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JBL Stage A130 Review (speaker)

maverickronin

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Any idea how much the built-in amplifiers might be influencing distortion performance

Probably quite negligible in the frequency range in which we see most of the 308P's distortion. Even cheap-as-chips class D amps don't tend to produce more than 0.1% or at worst 0.2% HD except at very high frequencies.

Graph from datasheet of the all in one DSP/DAC/amp chip the 3 series uses.

22nuUHX.png
 
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The 308P woofer is not really being asked to do more. It has a much larger radiating surface, so to produce a given SPL at a given frequency, it in fact needs to do less than the 305P's woofer.

That's true for a given SPL at a given frequency within the range that the 308p woofer is comfortable playing, but it's probably being asked to play frequencies that are higher than ideal for that particular woofer. For example, imagine trying to get that same SPL out of the 308p woofer at 5khz, or 10khz.
 

andreasmaaan

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That's true for a given SPL at a given frequency within the range that the 308p woofer is comfortable playing, but it's probably being asked to play frequencies that are higher than ideal for that particular woofer. For example, imagine trying to get that same SPL out of the 308p woofer at 5khz, or 10khz.

Yeh, all I said applies only within the driver's pistonic range of operation.

Having said that, I believe the majority of the harmonic distortion we see around the XO point in the graphs of the 308P is produced by the tweeter.
 
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amirm

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One quick note about distortion measurements. These are rough and approximate! Matching levels with speakers is more of an art than science given the varying frequency response of speakers especially in-room as I do them. So while I say "86 dB" that may be the same as 88 dB on another or 84 dB on yet another speaker. I eyeball the level at 1 kHz and use that. Pink noise with weighting is used in research but I am not sure that is super defensible either.

As I have noted before, most of these measurements are in-room but some have compensation to make them anechoic. The latter graphs tend to be smoother and labeled as such.

My original reason for posting the distortion graphs was to see the potential problem areas. As it now gets used to compare speakers, some caution is in order.
 

infinitesymphony

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Graph from datasheet of the all in one DSP/DAC/amp chip the 3 series uses.

22nuUHX.png
Ouch, that thing ain't pretty! Thanks for posting it.
Can you guys provide some insight as to what the graph reveals relative to the speaker measurements?

Is this amplifier THD bad enough to cause or contribute to the distortion we're measuring from the drivers, or is it simply not as good as most amps you'd want to buy, like the Behringer A500 power amp used here at ASR for testing passive speakers like the A130?
 

Robbo99999

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Maybe when Amir has time remeasure the 305 we can know for sure, but the 308 is pretty unhappy well above the bass.

index.php


Not sure how much of that is the top of the woofer vs the bottom of the tweeter or how different the 5" and 8" drivers are. Maybe the 5 is better in the lower mids. I don't have the best place for measuring mine to find out.

Port noise could end up being just as objectionable as the distortion too, but it didn't seem to bother Amir.
The crossover for the JBL 305P is actually set similarly to the 308P (1725 Hz vs 1800 Hz), but the 308P is woofer is being asked to do more. Perhaps someone who knows more about speaker performance can speculate about how that might affect distortion near the crossover range in each model. Looks like no matter which bookshelf speakers you pick it's wise to HPF them and add a subwoofer if you want to avoid bass distortion.

Blows my mind that the 305P and 308P are using 41W and 56W amps respectively. Perhaps they're maxing out somewhere between 86-96 dB where performance seems to go off a cliff. I find it hard to imagine that they used substantially better drivers in the A130 but would love to hear more info.
The 308P woofer is not really being asked to do more. It has a much larger radiating surface, so to produce a given SPL at a given frequency, it in fact needs to do less than the 305P's woofer.
To add another data point to the discussion you folks are having, I measured my 308p a few weeks back for distortion. It's 2 speakers at 2 metres, so I think that's equivalent to 1 speaker at 1 metre (which Amir measures at), so mathematically I think you can compare the distortion levels at the same dB rating. Mine aren't quite at at 86dB (although REW labels the responses as 86dB for some reason), under 1% distortion across the whole frequency range pretty much, so perhaps there's unit to unit variation....... to factor into some of the conclusions you guys are drawing....here's my measurements:
absolute max listening level.jpgabsolute max listening level (percentage).jpg
In REW I measured at the 1M setting which is a long slow sweep, so supposed to offer more accurate results. (This is after applying a Listening Window Anechoic EQ, so not a stock speaker).
 

Adam Bernau

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The first time I cooked Shishito peppers on the charcoal grill. That came out great but I am not always in a mood to fire up the grill for something this quick. The new method I use comes out almost as good and is very convenient. I use a frypan on the gas stove and set it to max. Put some oil either in the pan or mix some oil with the peppers in a bowl. Once the pan is very hot, dump them in there. Leave them in there for a few minutes and one side chars. Then turn them once to cook on another side. Once they are soft they are ready to go. I then take them out and put the lemon juice, soy sauce and pink salt on it and it is ready to eat.
My favourite recipe is to grill red sweet peppers filled with feta cheese, if you haven´t tried before, i highly recommend it.
Perhaps would work with the shishito ones too, if you have bigger ones :)
 

witwald

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Does anyone have the details of the crossover network that is used in the JBL Stage A130? It probably wouldn't be too difficult to add an extra component or two and reduce the frequency response peak that occurs in the 800 Hz to 2.1 kHz region.
 

maverickronin

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Can you guys provide some insight as to what the graph reveals relative to the speaker measurements?

Is this amplifier THD bad enough to cause or contribute to the distortion we're measuring from the drivers, or is it simply not as good as most amps you'd want to buy, like the Behringer A500 power amp used here at ASR for testing passive speakers like the A130?

Cheap class D amps usually have steadily increasing distortion with frequency and the datasheet graphs are all at 1kHz. Given the distinct distortion humps at both levels and that neither has an upward slope I would guess that the amp is making an insignificant contribution to overall system distortion at those playback levels. It looks like the driver is giving out first.

For a chip that's >$2 a pop in Harman/JBL quantities I think the only thing you could possibly ding it for would be the noise level.
 

infinitesymphony

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Cheap class D amps usually have steadily increasing distortion with frequency and the datasheet graphs are all at 1kHz. Given the distinct distortion humps at both levels and that neither has an upward slope I would guess that the amp is making an insignificant contribution to overall system distortion at those playback levels. It looks like the driver is giving out first.

For a chip that's >$2 a pop in Harman/JBL quantities I think the only thing you could possibly ding it for would be the noise level.
So I guess the takeaway is that JBL used cheaper drivers in the LSR 3 series to end up at a similar price level ($200-400 depending on sales) with the addition of built-in amplification, balanced input, Image Control Waveguide, and DSP EQ.

Makes me curious about the A170.

JBL_Stage_A170_34_NoGrill_14738_x1-1605x1605px.png
 
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maverickronin

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So I guess the takeaway is that JBL used cheaper drivers in the LSR 3 series to end up at a similar price level ($200-400 depending on sales) with the addition of built-in amplification, balanced input, and DSP EQ.

More or less. The (probably) steeper crossover in the 305 gives them smoother directivity though, so it depends on what you're looking for.
 

Hiten

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Does anyone have the details of the crossover network that is used in the JBL Stage A130? It probably wouldn't be too difficult to add an extra component or two and reduce the frequency response peak that occurs in the 800 Hz to 2.1 kHz region.
Newbie post :
In following link you can see crossover details from 6:00 onwards.
(0.12mH inductor, One extra Inductor value can not be seen, 18uf and 5.1uF 100V Caps, 5.8 ohms 10W resistor.)
The midrange hump may be deliberate for home theater movie use. Not sure though.
Regards.
 

richard12511

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Maybe when Amir has time remeasure the 305 we can know for sure, but the 308 is pretty unhappy well above the bass.

index.php


Not sure how much of that is the top of the woofer vs the bottom of the tweeter or how different the 5" and 8" drivers are. Maybe the 5 is better in the lower mids. I don't have the best place for measuring mine to find out.

Port noise could end up being just as objectionable as the distortion too, but it didn't seem to bother Amir.

Yeah the 308p distortion is one of the worst we've seen so far. As someone who owns and enjoys them in my bedroom system, the distortion is definitely audible. A shame, really, given how excellent the speaker is in every other aspect. I guess you can't expect everything to be perfect with a $150(on sale) speaker.

The Stage a130 is almost the exact opposite. Much, much, much better distortion performance, bet less superb in other aspects.
 

A Surfer

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My favourite recipe is to grill red sweet peppers filled with feta cheese, if you haven´t tried before, i highly recommend it.
Perhaps would work with the shishito ones too, if you have bigger ones :)
How big would you leave the feta cheese for roasting? Big pieces or typical store bought pre-crumbled size?
 
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