JBL 308P MKII Studio Monitor Review

[ernestcarl]

... there are a few times where the 2nd Harmonic is above the noise floor, at 40Hz and at 200Hz, but again I don't know how valid this kind of test is in determining true distortion. Will redo my calculations from my first edit now......

Besides summing, If you use 512k or 1M-4M length in your sweeps you will get a lower noise floor as well. Do take that into consideration.

 

[Xyrium]

What other speakers in this price range are you looking at that Amir didn't recommend that led you to believe he prefers more distortion? .

I wouldn't compare it to anything in its price range, since I don't really expect anything from a speaker in that range. I suppose I would reference the m105, which seems to have trouble below 500Hz , especially at high levels. He seemed to love those, so goes the assertion....

That said, he has clarified his position in this regard, so it was never a concern, merely a very loosely constructed observation so I can understand what he's hearing, to what I might hear in a speaker. Such an understanding would help me interpret his subjective analysis better.

I'm also trying to figure out exactly what gets impacted by THD above 0.5% above let's say 200Hz. Where is instrument placement, timbre, imaging, etc. beginning to decline due to THD...that type of thing.

 

[Robbo99999]

Besides summing, If you use 512k or 1M-4M length in your sweeps you will get a lower noise floor as well. Do take that into consideration.

I'm using the (I guess) default 256K when I checked just now. Is this in reference to where I said that I'd heard that you want your distortion below your noise floor in your measurements. Sooo, if I use a 512k or above then I get a lower noise floor, but then does that mean that the distortion readings are more likely to be above the noise floor? If that's the case, then where does that leave the validity of what I think I've heard, "that you want the distortion below the noise floor".

 

[Robbo99999]

Experiment:

JBL LSR 308
"Normal" room noise
Simultaneous measurement, single speaker active
About 82db SPL at listening position

Mic 1 at Listening Position
Mic 2 hanging over the front of the speaker, so the capsule is in the plane of the front of the cabinet - more extreme than the Klippel measurement position, but I don't have a stand to hold the mic where I might like to put it.

Using dBc setting - graph sets tone level received to 0dB, to allow comparison of levels of noise and distortion relative to the tone


View attachment 92262

Tone and harmonics are much higher relative to room noise in the close measure

Third harmonic just peeking out of the noise floor at the listening position

Disclaimer: quick test, not trying to make it look bad or good, there will be variations with frequency and the phase of the harmonics (levels will change) at the listening position. Take the measure with a little suspicion, but useful to illuminate the basic idea.

I set it up, frequency selection - random, at least, nothing specific and no tuning - saw harmonics at the speaker, raised amplitude until one of the harmonics peeked out of the noise floor at the listening position.

(Just to point out to everybody, this is the first generation LSR 308 being tested in RayDunzl's post, not the 308p Mkii that is tested in Amir's review). I think a lot of people seem to use LSR 308 interchangeably with 308p Mkii so just pointing that out.

 

[ernestcarl]

I'm using the (I guess) default 256K when I checked just now. Is this in reference to where I said that I'd heard that you want your distortion below your noise floor in your measurements. Sooo, if I use a 512k or above then I get a lower noise floor, but then does that mean that the distortion readings are more likely to be above the noise floor? If that's the case, then where does that leave the validity of what I think I've heard, "that you want the distortion below the noise floor".

Yes. You generally would use a higher setting if you need to obtain a measurement that cuts over the noise floor... for example, if you want to obtain a more accurate RT60 measurement which requires a high signal to noise ratio. I have not looked into it myself, but I’m guessing 128k or 256k which is the more normal/usual default setting is preferable for what your trying to do/compare.

 

[andreasmaaan]

I suppose I would reference the m105, which seems to have trouble below 500Hz , especially at high levels... I'm also trying to figure out exactly what gets impacted by THD above 0.5% above let's say 200Hz. Where is instrument placement, timbre, imaging, etc. beginning to decline due to THD...that type of thing.

Our ears are far less sensitive to distortion in the bass and lower midrange, where both this speaker and the M105 produce most of their distortion. The M105 in particular is extremely clean in the upper-midrange and treble, where our ears are most sensitive.

Moreover, both speakers have a distortion profile that is dominated by the 2nd harmonic, which (a) needs to get very high in level to exceed auditory masking thresholds and (b) implies relatively good IMD performance.

This M105 distortion graph looks bad below 500Hz, but note that harmonics 3 and above are all extremely low in level. It's only the 2nd harmonic that is above 0.5% from c. 110Hz up, and even in the bass the 3rd and higher harmonics are well-suppressed.

This is from Zwicker and Fastl (with my own annotation):

I didn't have a graph of the same data referenced to 100Hz, nor at precisely 96dB (although 100dB is pretty close), but the trend is for audibility thresholds to actually get higher as we move down lower in frequency.

Even at 96dB, I would expect the M105's 2nd-harmonic distortion to not be at all objectionable, and possibly not even audible. The M105 is extremely clean where it counts, that is, in the upper-midrange and treble, and at higher harmonics (of course, there are likely audible problems below the port tuning frequency, but this is going to be the case with any small ported speaker that is not high-pass filtered).

Clearly, at some SPL not too much louder than 96dB, that little woofer is going to pack it in ("bottom out" as Amir says), and then things will start sounding nasty. But it is most certainly not a speaker that is going to have a distorted sonic characteristic at SPLs below the point at which it does that.

EDIT: in my graph annotation it should say, "At 1000Hz/100dB..."

EDIT 2: fixed

 

[RayDunzl]

Just to point out to everybody, this is the first generation LSR 308 being tested in RayDunzl's post, not the 308p Mkii that is tested in Amir's review). I think a lot of people seem to use LSR 308 interchangeably with 308p Mkii so just pointing that out.

It's true.

A list of differences would be nice.

I see different faceplate, and a little different functionality on the back panel (trims)

There may be some firmware changes, but I'd wager the hardware is the same, otherwise (not wage much, I get to be wrong)

So, I'd consider them similar enough to include in the discussion of the new model.

---

Anyway, the point of post #221 above was to illuminate the difference in how clearly the harmonics stand out in a nearfield measurement, vs what is seen with a more distant measure, just using the old 308 as an example.

 

[ernestcarl]

It's true.

A list of differences would be nice.

I see different faceplate, and a little different functionality on the back panel (trims)

There may be some firmware changes, but I'd wager the hardware is the same, otherwise (not wage much, I get to be wrong)

So, I'd consider them similar enough to include in the discussion of the new model.

---

Anyway, the point of post #221 above was to illuminate the difference in how clearly the harmonics stand out in a nearfield measurement, vs what is seen with a more distant measure, just using the old 308 as an example.

I think I’ve read it’s only the tweeter that’s of any real consequential difference. Some like it better, while others say it’s a regression sound-wise.

 

[richard12511]

(Just to point out to everybody, this is the first generation LSR 308 being tested in RayDunzl's post, not the 308p Mkii that is tested in Amir's review). I think a lot of people seem to use LSR 308 interchangeably with 308p Mkii so just pointing that out.

Based on the Harman spin of the LSR 308(originally posted by MZKM), it seems that the older model is just as good.

 

[SpaceMonkey]

Our ears are far less sensitive to distortion in the bass and lower midrange, where both this speaker and the M105 produce most of their distortion. The M105 in particular is extremely clean in the upper-midrange and treble, where our ears are most sensitive.

Moreover, both speakers have a distortion profile that is dominated by the 2nd harmonic, which (a) needs to get very high in level to exceed auditory masking thresholds and (b) implies relatively good IMD performance.

This M105 distortion graph looks bad below 500Hz, but note that harmonics 3 and above are all extremely low in level. It's only the 2nd harmonic that is above 0.5% from c. 110Hz up, and even in the bass the 3rd and higher harmonics are well-suppressed.

View attachment 92276

This is from Zwicker and Fastl (with my own annotation):

View attachment 92290

I didn't have a graph of the same data referenced to 100Hz, nor at precisely 96dB (although 100dB is pretty close), but the trend is for audibility thresholds to actually get higher as we move down lower in frequency.

Even at 96dB, I would expect the M105's 2nd-harmonic distortion to not be at all objectionable, and possibly not even audible. The M105 is extremely clean where it counts, that is, in the upper-midrange and treble, and at higher harmonics.

(Clearly, at some SPL not too much louder than 96dB, that little woofer is going to pack it in ("bottom out" as Amir says), and then things will start sounding nasty. But it is most certainly not a speaker that is going to have a distorted sonic characteristic at SPLs below the point at which it does that.)

EDIT: in my graph annotation it should say, "At 1000Hz/100dB..."

EDIT 2: fixed

You know, you have just cleared majority of single ended amplifiers, boat load of speakers and other amplifiers.
One thing that puzzles me is how much people here are willing to support one piece of hardware (without paying attention to it's faults), while simultaneously willing to obliterate another piece of hardware.

 

[Robbo99999]

Anyway, the point of post #221 above was to illuminate the difference in how clearly the harmonics stand out in a nearfield measurement, vs what is seen with a more distant measure, just using the old 308 as an example.

That's cool, just pointing out the confusion as people seem to so often use LSR308 when talking about the Mkii, I don't know why.

Based on the Harman spin of the LSR 308(originally posted by MZKM), it seems that the older model is just as good.

Yeah, they do look good, I remember finding those when I was researching the 308p Mkii before I bought it....I remember thinking I hope they're just as good, but didn't think they would be....turns out they are!

 

[andreasmaaan]

You know, you have just cleared majority of single ended amplifiers, boat load of speakers and other amplifiers.
One thing that puzzles me is how much people here are willing to support one piece of hardware (without paying attention to it's faults), while simultaneously willing to obliterate another piece of hardware.

Haha. You might notice my advice when people ask if they should upgrade their DAC is almost invariably "don't", and when people ask if they should upgrade their amp, my question in response is almost invariably, "Is it powerful enough?"

Regarding the part of your comment that pertains to speakers, though, the M105 is quite far from a universal case, as its HD is primarily low-frequency and 2nd-order.

 

[SpaceMonkey]

Haha. You might notice my advice when people ask if they should upgrade their DAC is almost invariably "don't", and when people ask if they should upgrade their amp my question in response is almost invariably, "Is it powerful enough?"

Regarding the part of your comment that pertains to speakers, though, the M105 is quite far from a universal case, as its HD is primarily low-frequency and 2nd-order.

Actually, too bad that most reviewers just ignore measurement of HDs these days.

 

[m8o]

Wow.

 

[Xyrium]

Our ears are far less sensitive to distortion in the bass and lower midrange, where both this speaker and the M105 produce most of their distortion. The M105 in particular is extremely clean in the upper-midrange and treble, where our ears are most sensitive.

Moreover, both speakers have a distortion profile that is dominated by the 2nd harmonic, which (a) needs to get very high in level to exceed auditory masking thresholds and (b) implies relatively good IMD performance.

This M105 distortion graph looks bad below 500Hz, but note that harmonics 3 and above are all extremely low in level. It's only the 2nd harmonic that is above 0.5% from c. 110Hz up, and even in the bass the 3rd and higher harmonics are well-suppressed.


Even at 96dB, I would expect the M105's 2nd-harmonic distortion to not be at all objectionable, and possibly not even audible. The M105 is extremely clean where it counts, that is, in the upper-midrange and treble, and at higher harmonics.

Absolutely, I totally get the sensitive area (of hearing) being a problem. That's why I'm surprised at review of various products that do seem to have an issue above 500Hz, such as the 308 reviewed here, yet still provide positive subjective listening experiences for some folks. I'm just trying to figure out where it could be audible...in the tonality, the timbre, the soundstage, etc.. It almost seems as if it (HD) creates a "warm" character, that isn't "analytical", but is that really the truth in sound, or can't we "handle the truth"?

 

[andreasmaaan]

Absolutely, I totally get the sensitive area being a problem. That's why I'm surprised at review of various products that do seem to have an issue above 500Hz, such as the 308 reviewed here, yet still provide positive subjective listening experiences for some folks. I'm just trying to figure out where it could be audible...in the tonality, the timbre, the soundstage, etc.. It almost seems as if it (HD) creates a "warm" character, that isn't "analytical", but is that really the truth in sound, or can't we "handle the truth"?

In reality, I think most electronic components do give us "the truth" (insofar as they surpass our hearing abilities).

But I do think certain levels/types of distortion can add either a warm or an edgy character to recordings (and I use distortion for this effect sometimes when producing music myself).

Keep in mind, too, that at lower SPLs, distortion is much more audible. Note how, with the "masker" at 60dB/1kHz, 2nd-order harmonic distortion starts to become audible at around 0.3%, which is way lower in relative level than when the masker is at 100dB (by the way, this graph assumes that the masker is narrow-band noise, i.e. the threshold is likely going to be higher than this with most music):

As to your musings about the possible subjective effects of audible distortion on soundstage, tonality, etc., why not experiment for yourself using @pkane's Distort software and see what you find?

 

[Xyrium]

In reality, I think most electronic components do give us "the truth" (insofar as they surpass our hearing abilities).

But I do think certain levels/types of distortion can add either a warm or an edgy character to recordings (and I use distortion for this effect sometimes when producing music myself).

Keep in mind, too, that at lower SPLs, distortion is much more audible. Note how, with the "masker" at 60dB/1kHz, 2nd-order harmonic distortion starts to become audible at around 0.3%, which is way lower in relative level than when the masker is at 100dB (by the way, this graph assumes that the masker is narrow-band noise, i.e. the threshold is likely going to be higher than this with most music):

As to your musings about the possible subjective effects of audible distortion on soundstage, tonality, etc., why not experiment for yourself using @pkane's Distort software and see what you find?

Are you using distortion as an effect (like an overdrive pedal), or pushing the 200-500Hz bands above 0dB in the mix, when creating "warmth"? Might be off topic...

Thanks for the reminder about that app! I haven't seen it in years, and I will indeed play around a bit!

 

[andreasmaaan]

Are you using distortion as an effect (like an overdrive pedal), or pushing the 200-500Hz bands above 0dB in the mix, when creating "warmth"? Might be off topic...

Definitely off-topic here, haha.

But yeh, I use it sometimes as an effect, i.e. specific software that is designed to add saturation or to emulate analogue gear, etc. This and this are examples.

Thanks for the reminder about that app! I haven't seen it in years, and I will indeed play around a bit!

 

[amirm]

Two more notes on distortion:

1. This speaker absolutely, positively generates audible distortion at mid volumes and higher. Indeed anyone who says distortion is not audible, should experience it. It is very gradual and subtle at first and then gets to the point of being obnoxious. I do not hear such distortion in passive speakers driven by super powerful amplifiers. For near-field use though, you really have to listen loud to hear the distortions but it is definitely there and below the level of "going deaf."

2. This speaker has independent channels to woofer and tweeter. This means that harmonic distortion generated in bass does not travel to tweeter where it manifests itself as harshness. Standard passive speakers don't benefit this way so their bass distortion can result in different artifacts.

 

[AnalogSteph]

Experiment:

JBL LSR 308
"Normal" room noise
Simultaneous measurement, single speaker active
About 82db SPL at listening position

Mic 1 at Listening Position
Mic 2 hanging over the front of the speaker, so the capsule is in the plane of the front of the cabinet - more extreme than the Klippel measurement position, but I don't have a stand to hold the mic where I might like to put it.

Using dBc setting - graph sets tone level received to 0dB, to allow comparison of levels of noise and distortion relative to the tone

Note: You have (perhaps involuntarily) conducted a test of the distortion levels of your mic. 3rd seems decidedly up in the nearfield test, which does not surprise me as the mic would be seeing >100 dB SPL there no doubt. This is part of why I have been playing with using large diaphragm (non-omni) condenser mics for measurements at distance, lower noise.

That's not what Amir meant when he was talking about nearfield vs. farfield either. He was referring to actual listening distance. It should be obvious that for a given level, nearfield listening would be less demanding on speaker level handling (and more demanding in noise levels).