I have two Meanwell 48V powers that I had planned to use in class D amp, using them somehow kept giving me shocks when I touch the chassis. Never figured out why because I never got that amp to work. But it was an interesting incidence though.
The datasheet has an error. It indicates that the V- terminal is connect to ground. In fact both V+ and V- outputs are floating relative to ground. (This error was confirmed by MeanWell). Of the two supplies the one that drives +36V to the amps has it's V- output connected to ground, and the one that drives -36V has it's V+ output connected to ground.
Thanks Brian. That's how I thought it would work, but then doubted myself after looking at the block diagram in the datasheet.
Looks very good to me, especially if you will also add a soft start and perhaps a speaker protection all in one.
I'll order the transformers for last, since the difference between 400 and 500VA is trivial on the ones I want.
I'll do the speaker protection separately, I think. That way you can bolt the speaker protection board directly onto the rear panel of the amp with the output connections. I'm not 200 % decided on this, but that's the direction I'm leaning. I'd also like to keep the speaker connections away from the mains wiring to the extent possible.
Good idea.
Tom
Thanks. I looked at that a while back. As always, the details are in the data sheet (which is available through the grey button in the upper right of the page you link to). Max output voltage is ±46 V, which is too much for the Modulus-686 (or any other LM3886-based amp).
Bummer... I was as excited as you probably were when I saw the ±36 V "spec", only to have that sinking feeling once I read the data sheet.
The data sheet says the typical output voltage is ±40 V, so I wonder how Hypex came up with the ±36 V figure. #whatever... Back to the Power-686 design. 🙂
Tom
Bummer... I was as excited as you probably were when I saw the ±36 V "spec", only to have that sinking feeling once I read the data sheet.
The data sheet says the typical output voltage is ±40 V, so I wonder how Hypex came up with the ±36 V figure. #whatever... Back to the Power-686 design. 🙂
Tom
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I am wondering, music is non-steady and non-symmetric signal, so how does this reflect on the power supply? I should be getting a data logger this year, and hope to look into this aspect, but I wonder how whether this has been looked into before. Matching the power supply to the amp would be one specific reason for a custom built.
Yep. It's basically a transformer emulator. Connex has a couple of supplies like that as well. I don't understand the logic of those. If you're going through all the trouble of building an SMPS, why not close the feedback loop? Weird...
Tom
This is where we actually try the different components via listening. If a difference is heard, then go through the process of figuring out why, or just pick what sounds better.
Sorry for raising false hopes 🙁
Regarding the Power-686, why design a linear supply if an SMPS is inehrently better?
I wonder what linear supply noise curves look like. Test lab I use can only measure down to some 150KHz.
It should be very similar to what goes downstream, i.e. 50hz/60hz ripple. The noise from the rectifiers doesn't pass the transformer primary. Then there is EMI (a can of worms) 🙂
EMI was not a big issue with the small modules I used. Just missed the standards by a small margin, change if switching frequency solved it along with the line filter.
I was talking about the linear ones. Switching should have more RFI issue i think. Still, nobody measured them (except the pitiful phone chargers)
Yes, I would like to know how linear power supplies do. But I would make sure listening pleasure is satisfied first before I would even try to send it through the EMI/EMC lab. Any improvements made related with those noise should be icing on the cake.
Linear power supplies can dump a lot of noise onto the power line even if the diodes are properly snubbered. It's likely that supplies such as the MeanWell which have active power factor correction (PFC) would dump less noise onto the power line and any noise from them is of higher frequency and more amenable to filtering than that of a linear supply.
Absolutely correct.
Is this true? Downstream in the amp itself yes. But on the other side? What those RFI cause to the rest of the equipment?
I have no evidence whatsoever but I know some people uses isolation transformers and some little filters to isolate from swtiching noise, while others get to the point of changing all SMPTS to linear ones in any equipment connected to the same power line.
This is why I would like to see some proper measurements done.
The famous Benchmark amp makes those claims, but they do not say a word about upstream noise. Anectodal evidence shows that their amp is far from perfect. Likewise their DAC. This could be one of the reasons.