Interesting books....

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#141
It absolutely wrong we do make more with less ressources
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I own a McIntosh MC-30 amplifier. Itr's 30 -40years old. It weighs about 30 lbs (13 -14 kg).
It puts out 30 watts. It cost when it was made about $150. For the same money now I can buy 5.1 receiver with better technical performance and it will weigh half as much. If adjusted for inflation today's new product putting out same technical performance is a price level 80% less..

A better comparison would be a UCD module. $100 us and 180 watts and about the size of a small paperback book and weighs about 100grams. In terms of energy expenditure it must be at least 3 times as efficient and possibly lots more. It puts out a really clean signal. http://www.hypex.nl/

So, we do more with less, and it costs less in absolute terms

(Cars weigh less than 30 years ago, engines weigh less, engines of the same displacement have better efficiency, they are more comfortable, handle better, brake better, are safer. Today's bad car is much better than 30 years ago good car.)

You want to turn an already bizarre discussion into a political -if not religious one-

we only export problems from the US to other countries. Oil needed each person and year, USA 24 barrel, China 1 barrel
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China has a population of over a billion and is moving from a mostly agrarian economy to a modern one. It's energy requirements will increase enormously. A mark of modernizing societies is increased use of energy. It's certain the country will over the next twenty years move to more efficient energy technologies, as will the rest of the world.

Were does all the toxics from chip mass production go ? asia.
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Another mark of modern societies is increased demand for amenity. Asian populations will demand, and get, clean air and non polluting industries as the rest of us have.

The world doesn't work for perfection - it works for good enough for now.
 
#142
john curl said:
By the way, you had trouble with complementary differential inputs? How, why? Because Doug Self didn't invent them? ;-)
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No actually,.....i found pseudo complementary drivers very appealing when i was an engineering student, easily impressed by the phony symmetry designed by pillars of subjectivism.....

Unfortunately, many years and experiments later, i am satisfied that the appeal was and is superficial....

More to do with what some people grasp with their hands rather than with their minds..... 😉
 
#143
on thread...

Hi All,

To restart the original intent of the thread...

I have a couple of books by John Linsley Hood I quite like, "Audio Electronics" and "The Art of Linear Electronics", not as college level texts, but certainly for a good overview of the various audio technologies and some quite detailed presentations of some of his designs...sort of similar to NP's Zen articles.

Stuart
 
#145
Where......?

I think that I know:

He makes it up to watch us go nutz!

Right???

Sometimes I think he is a perverse pysch grad student, making up this stuff as some experiment so he can write thesis on it.

(Hey......I live in Texas......we live for conspiracy theories!)

OTOH....he did write some nonsense article on SOA protection. There is the root of some of his ideas.

Jocko
 
#146
Only an indirect relation to audio but if you are interested in maths Mathematics: From the Birth of Numbers by Jan Gulberg. I find it not only interesting but useful as a reference as well.
BTW are there ANY reasonably useful DSP text books that won't make your brain explode?
Also interesting. Green Eggs and Ham.
 
#147
Re: Where......?

Jocko Homo said:
OTOH....he did write some nonsense article on SOA protection.
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Jocko, did you read it? I've got a copy if you or anybody else wants one. Some of the views in the article may be controversial, but there's quite a lot of design equations in there that are extremely useful for designing SOA protection circuitry. In fact, it's the best reference for SOA protection circuit design I've ever seen. In particular, there's a triple-slope protection circuit design in there that's probably better than anything in any commercially available amp. Unless they copied his.

Of course, protection circuit design isn't sexy, since it can't improve the sound. But the sound of an amp that's working sure beats the **** out of one with a blown output stage 🙂 .

If you take the time to give it a thorough read, you'll see that the analysis of one popular protection circuit shows that it can go into false triggering even with an open circuit load on the amp! There is popular folklore that says that all protection circuits must necessarily degrade the sound. I suspect this came from listening tests of improperly designed circuits. It's actually pretty difficult to design one that doesn't go into false triggering with a highly reactive load. So it's no wonder that such legends have become accepted as fact. When it comes to determining fact from fiction, I'll take rigorous technical arguments from anybody over the hand-waving of a "guru".
 
#148
rfbrw said:
Only an indirect relation to audio but if you are interested in maths Mathematics: From the Birth of Numbers by Jan Gulberg. I find it not only interesting but useful as a reference as well.
BTW are there ANY reasonably useful DSP text books that won't make your brain explode?
Also interesting. Green Eggs and Ham.
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Heeeeeeeello! You rang?

Try "A Digital Signal Processing Primer" by Ken Steiglitz, or
"Understanding Digital Signal Processing", Richard G. Lyons.

Steiglitz goes from continuous time systems (analog style) to sampled systems (digital style) via filters; indeed much of his book talks about filters of various sorts. His approach is somewhat idiosyncratic but useful nonetheless.

Lyons goes from sampled systems right into FFTs (Fast Fourier Transforms) for a few chapters, then to FIR (Finite Impulse Response) filters before approaching transformation from the continuous to the discrete time domains. Lyons' approach is more classical, modulo the early emphasis on FFTs, and his treatment of IIRs is superb. Both of the above are reasonably text-oriented for engineering texts.

Once you're done with those, try
"Digital Signal Processing", Proakis and Manolakis, and.
"Discrete-Time Signal Processing", Oppenheim and Schafer.
These are heavier books, so you really want to understand the introductory material first. Trusssst me.

Each author brings unique strengths to their teaching, so it wouldn't be out of place to get all four books and read them in the sequence listed above. Don't expect to be done in a week. You WILL be looking at a fair number of equations and diagrams, so bring a helmet. Exploding brains are part of the agenda. 😀


Cheers,
Francois.
 
#149
Yes, I've read it.

Controversial in the respect that guys like me will contend that with modern output devices, and good engineering practices, SOA protection is probably not needed.

Many of us feel that Mike overdramatises all that can go wrong. Nothing wrong with his analysis if you concede that point. So, to us dumb hillbilly engineers, it is an academic exercise.

I wonder if GA Tech qualifies as "hillbilly"? It is in the South, and the AES pooh-poohs most everything that Prof. Leach comes up with.

BTW......thanks Francois. Many of us would like to learn that, sans brain explosion.

Jocko
 
#150
Re: Yes, I've read it.

Jocko Homo said:
Controversial in the respect that guys like me will contend that with modern output devices, and good engineering practices, SOA protection is probably not needed.

Many of us feel that Mike overdramatises all that can go wrong. Nothing wrong with his analysis if you concede that point. So, to us dumb hillbilly engineers, it is an academic exercise.

I wonder if GA Tech qualifies as "hillbilly"? It is in the South, and the AES pooh-poohs most everything that Prof. Leach comes up with.

BTW......thanks Francois. Many of us would like to learn that, sans brain explosion.

Jocko
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That article was pretty good I thought, clear, logical and to the point, if somewhat long-winded. If you think your amp "probably" can do without protection, Jocko, you may want to more accurately look at the SOA. Unless you put so many output devices in parallel that you can survive anything.

Jan Didden
 
#151
Re: Yes, I've read it.

Jocko Homo said:


BTW......thanks Francois. Many of us would like to learn that, sans brain explosion.

Jocko
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It's not that bad, really, if you take the material in bite-size chunks and make *sure* you understand each part before going to the next. That's why I have a small quibble with Lyons starting with FFTs, since they add some complexity while being somewhat orthogonal to learning elementary filtering operations. (Later on, of course, FFTs become vital if you want to compute big FIRs.) I prefer Steiglitz's approach, which is the reason I listed his book first, although he introduces a couple of things I haven't seen much used elsewhere.

Anyway, work the texts slowly and you'll be fine. The math starts off being not much tougher than working out a Sallen-Key filter or a gyrator. Some of the concepts start off feeling a bit strange for analog folks, but there's all kinds of neat tricks you can do with this stuff (none of which negates the value of having good analog after the DACs once the numbers are finished crunching!).


Cheers,
Francois.
 
#153
Re: Yes, I've read it.

Jocko Homo said:
.................with modern output devices, and good engineering practices, SOA protection is probably not needed.....
Jocko
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You wouldn't disable the brakes on your 'modern' car on the grounds that 'good engineering practices' make such unnecessary......Sophistry springs to mind... 🙄

OK Jocko.....how many complementary output devices do you build into your 100W power amps. to prevent them from blowing up in the event of a dead short to ground???????? :angel: :smirk: :sing:
 
#156
Hi, Mikeks,
Do you know who made the BSS FDS336? It is digital active Xover with time delay, eq. The unit is small, the functions are great and easy to handle. Is the one who programmed it is your friend?

Hi, Mr. Curl,
Is the "non global feedback" is trendy now among designers at your level? Sounds better than global feedback designs?
 
#157
john curl said:
......Digital essentially sucks!
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This is not neccessarily true.....depends on the source material, mastering, (i.e: is the recording AAD, ADD, or DDD......etc).....

Much of the older analogue material was poorly transfered to digital....Hence the persistent myth about 'inherently poor' digital quality...

To be fair, the first digital sources (circa '82), were crapulous.....This is most certainly no longer the case......
 
#158
lumanauw said:


You are right. I'm very lucky to have compared face to face "hi-end" CD player and "hi-end" turn table (with those Japanese exotic pick-up, made from spider's filament?), with the same album (Earth Wind and Fire, Phil Collins, Laura Fygy, etc).

What can I say. The "Old stuff" turn table excels the session. It has "air"and"lifeness" that CD player dont have. More tonal pleasure. There is a lack a bit of "scratch sound" when track is empty, but the sound of turn table is unbelieveable.
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An unfair comparison indeed! The EWF CD was very (extremely!!) poorly mastered....while the LP version was excellent... 🙄

So, far from establishing the merits or lack of both formats, all you managed to conform was the superior recording quality of the LP....

For example, compare marvin's sexual healing LP with the remastered CD here:

http://www.amazon.com/exec/obidos/t...f=sr_1_7/104-8070997-2718340?v=glance&s=music

The LP version does not even come close!
 
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