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Multi-Way Conventional loudspeakers with crossovers

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Old 23rd March 2006, 11:40 AM   #11
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Nice work there by Mr. Le Cleach, though his approach is not transient-perfect but transient-improved.
There are also some patents by John Meyer that deal with improved transient response AND uniform radiation.

Regards

Charles
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Old 24th March 2006, 02:21 AM   #12
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Thanks for the links to LeCleach. Haven't gotten through all of it yet, but I can see he aready raises some important points.
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Old 24th March 2006, 12:47 PM   #13
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PHASE ACCURATE
---There are many possibilities to achieve a transient-perfect response that don't need an additional driver like the filler driver concept does.---
---Nice work there by Mr. Le Cleach, though his approach is not transient-perfect but transient-improved.---

Any reference for transient-perfect crossovers ?
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Old 24th March 2006, 02:26 PM   #14
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O.K. I must admit that a really transient-perfect speaker doesn't actually exist. But there are transient-improved topologies that come close enough to be called like that.

1.) Single-driver fullrange.
2.) 2nd order with overlap and delayed tweeter
3.) 2nd and third order with overlap and EQing.
4.) The combination of points 2 and 3 like it is used in some active studio monitors (Meyer, K+H, Relec)
5.) Transient-perfect constant-voltage crossovers. Only the first order version can be done passively (i.e. the ordinary 1st order crossover). The other ones have to be built as active subtractive topologies.
6.) Digital FIR filters

2, 3 and 4 could even be done passively but one is better off with active solutions.

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Charles
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Old 24th March 2006, 03:19 PM   #15
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Hi Phase_Accurate,

The question, then, is : is a transient perfect response important ?
Most renowned authors and studies agree that it is detectable on some selected signals having special waveforms but not on programs (music...).

Nevertheless, if it is thought it must be an aim for ultimate fidelity, two remarks :
- the achievement of a transient perfect reponse must not be detrimental to the forward frequency response which is recognised as as the primary quality of the louspeaker (see Toole's studies among professionasl and critics).
- most improved transient crossover imply slow slopes. A hi-passed loudspeaker has a constant (12 dB/o) or increasing (6 dB/o) excursion down to its resonance, so it is prone to intermodulation.

Because of the transient nature of sound, easily associated with square waves, good figures for these last ones may have more impact than a linear frequency response on many customers or amateurs. For long, I was in this error despite the fact that my favourite speakers were not at all designed with consideration towards the transient response.

I am not sure to ever adopt the Le Cleac'h's solution, however I think it is a good compromise (easy to test with numeric crossovers such as the Berhinger DCX ) and worth to mention. Curiously, I should have think that people who have tried it and whom I am aware of would have show more enthousiasm.
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Old 24th March 2006, 03:44 PM   #16
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- most improved transient crossover imply slow slopes. A hi-passed loudspeaker has a constant (12 dB/o) or increasing (6 dB/o) excursion down to its resonance, so it is prone to intermodulation.
This is depending upon filter order in the same way as if used with non-transient perfect x-overs. I have to admit though that some transient perfect x-overs are less steep for a given order.

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Charles
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Old 24th March 2006, 05:10 PM   #17
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If I can exprime only my personal opinion,

Some renowned researchers, at his time , was able to "demonstrate":
- all amplifiers sound the same
- all cables sound the same
- A/D + D/A zero differences
- Mp3 was "sufficient"
- audiophile lovers have only mirages and imaginations...

Then I am not surprise if they claim the inaudibility of "transient perfect speakers".
I think we must experimentate with our head and our ears...

Good weekend at alls,

Inertial
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Old 25th March 2006, 06:29 PM   #18
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Since transient perfect speakers are 1.) not easy to build and 2.)>99% of all multiway speakers aren't transient-perfect it is not that astonishing that most designers regard it as unimportant ..........

Regards

Charles
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Old 25th March 2006, 08:39 PM   #19
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Even Le Cleach's admits that only few people are able to detect transient perfect responses. I would'nt deny the authorority of authors who have study the subject and who tell that this response is detectable with some signals and not on music. But there is one more question, difficult to answer. When listening to these special test signals, which are the prefered renditions : good transient or not ? When studying the audibility of group delays at very low frequencies, Fincham found that there was a detectable difference between small and large group delays, but he did'nt mention any preference among the testing listeners. A preference is not necessarily what one may think. It must not be forgotten that distorsions (group delay is a kind a distorsion) are not always interpreted as less good sounding.
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Old 25th March 2006, 11:06 PM   #20
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Phase_Accurate
---99% of all multiway speakers aren't transient-perfect it is not that astonishing that most designers regard it as unimportant---

Tests on the audibility of phase or group delay have made with earphones to eradict the uncertainty of transients rendered by traditional loudpseakers.


Inertial
You seem to imply that science and audiophily are contradictory. Statistically, the percentage of audiophiles among researchers in acoustic engineering must be higher than the percentage of researchers in acoustic engineering among audiophiles. Otherwise I may misunderstand the real meaning of the expression "audiophile".
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