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Post by brucew268 on Mar 15, 2021 13:38:02 GMT
I'm looking at amplifier chassis options for an upcoming Modulus 686 build and wanted to get the benefit of your experience here. It will be driving Maggie's and so am going for a 800VA 4x24V transformer, which implies the larger 440x400x165 case and heatsinks.
My build experience so far has been a couple preamps and some power supplies, so no large beasts.
I’ve noted the same problems several have with Modushop’s lack of mounting hardware where the top and bottom panels meet the front and back panels.
For larger chassis (amplifiers w/heatsinks) do you prefer to add extra fixing brackets to resolve this or do you source the case from elsewhere?
I'd thought of getting 12mm aluminium square bar, drilled and tapped.
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Bigman80
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Post by Bigman80 on Mar 15, 2021 14:28:45 GMT
If i were to be building one now, I would avoid the Modushop box.
There are multiple reports of the casework not lining up properly, shonky workmanship and the lack of fastener for the lid and base at the front and rear makes them quite rattly.
I would find a suitable amplifer case off Alixpress and get a local machine shop to drill and tap the holes in the heatsinks, if i couldnt do it myself.
Other than that, if you stick to the full compliment of Neurochrome PCBs, it looks really simple to connect together and get up and running.
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Post by brucew268 on Mar 15, 2021 15:39:28 GMT
With aliexpress, I haven’t figured out how to make the search engine work for me. The search results usually seem to have little relation to what I typed in. Have you better results?
Also I’ve noted significant variation in specs, claims, and priced for what seems obviously the same item offered by different resellers. That lowers my confidence in what I’m getting.
Do you have one or two particular sellers you like for large amplifier chassis?
I expect to do my own drilling and tapping.
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Bigman80
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Post by Bigman80 on Mar 15, 2021 15:40:33 GMT
With aliexpress, I haven’t figured out how to make the search engine work for me. The search results usually seem to have little relation to what I typed in. Have you better results? Also I’ve noted significant variation in specs, claims, and priced for what seems obviously the same item offered by different resellers. That lowers my confidence in what I’m getting. Do you have one or two particular sellers you like for large amplifier chassis? I expect to do my own drilling and tapping. Ooooh, I'll see. Hang on. Unusually search for "Aluminium amplifier chassis" and that gets closer results. |
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Post by brucew268 on Mar 15, 2021 15:59:25 GMT
Unusually search for "Aluminium amplifier chassis" and that gets closer results. Em, that search seems to have worked. I'll look around. Generally I've searched Ebay rather than Aliexpress because 1) their search engine is faultless an 2) they will get involved when a sold item does not match what was advertised or is not shipped properly, and don't make one wait 90 days to file a complaint. Maybe your experience is different to mine. My poor search experiences usually had to do with Headphone cables or headbands, where it seemed to give me anything they thought had anything to do with headphones or earphones! |
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Post by Bigman80 on Mar 15, 2021 16:03:31 GMT
Unusually search for "Aluminium amplifier chassis" and that gets closer results. Em, that search seems to have worked. I'll look around. Generally I've searched Ebay rather than Aliexpress because 1) their search engine is faultless an 2) they will get involved when a sold item does not match what was advertised or is not shipped properly, and don't make one wait 90 days to file a complaint. Maybe your experience is different to mine. My poor search experiences usually had to do with Headphone cables or headbands, where it seemed to give me anything they thought had anything to do with headphones or earphones! I buy a lot of machined aluminium from Aliexpress. they have refunded me when things havent been up to standard and they don't care what the seller says. If you want to be sure, pay via PayPal and you have double protection. I have had one issue in 3 years and Aliexpress dealt with it. no issues at all. I kept the box and they refunded me. All good. |
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Post by sq225917 on Mar 15, 2021 18:43:31 GMT
I've bought over 70 cases from modushop, only had missing screws once. The lack of a block to connect top and bottom to front and back to stop them rattling is an issue, thought easily fixed by asking them to tap the front panel for an m3 hole, the back you can do yourself.
My nuerochrome cases came from aliexpress one of the Goldmund clone makers. Nice cases, but still 400 Inc shipping and tax.
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Bigman80
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Post by Bigman80 on Mar 15, 2021 18:55:51 GMT
I've bought over 70 cases from modushop, only had missing screws once. The lack of a block to connect top and bottom to front and back to stop them rattling is an issue, thought easily fixed by asking them to tap the front panel for an m3 hole, the back you can do yourself. My nuerochrome cases came from aliexpress one of the Goldmund clone makers. Nice cases, but still 400 Inc shipping and tax. Yes, i have bought a few myself (not 70 lol) and never had an issue but there were workmanship issues with one Kevin ordered and there were more issues with a premade 686 case that i was told about too. They were both ordered around the same time so maybe it was just a bad time. The Italians have had it rough with Covid Having a couple of holes tapped for the lid and base is a wise move. They should do this as standard IMO. |
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Post by antonio on Mar 16, 2021 0:37:21 GMT
I haven’t figured out how to make the search engine work for me. The search results usually seem to have little relation to what I typed in.
I know exactly what you mean. I usually have a couple of tries with the search engine, but if you can find something similar to what you are looking for, scroll down to 'more things from the same seller' and 'more things to love' you can often find something there, not only that when you do find exactly what you are looking for, going down and looking, you can often find the same thing cheaper from a different seller.
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Post by brucew268 on Mar 16, 2021 13:51:15 GMT
I mentioned to Tom C that I was considering additional sources to Modushop, noting the variety of heatsink dimensions available and that I mean to drive Maggie's. His response was,
"If you’re going for max power, you’ll need 0.28 K/W or below for each Modulus-686. I suggest asking the manufacturer for the thermal resistance of the heat sink. If the manufacturer can’t provide those data, walk."
I asked three AliExpress shops (4 chassis) and all immediately replied that they couldn't provide that data. Most of them looked great, solid, and were actually higher priced than Modushop Dissipante once one pays shipping even if one somehow escaped VAT. Paying VAT, Modushop is a bit of a bargain.
So, I may experiment this week with additional fixing brackets for the top/bottom plates.
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Post by Bigman80 on Mar 16, 2021 14:34:17 GMT
I mentioned to Tom C that I was considering additional sources to Modushop, noting the variety of heatsink dimensions available and that I mean to drive Maggie's. His response was, "If you’re going for max power, you’ll need 0.28 K/W or below for each Modulus-686. I suggest asking the manufacturer for the thermal resistance of the heat sink. If the manufacturer can’t provide those data, walk." I asked three AliExpress shops (4 chassis) and all immediately replied that they couldn't provide that data. Most of them looked great, solid, and were actually higher priced than Modushop Dissipante once one pays shipping even if one somehow escaped VAT. Paying VAT, Modushop is a bit of a bargain. So, I may experiment this week with additional fixing brackets for the top/bottom plates. Hmm, in that case do as Tom says. |
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Post by sq225917 on Mar 17, 2021 0:32:22 GMT
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Post by brucew268 on Mar 17, 2021 12:30:11 GMT
Nice find, yes it's amazing how much more thermal resistance one gets when going up to 200-210mm height on the heatsink, as yours do. 210x300mm is better (0.18 K/W) than 165x400 (0.23-0.25 K/W).
I had considered manually estimating heatsink capability as you say. I noticed that many appear to be 40mm fins, but need to watch out for some that have shorter fins like 25mm, or have fewer fins with more spacing between them.
Note also that Modushop use a 'wave' or serrated fin design which adds surface area and so make them a little more efficient than others. Also, most amps are either 150mm high or 200-210mm high, whereas Modushops 4U is 165mm high. That means the 150mm high amplifiers are likely a bit less than requirements if one wants full power spec from the amplifier, which my demanding speakers are likely to appreciate.
The easy solution from these other sources is to over-spec, which means going with your setup or in a single chassis 200mm high by 400mm deep with 40mm standard spaced fins. Some of these really look sharp, but are 40mm taller chassis and about £40 more, which either matters to one or it doesn't.
If I'd not already purchased one Neurochrome ISS module (intelligent soft start), I'd probably have gone with 686 in a monoblock config with chassis something like yours. But Tom's ISS is pretty dear and I don't want to pay for another!
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Post by sq225917 on Mar 17, 2021 19:08:51 GMT
If I was doing another I'd buy heatsinks then build the chassis to suit.
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