4343 buyer's guide

[lfh]

Hopefully I'll get the chance tomorrow to listen to the 4343:s spotted by Figge! Since my experience with JBL monitors is limited to the 4311:s we have at work (which IMHO still are fine as "party speakers", but nothing I would like to use for critical listening), I'm not sure what to expect. Thus any and all advice on what to look/listen for is highly appreciated!

Needless to say, I'll visually inspect the drivers for foam rot, check for buzz 'n rub (I'll bring a tone generator), turn the attenuators, etc, etc.

What are the factory recommendations for positioning and dialing in the pads? I figure a "pretty large" listening triangle is required (reflecting the 4-way design), and some toe-in, slots in ear level, and pots at "0 dB" (or center detention) is a good starting point - right?

What if (God forbid!) I think they sound like crap? :eek: Shall I just blame it on (disregarding my own reality distortion field ;)) worn-out diaphragms and dried-out capacitors (and/or other parts of the signal chain), and still drop well above 3 grand, being confident that if only those issues are addressed, I'll reach Nirvana? Or maybe, after all, loudspeaker technology has advanced during the past 25 years to the extent that even a 100% up-to-spec pair really requires "neural nostalgia inverse filtering"... Stated another way: Will the old heroes give a recent pair of speakers at this price level a match?

[Guido]

You'll not find them sounding like crap!

For pad level I prefer mids 0, hf -2, uhf -2

Do not worry for dried caps. They last long. I changed all caps to high end types + bypassed them though.

Check if the 2121 are original, this is crucial!

Good luck! Get'em

[Robh3606]

Well from my experience with my home built mains and 4344 clones which both run 10" JBL midranges I would say you are in for a real treat. Well you should have good solid lowend a midrange that is fast dynamic, clean and clear as a bell and a high end that you can hear every touch of a brush on a cymbal. Actually every thing is dynamic clean and clear as a bell. As far as large window not really I can get very close to the 4344 and they sound cohessive, I use a different lense so that might change things a little. They seem to like to be farther apart than you would think and I have my slots outside and yes they need to be at ear level. If you can get them up off the floor a bit. I built stands for mine. As far as a recent pair I think they will very easilly once you get them set-up. Do you have any way to measure them like an RTA?? Would be good to help you balance them out. By ear gets tuff. You ears can do funny things as far as actual vs. percieved driver levels. If you don't like them at first don't loose heart you just may need a little work on the set-up. Mine did when I first turned them on I was like Hmmm. Once I put a little time in it was YESSSS!

Good Luck:)

[Ian Mackenzie]

The Pads will depend of the room acoustic and associated equipment, be prepared to experiement.

The last pair I heard in captivity were John Nebel's in Colorado.
Nectar to my ears. If you have a nice vinyl set up you are in for a treat.

I am continually surprise by the resolving power of my 4345 4 way's with a good MC cartridge, they are wasted on CD imho.

If you are serious, consider upgrade the compression driver diaphragm.

The classic 4 way demands the highest amplification you can afford, bi amp if you can. UK HIFI World reviewed the 4343 as the B&W801 answer for Jazz and Rock.

On first listening, if you are used to the classic JBL 2 ways they tend to sound critical and analytical on some program sources, but thats the price of accuracy.

Ian

[lfh]

All, thanks much for your prompt advice! A full report will follow (ETA tomorrow). For now, two more questions:

What are your typical listening levels (qualified guesstimates are fine)?

How does one best mechanically decouple the speakers from the floor?

(So what do I think? In short: This really should be a "non-brainer"...but (always a but) I have concerns, the nature of which you can tell from my questions... I already get the evil eye from a neighbour due to practicing bass (guitar) and electronic drumset using headphones. :( )

[Robh3606]

What are your typical listening levels (qualified guesstimates are fine)?

Hmm depends on the music. Most rock the average unweighted is in the low 90's weighted in the 80's


How does one best mechanically decouple the speakers from the floor?

I built stands on castors so the only thing touching is the wheels tangent point. Can't image much energy coupled through there. You have a pair of short strong foot stools???

(So what do I think? In short: This really should be a "non-brainer"...but (always a but) I have concerns, the nature of which you can tell from my questions... I already get the evil eye from a neighbour due to practicing bass (guitar) and electronic drumset using headphones. )

Oh boy! Glad I don't have to deal with that. You friendly at all?? Could invite to your next party when you celebrate your new additions???;)

Rob:)

[Ian Mackenzie]

The Widget is the Loud King, all those amps and 1500 subs..

I reackon if he thought draining all the water out of the Hoover Dam would make it go louder, he would.....LOL.

Rob is another mega amp nutter for Volume, stacks of Crown amps everywhere second only to the Downtowner Venue. ...although I was spared some mercy when I visitied.

A couple of issue on level. Play at a level where you can start to sense the transient dynamic and micro details...too loud and your ears will compress. Always set your pads at the level you normally play at due the equal loudner response of the human ear.

[Mr. Widget]

Ok, I do air it out on occasion, but I typically listen to peaks of 95-100dBA when critically listening to LOUD music and a bit less for a quiet female vocalist.


I do find that with the 4001s and 4003s I am listening at even lower levels as I get a real sense of being at the session without having to crank it up.

Widget

[Zilch]

Originally posted by Mr. Widget
Ok, I do air it out on occasion....Ah HA! So THAT's what I been hearin' over here.... :thmbsup:

[Robh3606]

"Rob is another mega amp nutter for Volume, stacks of Crown amps everywhere second only to the Downtowner Venue. ...although I was spared some mercy when I visitied."

Hey I ressemble that remark! Come on I am not that bad. And the Downtown:cheers: I wish! Spared some mercy huh!:flamer: :bs:She exagerates!! Well a little.:slink:


"Play at a level where you can start to sense the transient dynamic and micro details...too loud and your ears will compress."

Good advice and easy to forget. The dynamics should be easy to hear at a comfortable level.

Rob :) :

[Earl K]

but I typically listen to peaks of 95-100dBA when critically listening to LOUD music and a bit less for a quiet female vocalist.

Wow, Really ! I listen in the area of 80 - 90 dbA .

EDIT: ( Actually I use the "C" weighting on an SPL meter. )

Sometimes I just listen to classical music over the compression drivers .

( This is also my most "productive" time for listening to various capacitor combinations )
Ooops - wrong thread . :cool:

<> Earl K :)

[Mr. Widget]

Originally posted by Earl K
Wow, Really ! I listen in the area of 80 - 90 dbA .


Well, I just went downstairs and played some music and kept track of a few cuts and the SPL levels.

Joni Mitchell For the Roses from Travelogue. This is an album of Joni's classics with orchestral accompaniment. Peaks of 91dB

Zero 7 Home from When it Falls. Contemporary Electronica. Peaks of 85dB

Afro Celt Sound System Lagan from Further in Time. World/World Beat. Peaks of 90dB

Only 90dB peaks and the deep bass could still be felt in your guts!

Joe Jackson Sunday Papers from Afterlife. Live recording of Rock and Roll. Peaks of 98dB.


I guess that is in line with my earlier estimate. If I threw on The Who,Who's Next I imagine I would handily pass the 100dB threshold! Basically, for each type of music there seems to be an appropriate level. When I was younger the Maximum R&B of The Who was meant to be played at 120dB plus, but as we age we mellow. ;)



Originally posted by Earl K

Sometimes I just listen to classical music over the compression drivers .


Now I hope you are joking with us!

Widget

[Earl K]

Now I hope you are joking with us!
Nope, dead serious .
Probably amounts to a couple of hours a week -mostly Sunday mornings .


<>Earl K

[Ian Mackenzie]

JBL Sunday School........what a Tribe that must be..LOL


Ian:coolness:

[Earl K]

JBL Sunday School........
Good One !

But actually since June , its' been back to "Altec Sunday School" for some "Old Testament" studies .:D

<> Earl K:)

[Ian Mackenzie]

Originally posted by Earl K
Good One !

But actually since June , its' been back to "Altec Sunday School" for some "Old Testament" studies .:D

<> Earl K:)

A case of passing sour dough bread around the table and a full glass of Guinness no doubt.

Primitive but no the less effective.

Ian

[lfh]

Ok, so yesterday I went there and listened shortly - or at least that's what I thought I did - 2 hours flew by in no time at all (much to my embarassment when I realized what time it was)! My checklist and custom made test signals were all in vain, I was pretty much glued to the seat and just "enjoyed the concert", despite listening conditions being about the worst possible: The seller is in the process of moving to this apartment and has merely unpacked the essentials, so there was very little damping (no carpets, speakers directly on the floor) and the listening room is even smaller than mine. He's selling for the same reason I may end up not buying them (I haven't made up my mind yet!) - as lovely as they are, they're IMHO not really feasible for small apartment use. (Yeah, big surprise! ;)) More on that below.

Anyway, the speakers were rather close to each other with the slots towards the center, all pads at -1 (I didn't touch the settings), and toe set for on-axis listening (after some experimentation of mine - originally they were flush against the wall and that was no fun at this close distance). All electronics were of the "high-end" variety - a monstrous old Krell, McIntosh preamp, some exotic CD-player but no turntable. Now some unsorted impressions (I know you don't need to read this, but I do need to share it...):

The lower midrange/upper bass (balance or transition...or rather lack of transition if you know what I mean) is nothing short of amazing! I played lots of jazz (be-bop and contemporary big band stuff) and, oh man, baritone saxophone, bass trombone and bass clarinet sounded so real! (Of course (tenor men) Sonny Rollins and John Coltrane were right there with us, but that's just what I had expected.)

The deep end was impressive and certainly added to the live-feel, but I like the bass drier. Adding this amount of room gain (on top of a bass reflex system I figure marketing forced the designers to tune for bragging 3 dB points in a 2 pi steradian environment rather than for flat group delay, let alone flat response in japanese-size living rooms ;)) is obviously not the proper thing to do. I guess that given a proper environment, even a closed box-fan like myself would be fully satisfied, though.

Imaging/soundstage: Again, the acoustics and listening geometry was troublesome, but still I'd rate the reproduction as good. Imaging was my primary concern prior to the visit - would they really be capable of the "magic"? Well, frankly, I never reached the ohmigod-state WRT this, but I assume they have the potential. In fact I was surprised that they worked so well at the distance, and I fully second your statement about this, Rob. Tuning and experimentation is needed, just as you've told me.

Fun-factor: Almost infinite! This is now my primary concern: "Loud" listening at home peaks at 80 - 85 dBA at my near-field position, using two-way boxes with little output in the 30 - 60 Hz range... As a matter of fact, I brought my dB-meter to the session yesterday, and I (since the seller assured no neighbors were at home at the time) soon (despite telling myself not to crank them up just because I knew they could take it) played at 90 - 95 dBA peak levels...and 10 dB more on occation wouldn't have hurt either (although not at all needed - I know this is past optimum of the auditory system). It was as if the speakers told me: "Hey, dude, let us do our thing, raise the volume!" Such levels are however unthinkable of where I live, and restricting levels to 80 dB with these speakers would be like cruising in a big-block Chevelle with 4.11:1 gears and never ever being allowed to hit the loud pedal! What a torture! :banghead:

Now it's past bedtime (again), and you're probably tired of my ranting, so enough for now. BTW, thanks all for your dB figures!

[Figge]

its hard to get a grip of a system at sombody elses home...thats the tricky part buying speakers. i´d bet those 4343 in good condition, setup right would KILL whatever speakers u brought home, nomatter how much u pay for it! there is nutn like BIG jbl:s!

if i had the cash....i´d already been pinknoising em in my livinroom!

[lfh]

Originally posted by Guido
For pad level I prefer mids 0, hf -2, uhf -2


Is it 1 dB per division?



Originally posted by Guido
Check if the 2121 are original, this is crucial!


Good point! Substituting this driver is not a task for Joe Sixpack... Without closer examination, I'd say they're refoamed originals.



Originally posted by Robh3606
As far as a recent pair I think they will very easilly once you get them set-up.

I'll check out some new speakers tomorrow just for reference, haven't done this for years. BTW, I listened to the same programme material (at the same levels) over Genelec 1030A:s shortly after the 4343-session. I have never really liked the 1030:s - I rate them as "fair" at best - but this time I was like "Ouch, turn off those POS speakers!" Sure, this is a very unfair comparision, but still...



Originally posted by Robh3606
Do you have any way to measure them like an RTA?? Would be good to help you balance them out. By ear gets tuff. You ears can do funny things as far as actual vs. percieved driver levels.

Yes, albeit nothing easily portable. (I'm fortunate to have access to MLSSA and a B&K measuring mic.)



Originally posted by Ian Mackenzie
The classic 4 way demands the highest amplification you can afford, bi amp if you can.


Am I sensing discrete c/o evangelism here? ;) (I follow the thread - impressive stuff!)



Originally posted by Ian Mackenzie
UK HIFI World reviewed the 4343 as the B&W801 answer for Jazz and Rock.


Listening to jazz, funk and fusion was so immensely fun that I never came around to check stuff one could suspect isn't their strongest side.



Originally posted by Mr. Widget
I do find that with the 4001s and 4003s I am listening at even lower levels as I get a real sense of being at the session without having to crank it up.


I'm all with you (although I haven't had the pleasure to hear the TAD drivers) - top notch equipment conveys the magic already at lower levels. Frankly I'm a bit dissapointed at the 4343:s in this respect - I felt they needed some volume to open up and begin to shine. Perhaps this is an indication of that the alu-diaphragms are worn out?



Originally posted by Mr. Widget
Well, I just went downstairs and played some music and kept track of a few cuts and the SPL levels.


Just of curiousity: What speakers did you use (IIRC the way cool 435x hybrids of yours were for sale some time ago)?



Originally posted by Mr. Widget
When I was younger the Maximum R&B of The Who was meant to be played at 120dB plus

In fact (12) 4350:s are required to do The Who justice ;)



Originally posted by Figge
i´d bet those 4343 in good condition, setup right would KILL whatever speakers u brought home, nomatter how much u pay for it!


Almost true - don't forget there's more than one JBL model ;) Seriously, the alternative I'm contemplating is a JBL DIY system that could be a more suitable tool for the task at hand (i.e. making me grin from ear to ear, while keeping my neighbours happy and w/o eating too much space of my livingroom...). I'm more and more thinking that I shall pass on the 4343:s. They're someone else's dream, and deserve a better home than I currently can offer them. I have been collecting JBL parts I want to test - and nothing sounds better than speakers you've designed yourself :D



Originally posted by Figge

if i had the cash....i´d already been pinknoising em in my livinroom!

Aren't you happy with the 4430:s?

[Guido]

[QUOTE]Originally posted by lfh
Is it 1 dB per division?

The scale is no dB scale. But I would say -2 is -2dB though.

[Mr. Widget]

"Just of curiousity: What speakers did you use (IIRC the way cool 435x hybrids of yours were for sale some time ago)? "

No the 4355s are long gone. The current set up made them redundant. It would be fun to keep one of everything, and some on this forum seem able to do just that, but alas I am lucky to have the space I do have.

I've described my current setup on other threads, but it is a DIY with JBL and TAD 4003s. This setup is by far the best I have had and one of the very best I have heard.

Infredible Fred owns a pair of 4343s and with newly replaced diaphragms (see "How Smooth is Smooth"). He would agree that the 4343s were outclassed by this setup, but bear in mind it is also several times more expensive as well.

Widget

[Figge]

Originally posted by lfh
Aren't you happy with the 4430:s?

course i am! but the 4343:s would have a home here along with em 4430:s...but now im dreaming... i probably will never own a pair!

[B&KMan]

Originally posted by lfh
(I'm fortunate to have access to MLSSA and a B&K measuring mic.)


Hello,

happy time for you but I'm not shure if the result is sound good ...

I have entire stuff b & K : generator, mic, preamp, amp, RTA , analyser, etc.

Well I have a 4343 TOO :dancin:
(only modification is the terminal speaker is remplaced for a WBT plug for accomodate my big SCSI gage 2 silver wire...
(the rest of the system is big turntable reference CD/sacd and accuphase amplification/ac regulation)

My room is 12 feets by 20 feet 9 feets height .
Carpet, RPG room treatement reference system connected with...

In general the first big problem for mesure respons is the mic.

the mic is instrumentation precision and it is not presure fiel and not free field.. In this situation th diffusse field is the best or free field with random cap mic but limited in upper frequency...

Big big importance because the hight frequency is cut off or exgagered if you not choose the good mic.
(the radio shack SLM is realy to much limited in range and no technical information of type precision mic... I know I have run test with comparison)
After, the analyser precision is important but minus of mic, The best is type ) (reference laboratory, or type 1: in good commercial computer card is type 2 )
The type 3 is absolutely for kids only...)

In the other hand the position of mic is critical. any each position reflect the reaction in room by cancellation and reflection. So What is the best spot ???

Nothing, average is the key... More different mic more statitical response close to the true...

After check system, original driver and membrane install, connection, etc, I put the pink noise test and run average position (statitical more than 2000 different input data spectrum.)
my set-up for the pots is
very close to off for UHF: botton of -3 (8:00)
around -2 for HF (10:00)
and -3 for MF (9:15)

Tips: in general the best set-up is the set-up who earing minus variation at the many place for the HF....

2 tips : in general the electonic and cable is not critical effect of frecquency response...

My set-up is produre spectrum 1/3 octave respons inside of 5 db variation (+- 2,5 Db if you prefer) SO, it is very close to the ideal speaker response design.

------------

My toe is in long procedure with set up the position in the floor and precisely rotate with laser light for verification of non flutuation rotation axe and garanty to same rotation mirroir. my result is open arount 11,5 degree.

------------
For the feet.

Delicate question and in relation of speakers and the height of room.

Center of LF and ideally all driver is positionned in non cancellation as possible.

well it is impossible but good tip is the height of room divided by premium number (3,5,7or 9) and put the center of you LF in this area. But this is not only factor, a ton of details is critical but normally the botton of the lens of HF is the level of 0 AXIS position. Other master problem is the structure to put up your speakers is critical for garanty the inertia factor, mass fixed and mechanical decoupled is the rules.
I choose to but massiv maplewood beam glues and bolted in speaker and the feet is the superSpike with zinc ...
:nutz:
In the reality this speaker is conception to integrate flush in the wall studio (sic) You understand the pressure the 4343 build in bass level at flush wall !!


OK OK OK . I wait for now, I smell many guy ready to shot me... :screwy:

[lfh]

Originally posted by B&KMan
OK OK OK . I wait for now, I smell many guy ready to shot me... :screwy:

Hey, you present lots of food for thoughts there. And no worries - I think everybody here appreciates the massive effort you're obviously putting into setting up your system. :)

[B&KMan]

thanks for your confidence... Her IFH

For manys minds, the "specials" details appears a simply a Voudou...


And consider this is a mystic illumination... :banghead:

for others certains details is regarding to a cricital and other nothing, manys scool in this zone and many person adept a one and rejet any others arguments is not include in the way.

fanatic. :biting:

I hope, this groups is focus in JBL product and it is OK, I have a JBL too. :D

But the road between music an me pass by a scientific approach who a ton of details in manys way and perspective is include...

Exemple the problem of electrical connection, match and oxidation, inertia ad stability of speakers, and electronic, coloration, match cable, discovery the aprroch and color and ton products and what is match ...

Problem of acoustic, treatement, damping , diffusion, flutter, bass trap and tuning, :blah:

imaging a group of ingeneer is run over 4 years for find and improvemnent dissipation of vibration of the frame, electronic board, cable, and parts for improvement sonic result. Yeah the big sony ES serie is a specail body and feet, Accuphase too, in couple of years, krell, build special feets, the refence cd Linn in 2000 and Chord is buid in massive block of aluminium for reduce the micro vibration .........
But the vibration is not only point, the chain is effective strong determine by the lightly part of it.


And look Carefully the fundamental rechears deplyment for buid a revolutionnary driver inside a S9800 and S 5800 ans 4348.

But Where is the guy is look a beautyful JBL 4348 monitor studio...

I just fact last year, in Best buy award Japan, 3 of the 5 top on the line speakes is JBL... and golden sound award for JBL S9800.

:o Hey this is a JBL cormercial :cool:

[B&KMan]

Originally posted by lfh

What are the factory recommendations for positioning and dialing in the pads? I figure a "pretty large" listening triangle is required (reflecting the 4-way design), and some toe-in, slots in ear level, and pots at "0 dB" (or center detention) is a good starting point - right?



Refer to guide line of 4344 PDF, this is a good starting point...

For the Ethernal question of POt, in the old speakers is unique, The master of energy is run in LF and depend of lond play, is demagnetize the magnet, quality of membrane, contact, but state of the rest determine the variation of setting one guy to other. But the principal problem of the variation of pot is the Room !!! Variation very very hight is possible depend of cancellation and reflexion. the mesure of echoe is explain why certain frequency is echo amplification...

The rest of speaker is affect a subjectif reproduction but is fine tune problem not for a big 20 BD problem...

3 solutions,

---- Long therapy with improvement drink subtances fading problem perception, Beer and wine is solutions is regulary cited in this forum. :D

---- you run triple overtime and paid a couple of tousand of box for tunning romm and position speakers. :(

---- you never sleep and run many years for collect any informations for build really grid analyse and tecnique for do it yourselft... :bomb:

Best regards, and sorry I will go to run in front this 3 ways... :hyp:

;)

[Tom Loizeaux]

[QUOTE=lfh] ...and nothing sounds better than speakers you've designed yourself.

Yes, knowing that YOU put together a speaker you're listening to does make it sound "better", but after some extended listening, I think you'll find that some of these JBL classics, the 4343 for example, exhibit the subtlies and quality that only comes from gifted engineers toiling for many hours, using expensive equipment and working to achieve the best balance of attributes. They put it all together, from cabinet design, specific drivers, exact driver placement, and unique crossovers, all in a finished design that pleases pros in the audio industry.
Though the JBL 4343 was designed for use in professional mastering rooms, I find they sound great in my room and give me more detail, smoothness and balanced high levels without fatigue then any other speaker I've ever heard.
I don't think that any speakers I put together, even using the best Westlake, JBL or TAD componants, would actually sound any better then the 4343s. I suspect there's more to building a quality speaker then putting componants in a cabinet.

Tom

[lfh]

Yes, knowing that YOU put together a speaker you're listening to does make it sound "better",
/.../
I suspect there's more to building a quality speaker then putting componants in a cabinet.

Actually, my remark was slightly ironic. I'm very well aware of all the above, Tom. :yes: However, I'm confident that I over time can put together a system that gives me listening satisfaction that rivals that of the 4343s - in a smaller package. Please let me explain why (such that you don't get the impression I suffer from hybris!):

Fortunate for all DIY:ers, the efforts of said gifted engineers are well documented (and easily available thanks to this forum!), so there are lots of well defined, excellent starting points for custom designs. Furthermore, time is on our side: Later findings (bypass caps, charge coupling, contemporary horn theory etc) can be incorporated, and better components are of course available today. This also holds true for the tools: G.T. et al didn't have access to MATLAB, PSPICE, LEAP, EARS, MLSSA etc back in the days. Last but not least, a custom design can be tuned (port tuning, directional pattern, FR) to a specific acoustical environment as well as to meet personal preferences (all audio pros are not equal...).

I'm in for a long journey (I've done a similar trip 10 years ago when designing my bass rig, so I know from experience what's ahead of me...), but that's a big part of the fun! In the end I will probably have spent more than the 4343:s cost (not counting manhours...) on a system that has a market value corresponding to the value of the parts. OTOH, I'll get the satsifaction a self made, one-of-a-kind system gives, I'll learn a ton, and I'll hang out (more!) with you JBL aficionados here! :)

[Triumph Don]

Very well spoken! Recently completed a "cobled up" bedroom set with my 15 yr old with LE-10's, LE-5's, and LE-25's. Lots of time on veneer, insulation, and a little bracing. Explaination of Alnico, refoam, etc. They do sound better than an old pair of L300's I still have, but the learning curve is, well, unmeasureable. For both of us! By the end of the month dad's bi-amp project with "our" 4343's should be completed. Testing combinations of McIntosh, Rane, Crown and JBL electronics. Pics forthcoming!

[B&KMan]

Hey, you present lots of food for thoughts there. And no worries - I think everybody here appreciates the massive effort you're obviously putting into setting up your system. :)

AHHHHHH... do you remember this sympatic answer...

WEll I'M Back with new info and many questions for you and communauty...
I just put my two feet in a crazy world of crossover.

After Realize my Original 4343 is connected many wrong inside because confuse color code, after refresh the driver with origianl JBL parts
(I'M realy big chance or not to keep the last original cone kit for original 2121A) :D

After many creazy test for Lpad and position and tweeking box I realize the crossover is probably realy poor... and electrical response is corrolar to mic response...

:blink:

well I send a couple of pict of response of electrical driver who all driver is connected in network and each respons is keep on the posts driver... look the surprise...

I start with 2131A

[B&KMan]

the response of 2121A

[B&KMan]

the response of 2420A look the driver is never shout down at hight frecency...

[B&KMan]

the response of 2405A look the driver is start at 8000 K ??? the cut frequency is 9500 K
:blink:

[B&KMan]

Well other type of frequency response linear In fft dual channel
for the 2131 look the notch at 30 Hz and double slope ....