Sound Quality Vs. Measurements

Status
Not open for further replies.
Hi,

I did say RF, explicitly. And RF is not going to fall in the category 'large'. Differential mode leakage is inevitable if you want to, you know, draw power from the mains.

Leakage is unavoidable, however magnetic coupling at high (RF) frequencies is minimal due to eddy current losses in the core, so what remains is capacitive coupling. And that is something that can be readily addressed using traditional transformer design techniques.

Medical safety has spec for RF leakage currents? If so, do you have a link, I'd like to follow up.

No, it has a spec for leakage current however, that forces certain design approaches that as a side-effect minimise RF leakage.

It is however possible to improve on this too.

One may also employ additional RF filtering, though this is usually only operates above a few 100KHz, leaving a wide open door for some of the most pernicious stuff.

R-Core, LL-Core and Double-C Core transformers allow for example a much more thorough optimisation than EI, M or Torroid transformers.

As for using two transformers, while high HF frequency gunk is not amenable to improvement using two generic transformers, Low RF gunk can be fairly successfully cancelled using suitable arrangements.

Ciao T
 
Well I reckon balanced inputs are largely immune to common-mode induced sound quality issues, provided pin1 is properly terminated on the XLRs. Unbalanced inputs? - don't touch them - on big, toroidal-fuelled poweramps would be my advice. If you only have unbalanced ins, wide-band mains filtering would be the mitigating option. Problem is - with the heavy current demands of a beefy amp it becomes increasingly difficult to filter effectively.
 
Hi,

Yep, go for the single big 'un. But toroids have maybe 10X the capacitance to mains of the other types, at equal VA ratings.

This is only true for generic transformers. Ones correctly optimised for audio use may have much lower RF coupling than generic EI or related designs.

Ciao T
 
Then you need to tell those guys with the trafo GB.....!!!:p

Oh the F5X guys? A quick look shows their spec has only the two secondaries bifilar wound. No problem with that - I was thinking you were talking about primary and secondary being wound that way. But I see they are specifying electrostatic screens - which are just dandy so long as your earth is clean ;) I know mine isn't..... :p
 
Hi,

Then you need to tell those guys with the trafo GB.....!!!:p

Why? They probably are looking for the most efficient way to couple noise into their circuits, so they can hear maximum differences between interconnects and mains cables (note, minimising noise coupling does not eliminate differences, but it makes them a lot harder to hear... :rolleyes:).


Switched mode power supply.

The way most (or as RAW would say Mosbunall) are implemented they are to audio circuits and audio devices what Fed-Ex is to packages... A trial not only of design and implementation, but also of faith.

Ciao T
 
Hi,

So 2 in parallel is better than one big un ..? :confused:

No, not as such. But two sufficiently identical transformers may be configured mechanically and electrically to cancel both some of the stray fiields and most of the stray capacitance (the more precise the match the better the cancellation, so generic transformers from really big industrial winders in the US and EU are better then eastern european and far eastern ones.

what is plitron doing differently

They have a website at Plitron, why not peruse it?

bifilar wound ..?

Thanks heaven, no...

That is a very good way to make a transformer with exceptional coupling up into the MHz range, which may make some sense (at least for bragging rights - my balanced output transformer goes to 15MHz - Hey mine goes to 22!) in audio, but zip in mains transformers.

Ciao T
 
Why still put a steam engine into your amp? There is a better technology around, SMPS.

Because SMPS is the same steam engine rotating with thousand times higher RPM. In addition to low frequency ripples we need to filter as well high frequency ripples created by SMPS itself. I.e. in attempt to reduce weight ans size we create more problems that affect sound quality, unlike weight and size.


Like, in modern power plants nuclear reaction produces still the same steam from the same water. As the result, such power plants create more problems than simple steam engines.
 
Status
Not open for further replies.