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Old 18th February 2012, 01:38 PM   #2591
dvv is offline dvv  Serbia
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Quote:
Originally Posted by tvrgeek View Post
".5KV HT lines for 211 or 845 Amp's, ok? Be safe."

When I worked on 480 and 208 PDU's, I always did one in the pocket.

A B&W TV will knock you across a room. Color just stops your heart. A few people have found out modern ignition systems can do that too.
How did you measure the color?

Was it a scientfic test, or just fooling around?

Which spectrometer did you use and why?

How big are the phase shifts of the three prime colors?

Is the wife frowning or clowning?

Is price a painful memory?

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Old 18th February 2012, 01:47 PM   #2592
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Folded foil current shunt is really HF current sensor... a piece of thin copper tape, a piece of PET film from capacitor, two drops of shoe goo, wise to clamp it while goo is drying... voila
P.S. Tek probes are out of league due to HF and DC accuracy simultaneously and it can calibrate itself...
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Old 18th February 2012, 04:12 PM   #2593
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Default Progress since 1979?

Back to the thread topic as such, a historical note:

Some years back I took advantage of an offer on back issues of Audio Amateur, and got the complete set. Some were wrapped in plastic, some had rusty staples.

Like so many things, when you have something readily accessible, there's no feeling of urgency getting round to reading it. So these magazines sat in shelves or, when I "downsized", in boxes or cabinets. But recently, running across references to old articles, I've excavated them and started to digest some.

Two things stand out already. One, many of the controversies raging then continue now, and as well the emotional intensities of the protagonists.

Two, the designs presented are often remarkably primitive based on what has become fairly well-accepted practice.

Another attribute is that typographical errors and bad grammar are about as common then as now (with audioXpress), although one is impressed by the sheer volume of material in those days, and immensely grateful to Dell, cohorts, and contributors for keeping the enterprise alive for so long.

It happened that a stack I brought out of storage had exchanges about sound quality versus measurements, very apropos. The allegation that linear distortions accounted for all perceptible differences between two phono preamps (and by extension ALL components), expressed in a letter from Lipshitz, Vanderkooy, and Young (a letter they wanted to withdraw but it was too late) was followed by forum contributions and letters from Jung, Moncrieff, and Curl, and additional articles about subjective/objective stuff. These latter are in TAA 3/1979 and following issues.

In any event, fascinating stuff. In those days I wasn't paying much attention to audio per se, and 1979 marked a milestone as an instrument I'd labored over for some four years was finally on a telescope. It was fun to see that a well-known astronomer, an x-ray specialist, Mike Lampton, was also an audio hobbyist, and with his associate Zukauckas and collaborators contributed a preamp design. The article is one of the better examples of technical clarity, while still having some amusing bits, including the use of solid tantalum caps in the signal path As I say, there has been some progress...
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Old 18th February 2012, 04:32 PM   #2594
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What I find to be regrettably different these days in compaison with those days is a loss of drive, loss of impetus to get out there and really do something better. We seem to have lost a kind innocence, if you like, we had in those days. A perhaps foolish and naive concept that we could change something.

And in the end, it was all just a business to some, and we took too long to understand this.

The audio market was first hit hard by the appearance of the video tape market - a new toy which drew money away from audio. But the advent of the PC was what killed the audio of old, it barely survived that, at least some, while others did not (such as Sansui, Akai, JVC and a slew of others).

And what is left of it today is pitiful compared to those pioneering times. These are the days of whiyy kids, hit-and-run companies all geared to making a fast buck.

Whoever doesn't see that the audio as we knew it is in its last days is either unwillig to see it, or has a hard problem. We have turned into a cheapskate civilization, in which price is EVERYTHING. Everybody wants it all for virtually free.

As affictionaods, we cried out for 15+ years that 16-bit just wasn't enough, and when they decided to go 24-bit, here comes MP3 in its essentially 4-bit format. It's easy, it's accesible via the Internet (i.e. from home) and it's free. Never mind that it has been effectively stolen, we want it.

The old system had its faults, but worse, it decided not to change, thus signing its own death warrant. Too many middlemen, too many price hikes, too much control in the hands of too few. It didn't stand a chance in a fast moving world.

So it was torn down, but that's not the problem, as I see it the problem is while we have torn it down, we have NOT replaced it with a different set of values. Nobody really knows how the game is played today, it's all rather chaotic.

Yet, one thing seems obvious (to me, at least) - we are about to witness the audophile's worst nightmare, seeing his beloved hobby being turned into just one more VLSI inside a tablet. The end of audio as we have known it.
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Old 18th February 2012, 04:43 PM   #2595
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Originally Posted by dvv View Post
What I find to be regrettably different these days in compaison with those days is a loss of drive, loss of impetus to get out there and really do something better. We seem to have lost a kind innocence, if you like, we had in those days. A perhaps foolish and naive concept that we could change something.

[snip]


Yet, one thing seems obvious (to me, at least) - we are about to witness the audophile's worst nightmare, seeing his beloved hobby being turned into just one more VLSI inside a tablet. The end of audio as we have known it.
This too shall pass.

Whether we, here, will be alive to see and hear it, is another question.
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Old 18th February 2012, 04:55 PM   #2596
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Quote:
Originally Posted by dvv View Post
What I find to be regrettably different these days in compaison with those days is a loss of drive, loss of impetus to get out there and really do something better. We seem to have lost a kind innocence, if you like, we had in those days. A perhaps foolish and naive concept that we could change something.[snip]
I fully agree with you. Yet, there are many out there that still 'go out and really do something better'.
I try to capture that, twice per year, in my Linear Audio bookzines.

Sure, there's not enough to support a multi-10k-copies monthly, and Linear Audio doesn't make any money.
But the interest is there, and the very high level of designs and analysis is there as well, you just have to look for it.

jan

Disclosure: I am the editor & publisher of Linear Audio
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Old 18th February 2012, 05:05 PM   #2597
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Not wanting to derail the current direction of the thread and drag it back to where it was a few weeks ago, but I found the part of the conversation discussing different design techniques and topologies for power amps quite interesting, particularly different approaches to feedback like high open loop gain with high total loop feedback vs local degeneration with lower open loop gain and feedback etc... and the seeming inadequacy of "conventional" measurements like THD to describe whether an amplifier sounds good or bad...

I have to admit that in years gone by I've been a bit of a sceptic about one amplifier that "measures well" sounding any different from another amplifier that also "measures well", (given how small the measurement differences between good amplifiers are, compared to the huge differences in measurements between one speaker design and another) but I now have to admit that I have heard amplifiers that sound significantly better than many others yet don't measure particularly different, at least in terms of frequency response and distortion.

(I'm aware that there are certainly more advanced measurements than this that can be taken, but not being an amplifier designer myself I don't know what they might be, and which might correspond to perceived quality, which I guess is the whole point of this thread...)

Out of curiosity I've attached the schematic of an amplifier that I particularly like the sound of, which measures well with conventional measurements but I find sounds significantly better than many other similar spec amplifiers I've heard, and I'm quite interested in any comments from the likes of Wavebourn and ThorstenL on (a) whether they think the design is good or bad in their opinion and (b) whether its just a typical by the numbers "textbook" design or whether there is anything clever/unique/novel about it that might account for a subjectively pleasing result. (or is it all just in my head )

Extra points for recognising/guessing what brand/model it is
Attached Images
File Type: jpg main amp1.jpg (399.2 KB, 95 views)
File Type: jpg main amp2.jpg (387.9 KB, 95 views)
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Last edited by DBMandrake; 18th February 2012 at 05:16 PM.
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Old 18th February 2012, 05:12 PM   #2598
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Bcarso, good for you in looking at the articles and controversy in TAA in the late 70's. Please remember that in those days, home computers were crude, and we hand typed our LTE's and submitted them by mail. One important person who you might unfortunately overlook, is Dr. Rod Rees and his articles of listening tests. Please check him out.
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Old 18th February 2012, 05:31 PM   #2599
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Originally Posted by DBMandrake View Post
... Extra points for recognising/guessing what brand/model it is
Aaaa, ... that'd be some kind of Luxman, boss.
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Old 18th February 2012, 05:38 PM   #2600
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Originally Posted by john curl View Post
Bcarso, good for you in looking at the articles and controversy in TAA in the late 70's. Please remember that in those days, home computers were crude, and we hand typed our LTE's and submitted them by mail. One important person who you might unfortunately overlook, is Dr. Rod Rees and his articles of listening tests. Please check him out.
Let me just add that as far as I am aware:

1.NONE of the controversies and/or questions raised then have been resolved to this day, althoug some have been greatly clarified since those days, and

2. Not many - indeed, if any - siginificant and crucial new questions have been raised, and those that have, are mostly variations to those "old" themes.

Which to me clearly shows that THOSE were the days of true innovation, while these are the days of mostly compliance to marketing laws.
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