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Old 21st April 2012, 07:31 PM   #4601
jcx is offline jcx  United States
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while I know our guru's prejudices go the other way it is a easily demonstrated that high global loop gain reduces distortion components at frequencies where the loop gain is high (duh) - high loop gain in the audio band reduces errors measured by the feedback network, diff input that have audio frequency components - even IMD difference products from ultrasonic signals – even if the test signal is injected into the output stage from the speaker terminals

making sure that the input diff stage is linear with the test signal, expected source - local degeneration/fet input diff pair, 200KHz low pass in front of a audio power amp seems like good ideas

DSD does need heoric filtering to remove the rising with frequency shaped noise - should exceed 5 th order, Sony had to reduce the original rec of 100 KHz fc dow to 50 KHz afeter some audiophile amps had problems with the high frequency noise content

Last edited by jcx; 21st April 2012 at 07:35 PM.
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Old 21st April 2012, 07:38 PM   #4602
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Hi,

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Originally Posted by jcx View Post
while I know our guru's prejudices go the other way it is a easily demonstrated that high global loop gain reduces distortion components at frequencies where the loop gain is high (duh)
Actually, I never disputed this "greater distortion reduction where NFB amounts are high". Further, it is so brutally obvious, anyone to whom this is not immediately obvious should retake EE201, at a minimum.

However, would you mind elucidating us what this has got to do with the price of Jasmine Tea in China?

It has been known for the last 6+ decades, that "THD" is meaningless.

So what is your point?

Ciao T
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Old 21st April 2012, 07:43 PM   #4603
jcx is offline jcx  United States
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where did my post say anything about THD?
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Old 21st April 2012, 08:24 PM   #4604
SY is offline SY  United States
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Originally Posted by jcx View Post
where did my post say anything about THD?
It didn't have to. You're a criminal scientist, so we all know that what you're saying is in a secret code. The cognoscenti are merely performing a service by translating for the masses.
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Old 21st April 2012, 08:35 PM   #4605
a.wayne is offline a.wayne  United States
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Originally Posted by dvv View Post
For life like realism, good buddy, you also need to have a front end capable of it, and a back end (speakers) capable of reproducing something like 114 dB SPL in peaks.

And the size and furnishing of your room are also highly relevant factors.

Personally, I just made it. I have a small room, some 14*12 feet, fairly full of everything. My speakers do 92 dB/2.83V/1 m, and my Karan amp is rated at 180/250W into 8/4 Ohms. 180W/8 Ohms works out to 22 dBW, plus a single speaker's efficiency of 92 dB equals 114 dB. Two speakers in tandem will of course increase the actual SPL, but the room will soak up some of it, so let's assume I'm even on that point.

My point is, I know from first hand experience excatly what you are saying. But I must now dissapoint you - in real life, peaks of 114 dB are EXTREMELY rare, and I do believe 99.9% of all audiophiles have system which don't even get near that, yet play music very well. Also, both the HK 680 integrated (rated at 85/130 W into 8/4 Ohms) and the Marantz 170 DC power amp (rated at 85/8 Ohms) are extremely convincing in ANY reproduction.

Ah, if it all boiled down just to power ...
Size D, not just SPL, Lifelike , comes not from just SPL, but also from size. Small amplifiers and speakers can play loud, but the sound is hi-fi ish and there is no growth...

Listen to a single FR driver at 95db and compare it to a large 4 way at 95db, big difference ..
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Old 21st April 2012, 09:43 PM   #4606
tvrgeek is offline tvrgeek  United States
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OK A, just where does one get a full range driver? There are a lot of drivers with wider than the usual decade range, but none I have ever seen is full range. Even large ES panels, just can't get down to where , oh let's pick a simple multi-way, 2CE or good old B&W 801's can.
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Old 21st April 2012, 10:39 PM   #4607
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Quote:
Originally Posted by a.wayne View Post
Size D, not just SPL, Lifelike , comes not from just SPL, but also from size. Small amplifiers and speakers can play loud, but the sound is hi-fi ish and there is no growth...

Listen to a single FR driver at 95db and compare it to a large 4 way at 95db, big difference ..
It's a bit lame to say that it's not the size but what you do with it that matters, but it is true nonetheless. The problem with small speakers is mainly one of distortion at higher SPL. Driver technology is improving though, and in a moderately sized room, a 10 liter enclosure should get you a long way. No way in a 1-way though, 2-way minimum.
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Old 21st April 2012, 11:20 PM   #4608
tvrgeek is offline tvrgeek  United States
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All this confirms I need to address this in the speaker.
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Old 21st April 2012, 11:22 PM   #4609
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by tvrgeek View Post
OK A, just where does one get a full range driver? There are a lot of drivers with wider than the usual decade range, but none I have ever seen is full range. Even large ES panels, just can't get down to where , oh let's pick a simple multi-way, 2CE or good old B&W 801's can.
TVR,

What I said was a single FR driver cannot sound like a big 3 or 4 way speaker, even when playing at the same SPL. The major difference being dynamic compression, which relates to image size and Percussive energy.
Hit a tom tom and you will understand how speakers have difficulty with the acoustic power necessary for realism.

Quote:
Originally Posted by vacuphile View Post
It's a bit lame to say that it's not the size but what you do with it that matters, but it is true nonetheless. The problem with small speakers is mainly one of distortion at higher SPL. Driver technology is improving though, and in a moderately sized room, a 10 liter enclosure should get you a long way. No way in a 1-way though, 2-way minimum.
Small speakers lack percussive energy, of course small room , small speaker, there is no way around that, speaker to room ratio has to be optimized for proper reproduction ...
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Old 21st April 2012, 11:34 PM   #4610
tvrgeek is offline tvrgeek  United States
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a,
We agree on the result, but not at all on the reason. If you are thinking some 4", xmax of .5mm driver like is popular in the single driver-low power club, of course it can't produce the same levels. ( A dozen in a line array can) My point was no single driver is anywhere close to full range with respect to frequency, even large ESL's that do have the capability to provide dynamics within their bandwidth, they can't reach into the real bass.

Now put in a very limited bandwidth signal, like a 1K test tone. The 4" and the three way will probably sound identical. Why? the mid range IS basically the same as the FR. If they don't sound the same, at least one of them is wrong.

Yes, there is a reason I use two 12" woofers.
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