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Brian DK
03-21-2013, 01:42 PM
Hi.
A question regarding the low end.
can someone explain why its not possible to use one woofer that goes all the way down to 20hz.
insted of using to woofers that both roll of around 40hz.?

Mr. Widget
03-21-2013, 01:45 PM
Simple answer: They wanted to keep the sensitivity above 89dB watt. ;)

The woofers will plumb the depths well, but need a bit of electronic nudging.


Widget

Valentin
03-21-2013, 05:54 PM
Two Woofers
Increases sensitivityat low frequency as Widget says
Doublethe radiation area so only have the displacement is needed at agiven intensity /freq , this gives you less distortion. Having two motors givesyou more thermal advantages having a system that will be linear at very highlevels of continuous play . The system will not compress and dynamics will notsuffer linearity and the spectralbalance will be preserved

4313B
03-21-2013, 10:38 PM
Hi.
A question regarding the low end.
can someone explain why its not possible to use one woofer that goes all the way down to 20hz.
insted of using to woofers that both roll of around 40hz.?


Simple answer: They wanted to keep the sensitivity above 89dB watt. ;)

The woofers will plumb the depths well, but need a bit of electronic nudging.


WidgetBy using a second "helper" woofer, a designer is able to take advantage of the increased sensitivity caused by the bafffle step response of a system. This is how the Everest II maintains its higher sensitivity despite the fact that only one woofer is used up to the horn.

If the second "helper" woofer didn't exist to fill in the bottom end then the crossover network would have to have a mechanism to deal with the baffle step response and the resulting system sensitivity would be exactly what one would expect from a single woofer system.

Guido
03-22-2013, 12:24 AM
....insted of using to woofers that both roll of around 40hz.?


I suppose you don't own the Everest DD66000?
You really should not worry because of the datasheet low end roll off of these speakers. In my room I have flat response down to 20Hz.
If you need lower, by a servo sub.
Some people need lower, some not, me not.

The "helper" woofer design was already very successful in the 4435 and is continued with the Ev2 (with finer woofers). It works well ;)

mech986
03-22-2013, 02:01 AM
:D Great info and nice explanation.

grumpy
03-22-2013, 03:05 PM
Anyone know the status of the 66000->67000 update kit that was being considered?
(1501AL-2 drivers... perhaps minor x-over changes)

speakerdave
03-22-2013, 03:38 PM
Anyone know the status of the 66000->67000 update kit that was being considered?
(1501AL-2 drivers... perhaps minor x-over changes)

Oooo...interesting.

4313B
03-22-2013, 04:36 PM
They're having a real tough time convincing Mexico to make them above and beyond what is needed for whole systems.

They have very little interest in making raw drivers.

grumpy
03-22-2013, 05:14 PM
Wow... tail wagging the dog. That's just sad.

4313B
03-22-2013, 05:51 PM
Evidently Northridge is getting complaints from all over the planet (DD66000 owners).

Lee in Montreal
03-22-2013, 07:05 PM
Anyone know the status of the 66000->67000 update kit that was being considered?
(1501AL-2 drivers... perhaps minor x-over changes)

Dos it mean there will be used 1501AL-1 up for grab? ;)

pos
03-22-2013, 07:20 PM
Lee, you probably mean 1501AL: the 1501AL-1 is the new iteration made for the 65000.
Looking at the klippel measurements in the EDS that one is a real beast when it come to linearity at high excursion.
I am curious to know how they managed to make this one that much better than the previous 150xAL, as it look very similar in conception (rubber surround).
Or maybe it is just a difference in the distortion measurement technique? (EDS for the "old" ones did not include klippel measurements for that matter...)

grumpy
03-22-2013, 07:42 PM
At the very least, the -2 cone is a paper/foam/paper laminate in the latest iteration.
I don't recall if there were other driver changes. Very nicely, the driver info has been
provided and is available in the Technical Reference section if you wish to dig through it.
The designer indicated a fairly strong preference for the new driver, so that was good
enough for me :) (although it is nice to see the technical differences)

Brian DK
03-23-2013, 03:19 AM
I suppose you don't own the Everest DD66000?
You really should not worry because of the datasheet low end roll off of these speakers. In my room I have flat response down to 20Hz.
If you need lower, by a servo sub.
Some people need lower, some not, me not.

The "helper" woofer design was already very successful in the 4435 and is continued with the Ev2 (with finer woofers). It works well ;)

Yes, I own the Everest Dd66000. And I dont realy miss anything.
its the best allround sounding speaker I have heart.

But in some kind of Music I somtimes miss a bit low end, the Music seems a bit bright..

hlaari
03-23-2013, 04:43 AM
Evidently Northridge is getting complaints from all over the planet (DD66000 owners).

What are the Everest DD66000 owners complaining about?

4313B
03-23-2013, 07:16 AM
What are the Everest DD66000 owners complaining about?Lack of an upgrade kit.

I suppose it should have been made available with the release of the DD67000.

Guido
03-23-2013, 08:06 AM
..the Music seems a bit bright..

Somewhere in the "3 ways to climb everest" thread there is a network modification suggested by G.T. that take care of this.
I also found this modification when optimizing my own networks and found it confirmed when I read the mentioned thread.

Found it:
http://www.audioheritage.org/vbulletin/showthread.php?31733-3-ways-to-climb-Everest/page6

Mr. Widget
03-23-2013, 08:31 AM
Yes, I own the Everest Dd66000. And I dont realy miss anything.
its the best allround sounding speaker I have heart.

But in some kind of Music I somtimes miss a bit low end, the Music seems a bit bright..I own a pair too and have been enjoying them for about a year now. My previous system which incorporates Sub1500s definitely had deep bass extension that I do occasionally miss. I could add subs but missing subterranean bass is rare enough that I can live without it. I originally found the bass a bit murky on some music but I eventually rearranged my listening room fairly subtly making a significant improvement.

Too bright? I did find the system too bright with one preamp I tried, but I certainly don't feel it is too bright in the current arrangement.

Overall I am quite pleased with the DD66000s... sure they could have a tiny bit of additional bass extension and they could image more like the 1400 Arrays, but nothing is perfect. These things are pretty close though. :bouncy:

And yes, I would love the opportunity to try the new woofers!


Widget

Brian DK
03-23-2013, 09:25 AM
Somewhere in the "3 ways to climb everest" thread there is a network modification suggested by G.T. that take care of this.
I also found this modification when optimizing my own networks and found it confirmed when I read the mentioned thread.

Found it:
http://www.audioheritage.org/vbulletin/showthread.php?31733-3-ways-to-climb-Everest/page6

Nice:)
That I have got to try.:bouncy:

Thanks.

Mr. Widget
03-23-2013, 11:14 AM
Nice:)
That I have got to try.:bouncy:

Thanks.If I didn't miss something, the mod to lessen the apparent brightness is to simply replace a 3K resistor with a 2.7K? I suppose that could be done easily enough though simply pulling these massive woofers is a big deal. It is way too easy to drop one and ding the cabinets.

I'll wait and see about playing around if/when a woofer upgrade option materializes. I'm also just not sure that loosing a bit of 2KHz is really needed. From my own measurements of my pair... they are damned flat from 500Hz to 10KHz... rising a bit above 10KHz. Below 1KHz, in my "real world" room any measurement is pretty suspect.


Widget

pos
03-23-2013, 01:59 PM
I'm also just not sure that loosing a bit of 2KHz is really needed. From my own measurements of my pair... they are damned flat from 500Hz to 10KHz...

Have you tried off-axis measurements?
Those JBL biradials all seem to have a range somewhere in the upper midrange where they tend to loose directivity control, and go u-l-t-r-a w-i-d-e. In this situation aiming for a flat on-axis response might result in a bump in the power response.
http://www.audioheritage.org/vbulletin/showthread.php?32446-DIY-Everest-DD66000-finally&p=331703&viewfull=1#post331703
http://www.audioheritage.org/vbulletin/showthread.php?33024-why-does-JBL-4365-only-rank-10th-in-Japanese-eyes&p=344924&viewfull=1#post344924

At one point I tried playing with thin layers of foam on the inner lateral parts of the H980, and it did to reduce the problem, but I would have to look that up a little bit more...
I do not really understand where that comes from to begin with, but it is real :dont-know:
Any idea?

Brian DK
03-23-2013, 03:07 PM
If I didn't miss something, the mod to lessen the apparent brightness is to simply replace a 3K resistor with a 2.7K? I suppose that could be done easily enough though simply pulling these massive woofers is a big deal. It is way too easy to drop one and ding the cabinets.

I'll wait and see about playing around if/when a woofer upgrade option materializes. I'm also just not sure that loosing a bit of 2KHz is really needed. From my own measurements of my pair... they are damned flat from 500Hz to 10KHz... rising a bit above 10KHz. Below 1KHz, in my "real world" room any measurement is pretty suspect.


Widget

To add some low end.. How about replace the helper woofer to the 1500Al-1 with the lower impedance?
Or perhaps both woofere to the 1500Al-1.
That should reduce the system impedance, increase the total sensitivity.

or am I wrong? :o:

pos
03-23-2013, 03:30 PM
Adding some EQ (tailored to your room) would probably be the better idea

Brian DK
03-23-2013, 03:40 PM
Adding some EQ (tailored to your room) would probably be the better idea

And probably cheaper.. I have had the same idea my self.
But dont know what to buy..
do any of you know the Deqx Hdp4.?

pos
03-23-2013, 04:07 PM
If your sources are mainly analog you could probably find some parametric EQ that would fill your bill (meyer CP10 comes to mind).
If your sources are mainly digital *or* if you don't mind A/D and D/A conversions (which should not be armful at all if your gain structure is well handled) then digital EQ will bring a lot more options (room EQ, phase linearization, ...). If your source is a computer then it is even easier (and free)...
DEQX is one (pricey) option, but some other exists nowadays, such as the miniDSP openDRC (which exists in both analog and digital I/O versions) associated with external software (most of them free) for almost unlimited correction possibilities.

Brian DK
03-23-2013, 04:37 PM
If your sources are mainly analog you could probably find some parametric EQ that would fill your bill (meyer CP10 comes to mind).
If your sources are mainly digital *or* if you don't mind A/D and D/A conversions (which should not be armful at all if your gain structure is well handled) then digital EQ will bring a lot more options (room EQ, phase linearization, ...). If your source is a computer then it is even easier (and free)...
DEQX is one (pricey) option, but some other exists nowadays, such as the miniDSP openDRC (which exists in both analog and digital I/O versions) associated with external software (most of them free) for almost unlimited correction possibilities.

My source is digital.
I use a Krell Kps28 cd player, and a Krell Kct pre, and Krell Fpb700cx amp.

I am a bit worried about the A/D and D/A conversion in the Deqx.
But it is worth the try.:)

pos
03-23-2013, 07:20 PM
You could use the digital output of your CD player to feed the DEQX, and then use the DA converter of the DEQX to feed your preamplifier.
You could also buy an openDRC-DI (digital version) the same way and add a DA converter of your choice on its output.

That way you would still only have one DA conversion operation in your signal chain.

With both processors beware of fully automated corrections, and if you use them make sure the measurement(s) on which they rely to calculate their correction is accurate and representative.

Dave_72
03-27-2013, 11:39 AM
My source is digital.
I use a Krell Kps28 cd player, and a Krell Kct pre, and Krell Fpb700cx amp.

I am a bit worried about the A/D and D/A conversion in the Deqx.
But it is worth the try.:)

Nice system!

Brian DK
04-22-2013, 12:01 PM
I have now moved my speakers 5 inches closer to the backwall/corner.
it ment more to the Sound that I could imagine..:bouncy:
The bright Sound is gone, and the low end is more powerfull.

I would never think that the placement hat such a big impact.
Is it because of the double woofer that it is more sensitive to roomgain.?? :confused:

JuniorJBL
04-22-2013, 03:04 PM
It is not the speaker that is sensitive to the room, it is the room that is sensitive to speakers and sound in general.

macaroonie
04-22-2013, 04:46 PM
I have now moved my speakers 5 inches closer to the backwall/corner.
it ment more to the Sound that I could imagine..:bouncy:
The bright Sound is gone, and the low end is more powerfull.

I would never think that the placement hat such a big impact.
Is it because of the double woofer that it is more sensitive to roomgain.?? :confused:

Placement is crucial with respect to room response. You may well have had a cancellation in your first position.
Every room is different.
Glad to hear you have found an improvement , I suggest you continue to try small adjustments to the position.
Its a good idea to mark the floor with tape now that you have found a good spot.

Happy listening.........M

4313B
10-20-2014, 11:32 AM
I suppose you don't own the Everest DD66000?
You really should not worry because of the datasheet low end roll off of these speakers. In my room I have flat response down to 20Hz.
G.T. reiterated that just this morning: "Our measurements are made in a chamber with the ports pointing to the rear. The curves are very misleading regarding the true low frequency output of the system in a room."

Additionally, those published curves were the curves used in LEAP to design the crossover filters as opposed to showing exactly how low the system would go in an actual room. If I remember correctly, the large anechoic chamber is good down to ~ 25 Hz which means that there is going to be very little, if any, boundary reinforcement in the first octave. The anechoic chamber curve bears that out.

In short, the published response curves of the DD65000, DD66000 and DD67000 mean very little with respect to the response of the systems in the bottom two octaves in an actual room. JBL no longer takes measurements of their loudspeaker systems in "the pit" facing up towards the sky. It would be pointless to do so with the rear ported Everest II in any case.

At one point I posted that the Everest II was tuned around 30 Hz. It is in fact tuned around 34 Hz. What this means is that output it solid down to around 34 Hz and then the system will begin to roll off without any boundary reinforcement.

Guido already knows all this. This is for general reference.


In my room I have flat response down to 20Hz.No doubt!