JBL 4 Way Build Questions

Not a speaker designer so I don't know...just curious if that's a consideration on that side of the cone..
 
laatsch55 said:
Not a speaker designer so I don't know...just curious if that's a consideration on that side of the cone..
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Not a designer either but have done some experiments and a fair bit of reading. The short answerer is I don't really know but there will be some cancelation and some coupling. I would certainly dampen and stuff the box and since he has essentially a unlimited crossover to play with, keep trying to integrate the pair into the stack. Whether separate or combined enclosures, two 10's will probably be too much and I would try the single 10 myself but as with all things audio, YMMV.
 
When I was designing my three way cabinets I was in contact with Eminence and while I can’t remember all the sciencey details, they recommended a common chamber for my two 15’s. Also at the higher frequency you’re talking about here porting is not required and box size will have little effect on mid range frequencies. My shop uses sealed basket 10” mids and I use sealed basket 6” mids in the house, they have effectively no “box volume”. They run 500-3khz then the compression horns handle the top end.
 
Morning !

I missed a bunch of posts last night ....

I like never satisfied's reasoning ..That makes sense to me .
2 drivers effectively acting as one.... So, say 2 drivers each need .25ft3 that's a total of .5ft3 Just have a transition hole in the brace / partition between the two ?

I've been all over the net looking for a definitive answer but there are simply differing opinions ....

The 10's will be driven by another PL400 2 per side / channel ... Most likely in series. 8+8 to give me 16 ohms to match the horn driver and tweeter.

The boxes on top of the bass cabinets hold the protection caps and a series/parallel attenuation ckt to drop the sensitivity (idle noise/ hiss)
The comp drivers & horns are 118 db efficient, the 15's are around 98 db ... This mod made a big difference in keeping things quiet between tracks while protecting the diaphragms from any DC.

The volume/space behind the drivers will be filled with acoustic insulation of some type to negate any standing waves ....
 
Series ckt ? No... Essentially the impedance is added (summed) ... 2- 8 ohm speakers in series is 16 ohm load . 2- 8 ohm speakers in parallel is a
4 ohm load .

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How would JBL engineer it? Have they built something similar? When I 'm unsure of how to do or build something I copy the experts.
 
Mohawk said:
Series ckt ? No... Essentially the impedance is added (summed) ... 2- 8 ohm speakers in series is 16 ohm load . 2- 8 ohm speakers in parallel is a
4 ohm load .

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Yep, I understand the impedance implications. Damping factor is shot, just dont know if they are in phase with each other..
 
Maybe look at the JBL Lancers. They made many variations of these over the years.
 
You would see it out of phase if you reversed one of the drivers polarity connections. Drive one cone out while the other pulled in.
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The D series had large twin driversIIRC, wonder how they had them wired...

Where's Pennysdad when ya need him...
 
Yeah, that would be mine too. With no definitive info at hand makes that even worse. Well, ya know that each driver requires a certain amount of volume, having a separate volume for each driver would keep you from reconfiguring the cabinets if the common volume trick didnt work.
 
I would wire them in parallel. Nothing wrong with a WOPL pushing 4 ohms..
 
laatsch55 said:
Yeah, that would be mine too. With no definitive info at hand makes that even worse. Well, ya know that each driver requires a certain amount of volume, having a separate volume for each driver would keep you from reconfiguring the cabinets if the common volume trick didnt work.
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That’s the dilemma I’m in with my 15’s... 4 or 16 ohm total. I went with parallel 4 ohm as I needed/wanted the extra power. The 400 will be ~100wpc at 16 ohm, adding an extra driver physically adds 3dB also so maybe 16 ohm will have enough power? I would share their box, like I said, volume isn’t critical at these frequencies smaller is probably actually better. What are the speaker T/S parameters? That will tell you the suitability of those drivers for those frequencies... you’re looking for stiffer compliance to be effective as mid speakers. Box Fs not a factor at those frequencies...
 
Have a poke around in the specs and let me know what you think ...
I agree with the smaller volume, Win ISD modeled it that way also ...
.25 ft3 gave a flatter and 1 db louder response @ 250-300hz compared to
a .5 ft3 box.... (ish...)
 

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Mohawk said:
Have a poke around in the specs and let me know what you think ...
I agree with the smaller volume, Win ISD modeled it that way also ...
.25 ft3 gave a flatter and 1 db louder response @ 250-300hz compared to
a .5 ft3 box.... (ish...)
Click to expand...
I would agree, unless you’re trying to use them down near their resonant frequency they don’t need much box. Those are a proper mid range speaker too, id probably run them 500-3k and see how that sounds. If you’re using a DSP you have easy flexibility too. You may want to call JBL and talk about on/off axis phasing at different crossover frequencies also. For too technical for me but I was advised of this and recommended not to vary too much from eminence’s recommended crossover points due to this.
Here’s a pic of the 10” sealed basket mids I use in the shop, you can see there is virtually no volume...
 

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AngrySailor said:
I would agree, unless you’re trying to use them down near their resonant frequency they don’t need much box. Those are a proper mid range speaker too, id probably run them 500-3k and see how that sounds. If you’re using a DSP you have easy flexibility too. You may want to call JBL and talk about on/off axis phasing at different crossover frequencies also. For too technical for me but I was advised of this and recommended not to vary too much from eminence’s recommended crossover points due to this.
Here’s a pic of the 10” sealed basket mids I use in the shop, you can see there is virtually no volume...
Click to expand...
That is pretty cool. I have never seen a 10" speaker with a sealed back like that. Nothing even similar.
 
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