@ Skylar88 Good to hear that you managed to wire up two MJ / Gtose Cap multipliers without facing hum problems. I also tried that, but with a single power transformer, one pair of bridges and two cap multipliers. That did not work out hum free.
I like your approach to use two meanwell smps to power the two channels. Would you be so kind to provide a wiring diagram, especially the ground wiring?
Yesterday I returned to the good old diyaudio universal PSU configuration and the hum has gone. But I really want to understand how to wire up your kind of set-up.
Regards, Addi
I like your approach to use two meanwell smps to power the two channels. Would you be so kind to provide a wiring diagram, especially the ground wiring?
Yesterday I returned to the good old diyaudio universal PSU configuration and the hum has gone. But I really want to understand how to wire up your kind of set-up.
Regards, Addi
@AddiDub
The two Cap Multipliers work very well and were much cheaper than a toroid transformer would have cost – without any of the associated hum and noise in the M2.
I followed xrk971’s layout from post #553 in the Juma's Easy-Peasy Capacitance Multiplier thread, but replaced the transformer with two smps's, using the same wiring principle.
I have not grounded/earthed the Cap Mx’s yet, but I want to try that soon. At the moment I’m using it much like one would with the external smps brick on the ACA amp, which isn’t grounded either. If grounding introduces hum, I’ll know what to do – remove the ground/earth wire from the cap Mx's and just keep the two smps's earthed.
The two Cap Multipliers work very well and were much cheaper than a toroid transformer would have cost – without any of the associated hum and noise in the M2.
I followed xrk971’s layout from post #553 in the Juma's Easy-Peasy Capacitance Multiplier thread, but replaced the transformer with two smps's, using the same wiring principle.
I have not grounded/earthed the Cap Mx’s yet, but I want to try that soon. At the moment I’m using it much like one would with the external smps brick on the ACA amp, which isn’t grounded either. If grounding introduces hum, I’ll know what to do – remove the ground/earth wire from the cap Mx's and just keep the two smps's earthed.
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Thanks for the headsup, floccini. I will definitely check it out.
Here is a pic of the M2 build as it is now with temporary base-plate and back-plate for testing purposes. I love how minimalist and neat the cabling turned out with the Cap Mx's mounted between the two amp PCB's. Once the enclosure is complete and anodized, I'll install quality cabling. The two Meanwell SMPS' will be housed in a separate vented enclosure with a 4-core umbilical and 5-pin screw-on connector. I still can't believe how silent this amp is with the SMPS'.
The heatsinks are of Chinese origin (Zenli brand) and the size is 301x50x160 high with a thermal coefficient of around 0.3K/W and the amp stays reasonably cool. Slightly cooler than my ACA, if I have to compare.
On the main boards or from the cap multipliers (in my build).
Update: The enclosure of my build is now done. All aluminium parts have been anodized black. The two external SMPS's are housed in a custom sheet metal enclosure and connected via 4-core cable to the amp. Everything except the heatsinks stays cool. The noise floor is incredibly low. With my ear pressed to the drivers of 94dB speakers I can hardly hear any hiss. This is probably due to the autoformers not having a toroid in close vicinity.
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Yes, that’s good then. My ACA’s are a bit hummy. M2 less so. I think with the stock FirstWatt supply you have partial isolation of signal ground from mains earth through a thermistor TH1 on the F5 schematic. With SMPS bricks, you are generally connected hard to mains earth, is my understanding. Of course, you must never disconnect mains earth for safety reasons and you are susceptible to a mains loop. Is your M2 supply connected to mains earth? You have a good result with the lack of hum.
Yes, exactly like the diagram in post #3526, except the Antek and rectifiers are replaced by two SMPS externally.
That looks like an excellent build! Getting the SMPS units in a separate chassis certainly helps with any radiated noise those might generate.
I suggest adding some bulk capacitance between the CapMx boards and the amp boards. About 10,000 uF to 24,000 uF will help with bass response and definition. In engine building the saying is "no replacement for displacement." In amp building that translates to no replacement for bulk energy storage.
I suggest adding some bulk capacitance between the CapMx boards and the amp boards. About 10,000 uF to 24,000 uF will help with bass response and definition. In engine building the saying is "no replacement for displacement." In amp building that translates to no replacement for bulk energy storage.