Batteries do great things for sound but can be a PITA to keep going..
Years ago, our reference system consisted of a DAC with all separate battery supplies for everything including tube heaters, save the HT tube supply. The power amp was fully balanced, zero FB, class A and ran off +-36V rails supplied by batteries.
It sounded incredible, but the constant charging wore me down. Life has to be simpler. I eventually dumped them all. Haven't got back to that level of sound yet.
Sounds reasonable 🙂
Otoh you have to admit that there were times when an audio endpoint using a synchronous UBS mode was also considered as to represent a reasonable system a lot of people were dismissing any possible perceptible difference because of ...... (fill in errorfree computer file transfer, missing blind listening test results, measured audio perfomance below the known hearing thresholds etc. etc.).
Overall very a discussion very similar to the days when any audible difference when using the SPDIF (koax or Toslink) couldn´t be. Back then it needed the analysis work from Julian Dunn and Chris Dunn/Hawksfor as well.
In the case of the USB interface a lot of people clearly hadn´t read the specification but were nevertheless adamant in their "can´t be anything audible" argumentation. 😉
IMO synchronous USB IS a reasonable system. It's the non-RTS operating system that seems to mess it up.
On a 1.2 kVA tortoid I measured 1.3 nF without the inter winding screen connected and with the inter winding screen < 100 pF.
I would always recommend you specify an interwinding screen.
GOSS band (aka ‘belly band’) also makes a huge reduction in radiated EMI. One trick I picked up with torroid as well is to rotate them clockwise and anti clockwise about 60 degrees. They’re is more often than not a noise null point that is quite significant at circa 6-8 dB. The radiated fields from a typical torroid are not uniform and I suspect this has to do with the way that windings are bunched - JN will be able to explain this better.
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Another interesting one is to do with the enclosure - whether aluminum or ferrous. When you put the lid on the the completed amplifier such that the PSU transformer is enclosed, the noise (harmonics of the mains) drops significantly. I suspect this is because the radiated mag field chooses the path of least reluctance which is the housing rather than air. The effect is greatly reduced when a GOSS band is fitted.
I was accused for spreading false information by stating that a lid forms, in some sense, one more turn of the transformer. Was I wrong stating this?
There is some interaction after all as you state...
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There is some interaction after all as you state...
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I did propose a possible explanation for the observation that two files with equal checksums can sound different.
Do any of us understand how conduction, ie energy transfer and transduction works, how it really works ?.
I don't say I do but I do observe interesting effects that I have not seen explanation for and I am gathering audio system measurement proofs for subjective effects that I and others readily observe.
TNT if you have an audio system that is completely free of excess noise mechanisms then you have no concern for my research.
The rest of us great unwashed do not have that privilege however.
I find that excess noise more particularly the nature (it is complex/interactive) of excess noise in large part determines 'signature' or 'voicing' of systems.
System excess noise behaviours are driven by system intrinsic noise, original signal, signal embedded noise/distortions and the standard distortions......low level chaos abounds riding on top of the original audio signal and getting progressively modified system stage by system stage.
This is normal, we all hear this 'irrational' (not purely random) noise as part of the sound character of individual systems and audible character/signature is to be expected for 'consumer' level systems and devices.
It also follows that small changes at the source end of the system can cause a disproportional change in system final output, and this is to be expected for any non noiseless system.
The best of audio manufacturers strive to minimize excess noise which renders a system or device clean or characterless, said another way is reproducing without embellishment.
For affordable domestic systems and devices we are stuck with dirt riding with the music.....I have a retrofittable way of rendering that dirt subjectively innocuous/absent and for the good of all.
Dan.
Good information, thanks.
I have heard differences in many amps according to lid on/off, and what material that the lid is made of.
So a screened steel can potted toroid is good ?.
Dan.
TNT, I don't think the housing forms a 'turn' - you would need to pass through the centre of the toroid for that to be the case.
I should have been a bit clearer in my hypothesis earlier. In my case the top of the metal housing is about 5mm from the transformer mounting bolt. Without the lid on the housing, the stray flux will loop out from the transformer and back to the opposite side - i.e. the bottom - and in so doing cut wiring loops within the amplifier as they may exist and introduce noise. Clearly the better ones layout and cable dressing (twist wires where appropriate etc), the less noise problem. When you put the lid on, the stray flux rather couples to the metalwork (and around the housing back to the other side of the transformer) more readily than the air and any cabling in the vicinity. As long as you have one and only one 0V bond point to the chassis, you wont have any noise loop formed that can inveigle its way into the audio signal path. Note we are talking -90 dBV to -110 dBV levels
Dan - yes - steel enclosure for the transformer I would expect will reduce noise very substantially - I have not tried that though since I use custom wound transformers for both DIY and commercial.
Again, JN is best positioned to explain the theory behind this stuff - these are only my practical observations.
I should have been a bit clearer in my hypothesis earlier. In my case the top of the metal housing is about 5mm from the transformer mounting bolt. Without the lid on the housing, the stray flux will loop out from the transformer and back to the opposite side - i.e. the bottom - and in so doing cut wiring loops within the amplifier as they may exist and introduce noise. Clearly the better ones layout and cable dressing (twist wires where appropriate etc), the less noise problem. When you put the lid on, the stray flux rather couples to the metalwork (and around the housing back to the other side of the transformer) more readily than the air and any cabling in the vicinity. As long as you have one and only one 0V bond point to the chassis, you wont have any noise loop formed that can inveigle its way into the audio signal path. Note we are talking -90 dBV to -110 dBV levels
Dan - yes - steel enclosure for the transformer I would expect will reduce noise very substantially - I have not tried that though since I use custom wound transformers for both DIY and commercial.
Again, JN is best positioned to explain the theory behind this stuff - these are only my practical observations.
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Of course do not forget the protip of ensuring fixing bolt doesn't touch the top of the enclosure. At which point bad things DO happen
As said before, i think it is possible to share some informations (of course limited) educational purposes, so if you are in need for some publications, it could be an idea to drop me a note......
But in this case the main point isn´t the amount of jitter in modern equipment, but the IMD resulting from the jitter.
If you might reread my post, you´ll see that i responded to a post by PMA who seems to doubt that there are listening test results for IMDs below -40dB while the IMD components found to be detectable in the Benjamin/Gannon experiments were already below that i.e. around -60 to 65dB .
In this special case they used music samples from the McGill MUMS CDs and quite low frequency jitter of ~1650 Hz .
So the interesting point is just the level of IMDs in relation to the level of the "music" and as long as we don´t want to argue that the audible effect of jitter induced IMDs is (sinusoidal jitter) somewhat larger than the audible effect of IMDs induced by another signal frequency in the music sample (comparable in level and frequency) so that the resulting IMD components are of the same level and frequency as in the "Jitter case" we have to assume that the audible effect will be similar.
I hope it helps to clarify what i´ve meant?!
On a uniformly wound toroidal transformer, the area of the coils ends, where input/output wiring exit is always a radiating section.
Coils on a toroidal transformer couple better with the core and to each other, so less leakage inductance. Also higher capacitive coupling between coils.
This is what makes wideband energy transfer with a wound laminated strip core toroidal unless you mean something else with “tuning” hitsware.
George
Right, I believe I was confusing single/double with ABX VS AB.
When i am playing this blind game, I ensure to be in the same time the driver and the passenger, so I don't care about single or double ;-)
I mean, the musical content has to be well known by me, so my own content. The length of each sample: under my need depending what i'm searching to. And instant switch at the exact moment I need. Switching during the play, or comparing short samples from their start (like a drum kick).
I usually use samplers for this and *need* to drive myself the tests.
A boring and complicated process that do not provide obvious difference if it is blind or not, according to my own experience. This is only valuable for me and i don't care about other's opinions on this matter. While I respect that others can prefer other methods for themselves as long as they do not want to impose-it on me .
If the goal is to chose between two solutions during a design process, we have no reason to promote a solution or an other. And we have obvious reasons, why to hesitate and even listen ?
And, if it is about to chose a gear in a shop, well, it is my problem, i chose the thing I prefer, I'm not snobbish, I dont care about reputation, brand image, reviews and all the posturing of the salesman I attend with amusement. And I care about value for money more than everything else.
And if YOU are snobbish, I don"t give a s...: your snobbery is part of YOUR pleasure.
If it is about buying a gear meant to enter my living room, I *need* peaking... because the design and the aesthetic is not a negligible part of the pleasure as well ...
I was a sound engineer too. Do-you imagine blind tests at each steps of the thousand of decisions you have to take during a mixing session ?
This quest of absolute, truth, politically correct, this paranoid war against snake oil etc ... that seems like a religion for some people here, look totally ridiculous and unrealistic to me. Each one is free to chose the ways and the goods he prefers, the result is judged on arrival.
Do you make yourselves so many troubles to choose your cars ?
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It took me years to get that. When toroids first came out, I thought they were the best. But (not much) later my main client wanted E-I back. I hear no difference myself 🙁
Yes - I used a sig gen (50 ohms Rs) and fed it into a 500 VA core and loaded each of the secondary's with 100 Ohms (R's I had to hand). The BW was 60 kHz which I found surprising.
If you apply the sig gen between the primary and secondary's the BW is > 3 MHz (the limit of my function generator) which is to be expected - its just capacitive coupling.
> unless you mean something else with “tuning” hitsware
What I mean is you can actually use (power) toroids as output xfmrs
as opposed to (power) E-I's and pass a semblance of a square-wave .
What I mean is you can actually use (power) toroids as output xfmrs
as opposed to (power) E-I's and pass a semblance of a square-wave .
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