Results 1 to 7 of 7

Thread: 4343b-Bi-Amping with 5234 / 250 Hz?

  1. #1
    Junior Member 4343b_bremen's Avatar
    Join Date
    Apr 2011
    Location
    Bremen Germany
    Posts
    10

    4343b-Bi-Amping with 5234 / 250 Hz?

    Hello..

    I got a 5234 acrtive crossover with 2 x 250hz division..

    The internal crossover of 4343b (3143) cuts the bass at 300 Hz.. so the 5234 will separate only a 'third' kower. Do you think this is of importance for the performance of the bass-midrange 2120 ?

    The advantage is saving one big capacitor for the whole MHT-Unit and the inductor for the bass speaker in signal-flow..

    Andreas

    Name:  WEICHE3143_biamping.jpg
Views: 5186
Size:  226.9 KB
    JBL 4343b-monitors and vintage german fullrange-drivers

  2. #2
    Administrator Robh3606's Avatar
    Join Date
    Apr 2003
    Location
    Rocinante
    Posts
    8,704
    Try it. I biamp my 4344's and they sound great!

    Rob
    "I could be arguing in my spare time"

  3. #3
    Senior Member HCSGuy's Avatar
    Join Date
    Jan 2009
    Location
    Bend, OR
    Posts
    726
    I will preface this with the disclaimer that I have not bi-amped my 4343's, so my input is purely theoretical. When you switch the speakers to bi-amp, you bypass both a 52mf capacitor and a 2.9mh inductor on the HF side, and the 5.4mh inductor on the LF side. However, the bypassed components on the HF side, I think, function to attenuate the HF side, not as a HighPass crossover. the HighPass crossover is not defeatable, so if you use a standard 250hz card in the crossover, you will have two HighPass crossovers in the circuit (one active, one passive) and one LowPass, in this case at slightly the wrong frequency, and your frequency response hole will be even larger than you thought. JBL's factory bi-amp solution was the 52-5140 crossover card (labeled 4343 LowPass), which did not have a HighPass section - it passed HighPass through to the outputs, though I don't know if it had any attenuation. I think it was 275hz LowPass only, 12db/octave. In your case, you could approximate this by splitting the fullrange output of your preamp and sending one leg through the crossover for the LowPass (woofer), the other straight to an amplifier with a gain control for the HighPass (MF/HF/UHF).

    If I'm wrong on this, I welcome corrections

  4. #4
    Administrator Robh3606's Avatar
    Join Date
    Apr 2003
    Location
    Rocinante
    Posts
    8,704
    Take a look in the 5234 manual. To change your cards over to the 4343 you would need to change R1-R5 on the cards. Very simple modofication if you don't like how it sounds with the generic 250Hz card.

    http://www.jblproservice.com/pdf/Vin...-5233_5234.pdf

    When you switch the speakers to bi-amp, you bypass both a 52mf capacitor and a 2.9mh inductor on the HF side, and the 5.4mh inductor on the LF side. However, the bypassed components on the HF side, I think, function to attenuate the HF side, not as a HighPass crossover.
    Why??

    Rob
    "I could be arguing in my spare time"

  5. #5
    Junior Member 4343b_bremen's Avatar
    Join Date
    Apr 2011
    Location
    Bremen Germany
    Posts
    10
    Quote Originally Posted by HCSGuy View Post
    I will preface this with the disclaimer that I have not bi-amped my 4343's, so my input is purely theoretical. When you switch the speakers to bi-amp, you bypass both a 52mf capacitor and a 2.9mh inductor on the HF side, and the 5.4mh inductor on the LF side. However, the bypassed components on the HF side, I think, function to attenuate the HF side, not as a HighPass crossover. the HighPass crossover is not defeatable, so if you use a standard 250hz card in the crossover, you will have two HighPass crossovers in the circuit (one active, one passive) and one LowPass, in this case at slightly the wrong frequency, and your frequency response hole will be even larger than you thought. JBL's factory bi-amp solution was the 52-5140 crossover card (labeled 4343 LowPass), which did not have a HighPass section - it passed HighPass through to the outputs, though I don't know if it had any attenuation. I think it was 275hz LowPass only, 12db/octave. In your case, you could approximate this by splitting the fullrange output of your preamp and sending one leg through the crossover for the LowPass (woofer), the other straight to an amplifier with a gain control for the HighPass (MF/HF/UHF).

    If I'm wrong on this, I welcome corrections
    Hi..

    .. perhaps I am wrong, but I understand the network 3143 this way.. "If I'm wrong on this, I welcome corrections too "

    Name:  WEICHE3143_biamping_2.jpg
Views: 2202
Size:  120.2 KB

    Section "4" (red) is the switched-off part (low-cut) of the Filter for MF, that works in addition on HF and UHF too, so the advantage to bypass this section will clear also HF and UHF.. ?

    Section "3" (blue) is the high-cut filter for MFs neighbour 2420+horn+lens (HF)

    Am I wrong?

    So I understand the advantage of bi-amping the 4343b in bypassing section "4", that works on MF, HF and UHF ... -- and bypassing high-cut for LF .. or am I wrong?

    Best regards..

    Andreas
    Attached Images Attached Images  
    JBL 4343b-monitors and vintage german fullrange-drivers

  6. #6
    Junior Member 4343b_bremen's Avatar
    Join Date
    Apr 2011
    Location
    Bremen Germany
    Posts
    10
    Quote Originally Posted by Robh3606 View Post
    Take a look in the 5234 manual. To change your cards over to the 4343 you would need to change R1-R5 on the cards. Very simple modofication if you don't like how it sounds with the generic 250Hz card.

    http://www.jblproservice.com/pdf/Vin...-5233_5234.pdf



    Why??

    Rob
    OHW.. :o))

    Thank you, Rob.. -- just changing the values of some capacitors, and my 5234 will work at 300 Hz crossover, al 4343b likes best..

    -A-
    JBL 4343b-monitors and vintage german fullrange-drivers

  7. #7
    Senior Member HCSGuy's Avatar
    Join Date
    Jan 2009
    Location
    Bend, OR
    Posts
    726
    OK, I took a look into it and learned something

    I'm stealing this graph from an old post (thanks Giskard!), here's the post:
    http://www.audioheritage.org/vbullet...345-4355/page2

    The graph shows the 4343/4350 card (JBL 52-5140) in yellow - Giskard puts it at about 255hz crossover. It looks pretty straightforward, 12db/octave, so you could swap out some components and make one.

    I think 4343b_bremen is right in that the #4 is the HP filter for the MF and that it is out of the circuit when the switch is set to Biamp. It looks to be in the circuit for MF, HF, and UHF drivers, though it is out of band for HF and UHF.

    My confusion stems from my having the stock JBL card for the 4343's (52-5140), and it is labelled "4343 Lo", which led me to assume it is low pass only, though it is loaded as JBL specifies for a 52-5140 card - anyone have any ideas what the "Lo" nomenclature is for?

    Thanks!
    Attached Images Attached Images  

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Any use for this JBL 5234?
    By pyonc in forum Lansing Product General Information
    Replies: 3
    Last Post: 06-26-2010, 09:09 PM
  2. Electric crossover 5234
    By NancyJ in forum Lansing Product Technical Help
    Replies: 18
    Last Post: 10-05-2006, 06:01 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •