Tricky mic position create random response mesure

[Mr. Widget]

"Studies have been done that support evidence that small amplitude broad band deviations of 2 - 3 octaves over the entire spectrum are accutely more audible as shifts in tonal balance than irregular or random peaks and dips. This is why RIAA curve accuracy is so important, a +- 0.75 db variation or less is quite audible. So obviously the better the match of the 4 driver spls the more true the system will perform, doing that at 3 metres in your room is lunacy."

I fully agree. Here is a quasi anechoic plot of a stock 4343 taken at 1.5m. The system was raised off the floor in a room with 15' ceilings. I limited the response below ~450Hz as my measurement was no longer meaningful at those frequencies. Due to severe comb filtering between the 2420 and the 2405, the response will measure differently as the mic is moved horizontally or vertically even at the distance of 1.5m.

Widget

[Ian Mackenzie]

A sigh of relief,

Thankyou Widget for posting this response curve.

I will be on the planet of the apes (work) tomorrow so please carry on.

The Doctor

[B&KMan]

Hi


Well I understand the relationship of net spl and electrical signal but reason of L-pad is not for this....

the reason of Lpad is for flatness response for sweet spot mixing room studio.

of course is play suberly in room house but this is a studio monitor, so asuming the nature of the thing.

It is really easy to fix relation of driver spl and electrical with high degree of precision in laboratory and determine exact resistance to put in place of l-pad and voilà home solution...

The professionnal speaker is for professionnal enviroment tool, exterior, interior, bar, disco, studio... the studio X refresh driver at 2 years and scrap speakers fast because non accurate, better new drivers performance....

and the studio is not hesitate to pay a professionnal for calibration system or buy sofisticated tool...

Of course I accourage any to do it yourself set-up, but it is important to repositionning each method and the final precision value of each...


your method is exellent but too limite at final response of the room is not evaluated... and is effect dracticly the final balance tonal...

Anyway, if you try to found a magic set-up with SLM only or sofisticated tool but one record average, your loose to much more precision... I have a big tool and I experienced this... My point is just benefit the forum to the limitation...

for members who found more tips in SLM, go in cie of electronics network (rane is realy generous in this) and dowload manual instruction : is full of tips for tune with SLM... but after each tips, all is explain the best is sofisticated tools. Is not my fault...

finnaly , this controverse have exposed the complexity of this question and I hope members is understand more in this domain, the pleasure to play with L-pad...



Jean.

[boputnam]

One needs to know that the net spl of each driver is matched between all four drivers BEFORE one can start making claims to the effects of near field reflections, room reverberation and all this other crap. Phase anomallies and what happens latter on is not the point.

Yea, I get that. But you missed my closing...

Assuming the engineers/makers had things fairly close, FFT will reveal what is occuring at the listener position and guide your fine tuning.

I was implying this need not be necessary for a properly designed speaker, is all. But this does make hella sense for a ground-up DIY.

[B&KMan]

Yea, I get that. But you missed my closing...

I was implying this need not be necessary for a properly designed speaker, is all. But this does make hella sense for a ground-up DIY.

EXACT !! The designer have necessity to keep response without room effect or other, but in listening approach, you deal with. 2 approachs, 2 different nature of problem, 2 goals, ...

the quasi anechoic approach is try to simulate close the anechoic room. The designer have specialized tool to fix with precision the relation electric and real SPL output. So why L-pad ?? For corrected response in regard of room... the L-Pad is for corrected response in regards, angle, height, and other parameters. for compensation of non ideal anachoic room !!!




Jean.

[Ian Mackenzie]

Yea, I get that. But you missed my closing...

I was implying this need not be necessary for a properly designed speaker, is all. But this does make hella sense for a ground-up DIY.

Bo,

One of the problems of this type of discussion is relevance, and dealing with such a specialised topic as measurement (there are multitudes of volumes covering measuring) it is easy to become lost I agree.

I was proposing to cover the complete topic in a thread covering the upgrade of the 4343 to the 4344 specification.

But I am not sure that this will happen now as concerns have been raised that such imodifications should have documented subjective improvements so that those attempting such modifications can be assured of value for money.

While the issue of L pad adjustment is perhaps less ponderous if you altready own a 4345 monitor, as I understand it this thread was linked to 4343 crossover modifications to upgrade to the 3145 equivalent crossover.

Therefore anyone considering such an upgrade will need to address the issue of setting the L pads as I note in this schematic the L Pads are 8 ohms and the built in attenuation in the crossover is different to the 3143 network.

I also read the Rane operating instructions for the AC 22 last night covering level settings. From this reading they make it clear level testing and measurement is a tricky business. They suggest either test tones or pink noise at a distance of at least 15 feet in reference to a PA system using additional equipment. They also imply that the crossover levels can be used to moderate room and other system related issues which can be further addressed with specialised EQ.

For the benefit of those reading this thread I entertained the idea of the Tandy meter (in the earlier prescribed manner) so that A) you would not be frigthened away by the thought buying expensive test equipment over and above the cost of the upgrade from a 4343 to 4344 specs and then spending 6 months figuring out how to to use it properly and B) Having to languish the frustrations of such adjustments and the dissapointment of less than anticipated performance after the effort and the expense.

This is after all supposed to be a fun hobby where at least if you are following a guide written by someone who has done it before there is a good probability it will work out well.

So For those that are interested in following up on an upgrade from the 4343 to the 4344 ( or improvements to the 4343) send me a PM so I can put you on a list for a "detailed how to guide".

Best regards

Ian Mackenzie

[boputnam]

One of the problems of this type of discussion is relevance...

Exactly.

My reason for posting was to remind the average reader that this level of detailed measurement is not needed for a properly designed JBL Monitor Series multi-element configuration. However, if one does go about their own design, it is quite important that the elements are acoustically balanced, otherwise no degree of "room EQ" can remedy the symptoms.

And believe me I know this from working the FOH with some complete crap mains and wedges that are far from "acoustically balanced". In that scenario, the "un-optimised" build results in pathetically low GBF. And there is little that EQ'ing can do to surmount it.

[B&KMan]

Bo,

One of the problems of this type of discussion is relevance, and dealing with such a specialised topic as measurement (there are multitudes of volumes covering measuring) it is easy to become lost I agree.

I agree too


I was proposing to cover the complete topic in a thread covering the upgrade of the 4343 to the 4344 specification.

yes and I agree this tye of thread is dirth and extend too mouch the principal thread (this is reason I started this)

But I am not sure that this will happen now as concerns have been raised that such imodifications should have documented subjective improvements so that those attempting such modifications can be assured of value for money.

While the issue of L pad adjustment is perhaps less ponderous if you altready own a 4345 monitor, as I understand it this thread was linked to 4343 crossover modifications to upgrade to the 3145 equivalent crossover.

Therefore anyone considering such an upgrade will need to address the issue of setting the L pads as I note in this schematic the L Pads are 8 ohms and the built in attenuation in the crossover is different to the 3143 network.

so this methode it is good for all speakers ???


I also read the Rane operating instructions for the AC 22 last night covering level settings. From this reading they make it clear level testing and measurement is a tricky business. They suggest either test tones or pink noise at a distance of at least 15 feet in reference to a PA system using additional equipment. They also imply that the crossover levels can be used to moderate room and other system related issues which can be further addressed with specialised EQ.

yiah acoustic is realy tricky (see title )

For the benefit of those reading this thread I entertained the idea of the Tandy meter (in the earlier prescribed manner) so that A) you would not be frigthened away by the thought buying expensive test equipment over and above the cost of the upgrade from a 4343 to 4344 specs and then spending 6 months figuring out how to to use it properly and B) Having to languish the frustrations of such adjustments and the dissapointment of less than anticipated performance after the effort and the expense.

Well your right but in certains point if you play in mecanical it is normal you buy certains specialize tool, more your hand is go more specific tool... this is choice of each... buy it is important to expose the complexity of jobs and manys occurs surprise is come with it...



This is after all supposed to be a fun hobby where at least if you are following a guide written by someone who has done it before there is a good probability it will work out well.

So For those that are interested in following up on an upgrade from the 4343 to the 4344 ( or improvements to the 4343) send me a PM so I can put you on a list for a "detailed how to guide".

Well Ian, your a master and I respect you idea, maybe the language is push my expression or comprehension in wrong way...

Your experiences is deep, complex and relevant in manys parameters arround JBL... I respect your point of view... Many small divergeance appear but with more talking, probably just communication problem...

And because I respect you, i run your test on my old 4343 (unfortunately )
little modified by fresh caps on hf and uhf (but in same value)...

And because the eratum methode is easy I resume the test here...

1--- put SLM at A weighted for less low frecquency interference in mesure...
2--- I test noise floor (below 40 dB)
3--- I perform sinwave at 15K, 5K, 500hz for respectively ech driver...
4--- I put SLM in 2 inch of flush verticale plane. full axis and full 0° all side
5--- I put pot in full range
6--- I perform sinewave at average 85 dB.
7--- I adjust SLM and I positionning in same time my body in exact placement for altering L-Pad.
a--- the uhf is not sensible of body in field but hf andparticulary med is big influence of you presence close to slm...
b--- because I have calibrated tone pulse for SLM I keep on my and to uncalibrate my SLM for this test==> If you have not this tool do not touch adjustement of yous SLM...

8--- I put 4 DB down response for UHF and HF and 3 for Med...

9--- Same procedure in other channel...

================================================== =====
10--- result:

(see first pict of L-pad position)

Listening test...

I perfom a SACD Fim 029 for the tesT listening. (no wine or other drink before or after... )

before read it is extremely subjectif aspect and it is not a judgement just my feeling on the spot...

First impression is more details and more informations, the med is more foward and the high is sweep and liquid, no harsh,etc...

but the bass guitar, timbal, contrebasse, is here but no body, power loose.. the drum is snap but you feel less the body of casing drum...

I replace my L-pad on regard on complex average mesurement set-up.
(see second pict of L-pad placement)
look the difference set-up ( )

Of course, if you look the pict, you undertand easy the sound is more bloom so I put little more power for same clarity level of high... but the detail of female voise is little desapear but more natural resonnace body: is feeling you put out mic on the mouse to put at 1 or 2 feet...

anyway, the major difference is bass presentation... in SLM set-up, I listen bass note but not power of bass and is relatively back presentation... now the integration is more coherence... all instrument have body and feel the body of xylophone, piano, sax, bass, drum, voice... Better ??? question of point of view... but yes the bass create the feeling to loose high fr details...

But attention surprise : 2 methods create a good integration driver and feeling of transparence

The major tips in this comparable is : where if your fine tune your speaker, position and pad is linked, so you change pad maybe you have obligation to change speaker position... more complexe comparison... and repetability

Anyway I expose this not for try to foward one method or other but just expose each aspect of tricky and complex problem and question of speaker tune... I hope member is more understand the tricky aspect of mic)


Now I keep a glass wine



BTW Other members have tried this SLM method ??? your feeling ???

Jean

[Ian Mackenzie]

Jean,

Are those tests with the new crossovers installed?

Also I am afraid the markings on the 4343 foil cal appear arbitrary and appear not to be calibrated in the manner of the 4344 & 4345 foilcals therefore nominal pink noise equidistant from each driver may be the only way to set the levels on the 4343....perhaps this is why people have so much trouble setting the levels of the 4343?


Ian

[Ian Mackenzie]

Well Ian, your a master and I respect you idea, maybe the language is push my expression or comprehension in wrong way...

Your experiences is deep, complex and relevant in manys parameters arround JBL... I respect your point of view...

Some time back I think it was in the 1940's I landed my Tardis in a young man's workshop in Los Angeles and found him winding round wire on a former for a loudspeaker voice coil. It took some convincing but he eventually accepted the idea that winding edgewound copper on the former was much better.

I forget his name .....it was Jim something........

The Doctor.

Ps Time to go .....I can hear the hoards stampedi

[B&KMan]

i run your test on my old 4343 (unfortunately )
little modified by fresh caps on hf and uhf (but in same value)...

Jean

I not perform with new network because it is not ready...



I create as schematic with conjuction of your concept cascade caps with the concept of Dc charge but I insert many erratum by cut & paste and other mistake electrical interpretation... (I'm null in electro)
And I run many tech test, (this thread and 4343 mod thread who expose the mesure of different transfert vibration of depend of the support fixation...)


so I limit time in a days : the BigNet is not ready...


If this set of speaers is able to talk long ride nightmare is expose...

I found this pair in morom cie of instalation pro audio... the 15" is reconed multiple time with with dirst third stuff... the guy is save a thrird part coil (standart circle type wirewound, is fix a other paper cone cutted in other driver and glued all in this ... the 10" is tilt inside... after verification the diagram of Hf is original but chaged and bad inverted signal path... so driver is out of phase... originally this spearker is works many years in great studio record... I hope this state descrition is not revalue in this time ...
before cancel the swich of post speakers and change selected caps section, the put is more downbecause the energy of the 15" is more low power... orignally the tweeter is really close to off med -3 and Hf is -4 or 5...

Maybe your method is work better in all correct components...
(remember, It is my first impression reserve on this approarch... )

My room correction is not perfect because it is not dedicated room but substential correctif is here, echo control on regard of sabine and kuttruf curve. position speaker in regards of phenomenon in 3 axis and phase respect, hight level components electronic, control, noise electrical and vibration analyse in each path. Yiah Yiah, I loose the count of couple hundred hours heres...

For just SLM I perform the best close performance to average by Rane Instruction... 1.5 meter is appear for my room the relativement better response in regard of reference test. the critical point is your position in room during test altered big the signature response so anybody is work test please put yourselt exactly same place and outside of 1.5 meter of SLM area...

and for average approach I repost my ask of any member...

Anybody please try SLM method and post your impression or mesure system...
maybe I great idea here but too other parameter slash the result...




I put picts for this thread my old network, modified, and the BigNet in work

[Ian Mackenzie]

As proof in the pudding here is a response run of the 4345 after adjustment with the meter as described earlier using the equivalent 3145 network. The system is unequalised.

I defy anyone to attain a flatter un-smoothed in room response.

For comparison the JBL 4345 tech sheets.

The Doctor

[B&KMan]

As proof in the pudding here is a response run of the 4345 after adjustment with the meter as described earlier using the equivalent 3145 network. The system is unequalised.
The Doctor

Bravisimo !!!

This is a excellent proof...

I have never doubth your method is works in yours stock...


I try to understand what is what and if many experience is repeatable in other set-up... with other member


is not work in my room + my systems + my old 4343...
But maybe it is not a hasard to rebuild my crossover...





BTW
I'm curious for couple point mesure...

1--- It is possible to explain your method mesure and expose your set-up software parameters and placement mic for more comprehension ???

2--- why your cut low mesure at around 75Hz ??
3-- why you have big drop at 10K ???


thanks for all

Jean.

[Ian Mackenzie]

Bravisimo !!!

This is a excellent proof...

I have never doubth your method is works in yours stock...


I try to understand what is what and if many experience is repeatable in other set-up... with other member


is not work in my room + my systems + my old 4343...
But maybe it is not a hasard to rebuild my crossover...





BTW
I'm curious for couple point mesure...

1--- It is possible to explain your method mesure and expose your set-up software parameters and placement mic for more comprehension ???

2--- why your cut low mesure at around 75Hz ??
3-- why you have big drop at 10K ???


thanks for all

Jean.

I learn't my technique from watching a my tutor at tech college.

I used the highest sampling rate and sample length my computor will allow which is 44.1 kherts and 8192. The system is self calibrating.

You have to understand some issues of measuring in a home environment and have a strategy to obtain what you want. The software is a very basic package called Winairr. More elaborate software may produce pretty graphs but for the purpose of proving an existing design where most technical facts have already been determined it is not justified. (If I was designing a system professionally from scratch I might consider Leap with LMS, Clio or Praxis.)

The microphone and preamp I built myself using a long thin aliminium tube with a hi quality Panasonic electret insert mounted on a tripod.

As you no doubt appreciate muti way speaker it is not possible to have a single mic on axis with all drivers within 1 -3 metres and at longer distance room effects cause the measurement to be polluted. Gated measurements at longer distance to remove room effect also smooth out important details. It is also impossible to use small divisions at longer distance to obtain meaningful results.

For this reason I chose about 1.5 metres (as a compromise) on axis vertically with horn lense and mid way between horn and slot radiator. The mid range for this reason is slightly lower in level, but when measured directly on axis is level.

My objective was to assess overall flatness between the midrange driver, horn/lens and slot and I think this result is obtained.

The loss of details at below 100 hz is due to some time gating to minimise room effects from floor and ceiling. The sound lounge has only a 9 foot ceiling despite the Tardis being Dimensionally Transendential. This is so if the auto gravity fails, when I fall of the ceiling I don't break any bones...LOL

The sharp dip at 10 khertz is the comb effect of the horn and slot and is normal for this kind of measurement with this design. In practise it is imho not audible.

The Doctor

[Ian Mackenzie]

Some other curves of the individual drivers with crossover filters.

I was really just interested to see the function of the crossover filters here.

The Doctor