JBL 4 Way Build Questions

[Mohawk]

I want to fire this out to the forum members as I am looking for opinions or suggestions ....

Currently I have a 3 way setup with a 700B and 2 400's.
A mini DSP takes on the levels and all the crossover duties.

The 15" is crossed at 800hz and the compression driver & horn take 800 hz to 8 Khz
8 Khz to 20 khz is for the super tweeter.....

What I'm thinking is there is too big a frequency gap between the 15" driver's upper range and the lower usable range of the horn.
So..... I have acquired 4 10" JBL 2123's that I want to use to go to a 4 way system.

The though is to have the 15" crossed at around 250 hz- 300 hz and have the 10"s take the 300 (ish) hz to around 1.3 kHz to better
match the horns usable range....

But with 4 of the 10's on hand why not use them !

So.... Should the boxes holding 2 of the 10" mids have separate chambers ? JBL calls for approximately .25 to .5 cubic feet for one driver.
Or......Should the chamber be common to both drivers ?

Thoughts ?

 

[George S.]

Wow!

 

[Mohawk]

The mids (10"s) cabinet when done will be veneered in cherry as the 15"s are and sit on top....
The horns then sit on top of the mids.....

Gota' keep the whole thing just below the wall thermostat !

 

[Mohawk]

The Red plot is for a single driver, black plot is for 2 drivers.
About a full Db louder and flatter where I want it to be without any Eq .....

 

[laatsch55]

Pretty cool program there..

 

[NeverSatisfied]

The Red plot is for a single driver, black plot is for 2 drivers.
About a full Db louder and flatter where I want it to be without any Eq .....

This is interesting, I have often thought that many 3 way systems lack mid bass and an 8 to 10 inch driver mated to a 15 at your proposed crossover point would be beneficial (perhaps even a little higher). Two 10’s seems excessive and with the added height where are your mid’s and highs going to end up relative to your listening position?

 

[Mohawk]

The horn is right at ear height as it is now, the tweeter just a bit above....
So, with the added mid bass cabinet that should be just about right if I tilt the
horn and tweeter just a touch .....

 

[NeverSatisfied]

The horn is right at ear height as it is now, the tweeter just a bit above....
So, with the added mid bass cabinet that should be just about right if I tilt the
horn and tweeter just a touch .....

Nice, will be watching with interest to see what your final crossover and slopes end up at. One of the problems with 4 way systems is that you can end up placing a notch right in the frequency range that you are trying to improve.

 

[Mohawk]

Nice, will be watching with interest to see what your final crossover and slopes end up at. One of the problems with 4 way systems is that you can end up placing a notch right in the frequency range that you are trying to improve.

Thoughts on the 10's sharing a common chamber ?

 

[laatsch55]

I wouldnt.

 

[mlucitt]

I agree with Lee. Assuming the enclosure will not be ported, the individual chambers are a more efficient acoustic 'spring' to the speaker cone at the frequency band you are envisioning. A single chamber for both speakers will be double the size and not provide any additional benefit.

 

[NeverSatisfied]

Thoughts on the 10's sharing a common chamber ?

I might have to disagree with Lee and Mark on this one. Since both drivers are being fed the exact same frequency range and are presumably wired together and fed by the same channel of the amp, then effectively they are one single driver. Sharing the same cabinet will allow them to couple together, thus evening out any small variances between the two speakers.

 

[VSAT88]

Try it both ways. Dude, that is one bad ass set up.

 

[laatsch55]

Are you going to drive the 4-10's with 2 amps or 1?

 

[VSAT88]

One thing I gotta ask. You said you were using a mini DSP. That being so what are the resistors and capacitors in the box mounted on top doing ? I see they feed the tweeter and the horn.

 

[VSAT88]

Whats up Lee.

 

[laatsch55]

Not much bud, you???

 

[VSAT88]

Just finished the x overs on the AR-9's. They are sounding pretty good.

 

[laatsch55]

I bet they are!@

 

[laatsch55]

I might have to disagree with Lee and Mark on this one. Since both drivers are being fed the exact same frequency range and are presumably wired together and fed by the same channel of the amp, then effectively they are one single driver. Sharing the same cabinet will allow them to couple together, thus evening out any small variances between the two speakers.

What happens to resonance and standing/reflected waves in the box?