Impedance question on double 15 with a horn

Re: Impedance question on double 15 with a horn

Greg Cameron said:
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.
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I would not loose the crossover. I think they should be very tight, and installed correctly. Loosening them will possibly lead to rattling, and potential damage to the crossover.
 
Re: Impedance question on double 15 with a horn

Jack Arnott said:
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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Jack, I think you're half right.:blush:

Seems I gathered that he was modifying 4733s with aftermarket horns and LF drivers. But apparently the box doesn't exist, so it would be a complete DIY project.

I think that having a crossover first and getting drivers to work with it is backward; the crossover design comes after the box, horn, and driver arrangement is designed. Every aspect of the whole project affects actual driver impedance - box, horn, everything. The nominal impedance of the drivers don't really matter at all. And there's a reason people like Too Tall get lots of money for making crossovers - it's very precise business.

I'm sure that using the 4733 crossover is going to allow sound to be produced, but good sound is another story.

I still don't advocate DIY boxes. At all. And I've built dozens.

And I guess I was only considering resale value since most businesses expect some sort of ROI on stuff. People operating a sound company as a hobby is a different story, though.

Oh, and selling the pile of parts and buying a good professional box is still a better idea.

Anyhow, everyone...carry on...
 
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Re: Impedance question on double 15 with a horn

Silas Pradetto said:
Jack, I think you're half right.:blush:

Seems I gathered that he was modifying 4733s with aftermarket horns and LF drivers. But apparently the box doesn't exist, so it would be a complete DIY project.

I think that having a crossover first and getting drivers to work with it is backward; the crossover design comes after the box, horn, and driver arrangement is designed. Every aspect of the whole project affects actual driver impedance - box, horn, everything. The nominal impedance of the drivers don't really matter at all. And there's a reason people like Too Tall get lots of money for making crossovers - it's very precise business.

I'm sure that using the 4733 crossover is going to allow sound to be produced, but good sound is another story.

I still don't advocate DIY boxes. At all. And I've built dozens.

And I guess I was only considering resale value since most businesses expect some sort of ROI on stuff. People operating a sound company as a hobby is a different story, though.

Oh, and selling the pile of parts and buying a good professional box is still a better idea.

Anyhow, everyone...carry on...
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Pretty sure he has some JBL SR4733A's that he wants to swap the horn in(hence the WTB of a horn and bracket in the market place)...

And as far as DIY- if you've got the tools and knowledge, I'm a big supporter(even though this thread has nothing to do with building a cab).


Evan
 
Re: Impedance question on double 15 with a horn

Evan Kirkendall said:
Pretty sure he has some JBL SR4733A's that he wants to swap the horn in(hence the WTB of a horn and bracket in the market place)...

And as far as DIY- if you've got the tools and knowledge, I'm a big supporter(even though this thread has nothing to do with building a cab).


Evan
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My concern was trying to "DIY" an improvement to an off-the-shelf box, which, even if it sounds better after the DIY modification, is no longer the off-the-shelf box, and can't be represented as such.

And Alan has stated (or implied?) in the thread about the tunings for the LA325s that he doesn't have a way to measure the boxes other than his hearing.

I would think that the minimum measurement capabilities for designing and tuning a box with a passive crossover would include impedance sweeping along with some sort of dual-channel FFT measurement system such that phase and magnitude could be assessed. Of course crossover design knowledge would help as well. Plugging random and obviously-incorrect drivers into a crossover isn't going to yield any sort of good result.

Like I said before, in my annoyed voice :D~:-D~:grin:, trying to do all this without the proper tools and experience is not going to end up well. And even if one does have the tools to do it right, DIY boxes still don't make any financial sense in the real world.

Alan, if you are doing this purely for the learning exercise with the chance that you may end up with a better sounding box, I applaud your determination and quest for knowledge.
 
Re: Impedance question on double 15 with a horn

Evan Kirkendall said:
Pretty sure he has some JBL SR4733A's that he wants to swap the horn in(hence the WTB of a horn and bracket in the market place)...

And as far as DIY- if you've got the tools and knowledge, I'm a big supporter(even though this thread has nothing to do with building a cab).


Evan
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Nice bit of detective work.

However, if you had read this very thread, you would know that...

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.
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To your second sentence, yes it has seen its share of topic swerve.
 
Re: Impedance question on double 15 with a horn

I'm building new box's, using Faital pro's, eaw horns, and will use srx 725 x overs, they are setup for a 4 ohm load on the 15's, and 8 ohm on the horn. I wont buy the 4733 x overs.

I had 4 4733's, I put the faital 560's in 2 box's , I never use the 2226 loaded 4733's again. We did a blind test, I had all 4 4733's set up out side. I a/b ed the 2226 loaded box vs the faital loaded box. 5 out of 5 picked the faital box. No fancy sound measuring equipment, just our ears.

Now I'm stuck on the eaw smoothness of the high end. This set of box's I am building is a backup set, and experiment also. The 325's sound great, but something tells me to be worried about the durability of the eminence 15, and the common problem of blowing caps in x overs that I have heard and read about. Eaw sounds great, just don't like the cheapness of the 15's, the made in china stamped bracket for the horn, the overlly delicate made in china horn its self, the poor choice of connectors on the x over and 6'' mids. The box constuction is supurb though.

I'm not going to represnt these box's as jbl or eaw, I'm a weekend warrior, I don't do national acts, and everyone that uses me keeps calling me back.

I designed and built my own double 18 box using faital 1500xl 18's. So far I have had people ask me them to build them a set, people that use jbl and eaw double 18's at that.

I could care less about resale value, this is my hobby, I like it so I do it. If the new box is a flop, I'll move on. At that point I would have 4 extra 15's laying around, and a set of eaw 5001 drivers with new original b+c diaphragms. I paid $275 for both complete assemblies, Eaw want $390 for just 2 diaphargms, $260 at us speaker.

Need be I'll get another set of 325's as back ups if my design is a flop.

Thanks again for the help on the 8 ohm load on the xover designed for 16, I won't do it. May eventually just run the box with no x over and just by amp it, will see.
 
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Re: Impedance question on double 15 with a horn

Silas Pradetto said:
If you are going to buy a crossover rather than use something you already have, why not invest a few more bucks and have someone build you a real, correct crossover?
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I'll try the 725 xover first and see what happens. Running it byamped the 15's will be befor the x over anyways, I'll be running bi amp most of the time, probably all the time, but it will be nice to have the x over in there for the hell of it. Plus they come with some nice input panels ready to go. $150 for a pair of the 725 xovers.
 
Re: Impedance question on double 15 with a horn

Ivan Beaver said:
That is a very unusual orientation of the horn. What horn are you using?

I don't see any bracing in the cabinets-is that coming later?
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Unusual orientation of the horn? Why?

Horn out of a la 325

Bracing, no more or less then I see in a la 325 or a 4733. The front plate is braced though
 
Re: Impedance question on double 15 with a horn

Alan Sledzieski said:
Bracing, no more or less then I see in a la 325 or a 4733. The front plate is braced though
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Which is part of what lands those cabinets square in the middle of the MI range of speakers. Since you obviously know how to make sawdust, you really should take a little extra time to brace this cabinet well. You want it to be as non-resonate as possible. That's one of many factors that you pay big bucks for when you jump into truly pro speaker cabs.
 
Re: Impedance question on double 15 with a horn

Tim Weaver said:
Which is part of what lands those cabinets square in the middle of the MI range of speakers. Since you obviously know how to make sawdust, you really should take a little extra time to brace this cabinet well. You want it to be as non-resonate as possible. That's one of many factors that you pay big bucks for when you jump into truly pro speaker cabs.
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Got ya Tim, I'll go back to home depot after work for some more wood.
 
Re: Impedance question on double 15 with a horn

What's the port tuned to? You are aware that it's asymmetrical and is going to load the two woofers differently, right? Ports should generally load both woofers the same...so they should be in the middle, or at both ends. The way you have it set up, you will probably blow the bottom woofer way before the top one. This was actually a Community-recognized problem with the RS880/SLS980.

Also, if you did actually tune the port to something useful, adding a pile of bracing is going to change the enclosure volume, possibly by an amount significant enough to affect tuning.
 
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