Toroidal quality comparison?

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I planned to build a PSU for my new diy dac, and now come to decision of choosing the toroidal transformer. I planned to use 50VA with 2 x 0-15V output. And fortunately I can get access to many various brand of toroidal in my local shops:cool: Now I had following listing (all are 50VA, 2 x0-15V):


Hammond 182K15 US$52 http://www.hammondmfg.com/182.htm
Multicomp TA050/15 US$18
Multicomp TI-027335 (encapsulated) US$21
Airlink (no model num) US$?
Clairtronic 12023 US$21.15 http://www.clairtronic.com/toroidal.htm
Nuvotem 0050P1-2-xxxK (encapsulated) US$21 http://www.nuvotem.com/en/products/std_encap230v.shtml


I had searched for many place in Internet and seems cannot found a comparison of any combinations of about. I would like to ask if anyone had experience with these stuff? Which one is better regardless of price? :D

Tha Hammond is comparitive expensive(well, may be this is just mark-up in my local shop) Is that it had some superior performance?
 
Hi,
which ones include an electrostatic screen between the primary and secondary in the price? Do they all have dual 110V and/or 115/120v primary tappings. Are they suitable for just 60Hz or dual 60Hz/50Hz? Are any available with a Goss band to reduce hum field?
Then you might understand some of the cost difference. If all are identical then I would go cheapest.

By the way, I have an old Conrad Johnson PRE and it runs the regulator VERY hard from a much higher supply voltage than I expected. I don't know why. It also has NO electrolytics in the power supply nor anywhere else! Film and styrene caps throughout.
 
Thanks Andrew, I had not paid notice on spec parameters other than primary & sec. :smash:

But other than spec, any one had try AB sound quality comparison with differnet brand toroidal? I understand that is is very cost non-effective, but curious if anyone can share some experience on this.

BTW, I forgot to share mine experience at first :D I had build a headphone amp, and had tried 3 transformers:

- At first, I use a traditional EI transformer for PSU (the PSU is in seperate case). While providing more dynamic and power to the sound, its very noisy and detail is not good.
- Second, I borrow:D a unbrand toroidal from my friend. Its much more clean, clear and is no noise, detail is better, but the sound come out seems like limited somewhere. All things cannot extend enough, and not dynamic enough.
- At last, I bought a Nuvotem 0050P1-2-xxxK (encapsulated model). Well, shortcoming of the above 2 disappeared, and contain all goodies of previous 2, and even better :D:D

So, this is why I ask if anyone had comparison with those branded toroidal. I DO believe that branded one should perform better.

Thanks for any advise!
 
Hi siuguyguy

Don't i also wish such info was available? There were several threads about power transformer design and some sensible opinions were expressed regarding the effects of flux density, dc saturation and power bandwidth. Sadly, all provided little correlation with subjective effects.

So, what's a safe way to choose a good sounding transformer? It is probably best to use one of the 'industry standards' like Avel Linberg, Plitron, Lundahl.
 
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If you use a transformer for a low-power load like a DAC, definitely do not take a toroid! Toroids are very wideband devices as transformers go and that means all the noise, junk, scratches etc on the mains are neatly transferred to the DAC supply. For low-power loads a classical E-I transformer, preferably with totally separate primary and secondary windings, are the very best for low noise and good low-level detail. The only reason we use toroids in power amps is their low price and relatevely small size for a given power rating, but that should not be important for small transformers.

Jan Didden
 
thought they radiated less EMI

What exactly is EMI? :)

Toroids obviously tend to radiate less of everytnig and that's why they are the darlings of manufacturers - just perfect for really stuffed boxes. Radiation and wideband is not the same.


Anyway, this is theory and the original poster, siuguyguy, wanted to know how various brands sound. I have noticed, through experience, that generalisations don't work too well. Some toroids, even at low power levels can provide better sound than EI types. The wide bandwidth can be reduced with a suitable power cord.
 
I'm using this Hammond transformer (D229 type) in a DAC and I'm very happy with a performance. Proper filtering in subsequent stages provides better sounding supply than I was getting with batteries.

I mainly experimented with transformers in GC, and here I tried once EI type (250VA) and definitely the sound wasn't as good as with Plitron toroid ( it was sort of muffled and not very involving).

Then I tried cheap toroids from China (looking almost exactly like Plitron) and here the biggest defficiency was lack of bass and rythmical definition; although the transormers were half price of Plitrons, I couldn't use them.

It seems like single primary is better than dual.

My recent experiments indicate also that winding secondary first ( primary on the outside) produces better results: the sound is more direct and more natural, with less "haze" and grit.

I had some transformers were secondary was done with parallel runs of wire (to increase current capacity), but I didn't really like it, it seemed that I was loosing focus in the sound.

I recently started ordering toroids with amorphous core, and those are completely different ball game. The sound initially is somewhat bright, but the amount of detail and definition is greatly improved. Also, after breaking in the brightness dissapears.

Bigger wattage is not neccessarily better, while you gain on certain qualities, you might be loosing on others (more body and drive, less detail and immediacy) so it's best to balance it properly.

With GC, I usually go for 300VA toroids these days.
 

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AudioWizard said:
Jan, that's interesting.

I know toroidal transformers are more efficient, but I also thought they radiated less EMI... is that wrong, or is there something I overlooked?

Ok and if toroids are not the way to go for low-power circuits, how about the new R-types?


They radiate less indeed, because of their excellent and tight coupling. That is exactly the problem in our context. It makes them wideband, so if you have tens or even 100-s of kHz noise or something on the mains it is coupled right to the secondary. In contrast, E-I transformers being less wideband, will much more attenuate mains-borne junk from primary to secondary.
The ideal transformer for supplies would be very narrow band (only 50 or 60Hz) but they always have some response for higher frequencies as well. The relatively low cost transformers with the primary and secondary side by side in separate chambers on the core are the best in terms of isolation anything non-50 (or 60) Hz from your equipment.

Jan Didden
 
Hi Jan !
According to Bruce Rozenblit of Trancendent Sound there is just a myth, that toriodal transformers should be more wideband.
If one hear some (false) statements a sufficient number of times , they tend to become the truth. So , can you prove your statement with some measurments of scientific value?Otherwise
I will not believe you.

:D

Regards
Håkan
 
I think there's some confusion between bandwidth and coupling; toroidal transformers have more primary to secondary capacitance so more noise can get from pri->sec, but this can be largely eliminated with an electrostatic screen (which will have other consequences...).
 
There are two ways to do it. One is actually the dummy layer of wire, one end of which must be connected to PE. The other, better method is a thin aluminium or copper foil between the primary and secondary windings, which must also be connected to PE. The important thing is that the foil must not form a closed loop around any single wire or winding.
 
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