I actually had more issues in initial experimenting with the supplies floating. Things settled down a lot once everything was bonded to ground. In my case the supply I'm using has a loop breaker built into it, I would assume it was actually designed to operate with the SMPS.
It must be possible to use these supplies, and safely with earth ground connected, it's being done in commercial products every day. It's just a new learning curve to figure out how it's done which is to me the most enjoyable part of the hobby.
It must be possible to use these supplies, and safely with earth ground connected, it's being done in commercial products every day. It's just a new learning curve to figure out how it's done which is to me the most enjoyable part of the hobby.
I had many problems using laptop with an earthed smps .
Always i hear(H.F) noice when used as audio line source.
Truth is that those smps connect the main earth directly with the -V Out.
Always i hear(H.F) noice when used as audio line source.
Truth is that those smps connect the main earth directly with the -V Out.
Computer supplies are terrible! I can usually hear the scroll wheel on my mouse. It's always tough to get around that sort of noise. I think that's why motherboard companies like Asus don't have a coaxial digital sound card port, just optical.
Hi Hugh,
I've always been using good old linear supplies in the past, mostly using dual mono configuration, only this time I really wanted to use smaller lighter supplies and I had those two SMPS. I used a single 1200W Cresnet SMPS in two other amps with almost total silence but the supply was further away and it was not a dual mono config.
I'll be going back to the linear supply for this amp. Too bad though, I really wanted it to work. As Jeff stated, many commercial products are using them nowadays, but I guess mostly Class D amp designs?
Thanks
Do
I've always been using good old linear supplies in the past, mostly using dual mono configuration, only this time I really wanted to use smaller lighter supplies and I had those two SMPS. I used a single 1200W Cresnet SMPS in two other amps with almost total silence but the supply was further away and it was not a dual mono config.
I'll be going back to the linear supply for this amp. Too bad though, I really wanted it to work. As Jeff stated, many commercial products are using them nowadays, but I guess mostly Class D amp designs?
Thanks
Do
Car amps have always used SMPS and the early / better versions were all class AB. They also had very tight chassis designs. I'm going to look into those designs and see what they did.
I had used a salvaged car amplifier smps to power the NS with +/-35v in the past.
It was silent and solved the 50hz artifact in ARTA when a 12v battery is used.
It was an ancient car amplifier based on STK hybrids.
I know they were operating at lower frequencies than modern SMPS and weren't soft switching but from what I remember mostly they just used some small tin shields to eliminate interference. I don't remember seeing any elaborate filtering. I'll try do dig out a couple later today.
Do yourself (and the amp!) a favor and use a good quality linear supply.
With good linear supply I mean a good quality transformer to begin with (not the too small but efficient toroids, but the low T audio grade ones with screens, be it toroidal or c-core).
Way better than most of the SMPS rubbish that seems to dominate high end audio nowadays...
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I buy all my transformers from Toroidy, excellent build and super quiet operation at all time, well except if there is excessive dc on the ac line, but this is usually not the case in my region.
I'll wait for Jeff and Cresnet, they hopefully find a solution.
Do
I'll wait for Jeff and Cresnet, they hopefully find a solution.
Do
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Last try, did you try to connect the SMPS via an isolation transformer?
Any 110V to 110V will work. any transformer used for audio.
Unfortunately, I don't have one. Could be a nice thing to get but not at the moment. Maybe Jeff has one and he can test it on his side?
Hi Do, please buy one as it absolutely necessary for your safety!
Testing electronics equipments requires an isolation transformer.
Main is always danger!
For quick testing any dual primary wound transformer would work. Just power one winding from mains and power the amp from the other winding. Not truly isolated for safety but it's good enough for noise isolation.
I usually use a variac but I don't think it has any sort of isolation, just a direct winding I think...
I'll buy one but in the past 12+ years I never required one. I do understand the safety issue though.
Thanks
Do
A variable autotransformer (Variac is a trade name) is a single winding with several taps,
and a sliding wiper. There is no isolation.
Yes,variac is a useful part but not for a safety
isolation.
Secondary winding is a part of primary winding, not a separate one.
Variac save your device during the test.
Save your life!
isolation.
Secondary winding is a part of primary winding, not a separate one.
Variac save your device during the test.
Save your life!
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ok, connected a single SMPS only and completely unplugged all cables from the second unit. Set the connected unit further away from the amp module. Result... No changes at all.
Now you know it's not a ground loop. What I would do next is connect one channel to a conventional power supply and leave one connected to the SMPS. See if the noise remains on the channel with the linear supply. That will tell you if the noise is coming in through the power rails or if it's being radiated.