Hozen Japan make a WB transformer, its main benefits seem to be higher efficiency and small size, but you would think the radiated field on some axis would be very low.
I have only seen it used by one Japanese Audio brand, can't remember their name though.
The only R-cores I have found have been in Brother printers and typewriters.
An externally hosted image should be here but it was not working when we last tested it.
www.hzi.co.jp
Regards
James
Attachments
http://www.aes.org/publications/preprints/preprints_search.cfm
Soren Bech - 29 matches
Nick Zacharov - 26 matches
Soren Bech - 29 matches
Nick Zacharov - 26 matches
KSTR said:
Statistically, people generally find low/even order distortion products less audible and less objectionable than odd/high order distortion products.
Since we can measure an amplifiers distortion spectra, the blanket assertion that “In truth, no one can fully correlate measurement with statistically based listener preference” (uttered without the necessary caveats) is definitely not “in truth”.
WRT to the utility of THD measurements – I fully agree that a THD figure by itself is pretty useless for predicting the “subjective perception of nonlinear distortion” (and therefore as a figure of merit for a power amplifier) – provided that the distortion products are above the threshold of audibility.
If I build an amplifier, plug it into the distortion analyser and measure no more that 0.001% THD at all power levels between 20Hz and 20kHz, what predictions (based on scientifically demonstrated thresholds of audibility) can I make about how the amplifier is likely to "sound"?
AndrewT said:
Given all the wonderful tidbits Mr. Curl has shared here, why would you settle for buying one of these?
G.Kleinschmidt said:
None whatsoever.
If it has a puny power supply, it will lack dynamics. If it uses high rates of negative feedback there will likely be a forward upper midrange/lower treble. If it has low bandwidth (let's say 30kHz, though that's unlikely in today's market), cymbals and such will lack air. In short, the THD spec tells you nothing. Actually, it's worse than nothing--you think you know something, but it's empty knowledge.
Back when my mother was alive and living in Richmond, VA, she was a block from a high end shop. I dropped in to hear what they had on hand. At one point they were selling Rowland (I believe that's correct, it's been a while) and I had the opportunity to sit and listen for quite some time. The stuff had the curious property of sounding decent at low volumes, but utterly collapsing when anything dynamic came along. I mean compression of a major, obvious nature. I mentioned this to the sales critter, whereupon he fell to arguing with me about how it was impossible for this, that, and the other reason. I shrugged, said thanks for the opportunity to listen, and headed for the door. As I was leaving, he pressed a wad of sales stuff and review reprints on me in an attempt to show me the error of my ways. He said that all the reviews had been uniform in praise of the dynamics, and that I was wrong. I took the literature back over to my mother's place, sat down and read it, not having anything better to do until she got off work later that afternoon. Surprise, surprise, surprise...the review reprints didn't laud the dynamics, they said the unit fell apart on peaks, just the way I had heard. (I'm pretty sure there was a reprint from Stereophile, possibly Absolute Sound...Audio Critic might even still have been around then.) I confess that I went back the next day to point out the passages in the reprints where it said that the unit couldn't handle dynamics--which didn't sit well with the sales critter, but he had made rather a nuisance of himself--and noted that one reviewer had even chosen nearly the exact wording I had used the day before.
Moral of the story:
--One, if you're selling something, you really ought to read the literature you're handing out so as to avoid making a fool of yourself.
--Two, there was nothing in the specifications that gave any hint that the unit didn't do well dynamically. It met all published specs, but steady state measurements do not reflect what the circuit will do in the listening room. There might be some way to hit an amplifier with a pulse at something like 50% of rated output that might...maybe...tell the tale, but I've never seen such a test conducted.
To this day, I don't know what that amp did "wrong" technically to be so pathetic on dynamics. I never saw a schematic and I never had a chance to look inside. It's possible, but not probable, that it had a too-small power supply; most high end stuff tends to have a pretty hefty cap bank, backed up by a decent transformer. Something I find more likely, though still guesswork since I don't know anything about the guts of the amp, is that it used regulated rails, but with no capacitance after the regulation. If the regulator was slow enough, it wouldn't respond quickly to sudden current demands and the rail would drop. Or this, or that, or the other thing...who knows? I'll tell you, though, I'd like to know, simply as an object lesson in what not to do when building an amp. It's good to learn from your own mistakes, but better still to learn from others' mistakes.
But not a hint of this was to be found anywhere in the literature, whether puffery from the manufacturer or reprints of reviews. Useless, the entire lot of it.
Grey
You are correct, Grey. Harmonic distortion measurement alone won't tell enough to give you much.
G.Kleinschmidt said:
About the same as you can tell from an amplifier that measures double digit distortion on many power stress tests. Many exist and they garner raves from 'discriminating' listeners. My problem for years was to pin down a single high end designer that will commit to sitting down together and do a listening test that they will standby and has even a remote chance of going either way. There is always some excuse, endless excuses. The main objection has been double blind, real double blind, FULL production units with one and only one difference.
I've had large serious pro-sumer companies tell me that they have NO facilities AT ALL to listen to their products and that they relied solely on the heresay of their consultants.
At the opposite end of the scale, an interesting thread elsewhere on this site is filled with the results of an on-line distortion test, listeners gauging their ability to hear simple THD. Very, very few have thresholds below 1%, some as high as 10%. Where does that leave us?
Hearsay, more real than objective measurement, because it is what is, not what measures well. DB just doesn't work that well, and I know from experience. However, I will NOT tell you what my designs sound like, I trust reviews and customers.
GRollins said:
Comments like these are why old wives tales proliferate through the years. It gets to the point where a design isn't taken serious unless it's sporting all of the audiophile approved approaches. Nothing here is based on anything other than empirical observations repeated endlessly.
GRollins said:
That's just plain dogmatic baloney, backed up with zero substantiation. In the correct context THD measurement tell an awfull lot about an amplifiers performance, but trying to atriculate such to the likes of you is a complete waste of time.
scott wurcer said:
I think you are conflating two distinctly seperate issues and the fact that there are many high (double digit) distortion amplifiers that get rave reviews is irrelevant to my point.
If I make a pizza with a sodium content of 5000mg per slice, I can make a fair prediction about how it is likely to taste, regardless of whatever else I may garnish it with.
I personally wouldn't like to eat it, but I know for a fact that there are people out there who would love it.
I gave up being a guinea pig years ago. It gets seriously tiresome. Last week's test doesn't matter to the guy standing in front of you with his hands on his hips and the inevitable snotty attitude. It's only his test that matters (even if it's the same one as last week), because, you see, he wasn't there and he doesn't believe you can do what you say you can do. It's like the old gunslinger thing, there's always another punk...always...it gets damned tiring and I gave it up.
Whine all you want that I'm ducking your fair test (whoever you might be). Try it sometime. It gets really, really old because you have to prove your case to each and every one of those people individually--maybe two at a time, if you're lucky. Not just no, but hell no. Life's too short to run on someone else's little treadmill, only to have to run on someone else's treadmill next week, then another the week following. Ugh.
I can well sympathize with others who feel the same way.
Note that this is not an endorsement of equipment manufacturers who don't listen to their stuff and/or who don't have some sort of reference system. To me it's a big duh that anyone who builds equipment should have some way of listening to it. I say that knowing full well that there are numerous components that have gone straight from the test bench to the retailer with no more than the standard power, distortion, and S/N tests so as to have something to print on the literature. That's pathetic. That's so, like, you know, like, mid-fi to, like, not even listen to your stuff, you know what I mean? Anyone running that kind of business deserves to go spectacularly broke.
Grey
Whine all you want that I'm ducking your fair test (whoever you might be). Try it sometime. It gets really, really old because you have to prove your case to each and every one of those people individually--maybe two at a time, if you're lucky. Not just no, but hell no. Life's too short to run on someone else's little treadmill, only to have to run on someone else's treadmill next week, then another the week following. Ugh.
I can well sympathize with others who feel the same way.
Note that this is not an endorsement of equipment manufacturers who don't listen to their stuff and/or who don't have some sort of reference system. To me it's a big duh that anyone who builds equipment should have some way of listening to it. I say that knowing full well that there are numerous components that have gone straight from the test bench to the retailer with no more than the standard power, distortion, and S/N tests so as to have something to print on the literature. That's pathetic. That's so, like, you know, like, mid-fi to, like, not even listen to your stuff, you know what I mean? Anyone running that kind of business deserves to go spectacularly broke.
Grey
MikeBettinger said:
It's trivial to either increase or decrease the power supply capacitance in an existing amplifier and listen to the result. The results don't show up on any test--unless you decrease the capacitance to the point that power supply ripple becomes an issue--but you can easily hear the difference. The surprise is that more people don't conduct such a simple test.
Okay...maybe it's not such a surprise. They don't want to hear that their emperor has no clothing.
Grey
Grey, thank you for your perceptive and accurate comments. They are useful to people that are willing to learn and have an open mind. Kleinschwanz, on the other hand, continues with his personal insults and bullying attitude. What else is new?
Grey, power supply is VERY important. Just ask Nelson Pass about the time that I (improved) the sound of his preamp. I did't mean to do it, I just need a few extra dollars to pay the rent. Gordon Holt listened to it and bought it from Brian Cheney, on the spot! Then I had to make another one out of odds and ends in my lab. Then, Gordon Holt gave the preamp an A rating, only if it had my power supply! What a problem. I was not set up to make power supplies, but THEN I was reminded that my original Vendetta phono stage had a pretty marginal (engineer approved, however) power supply and the new improved design became the A version of the Vendetta. I never looked back and thank goodness, Nelson started making 'improved' versions of his remote power supply. Even today, I cannot PROVE to you why there was any audible difference, but there was, and even I heard it.
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