JBL LSR305P MKii and Control 1 Pro Monitors Review

[Thomas_A]

We need a kind of SINAD chart, for instance in the form of a calculation of the sum of areas (integrals) betwen estimated in-room curve & target. And rank them from highest to smallest.

See areas in green here:


View attachment 45274

Perhaps standard deviation of the residuals between ideal and measured data.

 

[soundwave76]

Wow. I need to re-read this again. Slowly.

Kudos and thank you Amirm for strating this!

 

[Xyrium]

Wow is right, I can't believe you popped the cherry on speaker reviews already!!! Great start, thanks!

 

[Koloth]

(Hey guys! I just registered for this account after being a daily lurker for more than half a year. Even though I feel like I'm out of the speaker market myself (I got an amazing deal on some Technics SB-R1), there's always a buddy or relative that needs advice. More generally, the entire audio world is in dire need of some clarity.)

The proximate reason I created this account is because of the wishes for an easily digestible and hierarchically rankable numeric value for each speaker measured (comparable to the electronics SINAD metric). Now I understand that there is no single such metric that could encompass the totality of a speakers performance - especially because of the differing preferences regarding narrow/broad listening windows among buyers, the varying rooms those speakers will have to fit into and the willingness of buyers to EQ.

However, if I understood Amirs explanations of the various plots correctly, there seems to be one metric which could be transformed into a simple numeric value and which would be unambiguously desired by all prospective buyers open to the idea of equalizing the speakers (which I suspect is a sizeable and ever-expanding percentage of ASR readers): the relation of the amplitude-frequency-curve within the listening window and the amplitude-frequency-curve of the early reflections.

Imagine you sample both curves n times at corresponding intervals.
Then you subtract the sampled values of the early reflections from the sampled values of the listening window at the same frequencies.
You get n numer of difference values.
(Ideally, you'd want all those difference values to be equal: No matter how crooked the curve within the listening window is, if the early reflections curve tracks it precisely (by whatever offset), you can then fix it in EQ.)
So then you calculate the inequality among all the difference values. I'm not familiar enough with the mathematics to know which measure would be most suitable here. Perhaps a Gini coefficient or similar measurement could be adapted to produce one simple to understand number that would then tell us how amenable to speakers are to equalization - irrespective of how fucked up the unequalized curves look. You could call it the FBEQ-metric (fixable by equalization) and design a nice hierarchical ranking using it.

Going beyond this suggestion... while one value cannot encompass the totality of a speaker's performance, maybe a set of five or six such values could? For example: How amenable is it to eq? How linear is it withing the listening window without eq? What's the -6db point in the low frequencies? etc. If we could come up with a set of such metrics that could individually be transformed into numeric values, we could then build radar charts that would enable at-a-glance assessments of the general outlines of a speakers performance.

 

[Matias]

Amir, a single rating metric could be how much percentage of the frequency range is outside an arbitrary limit, say +/- 2dB.
So a 100% speaker would have all its frequency response within +/- 2dB, while a 80% speaker would have 20% of its frequency response above or below 2dB from the mid line.
Mid line could be straight or descending, depends on the manufacturer's tuning.
The range would be between the extremes, so that a small speaker f3=60Hz it would count from this point on and a large speaker f3=30Hz from this point on.
I don't know how to calculate this manually, so Klippel would have to come out with a way to calculate this automatically.

 

[Ron Texas]

Wow!

 

[Labjr]

KEF LS50 next?

 

[oivavoi]

While one value cannot encompass the totality of a speaker's performance, maybe a set of five or six such values could? For example: How amenable is it to eq? How linear is it withing the listening window without eq? What's the -6db point in the low frequencies? etc. If we could come up with a set of such metrics that could individually be transformed into numeric values, we could then build radar charts that would enable at-a-glance assessments of the general outlines of a speakers performance.View attachment 45290

I really like this idea!

 

[MatteoS]

Congrats !

I will study your review this weekend. I haven't see nothing regarding crossover type, order used.
best regards

matteos

 

[Xyrium]

I had a pair of the older 305, the hiss drove me crazy and I eventually got rid of them. Bummed to see they haven't fixed the issue yet. They were otherwise great speakers.

I have the MkI model, and they are entirely hiss free. I'm sure the budget nature of this model caused the QC to be rather minimal. Some folks got a good pair, some didn't. I bought mine while one of my Focal Solo's were in the shop for an amp replacement (never again....), and they remained on board, but moved them over to my e-drum kit.

That said, I don't find them nice to listen to since they are quite flat. I use low end Dynaudio Emit 10s for my desktop listening, and find them easier to listen to. So, hopefully Amir will get a pair on his bench so I can determine what makes them better for "my ears". The JBLs do seem to go lower than the Dyn's, however.

I have to try and compare Amir's distortion measurements to the type that Soundstage was producing so I can get a baseline understanding of where these stand as well. Example of how Soundstage produces speaker measurements: https://www.soundstagenetwork.com/i...&catid=77:loudspeaker-measurements&Itemid=153

Edit: I'm hallucinating...must have been thinking about the Solos. I just put my ear next to the 305s and they're hissing like a cat. Evil lil' sob's. I still don't hear "flat" out of them, as many of the measurements imply.

 

[MediumRare]

Impressive amount of data! Although not an easy task, the "simple" guy in me would like to see also some kind of "digestible score" for layman... (but maybe I belong to minority in this forum

I agree. While an experienced person could review the graphs and see what's "wrong" with a speaker, a potential buyer would have a hard time comparing results from two speakers and make a selection on that basis.

So, @amirm, here is a modest proposal for key measures that you might want to use to set up your "league tables"

1. Measure of flatness, for example, a standard deviation.
2. Measure of Bass, for example, the sum of -db at 50 Hz, 45 Hz, 40 Hz, 35 Hz, 30 Hz, 25 Hz (closest to zero is best, of course)
3. Measure of distortion
4. Measure of directionality (I'm not sure how to use that but from your commentary it seems rather important)

Does anyone else have suggestions?

 

[gvl]

It definitely does help to have the volume as low as possible in the back and use my Topping D50 on its highest volume setting but when sitting at my desk it's there. How close do you sit to them?

2-3 feet, they are to the sides of my monitor.

 

[D700]

Will do. I will be refining what I present both based on what I am finding and feedback from you all.

Did the hiss show in the measurements?

 

[ribosradagast]

Is there any smoothing applied to those graphs? Or does the system take care of all that

 

[CumSum]

Great review @amirm . I absolutely love my pair of JBL 306P's. I am def looking forward to more of your speaker reviews.

Would you be able to add compression sweeps to your test suite? It would be nice to see how a speaker's frequency response and distortion levels change as SPL's rise. And to pin point what the Max SPL of a speaker is so we can determine the size of a room and the type of content (music/HT) that speaker can faithfully reproduce.

Similar to what https://data-bass.com/ does for testing a subwoofer's output capability.

 

[Noob]

I am grateful for you and the effort you have consistently put in to better the audio market for consumers. Well done.

 

[gr-e]

Agreed - to me, the measurements seem quite consistent with a perception that the speaker's tonal balance is a tad bright and has somewhat scooped mids. That's certainly been my subjective impression of the 306p.

306p also seem to have some weird dip around the crossover frequency:

Spoiler: Digital Stereophony

Spoiler: Joe N Tell

 

[jtwrace]

@amirm I don't have time to go through all the pages so I apologize. Have you asked your contacts at JBL to look at this and get their feedback? If so, what was it? Having been there and seeing the whole facility I know they believe in what Klippel does but I was just curious.

 

[Poseidons Voice]

Yes, what jtwrace said.

I've been a long time lurker but it's time to start posting! Thanks again for this, it's refreshing, and eye opening. You'll be receiving a pm soon.

Thanks,
Anand.

 

[Interference]

How would digital inputs work for speakers that are sold singly?

Two separate TOSLINK cables from your audio interface, one for each speaker? Or a whole bundle of them if you're mixing 5.1 / 7.1 / 7.2.2 / whatever?

You are right. There is no smart enough digital transport standard for this, unless going to complicate professional protocols.

I would be fine with just S/PDIF input and a L/R selector, though. Multichannel can still rely on analog inputs.