New JBL M2

[shoshaw]

Hi Everyone
I posted this yesterday in the general audio forum. I think it probably belongs here so I'm reposting it.

This weekend, I setup my home theater with JBL M2 monitors in the LCR positions. I'm using Crown amps with the M2 factory specified crossovers and modified EQs. The installation of the amp and speakers took roughly 6 hours. These speakers are huge and heavy. They are replacing Revel Performa F30's which are not small speakers by any right. The M2s make the F30s look like toys. I am not able to lift the M2 by myself.

The factory EQ, in my opinion, sounded great but it also sounded a little like a horn, if that makes any sense. After a little tweaking, I was able to take the attached measurements at the listening position. These are the left and right speakers, 1/6th octave smoothing. With this response, I am happy to say that the M2s are, without a doubt, the best sounding speakers I have ever heard. I am in awe of the width and depth of the image. Everyone who listens asks me if the surround speakers are on. The center image is so locked that you cannot believe the center channel is turned off. Several times, I walked up to the screen to prove to myself that I was indeed listening to stereo.

The efficiency of the M2 is outrageous as compared to typical "audiophile" speakers. Every gain in the system needed modification to account for the M2s. Subs and surround speakers needed 9dB boosts to keep up with the M2s.

The low end of the M2 is effortless at any volume I am willing to listen. Compared to the M2, the Revels have a bit more punch but the M2s certainly have more depth. The M2s are very articulate and revealing. Already, I am hearing parts of certain tracks that I have never heard before.

The imaging...I just can't get over the imaging.

JBL hit another homerun.

[hjames]

Looks like an affordable 2 way. (No affiliation - just providing a reference point)

Sweetwater has them for about $20k a pair, including the Crown amps!

http://www.sweetwater.com/store/detail/M2System/

"Two-way Reference Studio Monitor System with 15" Woofer;
Dual-diaphragm, Dual-voice-coil Compression Driver;
and Crown I-T5000 HD Amplifier (Pair)"

[audiomagnate]

Great review! Thanks. Is there a third one hiding behind the screen? What are you using for subs?

[shoshaw]

Great review! Thanks. Is there a third one hiding behind the screen? What are you using for subs?


Yes, the third is behind the screen on its side. The bi-radial horn is virtually identical in the vertical and horizontal axes so its response is almost identical to the sides.

For subs, I have built-in infinite baffle subs. On each side, there are 2x18" FI Audio IB18 drivers mounted in manifolds. Each pair is driven in parallel by a crown power amp. I've attached the response for reference. I have not applied EQ to the subs yet so I expect the response will get significantly better. With the IB design, the low frequency extension is amazing.

[Mctwins]

Hallo!

Nice speakers:applaud:

Regarding mesurements you can look here for comparison:D. This is two seperate rooms. One is with PRX600 series and one is with JBL Cinema Screen Arrays with additional subs. Measured both with REW and ARTA. I prefere ARTA as better than REW. REW seems to be much sensitive during measurements.

With PRX600 with subs.

http://www.gearslutz.com/board/9455716-post165.html

http://www.gearslutz.com/board/9455764-post167.html

With Cinema screens

http://www.gearslutz.com/board/9664574-post182.html

These measurements is with and without the Flower Wings on the floor.

In your measurements the suffer is in the control in the bass region. I am using tunable Varitunes Helmholtz resonators for my bass treatment. To me, this is the best treatment for low freq.

It looks very good from 200Hz and up in the freq response:bouncy:but you have to work with your bass anomalies. If you control the first axiell modal resonaces you will have more benefit from your speakers to produce a healava bass performance.

Could you show the Waterfall and Filterd Impulse reponse from REW and also show measurements with both speakers.

Nice.....:)

[Mctwins]

Yes, the third is behind the screen on its side. The bi-radial horn is virtually identical in the vertical and horizontal axes so its response is almost identical to the sides.

For subs, I have built-in infinite baffle subs. On each side, there are 2x18" FI Audio IB18 drivers mounted in manifolds. Each pair is driven in parallel by a crown power amp. I've attached the response for reference. I have not applied EQ to the subs yet so I expect the response will get significantly better. With the IB design, the low frequency extension is amazing.

Is this measured with all three M2 and with the subs?

[shoshaw]

Is this measured with all three M2 and with the subs?

Measurement is for the LR pair of M2s plus the subs. Center channel is off.

[shoshaw]

Hallo!

Nice speakers:applaud:

Regarding mesurements you can look here for comparison:D. This is two seperate rooms. One is with PRX600 series and one is with JBL Cinema Screen Arrays with additional subs. Measured both with REW and ARTA. I prefere ARTA as better than REW. REW seems to be much sensitive during measurements.

With PRX600 with subs.

http://www.gearslutz.com/board/9455716-post165.html

http://www.gearslutz.com/board/9455764-post167.html

With Cinema screens

http://www.gearslutz.com/board/9664574-post182.html

These measurements is with and without the Flower Wings on the floor.

In your measurements the suffer is in the control in the bass region. I am using tunable Varitunes Helmholtz resonators for my bass treatment. To me, this is the best treatment for low freq.

It looks very good from 200Hz and up in the freq response:bouncy:but you have to work with your bass anomalies. If you control the first axiell modal resonaces you will have more benefit from your speakers to produce a healava bass performance.

Could you show the Waterfall and Filterd Impulse reponse from REW and also show measurements with both speakers.

Nice.....:)


Hi McTwins.
Thanks for your interest. Attached are the responses you requested. I'd be interested in your feedback. Just getting into the whole audio measurement process so I'n not entirely sure how to interpret some of this data.

[Mctwins]

Hallo!

I will tell you some info regarding measurements but for the moment, I don't have much time right now.

Can you post the .mdat file so I can look at it in my REW.

What is the x-over settings. Between sub and M2.

I'll be back

[ivica]

Yes, the third is behind the screen on its side. The bi-radial horn is virtually identical in the vertical and horizontal axes so its response is almost identical to the sides.

For subs, I have built-in infinite baffle subs. On each side, there are 2x18" FI Audio IB18 drivers mounted in manifolds. Each pair is driven in parallel by a crown power amp. I've attached the response for reference. I have not applied EQ to the subs yet so I expect the response will get significantly better. With the IB design, the low frequency extension is amazing.

Hi shoshaw,

Is that any possibility to do a measurements of the SINGLE box, without subs, etc...
while M2 box is laying on its back side and the mic is about 1m up over the box top side,
so much more comparable data can be get, including appropriated gating in order to remove reflections.

Reagrds
Ivica

[shoshaw]

Hi shoshaw,

Is that any possibility to do a measurements of the SINGLE box, without subs, etc...
while M2 box is laying on its back side and the mic is about 1m up over the box top side,
so much more comparable data can be get, including appropriated gating in order to remove reflections.

Reagrds
Ivica

This might be interesting but I wonder about the EQ. How should I set the EQ for these measurements?

[Mr. Widget]

Just getting into the whole audio measurement process so I'n not entirely sure how to interpret some of this data.My guess is that once you do get a bit more experience with measurements and the relevance of the data, you will be pleasantly surprised that as good as your speakers sound now, you will be even more thrilled with their capabilities as you use that data to fine tune your DSP settings.


Widget

[Valentin]

nice HT set up

I will soon be geting a pair for my room

:applaud:

what made you go for the M2? did you hear them befor buying them ?

do you have Measurments with out the subs and the original eq stteings

congrats


Valentin

[ivica]

This might be interesting but I wonder about the EQ. How should I set the EQ for these measurements?

I have no idea, except to EQ the system to be "as flat as possible" on axis, and what is usually expectation for "standard speaker box".

[Bobecca]

Hi,

Nice speaker set up you got there, however, I personally think that there has to be some seperation between in room response and the actual response of the speaker. I do wonder why you have decided to not use the original setting on the M2 in the Crowns DSP. This is in the end what is tuned for the speaker and not your room.

Still want to know, like Mctwins pointed out, what kind of crossover is used. This has to be presented here.

Looking at your graphs indicate a very strong early reflections that has to be taken care of and why the response down to 10Hz? You have strong resonance in the bottom end as well. I suggest that this is a need of a HP filter to remove anything below 20Hz to reduce that resonance or start to deal with treatment so that resonance is reduced in your room. And let me tell you that this is not an easy task to tame a resonance of 10Hz!

I do hope that you can provide the mdat file so I and Mctwins can take a better look:D

Please remember that a rooms response is not the same as speaker response, but I think you all now this!

To tune a room is a lot diffrent than to tune a speaker;)

[shoshaw]

Hi,

Nice speaker set up you got there, however, I personally think that there has to be some seperation between in room response and the actual response of the speaker. I do wonder why you have decided to not use the original setting on the M2 in the Crowns DSP. This is in the end what is tuned for the speaker and not your room.

Still want to know, like Mctwins pointed out, what kind of crossover is used. This has to be presented here.

Looking at your graphs indicate a very strong early reflections that has to be taken care of and why the response down to 10Hz? You have strong resonance in the bottom end as well. I suggest that this is a need of a HP filter to remove anything below 20Hz to reduce that resonance or start to deal with treatment so that resonance is reduced in your room. And let me tell you that this is not an easy task to tame a resonance of 10Hz!

I do hope that you can provide the mdat file so I and Mctwins can take a better look:D

Please remember that a rooms response is not the same as speaker response, but I think you all now this!

To tune a room is a lot diffrent than to tune a speaker;)

Hi All,
Trying to respond to everyone in a single response.

I chose the M2 based on various recommendations I have received from various people I know within the Harman engineering team. Of all the speakers in the Harman portfolio, the M2 is the only speaker that EVERYONE agrees is awesome. I never had a chance to audition them prior to purchase. I do not have measurements of the M2 with factory settings but I do still have the settings in my amp. I will try to make those measurements and post them soon.
In fact, I DID start with the original factory EQ and crossover settings. When I used these settings, the sound was not as good as it should have been. There was quite a bit of midrange "honk". The factory EQ had many peaks and notches which were very small in amplitude (less than 2 dB) and high Q (higher than 6). In most cases, these filters are inaudible. I was using up most of my DSP resources with filters that made little or no difference. I'm not sure why the factory EQ was designed this way but I have my theories. I DID keep the factory crossover settings. The HP is a simple first order at 800ish Hz. The LP is a 3rd order LR at 800ish Hz.

I understand the idea concept of making an EQ to result in an anechoicly flat speaker and then treating the room to keep it flat but I also understand that each speaker is slightly different and this is especially true in my less-than-symmetric room. Part of the design concept of the M2 is to maintain a consistent frequency response across both horizontal and vertical axes so that reflected sound has the same character as direct sound. In round one of my implementation, I chose to EQ the speakers to be flat in their respective listening positions and the result (IMO) is nothing less than amazing. I will continue to experiment and that's the beauty of the M2 setup. I can tailor it to the point where I just might drive myself crazy! As this evolves, I will continue to share and learn from this community. I am very interested in the comment about early reflections. Can you point out where I would see that in my measurements so I can experiment with various room treatments?

Regarding the 10Hz, my setup is primarily for home theater. I really don't want to tame the resonance at 10Hz. I want to FEEL the resonance at 10Hz! With normal audio input, that resonance is rarely excited and not necessarily a problem for me. I'm a self declared "bass head" and I find flat responses to be lifeless. A rising response like that seen in my measurements is sort of a "house curve" that I find *most* people like. Of course, I will never debate personal preference with anyone because I know I have strong opinions too...

I've tried to upload the mdat files but it seems the forum page only allows pictures to be attached?

[Valentin]

thanks for your Reply


did you try leaveing in the speaker eq and just ad some room correction i would do it that way

allsow Are you avregeing your measurments or are thy been made at the same point in space

with avregeing you will have the room balance whitch will helpyou allot more to correct the room than single point measurments

my two cents

[Bobecca]

I can not more than agree with Valentin. The setting in DSP is for the loudspeaker and if there is deviation from that in your room then your room is the problem. I would leave the setting as is. I am using the setting that is for my speakers. When I dont use it I always feel that there is something missing. And in my room it just sounds better with this setting on.

Still want to know what crossover freq is used for the subs and is the main speaker in full range down to 20Hz?

I also miss what kind of treatment is currently used in your room and little info about the room in general. My felling is that it is damped with porous absorbent and the bass region is left untreated. This is just by looking at your previous posted graphs.

Is all of your first reflection points treated with porous panel absorber?

[Valentin]

your avrage room response shuold be have way between the first reflection curve and the sound power curve with a tiny bit of the direct curve at high frec

measure 8 difrent points from you listening point and all around in difrente axes

this is how your speaker measures with the factory settings in an anecoic chamber it does not get flater than this belive me but the target / predicted room response lies between those mention curves


61744

[shoshaw]

your avrage room response shuold be have way between the first reflection curve and the sound power curve with a tiny bit of the direct curve at high frec

measure 8 difrent points from you listening point and all around in difrente axes

this is how your speaker measures with the factory settings in an anecoic chamber it does not get flater than this belive me but the target / predicted room response lies between those mention curves


61744

Hey everyone. Thanks for the great discussion. Here are more measurements I took when I got home from work.

M2 with factory EQ in my listening spot.
M2 on back with Mic 1m from front panel at horn center.

My room is carpeted with thick carpet and pad. In the ceiling, there is 2" of rockwool panel insulation. I have not treated the side walls. I have also not used any sort of low frequency room treatment.

This weekend, I will use the old laser-pointer and mirror trick to determine where my first reflections are coming from and try to treat them.

The third measurement group shows the three listening positions across my couch. They are quite similar which is a testament to the M2 design. I have been making measurements in the center and not averaging. I believe that if I averaged measurements across the listening area, I would get something very similar to the center except it would be a little smoother.

Maybe after some room treatments I might like the factory setting but right now, it's just not quiet right.

[macaroonie]

Quick question , do you have enough PEQ to use over and above the speaker EQ ? Only saying this because the speaker EQ is very carefully worked out with subtle tweaks here and there. Rooms are more radical as you can see , perhaps its worth using a PEQ outboard to do the room :dont-know:

I hasten to add I have not had a test drive on the Crown DSP so don't know what it offers but I can see where if you delete the speaker basics you may not get these back into line with your room correction. Not sure its that simple.

BTW thanks for your first hand review , we've all waited for this. I'm sure once you get it all dialed in it will be splendid.

Enjoy, Mac

[shoshaw]

Quick question , do you have enough PEQ to use over and above the speaker EQ ? Only saying this because the speaker EQ is very carefully worked out with subtle tweaks here and there. Rooms are more radical as you can see , perhaps its worth using a PEQ outboard to do the room :dont-know:

I hasten to add I have not had a test drive on the Crown DSP so don't know what it offers but I can see where if you delete the speaker basics you may not get these back into line with your room correction. Not sure its that simple.

BTW thanks for your first hand review , we've all waited for this. I'm sure once you get it all dialed in it will be splendid.

Enjoy, Mac


Hi MAC
Thanks for the response. The factory EQ does leave some room to add EQ for room correction. I did not make the decision to delete the factory EQ parameters lightly. No doubt the designer knows what he is doing. Each and every filer was carefully examined before I either decided to keep it or delete it. To tell you the truth, I'm a little stumped as to why some of the EQ was in there at all. Who can hear a -1dB notch with a Q of 12? Some of it really makes little acoustic sense. I will know more once I start the room treatment experiment. Maybe I can get the room good enough that I can go back to the factory EQ. One thing is for sure, the M2s are excellent and well worth the investment.

[Mctwins]

Hallo!

Your last mesurement proves that you have anomalies in the bass region. I asume that it is only the right and left speakers without sub the graphs shows.

About your Filterd Impulse response, on the left upper corner you can switch between dBFS and %FS, can you present the dBFS graph. and enlage it like this...

The red graph shows the reflection bouncing from the floor.

61749

The green graph shows the reflection is gone by installing the Flower wings at first reflection point.

61748


Can you also show the waterfall from last measurement and expand it to 800ms and from 20Hz-20Khz. Like this...

61750

Comparing your waterfall with mine you see that I have decay time around 150-200ms from 100Hz to 20Khz and this is without ANY absorbtion in this room. This is the measurement from PRX600 series.

And, here is the ARTA's impulse response...

61751


Flower Wing time delay lines works broadbanded in the nearfield and transform the combfilter to dense reflections that shape up the frequency response.

Some info about Wings

http://www.hakode.se/wing/Wing.pdf

http://www.gearslutz.com/board/9703275-post255.html

http://www.whatsbestforum.com/showthread.php?9457-new-home-for-my-Magico-Q1

I agree with other that you should keep the parametric EQ for the M2. If it sounds bad it is not the M2 fault, it is your room that is the weakest link here, Sorry to say.

If you take time and read and treat your room properly you will never regret it, I can never go back and listen to an untreated room anymore.

[ivica]

Hey everyone. Thanks for the great discussion. Here are more measurements I took when I got home from work.

M2 with factory EQ in my listening spot.
M2 on back with Mic 1m from front panel at horn center.

My room is carpeted with thick carpet and pad. In the ceiling, there is 2" of rockwool panel insulation. I have not treated the side walls. I have also not used any sort of low frequency room treatment.

This weekend, I will use the old laser-pointer and mirror trick to determine where my first reflections are coming from and try to treat them.

The third measurement group shows the three listening positions across my couch. They are quite similar which is a testament to the M2 design. I have been making measurements in the center and not averaging. I believe that if I averaged measurements across the listening area, I would get something very similar to the center except it would be a little smoother.

Maybe after some room treatments I might like the factory setting but right now, it's just not quiet right.

Hi shoshaw,

Many thanks for the data You have shown us.

For sure it seems that JBL sound engineer have done quite good job applying EQ, especially over 800Hz (neglecting some peak around 10kHz).
May be some THD measurements would be interesting to be seen too.
Bass driver section is very difficult to analyze if no knowledge about the gate-time that was applied ( if any ? say about 30ms).
It seems that mic to ceiling distance was about 1.4m (is it?), so a kid of com filtering under 800Hz was present, so the data under several hundreds Hz were not so many informative.

Only general 'objection' that I can say about M2 is almost necessary application of sub-woofers in order to reproduce LF section.

But the most important thing is that You are satisfied with your new speakers.
Regards
Ivica

[audiomagnate]

Only general 'objection' that I can say about M2 is almost necessary application of sub-woofers in order to reproduce LF section.
Ivica

EVERY room/system needs a swarm of subs to get the bass right. That's not a speaker limitation it's just an acoustical fact. The OP's IB setup is a great start, but two or three additional conventional subs spread around the room would smooth out those bass anomalies. I agree with the OP, if you can do 10 Hz cleanly, go for it! Blu-rays go down to DC. It looks like the OP has 10-40K. Now that's wideband!

[ivica]

EVERY room/system needs a swarm of subs to get the bass right. That's not a speaker limitation it's just an acoustical fact. The OP's IB setup is a great start, but two or three additional conventional subs spread around the room would smooth out those bass anomalies. I agree with the OP, if you can do 10 Hz cleanly, go for it! Blu-rays go down to DC. It looks like the OP has 10-40K. Now that's wideband!

Hi audiomagnate,

As I can see from the:
http://www.audioheritage.org/vbulletin/showthread.php?35266-L300-Woofer-Phasing&p=357220&viewfull=1#post357220
You have been experimenting with L300 JBL speakers.
Owing to L300 data it seems that almost no sub-woofer is needed, but may be You have opposite experience.

regards
ivica

[Mctwins]

EVERY room/system needs a swarm of subs to get the bass right. That's not a speaker limitation it's just an acoustical fact. The OP's IB setup is a great start, but two or three additional conventional subs spread around the room would smooth out those bass anomalies. I agree with the OP, if you can do 10 Hz cleanly, go for it! Blu-rays go down to DC. It looks like the OP has 10-40K. Now that's wideband!

:confused:

I don't have a swarm of subs in my room. Yet, I have good bass response in the freq response. If putting swarm of subs won't eliminate those nasty resonances that is happening in the room due to standing waves and inteferences.

In this link, Matts Odemalm from SMT explains it better than me about room acoustics.

http://www.euphonia-audioforum.se/forums/index.php?showtopic=5342&view=findpost&p=173423

[Mctwins]

To the OP....

According to the brochure at page 8 about "Tuning and Room Integration", you have something called "floating-point digital signal processing integrated into Crown iTech HD power amplifiers and BSS Soundweb London processors."

http://www.jblpro.com/ProductAttachments/M2_Brochure_Jan2013.pdf

Why don't you give this a try to smoothen the freq reponse in your room, but still, keep the EQ setting for the M2.

Just give it a try.:)

[audiomagnate]

[QUOTE=Mctwins;360120]:confused:

...putting swarm of subs won't eliminate those nasty resonances...due to standing waves and inteferences... /QUOTE]

That's exactly what it does do. Turning on the DSP for the bass is a good idea too.

[Bobecca]

[QUOTE=Mctwins;360120]:confused:

...putting swarm of subs won't eliminate those nasty resonances...due to standing waves and inteferences... /QUOTE]

That's exactly what it does do. Turning on the DSP for the bass is a good idea too.

Do you have something to show that back this up??
Multiple subs will maybe even the freq response but removing resonances, well I dont think so!

OP wanted to have resonances in his listening experience, I wonder why? It is afterall the energy from the sub one wants to hear and not together with resonance caused by room boundary that interfere with the sub.
If that would be the case then why putting effort to treat those bad resonances in our small rooms.

Just saying

[shoshaw]

[QUOTE=audiomagnate;360138]

Do you have something to show that back this up??
Multiple subs will maybe even the freq response but removing resonances, well I dont think so!

OP wanted to have resonances in his listening experience, I wonder why? It is afterall the energy from the sub one wants to hear and not together with resonance caused by room boundary that interfere with the sub.
If that would be the case then why putting effort to treat those bad resonances in our small rooms.

Just saying

So, I have spent the day with a microphone and huge piles of Roxul. I piled Roxul, 11 inches thick, from floor to ceiling against the wall behind my speakers and found that it helped my bass response quite a bit. I also found those first reflections and treated them with 3.5" Roxul panels on the side walls. Tomorrow, I will look at the ceiling.

Interestingly, taking out those first reflections had little effect on the actual measured frequency response.

After further tweaking tomorrow, I will post measurements. In terms of turning on DSP, that's exactly what I've been doing all this time. I've been using the EQ to tune the system in my room. In my room, most of the factory EQ settings are not helping. In fact, if I left them in, I would simply be undoing them with more EQ. You guys are going to hate this but still the best response and sound so far is when I use my own EQ. Fire away...:eek:

[Robh3606]

You guys are going to hate this but still the best response and sound so far is when I use my own EQ. Fire away...:eek:

I don't understand why you need all that much EQ. Above the schrouder frequncy say 300-400 hz you shouldn't need much except posiibly a tilt cut to slightly roll off the highs if you feel you need it. They should be room friendly out of the box with their uniform off axis response. I could see a couple of filters for the primary room modes but not much else needed unless your room is a real bear.

Rob:)

[audiomagnate]

[QUOTE=audiomagnate;360138]

Do you have something to show that back this up??


http://www.harman.com/EN-US/OurCompany/Innovation/Pages/WhitePapers.aspx

[Bobecca]

[QUOTE=Bobecca;360139]

http://www.harman.com/EN-US/OurCompany/Innovation/Pages/WhitePapers.aspx

I've read this before:D. But there is nothing there that shows that resonance caused by the room is reduced by EQ. I cant find any waterfall plots that backs up what you imply, not yet at least. The only thing that is shown is that one can EQ out response by using multiple subs, and I dont see any harm by doing that any way;)

Interferance causing a dip in the freq response cant be solved by EQ, but I have solved my dips with tuned helmholtz resonator. And these devices will also reduce resonances and shorten the reverberation in the low end. I get so many beneficial aspects with treating a room then go with the route of EQ.

When the room is fixed then I can apply the EQ for a room curve as needed for my taste. And that is a big difference. I dont remove the setting that is there for the speakers.

[Robh3606]

Here is what the JBL Synthesis curve look like. The Revel sub software has the same elevated level for their optimum in-room curve as well. You can see the tilt EQ on the top end. You should easilly be able to come up with single tilt eq setting and the bass is self explanatory.

Rob:)

[audiomagnate]

What's the reason for the 10 dB downward slide in the top octave?

[Robh3606]

That's a 5db slide the 100-1K is the flat area with a 5db bass rise. That is their, or one of their target curves. If you go flat in the bass it sounds lean and if you go flat on the high end it sounds bright. So they put in bass fill and rolled of the top end a bit. I have a similar curve on my HT mains but I dont roll off the highend as much and my hinge is further out. Here is a measurement curve from a Revel Performa F208. Look at the predicted room response curve. See any similarity??

Rob:)

[Audiobeer]

I wonder how the specs compare to my favorite 2 ways the 4430's?

[shoshaw]

Hi Everyone. As promised, here is some data I collected over the weekend.

First graph shows the before (green) and after (blue) of placing 12" of Roxul in the room corner behind the speaker. Pretty dramatic improvement in the 70Hz range. Problem is not gone but it's way better.

Second graph shows the M2 with factory crossovers only (EQ deleted). Purple is without Roxul. Blue is with Roxul in the corners and placed to absorb first reflections from the side wall and ceiling.

In spite of the room treatments, I still cannot eliminate the peaks between 500-1kHz I detect in the M2 factory EQ in my room. The good news is that a touch of EQ makes it all better.










[QUOTE=Bobecca;360139]

So, I have spent the day with a microphone and huge piles of Roxul. I piled Roxul, 11 inches thick, from floor to ceiling against the wall behind my speakers and found that it helped my bass response quite a bit. I also found those first reflections and treated them with 3.5" Roxul panels on the side walls. Tomorrow, I will look at the ceiling.

Interestingly, taking out those first reflections had little effect on the actual measured frequency response.

After further tweaking tomorrow, I will post measurements. In terms of turning on DSP, that's exactly what I've been doing all this time. I've been using the EQ to tune the system in my room. In my room, most of the factory EQ settings are not helping. In fact, if I left them in, I would simply be undoing them with more EQ. You guys are going to hate this but still the best response and sound so far is when I use my own EQ. Fire away...:eek:

[Mctwins]

[QUOTE=shoshaw;360232]Hi Everyone. As promised, here is some data I collected over the weekend.

First graph shows the before (green) and after (blue) of placing 12" of Roxul in the room corner behind the speaker. Pretty dramatic improvement in the 70Hz range. Problem is not gone but it's way better.

Second graph shows the M2 with factory crossovers only (EQ deleted). Purple is without Roxul. Blue is with Roxul in the corners and placed to absorb first reflections from the side wall and ceiling.

In spite of the room treatments, I still cannot eliminate the peaks between 500-1kHz I detect in the M2 factory EQ in my room. The good news is that a touch of EQ makes it all better.

I am confused regarding your measurement, this before and after roxull, is it with the EQ or??

I asume you are using Audio Architect to set you amps and speakers. Are you familiar with pre PEQ and post PEQ?

You still schould use the settings for the M2.

Remember, when measureing before and after it is important that the mic is exactly in the same position, the mic shall not be moved.

[audiomagnate]

the mic shall not be moved.

The eleventh commandment?



When you "delete" the factory settings are they gone for good? It just seems like they would be a good place to start instead of just tuning by ear.

[Mctwins]

Take a look here, removed all of my Roxull.

http://www.gearslutz.com/board/8325451-post113.html

and how it is tuned

http://www.gearslutz.com/board/8912421-post114.html

You will have a hard time to solve your bass issue in your room with pouros absorber(roxull). Been there done that.

Seeing your measurement at post39, there is little changes to have some effect. You must phase shift your pressure in the corners. The Varitunes do three things, that is Phase Shift, reduce Resonances and reduce the Decay Time.

[Bobecca]

shoshaw...

But if you move the mic to a diffrent pos does the change made by roxull still holds? Like Valentin mentioned earlier, measure in a diffrent pos, especially in the bass region!

Why the heavy drop of the higher freq?

Is it possible to show the impulse response when absorbers on the sides where installed?

Still want to emphesize that the setting for the speakers should be there. It is a part of the loudspeaker setting;)

[Bobecca]

The eleventh commandment?



When you "delete" the factory settings are they gone for good? It just seems like they would be a good place to start instead of just tuning by ear.

The problem is that it is the room that is causing the anomalies in the freq response not the speaker. The speaker measures flat in anechoic condition. That is why the settings must be there for the speakers.

[Robh3606]

The speaker measures flat in anechoic condition. That is why the settings must be there for the speakers.

Yes I couldn't agree more. At least that way you know the speaker is"right".

Rob:)

[shoshaw]

The eleventh commandment?



When you "delete" the factory settings are they gone for good? It just seems like they would be a good place to start instead of just tuning by ear.


The factory settings are still alive and well in my amp. I can turn them on and off at will. Believe me, I understand the passion for keeping the factory settings. Whether I start with the factory EQ or with some other basis, I will use EQ to correct the anomalies I measure/hear and to implement a "house curve" that makes me smile. When I look at my final EQ and the factory settings, the basic differences are in the areas effected by the room. When I switch between factory EQ and my EQ, I hear the room effects. When I start with the M2 EQ and fix the room problems, the result us virtually indistinguishable from the EQ I made from scratch. It is clear that correcting a room with EQ can only make one listening position really great and others only better. That's OK for me. I reserve the sweet spot. At the end of the day, I'm not going to do much more in terms of treating my room. It's a place the kids play and the wife is comfortable. All in all, I like their company more than I like the relentless pursuit of audio nirvana. Thanks to all who have contributed.

All in all, the M2 is still way beyond my expectations. I couldn't be happier.

[jpw]

Some of JBL Synthesis home theater calibrations adhere to SMPTE curves, which are not flat. I believe there is a bass boost build in to a SMPTE curve. Perhaps somebody with more technical information than I have can post a SMPTE curve, and or confirm whether or not M2's, when EQ'd via JBL's processing and or instructions, are EQ'd to SMPTE rather than truly flat.

[Robh3606]

A curve they use for Sythesis systems has already been posted in this thread. The M2 are set flat with the factory curves. You put in your own room EQ.

Rob:)

[Robh3606]

Why don't you do a sanity check on your factory settings with the other DSP off? Take a measurement 1-2 meters from one of the M2 on axis to see what you get. By on axis I mean with the mic centered on the horn so the mic is looking right into the throat. What you are showing makes no sense. You should not have anywhere near that much HF roll-off with that system. You should also be realitively flat above 1K. If the settings are right at 1-2 meters you should get somethig like this or better.

Rob:)

[ivica]

Why don't you do a sanity check on your factory settings with the other DSP off? Take a measurement 1-2 meters from one of the M2 on axis to see what you get. By on axis I mean with the mic centered on the horn so the mic is looking right into the throat. What you are showing makes no sense. You should not have anywhere near that much HF roll-off with that system. You should also be realitively flat above 1K. If the settings are right at 1-2 meters you should get somethig like this or better.

Rob:)

Hi Robh3606,

May be, I do not understand well, but You have presented 476Mg driver response with PT-H1010 horn....

For M2 response ( driver D2430K ) I would expect quite different response without ANY DSPs EQs.

http://www.audioheritage.org/vbulletin/showthread.php?33972-JBL-Master-Reference-Monitor&p=343108&viewfull=1#post343108


BASS section has to be OFF, so that there would not be a kind of bass to VHF driver interaction, as was the case

http://www.audioheritage.org/vbulletin/showthread.php?35538-New-JBL-M2&p=360232&viewfull=1#post360232

with the shoshaw data.

Reagrds
Ivica

[Robh3606]

Hi Robh3606,

May be, I do not understand well, but You have presented 476Mg driver response with PT-H1010 horn....

For M2 response ( driver D2430K ) I would expect quite different response without ANY DSPs EQs.



Hello ivica

I didn't ask for all the DSP to be off. I asked for the speakers with just the factory DSP settings only. Above 1K you should get response similar to your on axis response. Why is there all of that roll-off and why is the response so uneven?? It shouldn't be that way. I posted the other curve as a reference, his measured in room response should be very close or better at 1-2 meters.

Rob:)

[ivica]

Hello ivica

I didn't ask for all the DSP to be off. I asked for the speakers with just the factory DSP settings only. Above 1K you should get response similar to your on axis response. Why is there all of that roll-off and why is the response so uneven?? It shouldn't be that way. I posted the other curve as a reference, his measured in room response should be very close or better at 1-2 meters.

Rob:)

Hi Robh3606,

I understand now. I can agree that the "HF roll-off " should not to be so large.
It behaved as WG without WG compensation....

Reagrads
ivica

[shoshaw]

Hi Robh3606,

I understand now. I can agree that the "HF roll-off " should not to be so large.
It behaved as WG without WG compensation....

Reagrads
ivica

The curve referenced below is the M2 with NO EQ. Incidentally, the factory EQ has about 9dB of HF boost to compensate for the roll-off you see.

Here is the M2 with the factory EQ measured at throat height at 1M. Indeed, the high end is nice and flat if you ignore the bump at 10k.

[Jakob]

It would be nice to get more information about crossovers: what kind of slope and at what frequency?

[ivica]

It would be nice to get more information about crossovers: what kind of slope and at what frequency?

Hi Jakob,

May be some info can be find in the our member's 4313B [ http://www.audioheritage.org/vbulletin/member.php?15-4313B ] precious work:

http://www.audioheritage.org/vbulletin/showthread.php?33972-JBL-Master-Reference-Monitor&p=354289&viewfull=1#post354289

http://www.audioheritage.org/vbulletin/showthread.php?33972-JBL-Master-Reference-Monitor&p=354296&viewfull=1#post354296


http://www.audioheritage.org/vbulletin/showthread.php?33972-JBL-Master-Reference-Monitor&p=354372&viewfull=1#post354372
http://www.audioheritage.org/vbulletin/showthread.php?33972-JBL-Master-Reference-Monitor&p=354340&viewfull=1#post354340
http://www.audioheritage.org/vbulletin/showthread.php?33972-JBL-Master-Reference-Monitor&p=354303&viewfull=1#post354303

Regards
Ivica

[Jakob]

Thank you for those valuable links Ivica!

I'm a bit confused though when it comes to the PEQ. Most common type used is a 6dB slope, shelfs is only used once per driver. Whats the background to that fact?
How can you determine from the table in which way the 6dB slope's tilts?

Regards,

Jakob