Impedance question on double 15 with a horn

A

Alan Sledzieski

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Sep 11, 2011
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Hamburg, NY.
If you have a cabinet with a crossover, ( A Jbl 4733a in this case ) and the crossover is designed for a 4 ohm load on the 15's and a 16 ohm load on the horn, what will happen if you put a 8 ohm load on the horn part of the x over?

Basically I want to replace a 16 ohm jbl horn / driver with a different brand and its 8 ohm.

Thanks.
 
Re: Impedance question on double 15 with a horn

Alan Sledzieski said:
If you have a cabinet with a crossover, ( A Jbl 4733a in this case ) and the crossover is designed for a 4 ohm load on the 15's and a 16 ohm load on the horn, what will happen if you put a 8 ohm load on the horn part of the x over?

Basically I want to replace a 16 ohm jbl horn / driver with a different brand and its 8 ohm.
Click to expand...

The crossover frequency will change, the phase response will change, and more current will go through the high frequency part of the crossover, which may or may not be up to it.

Mac
 
Re: Impedance question on double 15 with a horn

mackerr said:
The crossover frequency will change, the phase response will change, and more current will go through the high frequency part of the crossover, which may or may not be up to it.

Mac
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And to add to what Mac said-even if replaced the driver with a different brand or model of the same brand-and the impedance was the same-all the the factors mac mentioned would change (and probably the sensitivity and the freq response. Depending on how complex the crossover is (ie how well it is designed for the driver-horn-woofer combination), the result could be dramatic or not so much.

And then throw in the impedance change-and it all starts to go out the window-most likely.

So the question is-WHY do you want to change the driver? What do you hope to gain by changing it?

Some crossovers are very picky which driver is hooked to them-others not so much.
 
Re: Impedance question on double 15 with a horn

Ivan Beaver;28483 So the question is-WHY do you want to change the driver? What do you hope to gain by changing it? [/QUOTE said:
Long story, but,,,,.

Sick of Jbl horns. Eaw la325 horns sound a lot smother, I have 4 Faital 15fx560's sitting around, 2 crossovers out of a 4733a, I am contemplating building a cabinet. I want to load them with the faitals and some eaw horn, driver assemblies. A backup to my la325's that I just bought, along with just wanting to play around.
Click to expand...
 
Re: Impedance question on double 15 with a horn

Alan Sledzieski said:
Long story, but,,,,.

Sick of Jbl horns. Eaw la325 horns sound a lot smother, I have 4 Faital 15fx560's sitting around, 2 crossovers out of a 4733a, I am contemplating building a cabinet. I want to load them with the faitals and some eaw horn, driver assemblies. A backup to my la325's that I just bought, along with just wanting to play around.
Click to expand...
Another thing that often gets overlooked is "What happens to the pattern of the horn when you put a different driver on it". YES it DOES happen. Sometimes not-sometimes yes. So the pattern may be different than it is now.

Since you have the drivers-I would put different drivers on the same horn-and measure-or at least listen to the polar pattern and see if it changes with the different drivers. I have seen it RADICALLY change on one horn-and the same 2 drivers on a different horn made no difference. So it is not so much the driver-but how it responds on a different horns.
 
Re: Impedance question on double 15 with a horn

I agree with Evan, the JBL horns are very useable and tame-able. That said, if you're bent on changing them, you'd probably be better off loosing the crossover and bi-amping.
 
Re: Impedance question on double 15 with a horn

Alan Sledzieski said:
Harsh, but loud. Great longer throwing and outside, but most of the shows I do are smaller places. Just need to fill the imediate dance floor area and out to 125 foot'ish
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Sounds like you need a little CD horn EQ... What do you have for processing? Is biamping an option? I bet I can make those things shine. :)


Evan
 
Re: Impedance question on double 15 with a horn

Alan Sledzieski said:
Long story, but,,,,.

Sick of Jbl horns. Eaw la325 horns sound a lot smother, I have 4 Faital 15fx560's sitting around, 2 crossovers out of a 4733a, I am contemplating building a cabinet. I want to load them with the faitals and some eaw horn, driver assemblies. A backup to my la325's that I just bought, along with just wanting to play around.
Click to expand...

Whoa be unto you sir for talking smack about the "3 letter brand".......haha....I would have to agree that EAW sounds better
 
Re: Impedance question on double 15 with a horn

Ivan Beaver said:
Another thing that often gets overlooked is "What happens to the pattern of the horn when you put a different driver on it". YES it DOES happen. Sometimes not-sometimes yes. So the pattern may be different than it is now.

Since you have the drivers-I would put different drivers on the same horn-and measure-or at least listen to the polar pattern and see if it changes with the different drivers. I have seen it RADICALLY change on one horn-and the same 2 drivers on a different horn made no difference. So it is not so much the driver-but how it responds on a different horns.
Click to expand...

The jbl is a 1.4'' the eaw is 2'' exit

I have 2 new B+c drivers that came out of a la 325 along with original B+c diaphragms, I need the bracket and horns out of a 325 now
 
Re: Impedance question on double 15 with a horn

Ivan Beaver said:
Another thing that often gets overlooked is "What happens to the pattern of the horn when you put a different driver on it". YES it DOES happen. Sometimes not-sometimes yes. So the pattern may be different than it is now.

Since you have the drivers-I would put different drivers on the same horn-and measure-or at least listen to the polar pattern and see if it changes with the different drivers. I have seen it RADICALLY change on one horn-and the same 2 drivers on a different horn made no difference. So it is not so much the driver-but how it responds on a different horns.
Click to expand...
I recall years ago in the days of large format horns that one manufacturer that was promoting some comparisons of their compression drivers and horns versus their competitors. It looked like they really had a better product until you looked closely at the data to see that the testing was both manufacturer's drivers on their horns and both companies' horns with their drivers. Not surprising that a company's drivers worked better with their own horns and vice versa, especially when they weren't even matching throats.
 
Re: Impedance question on double 15 with a horn

Brad Weber said:
I recall years ago in the days of large format horns that one manufacturer that was promoting some comparisons of their compression drivers and horns versus their competitors. It looked like they really had a better product until you looked closely at the data to see that the testing was both manufacturer's drivers on their horns and both companies' horns with their drivers. Not surprising that a company's drivers worked better with their own horns and vice versa, especially when they weren't even matching throats.
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I remember the same controversy.

While the bolt patterns may match up-that doesn't mean the end result will.

Oh the things we used to think-------------------------------------

If I were to do it all over again-I wound how things would be different if I had the knowledge I do now (limited as it is) -and still had to use the tools of the day---just wondering----------------------
 
Re: Impedance question on double 15 with a horn

Ivan Beaver said:
Oh the things we used to think-------------------------------------

If I were to do it all over again-I wound how things would be different if I had the knowledge I do now (limited as it is) -and still had to use the tools of the day---just wondering----------------------
Click to expand...

if you don't have those thoughts it means you never progressed.. I think its a good sign when I think back and wonder how we ever got by the way we did..

Jason
 
Re: Impedance question on double 15 with a horn

Alan Sledzieski said:
Long story, but,,,,.

Sick of Jbl horns. Eaw la325 horns sound a lot smother, I have 4 Faital 15fx560's sitting around, 2 crossovers out of a 4733a, I am contemplating building a cabinet. I want to load them with the faitals and some eaw horn, driver assemblies. A backup to my la325's that I just bought, along with just wanting to play around.
Click to expand...

First off, disclaimer. I sell speaker components, and therefore have a biased opinion.

I also think that most people are reading this as you want to put the B&C driver on a JBL horn, in a JBL cabinet, with JBL woofers.
Not that you want to do a new project, and use only the JBL crossover.

My thought is that you will have a better sounding cabinet than the JBL, but the crossover will be the weak link.
As Mac pointed out, you will have a lower crossover point with the 8 ohm driver.
But, you will also have more sensitivity from the Faitals than the JBLs, so this will somewhat self correct.
Whether it will work out right is speculation.
But the Faitals should sound better at the crossover point in general, than the JBLs. Because the Faital has 3" VC, and the JBL has 4" VC.
Also, because of this, the JBL will have more low end.

I also think that B&C makes a better sounding driver than the JBL. So you will be better off there.

One thing. I would not seek out the same horn as the 325. EAW spec sheet does not say where the 325 crosses over, but judging by the size of the horn it is probably higher than the JBL, (1200hz).
This is just a visual WAG.

Regards, Jack
 
Re: Impedance question on double 15 with a horn

Evan Kirkendall said:
What have you done to the JBL's EQ wise? (Bi-amping makes a night and day difference)

Evan
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I agree that bi-amping would be better than using a passive designed for some other application.

I don't think the JBLs exist. Otherwise why would he need to build new cabinets?

Jack
 
Re: Impedance question on double 15 with a horn

I think this whole conversation is a waste of time. Sell it all and buy real speakers that sound good and do what you need. Customizing anything is just ruining the resale value and making whatever product you did have into a DIY, no-name product. And to represent your DIY product as an actual JBL, even if it 'sounds better' after modification, is not ethical.


Sorry if I'm overly blunt here.
 
Re: Impedance question on double 15 with a horn

Silas Pradetto said:
I think this whole conversation is a waste of time. Sell it all and buy real speakers that sound good and do what you need. Customizing anything is just ruining the resale value and making whatever product you did have into a DIY, no-name product. And to represent your DIY product as an actual JBL, even if it 'sounds better' after modification, is not ethical.

Sorry if I'm overly blunt here.
Click to expand...

Wow, who mentioned representing DIY as JBL?

Who said anything about customizing anything?
And what does resale value have to do with this conversation?

Not blunt, just wrong. Perhaps you read enough to get pissed off, but not enough to contribute.
 
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