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JBL Stage 135C Review (Center Speaker)

Rate this speaker:

  • 1. Poor (headless panther)

    Votes: 166 88.3%
  • 2. Not terrible (postman panther)

    Votes: 20 10.6%
  • 3. Fine (happy panther

    Votes: 2 1.1%
  • 4. Great (golfing panther)

    Votes: 0 0.0%

  • Total voters
    188

beaRA

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I don't know. It's easy to say "well a normal person will never notice this stuff", and it's true that they won't be able to EXPLAIN the problem, but... complaints about center channels and poor/unintelligible dialogue are the #1 complaint about home theatres that I've heard. And while it is sometimes the mix that is at fault, a lot of the time even known "poor mixes" like basically everything Christopher Nolan puts out, are mostly fine with a great center, even in very difficult rooms.

I generally steer friends towards the 3-way and coaxial(Kef) centers, which are available for reasonable prices. It's the main source of audio after all.
As do I. But there is still a segment of customers for whom you could explain the problem & demonstrate the effect, and they would still decline to accommodate a larger center.
 

sword

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I dropped off a brand new A125C with Amir and it is in his queue.
I noticed that the A125C is gone from the JBL website, but may be available from Crutchfield. That's where I got mine, but I haven't tried it yet.
 

sword

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Yikes.

Get a three way or no way.

The 3way Polk L400 is on sale right now.
$1449

I also believe accessories4less is expecting more Polk LSIM706c's soon for $399. Crazy good price for those. Both Black and Cherry should be in stock again soon. My Old Polk LSIM703's performed extremely well.

Airmotiv C2+ and SVS Prime are also $399, wonder how these perform?
The Monoprice THX-365C looks promising.
 

voodooless

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Theoretically it works when using a small fullrange driver (Peerless ANC-50N25AL04-04), so to speak, a cone tweeter with low frequency response and two 4'' woofer.
Then you can shift the inter driver interference over the crossover frequency of the "tweeter".

If the small fullrange driver can be used from 600Hz, there is no problem with horizontal MTM alignment, regarding the horizontal radiation.
Thus, at +-50° there is no inter driver interference in the frequency range of the woofers (when the crossover frequency is about 600Hz).
(You have to imagine it rotated 90°)
View attachment 168891
It's might be a reasonable compromise for a smooth off-axis response. It will however give you quite a bit of HF beaming inherent to wideband drivers. Even with something like SB65, 3" Faital, BRM or the excellent 10 cm ScanSpeak, this is apparent. It probably works if you do not have many seating positions.
If the center speaker only has to radiate evenly up to +-10°-15° in the vertical direction, you can also stack two small full-range drivers vertically to increase the power handling capacity of the center speaker.
That will result in lots of HF lobing. Better make it a 2.5-way then where only the upper wideband plays full-spectrum (up to woofer crossover). Still, most of those tiny widebanders will not go loud, even when paired.
 

ctrl

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It's might be a reasonable compromise for a smooth off-axis response. It will however give you quite a bit of HF beaming inherent to wideband drivers.
No, not really.
The ANC-50N25AL04-04 driver was chosen deliberately because it has the dispersion characteristics of a cone tweeter (and not that of a typical full-range driver).

The width of the radiation pattern is better than some tweeters - of course you have to check if the other parameters (HD, IMD, CSD,...) allow the use of the driver from 600-700Hz and above.
ANC-50N25AL04-04 at 10kHz and 60° dispersion angle, the sound pressure level is only 9dB below the on-axis frequency response. This corresponds approximately to a standard 1'' tweeter.
1638264122618.png


That will result in lots of HF lobing. Better make it a 2.5-way then where only the upper wideband plays full-spectrum (up to woofer crossover). Still, most of those tiny widebanders will not go loud, even when paired.
Yep, the inter driver interference is the price of good power handling.
But as I said, if you stay vertically in the range +-10°, the first cancellations are at such high frequencies that hardly any disadvantages arise, even at vertical +-15°, the sound pressure loss in the high frequency, when used as a center speaker, is within acceptable limits.
1638265640539.png
 

voodooless

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No, not really.
The ANC-50N25AL04-04 driver was chosen deliberately because it has the dispersion characteristics of a cone tweeter (and not that of a typical full-range driver).
It's a 2" driver with 5W of power handling and 83 dB (closer to 82 dB) efficiency... The thing can't even reach 90 dB on its own before running out of steam, and that's at 1m.
Yep, the inter driver interference is the price of good power handling.
But as I said, if you stay vertically in the range +-10°, the first cancellations are at such high frequencies that hardly any disadvantages arise, even at vertical +-15°, the sound pressure loss in the high frequency, when used as a center speaker, is within acceptable limits.
View attachment 168982
Well, at least you get to almost 96 dB/1m ;). That might be enough for some. You really don't need that much output > 5 kHz. It would be absolutely fine to let only one of them play full spectrum and then still enjoy the lack of lobing issues even if it can only do 90dB in practice. A simple 1st order network would probably do.
 
Last edited:

dasdoing

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directivity is still messy

The issue is mainly not due to the lack of midrange. It is because the tweeter is not inline with the woofer/mid.

the midrange helps because you can highpass the woofers before the lobing frequencies

here we can see effect of lobing: https://www.usound.in.ua/graphs/

having the woofers side by side is one option (and crossing low to to a constant directivity horn), isolating the woofers with waveguides another
 

anphex

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Is vertical directivity for a horizontally measured MTM speaker about the same as the horizontal directivity when measuring it standing vertically?
 

voodooless

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Is vertical directivity for a horizontally measured MTM speaker about the same as the horizontal directivity when measuring it standing vertically?
It's just a matter of shifting the perspective, so yes, essentially it's the same.
 

musicforcities

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Off topic but on brand: Harmon has the center for the JBL STUDIO 530/570/580 on sale for $80. Unreal.
 
OP
amirm

amirm

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What dac and amp do you use in your setup?
Dac is Matrix saber MQA. Amp is Mark Levinson (400 watts per channel).
 

DualTriode

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This is a review and detailed measurements of the JBL 135C center home theater speaker. It was kindly purchased new and drop shipped to me for testing. It is on sale now for US $170.

I really like the look of 135C:

View attachment 168762

This is a 2-way design and other brands we have tested of this kind have proved disappointing for center speaker usage. Will this be different? We will find out.

NOTE: our company, Madrona Digital is a dealer for Harman which includes JBL line. So feel free to read whatever level of bias you like in my subjective remarks.

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

Measurements are compliant with latest speaker research into what can predict the speaker preference and is standardized in CEA/CTA-2034 ANSI specifications. Likewise listening tests are performed per research that shows mono listening is much more revealing of differences between speakers than stereo or multichannel.

Reference axis was the center of the tweeter (aligned by eye). It is getting colder with the measurement room temp at 15 degrees C. Much more samples were taken for measurement of the 135C due to complex sound field created by the interference between all the drivers. Accuracy is better than 1% for most of the range but drops to 2% for part of the spectrum.

JBL 135C Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:

View attachment 168763

I must say, I was not ready for how ugly this looks. We have a bunch of flaws mixed in from lack of deep bass to resonances and directivity error. The only good news is high sensitivity to the tune of near 90 dB.

Due to directivity error which we will cover later, off-axis response is just as chewed up:

View attachment 168764

Somehow it becomes smoother when combined to predict the overall room response:

View attachment 168765

The increase in energy at 200 Hz gives the sensation of bass to the unitiated but I find such sound tubby and undesirable. We also have some increase in high frequencies combining to present somewhat of a "showroom sound" for a small speaker.

Near-field measurements show some pronounced resonances:

View attachment 168767

The ports by the way are at each end of the speaker.

Now we get to the disappointing part: horizontal directivity and beam width:

View attachment 168768

View attachment 168769

A center speaker needs to cover wide audience range and this is the opposite. The driver array has destructive cancellation that causes it to highly "beam" (narrow) in response from 300 Hz up to near 3 kHz. A lot of the vocal range falls in this area so voices are definitely going to be impacted.

While we don't need good vertical directivity, we have it here:
View attachment 168770

One nice thing I have found with multiple drivers is that they handle power very well. Even though these drivers are small they still do an excellent job here:


View attachment 168771
View attachment 168772

Impedance is typical of speakers these days, dropping down to 4 ohms:

View attachment 168773

For fans of timing analysis, here are the waterfall and impulse responses:

View attachment 168774

View attachment 168775

JBL 135C Listening Tests and Equalization
I always listen on-axis to speakers which helped the 135C hide its horizontal directivity. Here, I found the sound as predicted, tubby depending on the track and a bit bright. Moving just half a seat horizontally, killed the clarity and openness of vocals. Figuring some don't need multi-seat coverage, I attempted to fix the high level flaws using equalization:

View attachment 168776

I put in the filter at 200 Hz to get rid of overboosted response there. That got rid of the tubbiness but then highlighted the highs even more. So I dialed in the shelving filter on the right and got that fixed. Problem was, I now lost most of the bass response. I dialed in a quick and dirty low shelf and was surprised how well that worked. I had warmth and good bass now with no noticeable rise in distortion! Once there, as long as you sat on-axis, the sound was quite enjoyable with good ability to play loud.

Conclusions
JBL nails the price and looks of this speaker together with svelte form factor. Alas, it attempts to fight physics and loses on horizontal directivity. No doubt marketing and cost dictated this configuration as their competitors are guilty of the same. Fortunately it responded well to manual equalization (automatic may not work well). So if you want to listen alone, you should be fine. Note that you can't use it vertically due to the ports at each end unless you hang it on the wall.

I can't recommend the JBL 135C as a center speaker.

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As always, questions, comments, recommendations, etc. are welcome.

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@amirm,

I printed out the “waterfall” and impulse response plots from your last three speaker reviews. I looked over the plots on the picnic table at the park down the street.

It is curious to me that each of the three waterfall plots has a wide resonance(?) centering at 130hZ ish that does not seem to attenuate out past 3mS to the end of the plot at 4mS.

I am guessing that this hump in the waterfall is likely room effect or even noise in the room.

I just want to keep learning and having fun.

Your thoughts please?

Thanks DT
 

Bear123

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I'm not entirely convinced a centre speaker is that important. I don't have a multichannel system but I've got two JBL 308p Mkii speakers located at screen height pointed at my listening/viewing position in a pretty much perfect equilateral triangle, and the centre imaging is basically perfect and feels totally natural. Is the centre speaker in a multichannel system really necessary? Is it's presence more important for those not sitting in the sweet spot of the L & R channels, in which case you'd think this could only be solved by having a quality centre speaker with good horizontal directivity? Or is the centre channel necessary in order to actually play multichannel material, as praps AVR's don't allow properly for say 4.1 when playing 5.1 material, I dunno?
I have Revel F36 for my L/R speakers. Setup properly and toed in towards the MLP, activating the center channel(Infinity RC263, 3 way), is a much better experience than trying to rely on phantom center with L/R only. Even if I am the only one listening sitting exactly in the center. Yes, using my $149 center channel sounds better than using only my much higher quality L/R. This is just my subjective opinion though, so hardly scientific. If it matters, I certainly hold no bias to *WANT* things to sound better with the center channel in play. This certainly doesn't make spending 6x as much per speaker for the L/R seem like the best investment.

Honestly, I often find myself using multi channel even for music. Yes, in two channel, you can make people think the center is playing….but when its in use, it's even better IMO.
 

Toblerone

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I’m super excited this speaker was finally reviewed! The web is dearth on info about it which made me nervous to buy it when I did about 6 months ago. I actually went with some Klipsch speakers until I saw the review on here for the A130s and figured the center had to be decent enough. Despite being disappointed in the review for this center speaker I’m really pleased with it. Dialogue is clear from anywhere in the room and I feel like I’m getting a lot of detail from it. Can’t complain, but I probably don’t know what I’m missing since it’s my first setup. If anyone is on the fence and need this form factor I wouldn’t hesitate to recommend it. And if anyone is in Vegas and has a great setup invite me over so I can experience it. Thanks!
 
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