Bi-amping Array 1400

[cooky1257]

I have a question concerning bi-amping the Array 1400.
I've seen and think I understand the adjustments to and extra circuitry for the xovers when going active with these speakers.
My question is: They look like they could be bi-wired so..could they also be passive bi-amped too(without needing Mr Timbers' mods)?
Cooky

[Robh3606]

Based on the schematic the LF and HF boards are seperate. So you can do a passive biamp set-up if you don't want to try the active approach Greg provided for us.

Rob

http://manuals.harman.com/JBL/HOM/Te...array%20ts.pdf

[Andyoz]

Have you bought some Array 1400's Cooky?

[Loren42]

I have a question concerning bi-amping the Array 1400.
I've seen and think I understand the adjustments to and extra circuitry for the xovers when going active with these speakers.
My question is: They look like they could be bi-wired so..could they also be passive bi-amped too(without needing Mr Timbers' mods)?
Cooky

I could point you to numerous threads on the subject, but bi-wiring (passive bi-amp) is a worthless endeavor. I don't want to offend someone with a different opinion, but there is no scientific basis to support it.

All this assumes that you use reasonable gauged wire in the first place.

It is simple physics and mathematics. The claim is lower resistance and inductance between the driver and the amp, but the actual wire resistance (and wire inductance) compared to the resistances and inductances in the crossover is trite.

This means that any possible improvement by bi-wiring is statistically irrelevant compared to the effects inherent in a passive crossover and inaudible.

Another factor to consider is that 50% of the amp's power is consumed for frequencies below 400 Hz given a constant SPL level over the audio spectrum (20 Hz to 20 kHz). Most two-way crossovers cross well above 400 Hz, so there is comparably little current draw with the HF drivers.

Current and impedance are the important elements when it comes down to performance. If most of the current is consumed by the woofer, splitting the wires will do nothing for the HF drivers since they draw very little current.

Bi-amping is another matter altogether. The best way to bi-amp any speaker is to remove the crossovers altogether and add a 50 µF non-polarized cap in series with the HF driver to protect the horn or tweeter. Then connect each driver to a individual amp.

The amps need to be fed with an active crossover such as the Ashly XR1001 that splits the audio spectrum into individual frequency regions or domains.

[Robh3606]

Bi-amping is another matter altogether. The best way to bi-amp any speaker is to remove the crossovers altogether and add a 50 µF non-polarized cap in series with the HF driver to protect the horn or tweeter. Then connect each driver to a individual amp.

It is not that simple. You need to understand what the passive crossover is doing to see if there is any response shaping. An inexpensive analog crossover like the Ashley will not work if response shaping is part of the passive design. Almost all modern horns/waveguides have some kind of compensation built into the crossovers.

Using the Ashley to biamp a 1400 won't work. It has the wrong voltage drives for both the woofer and the horn. It also doesn't have the compensation/response shaping for the horn. The only solution that will work is what Greg has provided for us.

Rob

[cooky1257]

Thanks guys,
I'm cloning the Array xovers HF/UHF section as a starting point for use with the SAM horns recently acquired from Giskard but using the Be 2435 hpl's on mids then partnering with 2235 bass drivers to make a sort of 1400 clone.
Matching up the 2235 to the SAM1HF will be taken care of via an XTA 226 with some RTA and my ears!
So it looks like I can keep the hf passive driven(I just spent a fair wedge on xover components) and go active on the bottom end without too many headaches. Amplification will be via MC2 1250 and 650's.
Cooky

[Robh3606]

I'm cloning the Array xovers HF/UHF section as a starting point for use with the SAM horns recently acquired from Giskard but using the Be 2435 hpl's on mids then partnering with 2235 bass drivers to make a sort of 1400 clone.

Hello Cooky

I will doing my own clone as well. I took a couple of quick measurents of drivers on the Array Horn and ran them in LEAP with the stock crossover. I have a 2431 and a 2435. Both drivers look good. Are you going to run a tweeter above the horn?? It rolls off a bit early with the standard network.

Rob

[Loren42]

It is not that simple. You need to understand what the passive crossover is doing to see if there is any response shaping. An inexpensive analog crossover like the Ashley will not work if response shaping is part of the passive design. Almost all modern horns/waveguides have some kind of compensation built into the crossovers.

I am not familiar with the 1400's crossover, so it may be true that there may be a response curve correction of some sort. Not hard to test it empirically and find out or Spice analysis if you have the circuit schematic.

Using the Ashley to biamp a 1400 won't work. It has the wrong voltage drives for both the woofer and the horn. It also doesn't have the compensation/response shaping for the horn. The only solution that will work is what Greg has provided for us.

Rob

Well, here is where we can disagree.

1) "It has the wrong voltage drives for both the woofer and the horn." The Ashly works at what is called "Line Level" and is inserted between the source audio and the power amplifier. The input and output level of the Ashly is not an issue since the power amp is the only electronic device that is connected directly to the driver and all power amps are designed to accept a line level input.

2) "It also doesn't have the compensation/response shaping for the horn." If there is one.

3) "The only solution that will work is what Greg has provided for us." Why? If you do need to frequency compensate the horn a simple parametric equalizer will do the job easily (and probably better).

Whatever shaping or filtering you can do with a passive circuit can be done with an active circuit and at a lower expense (since you do not need inductors or large capacitors) and you reap the advantage of a higher damping factor at the driver (really only important for the woofer because it is directly connected to the amp) that you loose with a passive crossover no matter how well designed.

Lastly, leaving a passive crossover connected and bi-amping pretty much destroys all the advantages of bi-amping anyway. However, if you going the passive crossover route I can say that bi-wiring has no advantage at all over just using a properly gauged single run of speaker wire.

My main point, anyway, was that bi-wiring would be just a waste of wire.

[cooky1257]

Hello Cooky

I will doing my own clone as well. I took a couple of quick measurents of drivers on the Array Horn and ran them in LEAP with the stock crossover. I have a 2431 and a 2435 on the graph. Both drivers look good. Are you going to run a tweeter above the horn?? It rolls off a bit early with the standard network.

Rob

Hi Rob, Great stuff.
I got some 045 ti UHF comp drivers to go with them so hopefully things should be good to go up top. As both bass and mid/hf will be coming off the XTA I can still do some minor level/response eq tweeks should I need to.
One thing that has occurred to me was why JBL didn't opt for a cc'd network with the 1400(and why I didn't bloomin think of it beforehand)
Cooky

[cooky1257]

I am not familiar with the 1400's crossover, so it may be true that there may be a response curve correction of some sort. Not hard to test it empirically and find out or Spice analysis if you have the circuit schematic.




Lastly, leaving a passive crossover connected and bi-amping pretty much destroys all the advantages of bi-amping anyway. However, if you going the passive crossover route I can say that bi-wiring has no advantage at all over just using a properly gauged single run of speaker wire.

My main point, anyway, was that bi-wiring would be just a waste of wire.

Well yes and no,
Driving the bass fully active has all the benefits of driving the bass activelythere will be no passive network up to 750hz.
Driving the mid/top takes advantage of all the R&D listening/tweeking/fine tuning that went into the network and takes all the guesswork out of optimising the sound of the SAM1HF.

[Robh3606]

Hi Rob, Great stuff.
I got some 045 ti UHF comp drivers to go with them so hopefully things should be good to go up top.

Great so you are going have a SAM-1 Clone Nice!!!

One thing that has occurred to me was why JBL didn't opt for a cc'd network with the 1400(and why I didn't bloomin think of it beforehand)

I am going to go that way eventually. The first version will be a straight up clone. You can always add the extra caps later on as long as you plan ahead and leave room. Bet you your's are done before mine

Rob

[cooky1257]

Well the boxes are nearly ready, I'm waiting on bolts/screws and the last few components for the networks and as I work in education have the benefits of a 6 week long summer vacation to play

[Robh3606]

The Ashly works at what is called "Line Level" and is inserted between the source audio and the power amplifier. The input and output level of the Ashly is not an issue since the power amp is the only electronic device that is connected directly to the driver and all power amps are designed to accept a line level input.

I think we have a disconnect. Attached is a plot of the voltage drives needed to make that driver set a 1400 Array. You would be better off using a digital crossover if you want to try to replicate what the passive does. The Ashley won't even get you close.

Rob

[Loren42]

I think we have a disconnect. Attached is a plot of the voltage drives needed to make that driver set a 1400 Array. You would be better off using a digital crossover if you want to try to replicate what the passive does. The Ashley won't even get you close.

Rob

Um, just turn down the mid range gain on the Ashly and the midrange amp! I have a XR2001 and every filter has a gain control...

Same goes for the horn tweeter.

However, you still need equalization, as you pointed out. Interesting plot!

[cooky1257]

Um, just turn down the mid range gain on the Ashly and the midrange amp! I have a XR2001 and every filter has a gain control...

Same goes for the horn tweeter.

However, you still need equalization, as you pointed out. Interesting plot!

The plot you're looking at is the voltage drives, the mid doesn't need a 'boost' that is the drive required to allow for the extra sensitivity of the mid comp driver.
Cooky