[jtwrace]

I live in an apartment building.  I don't own (my primary habitat that is, I own other) so I can't do permanent installs.  I have a free standing moveable rack with three DCi/N amps in it and it isn't measurable above the normal white noise of living downtown in an apartment building.   But apartment living in downtown cities is louder than 'burbs living.   The I-tech amps though are meant to be leaf blowers.

No one who has demo'd my system has been able to hear the amps with the rack door closed.   I think I have had 6 guys now come over for a listen.

What rack are you using?  MA? 

[richidoo]

As I understand it most of the main peq functions are IIR with only a few FIR filters (can't recall if the xo is part of this), but that was for the M2, not sure what all the 708P has.

from what iv read the M2 uses minimum phase crossovers, which is why even a $80 minidsp can do it.

Oh well... 

I'm not surprised. I heard about the FIR dsp on yootoob vid of a JBL marketing guy at NAMM. 2 crossover filters at 1700Hz are a lot easier than several LF PEQs.
Thanks Josh and rabbit

[richidoo]

This is the video that claims 708P has "192kHz FIR filtering."  I asked my Sweetwater rep to confirm it's IIR.

Looks like FIR is in iTech amps and BSS processor. Maybe why standard $20k M2 package comes with iTech5000.

[Folsom]

Where are your M2's, jwtrace? You must be setting them up.

[jtwrace]

They are playing music!


 

[jtwrace]

The mic and REW are standing by though.  Going to chill out first as I've got a crazy busy weekend ahead.  Next I need to rearrange my equipment rack (swap them out) to prepare for the (2) Funk Audio 21.0LX subs.  Measure cable lengths and get the new speaker cables ordered too.  Then I'll start the measuring process but sounding incredible already and it will only get better.   

[richidoo]

Congrats Jason! 

(In honor of mother's day,) "Don't forget to eat and sleep."   

[goskers]

The mic and REW are standing by though.  Going to chill out first as I've got a crazy busy weekend ahead.  Next I need to rearrange my equipment rack (swap them out) to prepare for the (2) Funk Audio 21.0LX subs.  Measure cable lengths and get the new speaker cables ordered too.  Then I'll start the measuring process but sounding incredible already and it will only get better.   

Glad to see everything is firing.  I have confirmation that my last needed component is shipping on Monday.  I hope to have a smile on my face sometime late next week.

Enjoy!!!

[Folsom]

The mic and REW are standing by though.  Going to chill out first as I've got a crazy busy weekend ahead.  Next I need to rearrange my equipment rack (swap them out) to prepare for the (2) Funk Audio 21.0LX subs.  Measure cable lengths and get the new speaker cables ordered too.  Then I'll start the measuring process but sounding incredible already and it will only get better.   

We are going to need pics. Are those Funks going to be able to keep up?

[jtwrace]

Keep up?  I don't understand. 

[Folsom]

The JBL's are a pinnacle of articulation, subwoofers are not as frequently refereed as thus.

Those don't look as big as I think they actually are. You definitely could use some bigger speaker wire!

[jtwrace]

The JBL's are a pinnacle of articulation, subwoofers are not as frequently refereed as thus.

Those don't look as big as I think they actually are. You definitely could use some bigger speaker wire!

They're actually quite small.  Yeah I don't buy the whole "fast" or "slow" sub thing. Once you get it it's all clear but hard to covey in writing. You really need to hear it and see the measurements to realize it.  Seriously.

Speaker wire is coming, no worries. 

[Jonathon Janusz]

Yeah I don't buy the whole "fast" or "slow" sub thing.

Interesting to read you in particular say that, considering your long-standing position on objective differences and measures as a priority in evaluating potential equipment choices.

Maybe (I hope!) your new M2 will give you reason to pursue this further, as a matter of clear necessity in continuing to improve your system.  Considering the woofers in the M2 have to play up as high as they do, I would likely put them categorically in the fast camp out of functional necessity (and probably expertly so, considering they themselves have to keep up with a finely tuned horn loaded compression driver). 

As a hobbyist, I think that although it may be a sad day for your wallet, it will be an exciting one to have uncovered a new opportunity for increased performance of the system when the overhang of notes played by the subs (no matter how even and controlled throughout the room those notes are by way of bass management techniques - driver cones not stopping are still driver cones not stopping, even if they are doing so evenly) are noticeable enough compared to the notes coming from the mains to make it both obvious and (as a hobbyist) frustrating enough to make another system upgrade a necessity.

[Jonathon Janusz]

Has anyone who has heard these JBL speakers (M2 or 7-series) also heard a speaker using a BMS compression driver?  I read that the JBL drivers are using a non-metal diaphragm material which reminded me of BMS (different specific materials, and clearly different diaphragm geometries, for sure, but still similar enough to have caught my attention).  I really liked the sound from the BMS drivers I've heard in a few different speaker designs; I would call them having immediacy and presence, but not quite in so forward in presentation as some of the metal diaphragm compression driver speakers I've heard.  I wonder if the JBL driver gives a similar presentation?

(spoken as someone thinking out loud about how to get all the large-format compression/horn goodness he has heard from something that could work in a room plainly far too small for the above type of speaker...)

[rabbit]

while not proven there is alot to suggest the D2 is made by BMS.
others have come from there.

http://www.audioheritage.org/vbulletin/showthread.php?31125-2408H-vs-2408H-1-differences&s=f7e6998766a83cae84e31bc7e72f0ba2&p=313763&viewfull=1#post313763
"The 2408H takes its roots in the 2407H which was made by BMS (it really is a rebadged 4540nd) for JBL..."

iv seen a couple cloners highly recommend 2450sl with berylium cones over the D2
https://translate.google.com/translate?sl=no&tl=en&js=y&prev=_t&hl=no&ie=UTF-8&u=http%3A%2F%2Fwww.hifisentralen.no%2Fforumet%2Fdiy-og-utvikling-ha-yttalere-forsterkere-etc%2F74073-rai-rai-81.html%23post2272747&edit-text=

[goskers]

while not proven there is alot to suggest the D2 is made by BMS.
others have come from there.

http://www.audioheritage.org/vbulletin/showthread.php?31125-2408H-vs-2408H-1-differences&s=f7e6998766a83cae84e31bc7e72f0ba2&p=313763&viewfull=1#post313763
"The 2408H takes its roots in the 2407H which was made by BMS (it really is a rebadged 4540nd) for JBL..."

iv seen a couple cloners highly recommend 2450sl with berylium cones over the D2
https://translate.google.com/translate?sl=no&tl=en&js=y&prev=_t&hl=no&ie=UTF-8&u=http%3A%2F%2Fwww.hifisentralen.no%2Fforumet%2Fdiy-og-utvikling-ha-yttalere-forsterkere-etc%2F74073-rai-rai-81.html%23post2272747&edit-text=

Rabbit,

Can you please leave things about a M2 clone or modification out of this?  Yes, there is plenty of this information available.  All one has to do is search.

The development, inner workings and reasons for choosing the D2 driver were discussed during our visit to Harman.  Don't think that the other drivers utilizing exotic materials weren't an option.  The D2 is a different animal altogether because of the annular diaphragm.  This allows the using of a better diaphragm geometry which is able to move the breakup much higher.

[rabbit]

what are you going on about?
he asked about alternatives and BMS so i mentioned the connection JBL-BMS and a superior option driver. D2 is built to a Budget, and nowhere near the 2450sl-bl according to atleast two modders. wanting to believe the D2 is the best thing in th world doesnt make it so.

[goskers]

what are you going on about?
he asked about alternatives and BMS so i mentioned the connection JBL-BMS and a superior option driver. D2 is built to a Budget, and nowhere near the 2450sl-bl according to atleast two modders. wanting to believe the D2 is the best thing in th world doesnt make it so.

I don't believe I have said anything about the D2 being the best thing ever.  Everything is built to a price point.  Just because a couple of modders changed out the compression drivers with different units doesn't necessarily make it an improvement.  Doing this just makes it a change and an unknown one without another set of complete measurements and subjective testing.

I would rather this thread not get pulled off by modified and DIY efforts to change and 'improve' the design.  If people want to consider those options then that info is already avaialable elsewhere. 

[Nick77]

Curious what JBL says about breakin if any? Are you gonna give them a few days to settle in before measure?

[AJinFLA]

Curious what JBL says about breakin if any?

Didn't that go out in the 80's?? I remember guys spinning on their heads and stuff. Still around?