binding posts and XLR sockets (for RCA) and quite possible abandon those Shotky Diodes. Come to think of it, I wouldn't build it like that at all 🤣 |
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Post by electronumpty on Jan 9, 2022 11:54:26 GMT
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Post by lurch on Jan 9, 2022 12:09:37 GMT
Luckily I don't need anymore class D in my life as have my Nord One UP SE NC500Ms back. If I do change/add to my amp collection it will be either a class A muscle amp like a Plinious SA-103 or a super integrated (Hegel H390, Krell KAV 400xi/KAV 300i) would love a Gryphon Diablo 300 but alas my pockets aren't quite deep enough. ðŸ˜ðŸ˜ðŸ˜
So you boys can chunter away to your hearts content about this amp and the rights and wrongs of the build.
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Post by Bigman80 on Jan 9, 2022 12:32:47 GMT
Luckily I don't need anymore class D in my life as have my Nord One UP SE NC500Ms back. If I do change/add to my amp collection it will be either a class A muscle amp like a Plinious SA-103 or a super integrated (Hegel H390, Krell KAV 400xi/KAV 300i) would love a Gryphon Diablo 300 but alas my pockets aren't quite deep enough. ðŸ˜ðŸ˜ðŸ˜ So you boys can chunter away to your hearts content about this amp and the rights and wrongs of the build. It's not class D. |
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Post by Deleted on Jan 9, 2022 12:51:27 GMT
Class AB, I believe?
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Post by antonio on Jan 9, 2022 12:55:47 GMT
I didn't think it was class D, and with you, John, looking for a amp thought it might be a possibility. With the Nord's not selling, that changes things, and to be honest you did like them in your system. Sorry I mentioned that Gryphon, I'm a bloody nuisance.
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Post by phonomac on Jan 9, 2022 13:13:46 GMT
Why you need to know exactly how the speaker protection relay has been wired: www.halfgaar.net/posts/2012-01/relay-arc-dc-speaker.3gpall the time that arc is running it is passing typically between 6 and 10 amps and the voice coil/cone is at full extension with the voice coil essentially uncooled. So is that speaker protection on the 686 mentioned here NOT suitable? Don't want Lurch putting his MLs at risk. Can't tell without knowing the relay configuration and how it is wired. The relay needs changeover contacts with the amp output (and therefore the arc) connected to ground when the protection is triggered. |
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Post by sq225917 on Jan 9, 2022 13:23:52 GMT
I'm not a fan of the doubling up on thermal interfaces between chips and sinks. Just buy heatsinks with thicker back plate. Same goes for the long speaker wiring, I'd have protection boards on back panel.
Nice vertical separation of psu and signal wiring.
Beautiful build though.
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Post by Bigman80 on Jan 9, 2022 13:47:12 GMT
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Post by mrian on Jan 9, 2022 15:48:13 GMT
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Post by brucew268 on Jan 9, 2022 17:40:22 GMT
I'm not a fan of the doubling up on thermal interfaces between chips and sinks. Just buy heatsinks with thicker back plate. Same goes for the long speaker wiring, I'd have protection boards on back panel. Nice vertical separation of psu and signal wiring. Beautiful build though. Yes, I wondering about that too. What might be the effect of mounting the chips to an Al bar face that is on a different plane to the heatsink; how much more heat would be released inside the amplifier than otherwise transmitted to the external fins? Physically it is a neat way to get the boards to the sides in the enclosure.
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Post by sq225917 on Jan 9, 2022 23:40:44 GMT
Just mounting them straight on another bit of metal just adds another thermal interface but increases the total thermal mass. I wouldn't suspect there's much to be gained, maybe a tiny bit cooler running, maybe.
If they were on the extension on the T that'd be fuckery. Neat positioning, but you're forcing all the heat down a long thin section first, that's gotta be worse than straight on heatsink.
All that said, mine are on a 20x30cm heatsink, 2 stereo chips per monoblock, so basically a 486. They almost run cold and with no case venting...
I'm sure he's used an IR thermometer and checked.
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Post by mrian on Jan 28, 2022 20:36:28 GMT
Still for sale, surprised no one has tested a lower offer, as I said before i think the price will have to fall a few hundred to a sale, especially given the none "standard" build, not that i doubt the validity if the approach myself
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Post by Bigman80 on Jan 28, 2022 20:48:01 GMT
Still for sale, surprised no one has tested a lower offer, as I said before i think the price will have to fall a few hundred to a sale, especially given the none "standard" build, not that i doubt the validity if the approach myself The amplifier is worth every penny of whatever someone is willing to spend. You won't beat one for less than £10k IMHO, and considering there won't be any more PCBs until Autumn, it may be a wise purchase for someone. |
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Post by martiansunrise on Jan 30, 2022 21:04:00 GMT
Are the lower powered versions much cheaper to construct?
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Post by Bigman80 on Jan 30, 2022 21:53:17 GMT
Are the lower powered versions much cheaper to construct? There is a saving, yes. How much?, I don't know as Ive never built one. Thing to note is that although they all use the same chip, they don't all use the chip the same way. |
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Post by firebottle on Jan 31, 2022 7:55:24 GMT
Simple answer is yes but the word much is questionable.
You still need a case and nice ones are never cheap. Plus a power supply and (hopefully) decent connectors.
The '86 is a straightforward single chip board.
The 286 is a two chips in parallel (per channel) board.
Simon's unique build is 4 chips in bridge mode, two in parallel at the top of the bridge and two at the bottom (486).
The 686 is 6 chips in bridge mode, three in parallel at the top and three at the bottom.
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