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Old 24th April 2014, 10:53 AM   #21
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Quote:
Originally Posted by planet10 View Post
Most loudspeakers cannot reproduce a reasonable facsimile of a square wave -- it takes very good phase response & very extended HF extension.

Accurate is also a very hard term to nail down.

dave
Infinite low end extension also.

Dan.
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Old 24th April 2014, 11:56 AM   #22
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Quote:
Originally Posted by Max Headroom View Post
Infinite low end extension also.

Dan.
Why would you need 'infinite low end extension' to reproduce a square wave?
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Old 24th April 2014, 12:09 PM   #23
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The "roof" and "bottom" of a square wave are tilted when the latter is fed through a highpass. The closer to the cutoff frequency, the more it is tilted. And two octaves for instance can already be considered close. Thats why I doubt the 100 Hz measurement shown for the Rehdeko speaker. Apart from that: IIRC all Rehdeko speakers were reflex boxes which can't have such good square-wave reproduction at such low frequencies.

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Charles
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Old 25th April 2014, 07:27 AM   #24
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Dear All, i thank you very much indeed for all the very kind and valuable advice.
I have still one question, i swear the last one, even more basic than the original

Is it important that a driver (i.e. a woofer, a midrange or a tweeter) gives a good performance when asked to reproduce a square wave ?

My feeling is yes, but i would like to get some confirmations on this issue.
Because everything starts with the right selection of drivers
and the square wave test could be a very useful tool to perform this selection in my view.
Then after this we can talk about xovers.
Thanks again and kind regards,
gino
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Old 25th April 2014, 07:41 AM   #25
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Quote:
Originally Posted by ginetto61 View Post
Is it important that a driver (i.e. a woofer, a midrange or a tweeter) gives a good performance when asked to reproduce a square wave ?
gino,

Some background on what a square wave is Square wave - Wikipedia, the free encyclopedia.

Due to their limited bandwidth nowoofer,mid, or tweeter have any hope of doing a square wave. A really extended full-range driver would have the best shot, but alas, even today's best full-range is still only a wide band driver, and would still have some tilt.

dave
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Old 25th April 2014, 08:46 AM   #26
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Quote:
Originally Posted by planet10 View Post
gino,
Some background on what a square wave is Square wave - Wikipedia, the free encyclopedia.
Due to their limited bandwidth nowoofer,mid, or tweeter have any hope of doing a square wave.
Hi thanks and sorry if i am hard of understanding
But this applies also in their best range ?
I mean, a woofer has no chance to give a good 150 Hz square wave ?
I understand that outside its best working range will be poor ... but in its better range ?
Moreover ... what about a tweeter ?
If we agree that the square wave test is telling a bad behaviour should be a bad point.

Quote:
A really extended full-range driver would have the best shot, but alas, even today's best full-range is still only a wide band driver, and would still have some tilt.
dave
Thanks and again if we agree about the importante to give back a decent square wave this is a very strong point for full range drivers.
Because one thing is to have some tilt another one is to have a not acceptable response.
After all these years i am open also to uncoventional options.
Very open ...
I am willing to rethink entirely my approach to system set up.
Thanks a lot again and kindest regards,
gino

P.S. lately i have concluded that a full understanding of drivers behaviour is fundamental to get decent performance
Maybe it is a little trivial for many but still ...

Last edited by ginetto61; 25th April 2014 at 08:52 AM.
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Old 25th April 2014, 09:00 AM   #27
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Quote:
Originally Posted by ginetto61 View Post
a woofer has no chance to give a good 150 Hz square wave ?
A square wave can be decompossed into a sin wave fundemental + an infinite number of odd harmonics...

so lets look at this woofer(hopefully my math is right... i should be in bed asleep).

150 Hz fundemental, then 600 Hz, then 2.4KHz, then 9.6kHz... it can't really do that last one, so with only 2 harmonics so we have a REALLY poor representation of a square wave...

amps that have good square waves have flat response from really low to really high (100+ kHz)

dave
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Old 25th April 2014, 09:22 AM   #28
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Odd harmonics of 150Hz: 3rd 450Hz, 5th 750Hz, 7th 1050Hz, 9th 1350Hz etc.

Basically every odd multiple of the 1st harmonic (or fundamental if you choose to call them overtones instead).

What you listed looks like odd octaves.

Last edited by Charles Darwin; 25th April 2014 at 09:37 AM.
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Old 25th April 2014, 09:50 AM   #29
soyuz is offline soyuz  Chile
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the use of square waves for audio testing is very interesting specially at the end of the chain (speakers) , here is a very good thread from another forum:

Square Wave Response, Measured Acoustically


food for thought:
in one of the paragraph the OP writes
"none of my CD/DVD players could produce a decent square wave"

this can also be the case for vinyl:

Click the image to open in full size.

Click the image to open in full size.

if the most common sources for music are not accurate enough to produce a good square wave... hmmm ....
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Old 25th April 2014, 10:13 AM   #30
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Quote:
Originally Posted by soyuz
food for thought:
in one of the paragraph the OP writes
"none of my CD/DVD players could produce a decent square wave"
It is vitally important that a CD record/replay chain cannot produce a "decent square wave". Being able to produce a square wave means that one or both of the anti-aliasing and reconstruction filters are missing or faulty.

Quote:
if the most common sources for music are not accurate enough to produce a good square wave... hmmm ....
The issue is not 'accuracy' but filtering. You can't reproduce a square wave through any finite bandwidth system. All music sources have finite bandwidth. For music this is fine. For square waves this is disastrous. Hence naive square wave testing is unhelpful and misleading.
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