Hello Guys.
I'm shopping around for the PSU of my P101 rev-c.
So I did came across with some low noise trans from Plitron. they much more expensive..
like : Low Noise Power Transformers for Solid State Amps
Anybody has an opinion about it? are plitron trans much better that the others? even the standard toroidal trans ... because they are much more expensive than Antek for example.
other option is on the 40v: AN-8440 - 800VA 40V Transformer - AnTek Products Corp
I'm afraid of humming on my transformer as they are prone to saturation due to dc in the mains.
What you guys think about go with two 300 va transformers instead of one of 800 va to avoid humming from dc into the mains ? and also avoid a soft start.
Thanks
I'm shopping around for the PSU of my P101 rev-c.
So I did came across with some low noise trans from Plitron. they much more expensive..
like : Low Noise Power Transformers for Solid State Amps
Anybody has an opinion about it? are plitron trans much better that the others? even the standard toroidal trans ... because they are much more expensive than Antek for example.
other option is on the 40v: AN-8440 - 800VA 40V Transformer - AnTek Products Corp
I'm afraid of humming on my transformer as they are prone to saturation due to dc in the mains.
What you guys think about go with two 300 va transformers instead of one of 800 va to avoid humming from dc into the mains ? and also avoid a soft start.
Thanks
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high tolerance to Mains DC is not normally part of the low noise specification.
Plitron do state in item6,"DC tolerant design."
You would need to add that to your specification and see what Plitron could achieve and guarantee.
I also suggest you ask about core saturation at the highest specified mains voltage (they don't even give the recommended voltage range) and the transformer regulation, which also seems to be omitted.
Plitron do state in item6,"DC tolerant design."
You would need to add that to your specification and see what Plitron could achieve and guarantee.
I also suggest you ask about core saturation at the highest specified mains voltage (they don't even give the recommended voltage range) and the transformer regulation, which also seems to be omitted.
I see the Canadian flag. FWIW, i live in Toronto and have always had hum on my transformers. Over past few days followed advice of the DC Blocker thread and hum is gone. See post 134
http://www.diyaudio.com/forums/powe...uzzing-toroid-transformers-what-right-14.html
I use plitron and it was less affected but dc block is very effective with all brands.
http://www.diyaudio.com/forums/powe...uzzing-toroid-transformers-what-right-14.html
I use plitron and it was less affected but dc block is very effective with all brands.
Not easily detectable unless the mains supply is sub standard. (No pun intended). I have measured AC on the neutral line in old houses with dodgy mains but not in new build. DC of a few millivolts could be present but not for long. The SEB and Scottish Power will be surprised to find DC and when I worked for them. fault finding, I had never been aware of any reports of DC on the power lines..
Correct. I learnt my trade in the early days with 220v DC and on board most ships 110V AC and 220V DC. Live chassis wireless sets and early television. Lethal stuff!
That is where the saying, "All good Electricians keep one hand in their pocket whilst fault finding". No direct route to ground through the body.
I didn't mean DC mains, although that was used in some places back then. I meant DC on an AC mains supply. When maybe half of all radios took 50mA DC, and almost all TVs took 150-200mA DC from the AC mains then there would be a lot of DC flowing through the local circuit. A little ohmic voltage drop in the supply wires turned this DC current into a small DC voltage.
For some reason my house has DC all the time. I do have CF and hologen lights which some sites claim are a factor. Lots of dimmer switches, but seldom those systems are on when I listen to music. 70's residential neighborhood so fairly up to date. Hum does not vary be time of day. Big 400A service which had tons of electric heat that is no longer used. So likely the service on the street is out of balance as all the houses had electric heat now replaced by gas. I don't think out of balance distribution transformers leads to DC offset?? Usually industrial customers are the cause.
Your wife's hair blower, another appliance.
Best way to get rid of DC on the trafo is to use an isolation transformer.
I have a 1kVA isolation transformer. It is driving my music server.
Problem is it just hummed along as well. It is a torroid. But it replaced a 500 VA Hammond EI isolation that also hummed.
All of this went dead quiet with the DC blocker circuit, so based on my experience, I have to disagree with your point of view.
Problem is it just hummed along as well. It is a torroid. But it replaced a 500 VA Hammond EI isolation that also hummed.
All of this went dead quiet with the DC blocker circuit, so based on my experience, I have to disagree with your point of view.
I don't think that will work.
If the unbalance/asymmetry of the Mains waveform is the cause of the semi saturation of the toroid, or big EI, then an interposed isolation transformer will pass this asymmetry on to the toroid with little to no attenuation.
This reply confirms that isolation transformer does not block the DC from the mains.
DC blocking
I have more mains DC. My solution, for now, two DC blocking.
DC Trap Blocker Filter for Toroidal Transformers Assembled in Case | eBay
This week, Aleksandar is building a case with double DC bloking, aka, "turbo", with very good EPCOS B41505A7189M000 CAP, ALUM ELECT, 18000UF, 35V, CAN capacitors.
http://uk.farnell.com/epcos/b41505a7189m000/cap-alum-elect-18000uf-35v-can/dp/2283916?ost=B41505
My two cases are connected in series:
I have more mains DC. My solution, for now, two DC blocking.
DC Trap Blocker Filter for Toroidal Transformers Assembled in Case | eBay
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
This week, Aleksandar is building a case with double DC bloking, aka, "turbo", with very good EPCOS B41505A7189M000 CAP, ALUM ELECT, 18000UF, 35V, CAN capacitors.
http://uk.farnell.com/epcos/b41505a7189m000/cap-alum-elect-18000uf-35v-can/dp/2283916?ost=B41505
My two cases are connected in series:
An externally hosted image should be here but it was not working when we last tested it.
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An isolation transformer will block DC on the incoming mains from affecting devices downstream. It won't remove DC DC from the mains, so anything upstream of the transformer will still see DC. The transformer itself may be affect by DC, and so hum. Anything downstream of the transformer with half-wave rectification will still impose DC an this could be worse as the isolation transformer will have a much higher DC resistance than the incoming mains supply. So, if something in your own house is to blame for the DC then put that on the transformer and leave your audio on the incoming mains.
Yes, that's correct. Phase imbalance does not cause DC, although it may put some AC on the neutral wire.wlowes said:
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