JBL 4343B - bi-amped / active settings

[rafal_radom]

Dear colleagues,

I would like to ask you about your experience with the active crossover setting when 4343B bi-amped.
I’ve checked a lot of threads and ‘ve asked many questions (thanx Ian for your patience J).
First of all – trust your ears, so many tests and trials at home… but I’m still lost…

My room
17,5’ x 19,5’ /acoustical pro
Gear
Teac VRDS25 transport/ Lampizator DAC
Preamp Technics 30A
Active crossover: Luxkit Luxman A 2003 / Marchand XM26
Solid amp monoblocks Musa (bass) + tube monoblocks Luxkit Luxman A 3000
4343B --- toed in 12,5 / L-pads: MF turned max (+4); HF (+2); UHF (+2)
Placement
9’ apart (center to center) / 10,5’ speaker to listening position

back to my tests ...

1. Ian’s suggestion: “in BW 12db do use 230Hz and 350Hz as the 15 inch and 10 interact on the baffle. The logic is to minimise the coupling between the woofer and the mid vine by spreading thecrossover points. This recommendation is based on JBL crossover cards”

That is so interesting but I feel losing “weight” of sound. Lack of solid bass base (higher bass and lower mid) cause focus on HF. I could say – bright side

2. The other approach (230Hz / 280Hz) http://www.audioheritage.org/vbulletin/showthread.php?774-4355-3155-clones/page2 (http://www.audioheritage.org/vbulletin/showthread.php?774-4355-3155-clones/page2)

… here on the opposite way … loss of detail in the higher range. Here is the dark side ;-)

How to find the golden mean…?

Thank you in advance for any comments and suggestions.
Rafal /Poland/

PS. I plan to change the current 2121H on the 2123H and make a 4344mkII crossover… this may be beneficial?

[johnlcnm]

Not quite to your exact point, but I have had good luck stacking a 2nd. order B.W. filter - active, on top of the existing 2nd order high pass filter in a pair of 4333s. This in conjunction with a 4th. order L.R. low pass - active filter for the 2235 driver. The caveat is that the drivers must be time aligned. Easy to do with a DSP. With the 4343 this probably is not necessary. Here is some good information on L.R. networks: http://www.rane.com/note160.html

Regards,

John

[Goldjazz]

Dear colleagues,

I would like to ask you about your experience with the active crossover setting when 4343B bi-amped.
I’ve checked a lot of threads and ‘ve asked many questions (thanx Ian for your patience J).
First of all – trust your ears, so many tests and trials at home… but I’m still lost…

My room
17,5’ x 19,5’ /acoustical pro
Gear
Teac VRDS25 transport/ Lampizator DAC
Preamp Technics 30A
Active crossover: Luxkit Luxman A 2003 / Marchand XM26
Solid amp monoblocks Musa (bass) + tube monoblocks Luxkit Luxman A 3000
4343B --- toed in 12,5 / L-pads: MF turned max (+4); HF (+2); UHF (+2)
Placement
9’ apart (center to center) / 10,5’ speaker to listening position

back to my tests ...

1. Ian’s suggestion: “in BW 12db do use 230Hz and 350Hz as the 15 inch and 10 interact on the baffle. The logic is to minimise the coupling between the woofer and the mid vine by spreading thecrossover points. This recommendation is based on JBL crossover cards”

That is so interesting but I feel losing “weight” of sound. Lack of solid bass base (higher bass and lower mid) cause focus on HF. I could say – bright side

2. The other approach (230Hz / 280Hz) http://www.audioheritage.org/vbulletin/showthread.php?774-4355-3155-clones/page2 (http://www.audioheritage.org/vbulletin/showthread.php?774-4355-3155-clones/page2)

… here on the opposite way … loss of detail in the higher range. Here is the dark side ;-)

How to find the golden mean…?

Thank you in advance for any comments and suggestions.
Rafal /Poland/

PS. I plan to change the current 2121H on the 2123H and make a 4344mkII crossover… this may be beneficial?


Hi There I have a pair of 4343b's I biamp them with a First Watt B4. I think I settled on a 12 DB slope, low pass 230 hertz, high pass 300 hertz with the woofers out of phase. Actually I chose that on Ian's recommendation. Seemed to work well for me. Is it easy to configure different points with your X-over?

[rafal_radom]

Hi There I have a pair of 4343b's I biamp them with a First Watt B4. I think I settled on a 12 DB slope, low pass 230 hertz, high pass 300 hertz with the woofers out of phase. Actually I chose that on Ian's recommendation. Seemed to work well for me. Is it easy to configure different points with your X-over?

Hi,
Thats easy to adjust my Luxman x-over by the knobs.
In Marchand I need to change resistors each time I want different points.
As I explained I've checked so many crossover points.

I focus on male voices trying to find perfect balance between the woofer and mid one.
Ian said - 230 / 350hz and in fact that is very good choice but as I find clear sound (voice clarity), I lose bass volume a bit.

Can you hear significant pros or cons for 230 / 350 vs your 230 / 300 ?

Rafal

[Goldjazz]

Hi,
Thats easy to adjust my Luxman x-over by the knobs.
In Marchand I need to change resistors each time I want different points.
As I explained I've checked so many crossover points.

I focus on male voices trying to find perfect balance between the woofer and mid one.
Ian said - 230 / 350hz and in fact that is very good choice but as I find clear sound (voice clarity), I lose bass volume a bit.

Can you hear significant pros or cons for 230 / 350 vs your 230 / 300 ?

Rafal

Hi Rafal I will try 230 / 350 back to back and let you know. I suspect it will sound too thin as you commented. Will let you know. Have experimented with changing the phase of your woofers as well? I think this is needed with 12db. If you get it wrong it can thin out the bass a bit too.

[Mannermusic]

Hi,
Thats easy to adjust my Luxman x-over by the knobs.
In Marchand I need to change resistors each time I want different points.
As I explained I've checked so many crossover points.

I focus on male voices trying to find perfect balance between the woofer and mid one.
Ian said - 230 / 350hz and in fact that is very good choice but as I find clear sound (voice clarity), I lose bass volume a bit.

Can you hear significant pros or cons for 230 / 350 vs your 230 / 300 ?

Rafal

Second order crossover points (12 db/octave) need to be at least two octaves apart - it's simple physics. Three octaves is better. Otherwise, the slopes interfere with one another causing cancellation/distortion; loose any sense of acoustic coherence. Sound "strange" at best. I did all that when I was developing my 4-way and learning basic crossover design. You can plot the data and see for yourself - the curves are all over one another and simply cannot function. JBL did all this correctly - I hit the same values they did in the engineering development process. In terms of best overall sound, I found the lowest value for the woofer mid was 250 which put the upper at 1000 minimum (two octave spread). But, 270-300 / 1200 generally sounds best overall. It's a compromise in any case with those old 4-ways. But, any lack of clarity beyond this is likely rooted in acoustical phenomena related to the baffle/enclosure and the room environment. No magic. Mike

[rafal_radom]

But, 270-300 / 1200 (tel:270-300 / 1200) generally sounds best overall. It's a compromise in any case with those old 4-ways. But, any lack of clarity beyond this is likely rooted in acoustical phenomena related to the baffle/enclosure and the room environment. No magic. Mike

Mike,
Many thanks for some technical points!
I understood 270-300 for the MID to have the best match with HF driver (1200).
But still I have the open question how to adjust main woofer.
Playing biamped I could only install low pass for woofer and high pass for MID driver.
I know... trials and errors but so many have been done...


Hi Rafal I will try 230 / 350 back to back and let you know. I suspect it will sound too thin as you commented. Will let you know. Have experimented with changing the phase of your woofers as well? I think this is needed with 12db. If you get it wrong it can thin out the bass a bit too.

Thanks!
Woofers are out of phase. That is much better.

[Goldjazz]

Hi Rafal well I'm listening to 240 low pass 343 Hi pass (limited points i have to choose from) and its 12db/oct linkwitz riley. And I can say this is the best I've heard my 4343b's. It's tightened up the focus in the centre and it just all sounds really balanced and delicate. I will do some more experimenting and let you know. I've been listening to some Tannoy monitor red's for a while, and now coming back to the 4343's for a break of about a month or two it's very nice to be back with these improved settings.

The First Watt B4 has dip switches you can make up various combinations to make a crossover point. Will see if I can get something closer to 230/350 and let you know. I now can see the benefit in separting the two pass points a bit more.

Other important things I've done: Eliminate that awful biamp switch, this did make a big difference as mine was corroded badly. Also I connect directly to the woofers. Also the power amp I'm using for the Lows is a Perreaux 6000b will 300w (damping factor is good?). I also have nice fat speaker cable (as short as possible) to the Perreaux. I can also adjust the levels of the Low power amp (at the amp) and of the Highs (also at the amp). In addition hte First Wat B4 allows you to select either the high pass or the low pass for adjustment via knobs on the front. I have it setup to finely adjust the level of the highs.

[Goldjazz]

With my crossover I can choose Sallen Key at 6db or at 12 db or linkwitz riley at 12 db. It seems the Limkwitz Riley 12db 240/343 combo works best though it's not always easy to tell. It works better than Sallen Key 12 db 225/300 and also better than Sallen Key 12 db 225/350. I can't do linkwitz riley at 230/300 so I can't test that one. Not sure of the difference between the two types of crossovers. But to my ears the linkwitz riley 12db 240/343 sounds the most seamlessly integrated and is a good compromise between not being to thin in the bass but still clean and detailed in the highs. These things take a fair bit of listening and back and forth to get right I think. Will keep playing around with it.

[rafal_radom]

Hi,
Goldjazz - thanks a lot for your time and trials you have made.
Great!
I spent lot of hours during the weekend testing several different crossover points.
I could use only BR 12db but the conclusion is exactly the same as yours.
230/340 is the best compromise oferring perfect overall balance between the drivers.

I've also tried some different speaker placement.
Previously I had 9' distance apart between the speakers (center - center).
Now the speakers are 8 1/3' apart and 10' from the listening position.
More bass... but what about the quality?
I've checked some different toe in.
I was so surprise that even 2 or 3 degrees matter.

10 degrees - lot of bass but a bit boomy, out of control.
13 degrees - controlled, punctual but not as much when the speakers are more toed in.
Something between should be the best... compromise.

I will be grateful for any future suggestions.

PS. Electro-voice Interface Delta are on the way to me...
Will see and compare with the blue face beasts :-)

[Goldjazz]

Good stuff. I can also recommend using the software Room Eq wizard to see the frequency response, just download the free software and get a microphone or spl meter.

Ah yes ive been reading about the Interface series would be interested to hear what you think of it. Do you have the equaliser unit for it? I think I know where one is being sold. I also have a pair of KLH-1 speakers thhat have a sort of eqialiser box very nice speakers.