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-   -   Power Transformer size influence on preamp sound. (http://www.diyaudio.com/forums/power-supplies/226940-power-transformer-size-influence-preamp-sound.html)

Erlend Sæterdal 3rd January 2013 10:09 AM

Power Transformer size influence on preamp sound.
 
Hi anybody have some exsperience with power transformers size influence on sound in a pre or dac ?

If 100 VA is enough will 200 then be better ?

AJT 3rd January 2013 10:11 AM

yes, in that the 200va will run cooler....as to how it sounds, maybe......

analog_sa 3rd January 2013 11:04 AM

Quote:

Originally Posted by Erlend Sæterdal (Post 3309170)

If 100 VA is enough will 200 then be better ?


Many high end designs are based on this premise. IME though transformer design often trumps raw size as far as sound is concerned. Still, all things being equal bigger is generally better. It may, of course be purely coincidental, i.e. physically larger transformers may also have lower parasitic capacitance between windings.

Erlend Sæterdal 3rd January 2013 12:28 PM

BUT bigger transformer means bigger charging currents for capacitors and worsening sinus curves in supply. Sawtooths instead off sinus ?

analog_sa 3rd January 2013 01:27 PM

That's easily cured with choke/resistor preceding the cap filter. Anecdotally, it appears i am unable to tell the difference between a high and a low power secondary of the same transformer when feeding a dac.

AJT 3rd January 2013 09:50 PM

Quote:

Originally Posted by analog_sa (Post 3309220)
Many high end designs are based on this premise. IME though transformer design often trumps raw size as far as sound is concerned. Still, all things being equal bigger is generally better. It may, of course be purely coincidental, i.e. physically larger transformers may also have lower parasitic capacitance between windings.

not sure about lower parasitic capacitance since bigger traffo will have longer or greater coil area....i do however leans towards trying to oversize all my traffo builds...

martin clark 3rd January 2013 10:47 PM

Surely it only makes a difference if you haven't got the output voltages decently smoothed, let alone regulated.

My preamp uses a 10VA transformer. The only reason it's not still a 6VA unit is because I wanted slightly higher secondary voltages for more Vreg headroom (not available in original trafo core series): but the total draw is still under 5VA.

Temporarily swapping this for something >>20x greater VA rating didn't make a damn of difference on measurement, nor an audible improvement (I'd keep it if so)

Meanwhile the small unit being split-bobbin has useful leakage inductance and secondary resitance and very, very low Cap coupling pri:secondary and as a result - does what I want

AJT 4th January 2013 02:42 AM

for some reason, split bobbins seem to run cooler....someday i am going to find out why....

hymenoptera 4th January 2013 03:52 AM

Been wondering this myself, being new to electroacoustics and all, and seeing how a lot of high end gear has ginormous power transformers, and equally large price tags for said transformers...

I'm looking to power individual console input modules requiring ±17vDC (and hopefully another 48vDC if it'll all fit) and stuffing each into a 1U rack space. I'd like to get the best value without spending more than it's worth, and I can't afford a huge toroidal, and admittedl don't understand why that's preferred to begin with.

what's this VA rating thee speakth of?

gmphadte 4th January 2013 08:50 AM

V is voltage and A is current in Amperes. The transformers are rated as such. For example, if u have a transformer with a 10 volts secondary and its current rating/can output 2 Amps, the transformer is 20 VA.

Gajanan Phadte


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