You are obviously still in the dark ages of PA design
http://www.madisound.com/pdf/aurasound/nrt18-8.pdf
or simply speculating like DJ rather than presenting facts.
I take it you know nothing of the new TC sounds drivers either
http://www.tcsounds.com.unixweb-7.nethere.net/news_pa.htm
Welcome to the 21st century. Johan, gotta run
cheers,
AJ
Instead of reacting with lots of sarcasm, could you react with little bit more scientific or respectfull approach?
Sarcasm seems to be quite often used if there is lack of knowledge to the actual subject itself.
1. Reading the site of TCsounds and others it appears that such large Xmax requires different approach when it comes to the spider. Spiders other than ussual PA-drivers incluiding the 2268H use.
2. Also the use of neodymium opposed to ferrite is acuired to keep the weight down (relative as the neo versions weigh as much as populair ferrite drivers).
3. Efficiency stated for all drivers on both sites is still low compared to PA-drivers. TC seems to be doing a better job than expected but still not like the JBL states.
4. It would be strange to compare the performance of overhung designs directly to underhung designs like the TC and Madisound. The structure of the magnet is of course very different.
With kind regards Johan
Sarcasm seems to be quite often used if there is lack of knowledge to the actual subject itself.
1. Reading the site of TCsounds and others it appears that such large Xmax requires different approach when it comes to the spider. Spiders other than ussual PA-drivers incluiding the 2268H use.
2. Also the use of neodymium opposed to ferrite is acuired to keep the weight down (relative as the neo versions weigh as much as populair ferrite drivers).
3. Efficiency stated for all drivers on both sites is still low compared to PA-drivers. TC seems to be doing a better job than expected but still not like the JBL states.
4. It would be strange to compare the performance of overhung designs directly to underhung designs like the TC and Madisound. The structure of the magnet is of course very different.
With kind regards Johan
Hi Johan,
ok, you and DJ are both right. In the face of your overwhelming amount of evidence to the contrary, there are no PA woofers with 18mm, 23mm or 30+mm xmax. 5-10mm sounds just about right.
The xmax specs of JBL, Aura and TC are all wrong or simply outright lies.
I'll take your and DJ's words as fact. I apologize for doubting you guys and intruding upon your reality. Take care.
cheers,
AJ
AJinFLA said:
There goes that theory I suppose. Perhaps just a bit too much speculation on DJ's part.
Now, returning to the original thread question, I'd take the 2268HPL over the 2242H any day.
cheers,
AJ
Really? Why?
Not to start an argument but Dennis (djk) is of course the man with the knowledge here - he has extensive experiance with pro drivers and horns. I'd say more than anyone that has ever posted on this forum. He is a man to be trusted. These drivers are EXPENSIVE - It's your money.
2242's? They are AWESOME. I use three of them in horn subs - Just about right, maybe a bit of an over kill, for realistic bass in a typical home listening room. Two of of them in corner horns is probably enough.
2268? Three inch voice coil - That's what JBL uses on their cheap bass drivers.
DJK and Johan may know the world about PA drivers, but they knew nothing about the JBL2268H - and proved it with their ignorance of the facts.
Neither has admitted to being flat wrong about the JBLs spec'd xmax of 23mm.
That is one of the reasons I would prefer it. The 2242H is a woofer. The 2268HPL is a sub woofer that will play much lower and louder (except at midbass frequencies).
Again, DJK, Johan and possibly yourself, may think you know more about driver design than JBL, but you don't.
Speculation won't change that.
Do yourselves a favor and read up on the 2268HPL's technology before casting judgement and stating facts about this driver http://www.jblpro.com/pub/technote/JBL_TN 1-33 rev3.pdf
Or better yet, work with it in the field and hear it like I have.
Then tell me it doesn't have 23mm xmax or sucks compared to the 2242 with its 3"vs 4" coil, etc, etc.
cheers,
AJ
Neither has admitted to being flat wrong about the JBLs spec'd xmax of 23mm.
That is one of the reasons I would prefer it. The 2242H is a woofer. The 2268HPL is a sub woofer that will play much lower and louder (except at midbass frequencies).
You have now joined them in commenting on a driver you know little about. The DD motor uses two coils on a single former operating in seperate gaps. Believe it or not, if JBL thought there would be an advantage to using a larger diameter coil for the dual coil design - they would.
Again, DJK, Johan and possibly yourself, may think you know more about driver design than JBL, but you don't.
Speculation won't change that.
Do yourselves a favor and read up on the 2268HPL's technology before casting judgement and stating facts about this driver http://www.jblpro.com/pub/technote/JBL_TN 1-33 rev3.pdf
Or better yet, work with it in the field and hear it like I have
.Then tell me it doesn't have 23mm xmax or sucks compared to the 2242 with its 3"vs 4" coil, etc, etc.
cheers,
AJ
So AJ, it sounds like you got it right. My problem now is to make the decision to get two 2268's for $720 or the Eighteen Sound LW1400's for $660. I will be installing them into two SR4718A cabs. 8ohms @ 1100w. I have two QSC 1602's. I still can send back the 1400's, they will be here any day. I might need more power?
Hey AJinFLA , why don't you see if you can get some hard data from JBL on those drivers. I had already seen every word in print at JBL before you ever posted a single comment. No where do they list the gap height or coil length.
Considering that there are many small errors in the pdf of the drivers that they publish, when I see something that looks wrong, it's wrong.
People that aren't familiar with what a driver can and cannot do are welcome to use a computer program. I have one that JBL used to sell. You enter all the T/S parameters in and push calculate. Guess what? If something doesn't add up, it red flags it.
One thing the wise guys haven't noticed about the dual coil drive from JBL is that as the coil starts to move, there are fewer turns in the gap after the half x-max point. This means that the coil is still in one of the gaps, but not in the other. So at loud volumes the driver force decreases considereably. The dual gaps design is also only specified as having half the flux density of their older drivers.
This is obvious, the more gap volume for a fixed amount of energy, the less force over the coil. This is one reason EV always used a 2-1/2" coil even though the magnets were 4" in diameter (same alnico slug JBL used with the 4" coil).
It used to cost $100 to have a driver Du-Max tested. In the absence of any such data from JBL, I would spend my own money and have the thing independently tested before buying a bunch of these for any large PA company that I owned.
Considering that there are many small errors in the pdf of the drivers that they publish, when I see something that looks wrong, it's wrong.
People that aren't familiar with what a driver can and cannot do are welcome to use a computer program. I have one that JBL used to sell. You enter all the T/S parameters in and push calculate. Guess what? If something doesn't add up, it red flags it.
One thing the wise guys haven't noticed about the dual coil drive from JBL is that as the coil starts to move, there are fewer turns in the gap after the half x-max point. This means that the coil is still in one of the gaps, but not in the other. So at loud volumes the driver force decreases considereably. The dual gaps design is also only specified as having half the flux density of their older drivers.
This is obvious, the more gap volume for a fixed amount of energy, the less force over the coil. This is one reason EV always used a 2-1/2" coil even though the magnets were 4" in diameter (same alnico slug JBL used with the 4" coil).
It used to cost $100 to have a driver Du-Max tested. In the absence of any such data from JBL, I would spend my own money and have the thing independently tested before buying a bunch of these for any large PA company that I owned.
"I own two of these. I've seen them running. I know what the excursion capabilities of the speaker are. I've seen it first hand."
And what does this prove?
I built some 8 cu ft boxes with the K151 tuned to 31hz (30 years ago). This driver has a paper edge. That's right, not cloth, foam or rubber, but paper. When driven with a 150W amplifer it could be seen to move about 2" peak to peak. The stated x-max on that driver is only 2.54mm!!!
Driving the speaker below cabinet tuning to the limits of suspension travel produces no audible output.
Those of you that have box programs can follow this design excercise.
Plug in the published parameters for the 2242, use 8 cu ft and tune to 31hz. This is a reasonable box size and the modeling program distributed by JBL suggests it for this driver.
Plug in the published parameters for the 2268 in the same exact box.
Plot and overlay the response, and cone excursion at 800W, examine.
What you will find is the identical 9mm excursion at about 50hz, this is the worst case for this box tuning. At 1W the 2.83V sensitivity is the same at 96dB, ±.2dB. At 31hz the 2242 has about 1.5dB more output!
If the 2268 was capable of 23mm x-max (which I doubt), it is thermal limited to 9mm. That's right, it would burn up. Acording to the program, it would take 20KW to drive it to 23mm at 31hz!!!
That's why I said I didn't believe the x-max spec. No one in their right mind would design a speaker that needed 20KW to reach that full 23mm excursion and would only handle 0.8KW !!!
I'm sure the 2268 is a good driver, and so is the 2242. Only you can decide if the reduction in weight is worth the cost difference to trade.
I use JBL high frequency, but have my woofers custom made. For $120 I can have a driver compliment that in the same 8 cu ft box tuned to 31hz that will be about 1dB more efficient, and have about 2.5dB more output based on x-max limited displacement. The composite driver is actually a pair of 9.11mm x-max 15s mounted push-pull in a plenum that will fit over an opening for an 18" woofer. So I get 2.5dB more maximum output, less distortion (due to the push-pull mounting), and for 1/3 the cost of the JBL drivers.
And what does this prove?
I built some 8 cu ft boxes with the K151 tuned to 31hz (30 years ago). This driver has a paper edge. That's right, not cloth, foam or rubber, but paper. When driven with a 150W amplifer it could be seen to move about 2" peak to peak. The stated x-max on that driver is only 2.54mm!!!
Driving the speaker below cabinet tuning to the limits of suspension travel produces no audible output.
Those of you that have box programs can follow this design excercise.
Plug in the published parameters for the 2242, use 8 cu ft and tune to 31hz. This is a reasonable box size and the modeling program distributed by JBL suggests it for this driver.
Plug in the published parameters for the 2268 in the same exact box.
Plot and overlay the response, and cone excursion at 800W, examine.
What you will find is the identical 9mm excursion at about 50hz, this is the worst case for this box tuning. At 1W the 2.83V sensitivity is the same at 96dB, ±.2dB. At 31hz the 2242 has about 1.5dB more output!
If the 2268 was capable of 23mm x-max (which I doubt), it is thermal limited to 9mm. That's right, it would burn up. Acording to the program, it would take 20KW to drive it to 23mm at 31hz!!!
That's why I said I didn't believe the x-max spec. No one in their right mind would design a speaker that needed 20KW to reach that full 23mm excursion and would only handle 0.8KW !!!
I'm sure the 2268 is a good driver, and so is the 2242. Only you can decide if the reduction in weight is worth the cost difference to trade.
I use JBL high frequency, but have my woofers custom made. For $120 I can have a driver compliment that in the same 8 cu ft box tuned to 31hz that will be about 1dB more efficient, and have about 2.5dB more output based on x-max limited displacement. The composite driver is actually a pair of 9.11mm x-max 15s mounted push-pull in a plenum that will fit over an opening for an 18" woofer. So I get 2.5dB more maximum output, less distortion (due to the push-pull mounting), and for 1/3 the cost of the JBL drivers.
Hi DJK,
This analysis of yours just doesn't hold water. The 'evidence' you present against the 2268 having it's claimed Xmax is purely circumstantial based on gross assumptions. You cannot guess what was in the mind of the driver's designer anymore than anyone else.
Your assumption that this driver would only be useable in reflex alignment is baseless. It could just a easily be used in a sealed box.
The 2269, which you agree is capable of large Xmax, is similarly capable. Looking at the impedance plot of the VT4880A sub which employs the 2269, it appears that this design is in fact a sealed enclosure. Interestingly the text describes it as 'centrally vented' whatever that means.
I am still to hear of any evidence that shows the published Xmax data for the 2268 is in error.
Cheers,
Ralph
This analysis of yours just doesn't hold water. The 'evidence' you present against the 2268 having it's claimed Xmax is purely circumstantial based on gross assumptions. You cannot guess what was in the mind of the driver's designer anymore than anyone else.
Your assumption that this driver would only be useable in reflex alignment is baseless. It could just a easily be used in a sealed box.
The 2269, which you agree is capable of large Xmax, is similarly capable. Looking at the impedance plot of the VT4880A sub which employs the 2269, it appears that this design is in fact a sealed enclosure. Interestingly the text describes it as 'centrally vented' whatever that means.
I am still to hear of any evidence that shows the published Xmax data for the 2268 is in error.
Cheers,
Ralph
To be honest with you DJ (and Johan), the onus isn't on me to prove that JBL is right. Rather, it on you to prove that they are wrong.
I find no reason to doubt the JBL spec sheet. You both do. Prove it with data from an actual 2268 if so inclined. I have greater worries in life than to spend time on such frivolous endeavors.
I wonder why it is that you don't take issue with the (Pro) Aura's 18mm or TC's 30+ ? Somehow, in your minds, 23mm makes no sense. Go figure.
Anyhow, I done with this (non) issue. Time to move on.
Xciterking,
you should not base your decision on anything I or anyone else on an internet forum says. Base it on your exact needs that you should know best. If you need a sub look no further. The SR4718 cab should work, but for the ideal enclosure, either use the T/S parameters to tune it to your liking or copy the http://www.jblproservice.com/pdf/SRX700 Series/SRX718S.pdf .
My only question is where the heck do you get a pair of 2268H's for $720?
cheers,
AJ
I find no reason to doubt the JBL spec sheet. You both do. Prove it with data from an actual 2268 if so inclined. I have greater worries in life than to spend time on such frivolous endeavors.
I wonder why it is that you don't take issue with the (Pro) Aura's 18mm or TC's 30+ ? Somehow, in your minds, 23mm makes no sense. Go figure.
Anyhow, I done with this (non) issue. Time to move on.
Xciterking,
you should not base your decision on anything I or anyone else on an internet forum says. Base it on your exact needs that you should know best. If you need a sub look no further. The SR4718 cab should work, but for the ideal enclosure, either use the T/S parameters to tune it to your liking or copy the http://www.jblproservice.com/pdf/SRX700 Series/SRX718S.pdf .
My only question is where the heck do you get a pair of 2268H's for $720?
cheers,
AJ
AJ: Click here
http://www.performanceaudio.com/index.shtml
Call the 800 #, ask for Zack. Tell him, Kristopher King from Sacramento hooked you up. If you have any problems let me know. They were $339 for each JBL 2268HPL. I wanted your advice on which speaker; (if you had a choice) would you buy. The 2268's or the Eighteen Sound LW1400's. You know what cabs I will be using. The JBL 2241G's work OK for my band but if I start playing hp hop on the breaks things go wrong. The input levels from the original recordings are all out of whack. Some reasonable, others stupid. Hence, if I walk away from the rig, or don't pay real close attention, ect. In a heart beat a song will come on and pop the 2241G's. I need just a little more strength. Anyway that’s what I think. Might not be so. Anyhow, if you know something about the LW1400's or can recommend another speaker please respond, 1400's will be here 6/13/06. I could send them back and get the 2268's if you think that’s a better choice. I ran sound for a club where I installed four Bag Ends, I used two QSC 3402's in stereo and they were very strong. Don't want to pack more stuff. Thanks for your reply. Kris
http://www.performanceaudio.com/index.shtml
Call the 800 #, ask for Zack. Tell him, Kristopher King from Sacramento hooked you up. If you have any problems let me know. They were $339 for each JBL 2268HPL. I wanted your advice on which speaker; (if you had a choice) would you buy. The 2268's or the Eighteen Sound LW1400's. You know what cabs I will be using. The JBL 2241G's work OK for my band but if I start playing hp hop on the breaks things go wrong. The input levels from the original recordings are all out of whack. Some reasonable, others stupid. Hence, if I walk away from the rig, or don't pay real close attention, ect. In a heart beat a song will come on and pop the 2241G's. I need just a little more strength. Anyway that’s what I think. Might not be so. Anyhow, if you know something about the LW1400's or can recommend another speaker please respond, 1400's will be here 6/13/06. I could send them back and get the 2268's if you think that’s a better choice. I ran sound for a club where I installed four Bag Ends, I used two QSC 3402's in stereo and they were very strong. Don't want to pack more stuff. Thanks for your reply. Kris
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