jbl 4320 with 3110 or 3110a network

[bluewow]

Hi all,

Thank you for all the good information in the forum, I have learn quite a lot reading it.

I have a jbl 4320 with a woofer with an impedance of 16 ohm, so I should use a jbl 3110 crossover with it.

I have found a jbl 3110a crossover that is an improved version of the jbl 3110, but the jbl 3110 a should be used with a woofer of 8 ohm instead of 16 ohm.

My question is, Can I use the jbl 3110a with the LF of 8 ohm or I should modify the crossover first?

It's difficult to modify the jbl 3110s crossover to use it with a woofer of 16 ohm, like the 2215B?

Thanks,

Ismael.

[Odd]

If you switch to 3110a, you must change the values ​​in the filter.
I think it is best to keep the 3110, clean the switch and replace all capacitors.

[Baron030]

If you are set on replacing the 3110 for a different network.
Rather than hack up and modify a 3110A, you could build new crossover network from scratch.
The schematic below uses the 3110 design for the 16 ohm woofer and a new version of the 3110a for the HF driver.
Note that this new version does not use a tapped coil.

Here is a link to where “4313B” came up with the new 3110A design, starting on page 2:

http://www.audioheritage.org/vbullet...3110a-or-3115a

With the exception of the 0.02mH coil and rotary switch, I don’t think you should any trouble finding the parts.
Parts express stocks is a Jantzen 0.025mH 18ga coil (255-198).
So, it is the only item that will need some custom fabrication and trimming.
I am pretty sure that JBL is using an Electroswitch brand rotary switch.
But, without actual physical measurements I am not sure which Electroswitch switch series is being used. (“C4”, “D4”, or “D7”)
Electrically, any of these 3 series should work and could be interchangeable.
Now, there are some key words that must be followed when ordering this switch.
The switch should have “Solder Lug Terminals”, “1 deck”, “2 poles per deck”, and “3 or more positions” and “Non-Shorting”.
And have adjustable rotation stops.
So, if the switch has more then 3 position, you can reposition some stops to limit the shafts rotation to just the required 3 positions.
Considering cost and availability, I would have to say that the “Electroswitch D4G0205N” switch would be my best guess and it should work for this application.
Mouser Part # 690-D4G0205N
Baron030

[NickH]

At the risk of being dragged out of the forum and burned at the stack I'll make a suggestion.

You could use a matching transformer.

Just a though,
Nick

[Earl K]

Thank you for all the good information in the forum, I have learn quite a lot reading it.

I have a jbl 4320 with a woofer with an impedance of 16 ohm, so I should use a jbl 3110 crossover with it.

Never believe the impedance label on an old JBL woofer . They are known to be misleading .

I would actually classify the 2215B as a 12 ohm woofer .

Put a MultiMeter on your woofer ( disconnect the crossover from the woofer when you do this & make note of the wiring polarity / color-coding ) & then measure it's DCR ( dc resistance ) .

[Earl K]

My question is, Can I use the jbl 3110a with the LF of 8 ohm or I should modify the crossover first?

The values of the Zobel ( low-frequency, impedance leveling ) circuit ( R1 & C2 ) are the same for both networks ( 10R & 13.5 uF ), effectively forcing the lowpass components to act upon a 10 ohm load, ( no matter how high the woofers raw impedance curve rises to ) .

As a consequence of this observation , I would simply try out the 3110a with your components & see if it works for you .

[bluewow]

If you switch to 3110a, you must change the values ​​in the filter.
I think it is best to keep the 3110, clean the switch and replace all capacitors.

Yes, this was my first thought.


I think I will try this first and later compare with the two other solutions.

[bluewow]

If you are set on replacing the 3110 for a different network.
Rather than hack up and modify a 3110A, you could build new crossover network from scratch.
The schematic below uses the 3110 design for the 16 ohm woofer and a new version of the 3110a for the HF driver.
Note that this new version does not use a tapped coil.

Here is a link to where “4313B” came up with the new 3110A design, starting on page 2:

http://www.audioheritage.org/vbullet...3110a-or-3115a

With the exception of the 0.02mH coil and rotary switch, I don’t think you should any trouble finding the parts.
Parts express stocks is a Jantzen 0.025mH 18ga coil (255-198).
So, it is the only item that will need some custom fabrication and trimming.
I am pretty sure that JBL is using an Electroswitch brand rotary switch.
But, without actual physical measurements I am not sure which Electroswitch switch series is being used. (“C4”, “D4”, or “D7”)
Electrically, any of these 3 series should work and could be interchangeable.
Now, there are some key words that must be followed when ordering this switch.
The switch should have “Solder Lug Terminals”, “1 deck”, “2 poles per deck”, and “3 or more positions” and “Non-Shorting”.
And have adjustable rotation stops.
So, if the switch has more then 3 position, you can reposition some stops to limit the shafts rotation to just the required 3 positions.
Considering cost and availability, I would have to say that the “Electroswitch D4G0205N” switch would be my best guess and it should work for this application.
Mouser Part # 690-D4G0205N
Baron030

Thanks for your detail replay.

Many times my biggest concern to start doing my own crossover is to find the right components, with your post is much easier

[bluewow]

The values of the Zobel ( low-frequency, impedance leveling ) circuit ( R1 & C2 ) are the same for both networks ( 10R & 13.5 uF ), effectively forcing the lowpass components to act upon a 10 ohm load, ( no matter how high the woofers raw impedance curve rises to ) .

As a consequence of this observation , I would simply try out the 3110a with your components & see if it works for you .

Hi!

Thanks for the reply.

This is what I noticed, the value of the R1 and C2 are the same in both crossover, so what the woofer see in the circuit is the same.

[bluewow]

Never believe the impedance label on an old JBL woofer . They are known to be misleading .

I would actually classify the 2215B as a 12 ohm woofer .

Put a MultiMeter on your woofer ( disconnect the crossover from the woofer when you do this & make note of the wiring polarity / color-coding ) & then measure it's DCR ( dc resistance ) .

The impedance I can measure with the MultiMeter is the same as the impedance of the woofer when the speaker is working?

[Earl K]

The impedance I can measure with the MultiMeter is the same as the impedance of the woofer when the speaker is working?

No ( it's not the same ), what you measure with the multi-meter is DC resistance .

The crossover component values work with AC resistance ( amplified signal ) .

AC resistance is roughly 1.25 times the DC value .

AC resistance of a speaker will look like a large curve / exponentially increasing in value after a certain frequency .

Earl