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JBL 4349 Review (Studio Monitor Speaker)

Newman

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Luxury division that was led by Dr. Toole, etc.
I could be making the wrong attribution here, but iirc Toole wrote that the measured change in Q with break-in is quite obvious, but the measured change in bass frequency response is so small as to qualify for inaudibility.
 

Frank Dernie

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I’m not saying that your conclusions are wrong. I’m saying that your process for confirmation isn’t a valid process for evaluating sound waves.

And the reason for the push to CD speakers is not to “prevent room reflections negatively impacting LP FR”, but to prevent room reflections having a different tonality to direct sound, which is proven to be less preferred in controlled listening tests.

And even then, a CD speaker needs to be supported by room treatments that don’t much alter the spectrum of incoming sound. Otherwise the benefits of CD are canceled by the room.

cheers
Yes we all know about the influence of reflections of FR etc, etc on this forum, you are right. OTOH I wasn't in the least concerned by that well known characteristic.

I was discussing the potential for the accurate (rather than giving a pleasing impression) reproduction of venue acoustics.

In summary whilst many listeners have a preference for wide dispersion speakers and the sort of spacious image they create a substantial minority do not.

It is still important for the lateral and vertical FR to be even, of course, but the narrower dispersion must be more accurate in terms of venue acoustics reproduction.

My point is that the fact that the majority prefer wide dispersion speakers and th faux image they get from them simply shows that we, collectively, seem to be quite happy to enjoy what is undoubtedly in my mind a euphonic colouration due to extra reflection from speaker/room but some get quite snooty about adding euphonic colouration elsewhere in the chain.
 

DualTriode

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Yes we all know about the influence of reflections of FR etc, etc on this forum, you are right. OTOH I wasn't in the least concerned by that well known characteristic.

I was discussing the potential for the accurate (rather than giving a pleasing impression) reproduction of venue acoustics.

In summary whilst many listeners have a preference for wide dispersion speakers and the sort of spacious image they create a substantial minority do not.

It is still important for the lateral and vertical FR to be even, of course, but the narrower dispersion must be more accurate in terms of venue acoustics reproduction.

My point is that the fact that the majority prefer wide dispersion speakers and th faux image they get from them simply shows that we, collectively, seem to be quite happy to enjoy what is undoubtedly in my mind a euphonic colouration due to extra reflection from speaker/room but some get quite snooty about adding euphonic colouration elsewhere in the chain.

Hello,

You keep bringing up words like euphonic colouration and accuracy; we are trying to be sympathetic and objective here.

Please provide definitions; please tell us how you intend to measure these variables. If not those terms are only “Hypothetical Constructs” in your mind.

There will always be room reflections and direct sound from the monitors. It comes down to the proportions of each at your listening location.

If your preference is to reduce the proportion of reflections sit up close and personal in the near field much like they did mixing the recording.

Nothing confabulated here.
 

cistercian

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Thanks for the review Amir! I enjoyed it tremendously.
Great job as always and best wishes!
 
OP
amirm

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Is a link available to Toole's investigation?
It is in his book (and private presentation I attended). Here is the quote from the book:

index.php
 

puppet

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Looking at the individual responses of the drivers/(port interaction) makes me wonder if the port(s) influence on the woofer is to blame for that "dip" in the response. The tweeter gets to where it needs to be but the woofer does not ... and the port(s) influence seems to be particularly strong in that area and actually an octave or so below as well. Frequency cancellation, as a result of the port(s) contribution, would explain the woofers' behavior. It, the woofer, rolls off to the point that it doesn't even reach the stated xo point effectively. Which begs the question as to what degree applying a "global" EQ to that area accomplishes, other than making the frequency response graph look pretty. The woofers response is the issue ... not a combined woofer/tweeter response.

Plug 'em (ports) and reevaluate?
 

hardisj

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This would certainly make an interesting experiment if either @amirm or @hardisj would be willing to take the time to run at least one ported speaker through their Klippel with and without port plug just to see how the various measurements are affected.


I’ve done this kind of testing before with the Neumi BS5, IIRC. That was before I had the NFS.

https://www.erinsaudiocorner.com/loudspeakers/neumi_bs5/





But, I also just did this with another speaker I am reviewing soon. So you’ll have data for that at some point in the next week or two.
 

DualTriode

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Hello All,

Just for fun I am posting a couple of measurements of the JBL D2 2430H attached to the PTH 1010 waveguide. This thread has been pretty much been quiet for a few days.

In in this case the JBL D2 2430H is wired with the Voice Coils in series. The compression Driver with the Voice coils in series is wired to the equal of the JBL crossover parts in the M2. The capacitors in the crossover block DC from the compression driver and the resistors working with the voice coils ends up operating at near 22Ohms. The hard wired L-Pad lets the tweeter operate up and out of the noise floor of the power amplifier, much less hum and hiss than there could be with the Crown power Amplifier. My wife would say, “Power to Burn”.

For my prototype 3-way JBL’s the crossover from mids to the JBL D2 2430H CD’s and PTH 1010 waveguides I much prefer the higher 2000Hz crossover frequency and the inches smaller waveguide.

APx555
APx1701
AP measurement microphone (calibrated today)
zero equalization
In a couple of places 1/24 octave smoothing

Thanks DT
CSD JBL D2 2430H on JBL PTH 1010 waveguide.png
JBL D2 2430H JBL PTH 1010 waveguide on Axis FR 2.PNG
JBL D2 2430H JBL PTH 1010 waveguide on Axis FR.png
Level and Distortion 2.PNG
Level and Distortion.PNG
 

Robh3606

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Hello All,

Just for fun I am posting a couple of measurements of the JBL D2 2430H attached to the PTH 1010 waveguide. This thread has been pretty much been quiet for a few days.

For my prototype 3-way JBL’s the crossover from mids to the JBL D2 2430H CD’s and PTH 1010 waveguides I much prefer the higher 2000Hz crossover frequency and the inches smaller waveguide.

Hello DT

Looks very similar to 4" large format measurements on that wave guide. What are the other drivers you are using?

Rob :)
 

DualTriode

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Hello DT

Looks very similar to 4" large format measurements on that wave guide. What are the other drivers you are using?

Rob :)

Rob,

mids JBL 2123H 10 inch or JBL 2119H 8inch

Woofers JBl 2235H

see the attached plot of 4 inch JBL 2451J SL (with aquaplast coated diaphragm) with the same PTH 1010 waveguide.

Thanks DT

JBL 2451 J sl Level and Distortion -_ Smooth.png
 

DualTriode

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Hello All,

A couple more plots.

Jbl 2123H mid range; crossover at 400Hz and 2000Hz, extends well below and above XO frequencies.

Today I am using sealed woofers in 2.1 cubic foot boxes; extends well below sub-woofer XO frequency, 75Hz and above mid XO frequency.

JBL 2123H Level and Distortion -_ Smooth.PNG
JBL 2226H Level and Distortion -_ Smooth.png
 

Robh3606

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Hello DT

I am running a very similar set up. Using E-145's 2123 and 2453SL on a PTH1010. Crossing at 300 and 1.5K. Love it I am sure you will get a lot of enjoyment out of it once you get it all together.

Rob :)
 

puppet

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DT .. would love to see you post your progress in the DIY section. The 2123 looks super clean. How's the sound?
 

DualTriode

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DT .. would love to see you post your progress in the DIY section. The 2123 looks super clean. How's the sound?

@puppet ,

I had a similar stack of speakers in my listening room setup in a house that I sold last summer. Different speakers would rotate in and out of the stack. I had never measured them before. I used a hand held SPL meter to avoid blowing out my ears.

The JBL 2123H mid-range plays really loud really easy at very low levels of distortion. It hits transients crisply. It plays on just a few watts, 101 db’s at 1watt at one meter.

I like the way the JBL2123 sounds much better than compression drivers and horns/waveguides for the mid range voices. The JBL2123 does not sound like a horn.

The JBL2123 does not require much if any equalization, the Frequency Response is really flat enough.

You are correct; I will post progress of the latest setup in the new house in the DIY section.

Rane AC23s active crossover, Crown ComTech amplifiers, one amplifier per driver.

Thanks DT

tubejunkie (good guy, good seller) has pairs for sale on ebay.
 

Valentin R

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Valentin,
can you tell me how tall the stands are? I listen to a similar, but much less sophisticated DIY speaker and experienced that the woofer should not be too low, because then, the sound stage is kind of stuck in the ground. What is your experience?


20cm Aprox

Yes tower speakers like revel F228be image higher
 
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