time delay problem JBL 4343 (3143 network)

[B&KMan]

Time delay problem JBL 4343 (3143 network)

Hello fantastik group !!

(sorry for my poor english)

Recently, I run test calibration with my analyser for check spectrum response on driver.

Big surprise result the time delay integration is little false on cross-over 3143.
The time delay is 0,671 MS more faster for the 2405 for th rest of the drivers.

Well this effect is not change pretty well the sprectrum response but ruin the phase match...

Do you have any information for modification, repair or upgrade cross over for fix this effect ??

(I attache too small pict where the phenomenon is produce.)
thanks

[boputnam]

Originally posted by B&KMan
Do you have any information for modification, repair or upgrade cross over for fix this effect ??

Well, I ain't no expert in this, but one solution would be to take the 3143 out of the signal path, and go with an external four-way active crossover and time-delay the four signal components until you get the result you need.

Or, just have another glass of fine red wine, and sit back and enjoy the pleasures of vintage JBL engineering!

[B&KMan]

I hope found the trick for sending better pict in regards with the limitation forum.

[B&KMan]

Originally posted by boputnam
Or, just have another glass of fine red wine, and sit back and enjoy the pleasures of vintage JBL engineering!

Yes this second option is particulary work : the acohol have a hight fading effect in high frecuency perception...

and again...

[GordonW]

I'm just wanting to be clear here- so, the bigger of those two spikes on the time response curve, is ALL THREE of the other drivers in the 4343 stacked up on top of each other, ie, the midrange horn, the midbass and the woofer? If so, that's pretty remarkable... that would very consistent response from drivers of different mechanical acoustic centers.

My suggestion, might be to seperate JUST the 2405 from the other three drivers- run a tri-amp setup- with the 2231/2235 woofer on one amp, the 10" midbass and mid horn on one amp, and the 2405 on a third amp. Then, use a digital time delay, to delay the 2405 .67ms. That shouldn't be too terribly hard- all you'd have to do, is seperate the 2405's crossover section from the rest, and just run another amp from a time delay unit for just that tweeter and crossover...

[Bill Shenefelt]

Might another approach be to run the horn and slot radiator on a single amp and the midbass on a second one and the bass on a third? The way the physical configuration is right now is with the 15 inch in a 6 cu ft enclosure like an L300 laying on its side (It was the same box I had used in the home built L300) A second box about 15 inches square on the front face contains the 10 inch midrange. It just lays on the bass box. The face of the box for the 10 inch is extended vertically upward and free air mounted to that face are the horn and slot radiator. These could be moved rather than using an electronic delay.
My main problem right now is that after I changed from the 3 way design of the L300 to the 4 way design incorporating the 10 inch midbass the system sounded "warmer" but lost the great punch it once had. I thought a mismatch of the crossover from 15 inch to 10 inch was the culpret. The 15 could no longer go up to 800 cps and possibly provide the leading edge of the waveform. This is just what I imagine to be happening.
I do have coming to me a 3 way crossover from Marchand currently configured for either a 300 or 400 cps 24/ocatve for the cone speakers and provisions for adding a 1200 cps crossover for the cone to horn interface. Looking for the best way to set it up right now. I want to recover the nice punch I had with the L300 setup, yet keep the warmth I get with the 10 inch. All drivers and passive crossover design and parts are from the 4343 but I have no 4343 15 to 10 inch cone passive and wanted to use active there if beneficial. With my age and ears I cant hear much from the slot readiator anyway.

I'm just wanting to be clear here- so, the bigger of those two spikes on the time response curve, is ALL THREE of the other drivers in the 4343 stacked up on top of each other, ie, the midrange horn, the midbass and the woofer? If so, that's pretty remarkable... that would very consistent response from drivers of different mechanical acoustic centers.

My suggestion, might be to seperate JUST the 2405 from the other three drivers- run a tri-amp setup- with the 2231/2235 woofer on one amp, the 10" midbass and mid horn on one amp, and the 2405 on a third amp. Then, use a digital time delay, to delay the 2405 .67ms. That shouldn't be too terribly hard- all you'd have to do, is seperate the 2405's crossover section from the rest, and just run another amp from a time delay unit for just that tweeter and crossover...

[Chas]

Bill, this should not be a problem. Per my PM earlier today, I moved from three ways to four way 4345's and certainly found nothing missing in this department.

If I recall correctly, the 2122H's in my 4345's need to be installed in 0.5 cu.ft. enclosures for optimal transient response. Mine have a light fibreglass fill, covering the rear and all sides. I think it's about 0.5 to 1" thick. What box volume and fill are you using?

[Bill Shenefelt]

My suggestion, might be to seperate JUST the 2405 from the other three drivers- run a tri-amp setup- with the 2231/2235 woofer on one amp, the 10" midbass and mid horn on one amp, and the 2405 on a third amp. Then, use a digital time delay, to delay the 2405 .67ms. That shouldn't be too terribly hard- all you'd have to do, is seperate the 2405's crossover section from the rest, and just run another amp from a time delay unit for just that tweeter and crossover...

With the active substituted for the passive 077(2405) using a 24/octave at 300 and the 077 at 9000(?) with 24/0ctave is that the delay needed or is it different. I would think the phase would shift and the delay would be quite different compared tog using 24/octave. I can use whatever is best in tthe active 3 way and get is set for the needed delay. Physical location of the drivers would suggest to delay the top and bottom bands to move them back to the location of the horn output, not the other way around or is the target to get summed outputs not time alignment? . Ellectrical stuff always did not make sense to me like mechanical stuff did. Even looking at the schematic on the 3143, what are the driver crossover slopes. I have a tough time discerning zobels from hi from low in the bandpass network for the horn. The 10 inch and slot radiator crossovers look like 12/octave but the horn (12 at 1200 and 6 at 9000????)

[B&KMan]

Originally posted by GordonW
I'm just wanting to be clear here- so, the bigger of those two spikes on the time response curve, is ALL THREE of the other drivers in the 4343 stacked up on top of each other, ie, the midrange horn, the midbass and the woofer? If so, that's pretty remarkable... that would very consistent response from drivers of different mechanical acoustic centers.

YUP, the rest of the driver is very consistent time delay integration. But other hand the lower frequency is low = long in time so, the impulse test response on lower frequency is too long for test as the same rate speed.

But my many test with corrolaire speed vs frequency is expose excellent integration for the rest of driver... Superbe job.

but if the engeener is macht delay of the HF why is not ability to match UHF ??? the rest of picture is too clean for I accept this delay...
---
If I calculate the distance to backward UHF driver for delay alignment: it is +- equal to position of the HF diaphram position (back 22 cm) (sic)

Unfortunately I'm not very good in electronic theorie and I have difficult to understand if my cross-over (3143) is busted in one component or is a error design... or mismatch connection inside cross-over...

but this problem is same at two monitor in exact same time delay result.

this time delay it is consider small or realy problematic ???

[Ian Mackenzie]

JBL has previously published a grou delay for this and other monitors. They claimed its group delay falls within the accepted limits of human perception (ref Sound Engineering John Eargle)

Ian

[B&KMan]

Originally posted by Ian Mackenzie
JBL has previously published a grou delay for this and other monitors. They claimed its group delay falls within the accepted limits of human perception (ref Sound Engineering John Eargle)

Ian

WOW !!! you have a big and precious conncection

It is possible to give the link or exact reference of paper or copie paper

please please please

I'M shure anybody is real interestd by this paper issue.

[Guido]

Originally posted by boputnam
Or, just have another glass of fine red wine, and sit back and enjoy the pleasures of vintage JBL engineering!

Bo,

[Ian Mackenzie]

Originally posted by B&KMan
WOW !!! you have a big and precious conncection

It is possible to give the link or exact reference of paper or copie paper

please please please

I'M shure anybody is real interestd by this paper issue.

Are you kidding.

Go buy the book on Amazon, millions of copies sold

ISBN: 0442222211

My copy is currently on loan to Kent English Passlabs

Ian

[boputnam]

Originally posted by Ian Mackenzie
(ref Sound Engineering John Eargle)

Sound Recording by John Eargle - on Amazon:

http://www.amazon.com/exec/obidos/tg...glance&s=books

My copy is way too valuable to loan-out to any hi-falootin' audio wizard in the mystical Sierra...

[Ian Mackenzie]

My copy is way too valuable to loan-out to any hi-falootin' audio wizard in the mystical Sierra...

I find sharing knowledge the most valuable aspect of this interest.

Those who don't stand dormant.

The question is Bo do you understand and have learnt from the John Eargle text or does it sit gathering dust in the bookcase.

"For those unaware Kent is a physicist formerly of the nuclear energy commission and one of the nicer people I met in my travels and the least I could offer for his hosting & friendship was a permanent loaner of my in-flight reading. Besides I plan to order the current edition soon enough."


Ian