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Multi-Way Conventional loudspeakers with crossovers

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Old 28th September 2009, 01:00 AM   #6231
soongsc is offline soongsc  Taiwan
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Quote:
Originally Posted by gedlee View Post
...
Also, I somehow find it hard to believe that all electronic circuits engineers are incompetent. Looking at the effects of out of band signals was fundamental in automotive - it was ALWAYS done. And that could be some pretty bad sounding stuff. At any rate, any engineer who worked in automotive would certainly know to do this. Did none of them ever make it into audio design? And these problems are not so tough to deal with. A simple cap in the right place and of the right type and value and "poof" problem gone.
I really takes as much effort to do good electronics as it does good waveguides. If you calculate the amount of manhours you spent in development and converted them to $, most companies find it hard to beleive they should pour such investment. As Lynn mentioned, most circuits are out of the application notes; if it works, and the other managers feel it good enough, there is no justification to spend more manhours. There was a little company that did some work on an amplifier. When they got merged back into a mother company, the new managers could not figure out why a project too so long.
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Old 28th September 2009, 02:15 AM   #6232
gedlee is online now gedlee  United States
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Originally Posted by soongsc View Post
I really takes as much effort to do good electronics as it does good waveguides. If you calculate the amount of manhours you spent in development and converted them to $, most companies find it hard to beleive they should pour such investment. As Lynn mentioned, most circuits are out of the application notes; if it works, and the other managers feel it good enough, there is no justification to spend more manhours. There was a little company that did some work on an amplifier. When they got merged back into a mother company, the new managers could not figure out why a project too so long.
When I was at Ford many of our components (amps, Cd players and the like)were made by other companies. Companies like Sony, Pioneer, Harmon, Panasonic, etc. The engineers at these companies were all very good and would never have missed something like is being claimed here. Maybe thats why my $200 Pioneer amp sounds so good while the mega buck Hi-end stuff has all these problems.
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Old 28th September 2009, 02:53 AM   #6233
soongsc is offline soongsc  Taiwan
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Quote:
Originally Posted by gedlee View Post
When I was at Ford many of our components (amps, Cd players and the like)were made by other companies. Companies like Sony, Pioneer, Harmon, Panasonic, etc. The engineers at these companies were all very good and would never have missed something like is being claimed here. Maybe thats why my $200 Pioneer amp sounds so good while the mega buck Hi-end stuff has all these problems.
Some day I'll arrange for comparision between the rich and the poor. Once I walked into an audio store, and saw a locally designed CD player which received good reviews, and asked how it comnpared against another $$$ player. The owner mentioned that the difference was mostly in playback of highly complicated music and the capability to reveal the detail. I think some day I will dig into this, but still I think the critical issue in audio is speaker performance. For now, the most I do is change the power cord on the CD player to a thicker one.
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Old 28th September 2009, 03:46 AM   #6234
Pano is offline Pano  United States
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Originally Posted by gedlee View Post
Maybe thats why my $200 Pioneer amp sounds so good while the mega buck Hi-end stuff has all these problems.
In some ways, yes, quite likely. But that does not mean that all $200 amps sound great.

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Originally Posted by soongsc View Post
For now, the most I do is change the power cord on the CD player to a thicker one.
A good external DAC can make a nice a improvement. But I'm biased in that dept.
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Old 28th September 2009, 09:39 AM   #6235
soongsc is offline soongsc  Taiwan
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If I really wanted to work on a CD player, I would do it in the following priority using a player with HDCD decoding capability:
1. Power supply.
2. Clock.
3. Transport.
4. Noise reduction.
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Old 28th September 2009, 12:51 PM   #6236
gedlee is online now gedlee  United States
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Originally Posted by panomaniac View Post
In some ways, yes, quite likely. But that does not mean that all $200 amps sound great.
I have never said that! I have only ever said that very good $200 amps DO exist. These are vastly different claims.

In fact of the receivers that I test, on average most were not any good, but the Pioneer was. In general the "discrete" amps were very bad and some of the chip amps were pretty bad.
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Old 28th September 2009, 01:22 PM   #6237
Bill F. is offline Bill F.  United States
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Dr. Geddes,

What's your Pioneer's model number?
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Old 28th September 2009, 02:22 PM   #6238
Pano is offline Pano  United States
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Quote:
Originally Posted by gedlee View Post
I have never said that!
Sorry! Did not mean to imply that you did. Not at all. That was my comment.

Quote:
In fact of the receivers that I test, on average most were not any good...
A better way of putting it.
I was having a poke at $200 amps.

Last edited by Pano; 28th September 2009 at 02:26 PM.
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Old 28th September 2009, 04:15 PM   #6239
mige0 is offline mige0  Austria
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Quote:
Originally Posted by gedlee View Post
If you want speakers that "bring a lot of magic out of rather poor recordings" then we are certainly "after completely different things" To me a poor recording should sound like, well, a poor recording. I must be nieve, but that just seems like such an obvious requirement for "Hi-Fidelity".
Its simply a question to bring out the best of what's in there - let the nuggets shine through – see it as a matter of focus.


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Originally Posted by gedlee View Post
..A good friend of mine is a classical pianist with many CDs to his credit. He played one for me on my system that was truely an inspired performance of a solo piano "Rite of Spring" - the only recording of this score available anywhere. He, of course, asked me how I liked it. I said the performance was "magical", "too bad the recording was flawed". He was agast. "Where?" So I showed him. He listened and listend and said "there's no mistake there". He could not hear the clipping. I had to show him on Cool Edit how the waveform had been clipped by a particularly loud passage. And then he listened again and again. Finally after he ceased to hear his performance he heard the clipping. ...
nice story – reflecting partly also my experience.


Quote:
Originally Posted by gedlee View Post
...I have only ever said that very good $200 amps DO exist. ....

In fact of the receivers that I test, on average most were not any good, but the Pioneer was. In general the "discrete" amps were very bad and some of the chip amps were pretty bad.


Given the essence of this thread
Geddes on distortion measurements
I suggest to take such statements with some grain of salt



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Old 28th September 2009, 04:39 PM   #6240
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Originally Posted by Lynn Olson View Post
The slewing problem for DACs, CD players, and HT receivers only exists in one stage, the I/V converter, or is buried deep within the DAC chip itself, for voltage-mode devices (where it cannot be removed or bypassed). That's the real merit of passive I/V conversion - a resistor and lowpass cap to ground aren't going to slew. But this approach is not that common.

<snip>

How many CD players use passive I/V conversion or ultrafast electronics? Very very few. The problem is simply ignored, since reviewers don't care or even know about it, and it doesn't show up on conventional measurements, so the chip vendors don't care either. Out of sight, out of mind.
Actually Lynn, there are several ways round this problem; see for example the paper by Martin Hawksford, which has 3 approaches documented.

I thought had invented something clever in this area, and started doing a patent application, but it turned out to already be in an Analog Devices application note. The basic idea is to avoid slew rate limiting in the op-amp, by bring the dominant pole compensation out to the virtual earth point, before any active devices. In simplest terms, you just put a cap from the inverting input to earth, which reacts with the feedback resistor to form the dominant pole, shunting HF to ground before the input device.

For best effect, it needs a chip or discrete design that is completely externally compensated, but you can get a win with internally compensated devices too. Loop stability needs to be managed.

This idea filtered out to the Twisted Pear guys, where it is known as "the cap mod".
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