Low noise toroidal transformer vs Normal toroidal - diyAudio
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Old 23rd April 2015, 04:43 PM   #1
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Default Low noise toroidal transformer vs Normal toroidal

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

Last edited by brunogiovs; 23rd April 2015 at 04:46 PM.
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Old 23rd April 2015, 04:50 PM   #2
AndrewT is offline AndrewT  Scotland
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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.
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Old 23rd April 2015, 05:22 PM   #3
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Thanks , how about to have two 300 va transformers?
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Old 23rd April 2015, 09:55 PM   #4
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DC on your mains AC supply? Where is it coming from?? It is not produced by the supply companies or they would have problems with their transformers!
Maybe you are using a DVM and it can't handle the mains AC?
Are you suggesting the sine wave is not symmetrical ?
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Last edited by JonSnell Electronic; 23rd April 2015 at 09:57 PM.
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Old 23rd April 2015, 10:11 PM   #5
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Its a toss up between low noise transformer and extra filtering in the power supply.
I cant say transformer noise has been an issue in my 35 years of electronic engineering.
I just add plenty of smoothing and decoupling to the supply.
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Old 23rd April 2015, 10:41 PM   #6
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I have a classAB amp that I'm having problems with its 500 VA transformer.. it humms time to time ... and if I use a 200VA from antek on the same amp with the same capacitor bank... it doesn't humms..
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Old 23rd April 2015, 11:03 PM   #7
wlowes is offline wlowes  Canada
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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
Variations of DC Main Filter against buzzing Toroid Transformers - what is the right?
I use plitron and it was less affected but dc block is very effective with all brands.
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Old 23rd April 2015, 11:12 PM   #8
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72mf .. Isn't excessive?
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Old 23rd April 2015, 11:14 PM   #9
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Did you look into this ?
Mains DC and Transformers
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Old 24th April 2015, 09:17 AM   #10
DF96 is offline DF96  England
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Quote:
Originally Posted by JonSnell Electronic
DC on your mains AC supply? Where is it coming from??
One of his neighbours? Anything using half-wave rectification (whether by accident or design) will impose a little DC on everyone else on the same mains circuit.
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