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JBL 308P MKII Studio Monitor Review

FrantzM

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Hi

I am so satisfied with the LSR308 that at times I wonder if there is much need to change from it ... This being said, I wonder if it would not make sense to modify the 308 with additional amps and buffer.. Thought experiment: Would it be possible to use a pair of mains powered Hypex NC122MP (or other mains powered dual channel Class D amps) in these? The output of the internal amps would feed the Hypex .. Would the resulting speaker be better, seems that most of the distortion is from the amps not the drivers .. I could be wrong.. What do you think. People? Worth it?

Peace.
 

Citizen

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Funny about the noise, I tried to see if lowering the gain would bring it down and it does not, I turn the pot from 1 to 2 and the is no noise and then to 3 and the noise just turns on and stays the same volume all the way up to ten.
 

Citizen

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Hi

I am so satisfied with the LSR308 that at times I wonder if there is much need to change from it ... This being said, I wonder if it would not make sense to modify the 308 with additional amps and buffer.. Thought experiment: Would it be possible to use a pair of mains powered Hypex NC122MP (or other mains powered dual channel Class D amps) in these? The output of the internal amps would feed the Hypex .. Would the resulting speaker be better, seems that most of the distortion is from the amps not the drivers .. I could be wrong.. What do you think. People? Worth it?

Peace.
It would be a good bet that the limitations are on the amps and not the drivers.
 

Archaea

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Funny about the noise, I tried to see if lowering the gain would bring it down and it does not, I turn the pot from 1 to 2 and the is no noise and then to 3 and the noise just turns on and stays the same volume all the way up to ten.
Is this test with no signal cables attached? Just power?
 

respice finem

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It would be a good bet that the limitations are on the amps and not the drivers.
According to my aging hearing (and certainly bias towards classical) the main limitation is the lack of a midrange driver, though it's less severe than I expected (comparing directly and somewhat unfairly to Neumann KH 310A). For their price, the 308P are very good. If only they had less cheap amps in them... IIRC these are integrated DSP and amp chips, so binning them and throwing Hypexes at the drivers, while already too expensive, would confront us with the problem of missing active crossover - bye bye tweeters... But possibly, pin compatible chip amps exist, with lower noise? Still, we would then need a proper curve for the DSP...

If I couldn't bear the noise, and were unable or unwilling to pay up, I'd sell them and get the ADAM T8V.
A much safer bet than trying to repair what the manufacturer had spoiled.
Maybe JBL will hear us through the noise :p and make a premium low-noise version, or even a replacement module.
 
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respice finem

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...The output of the internal amps would feed the Hypex ..
The moment when the stuff hits the fan. The integrated amps are the source of the noise, probably the "preamp"/DSP section being the main culprit. So, if you ask me, no... The price would also be higher than replacing the speakers (see above), and you would have to replace the DSP/active crossover as well.
 
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FrantzM

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The moment when the stuff hits the fan. The integrated amps are the source of the noise, probably the "preamp"/DSP section being the main culprit. So, if you ask me, no... The price would also be higher than replacing the speakers (see above), and you would have to replace the DSP/active crossover as well.
I am not bothered by the noise TBH. There could be some kind of hacking involved perhaps.. taking the line level feed to the amp that could , perhaps, help in the noise department.
OTOH distortions set in pretty early IME. Around 90 dB, they start to shout and screech and ....
The Hypex runs about $350 each... The questions remain:
Would this mod results in an overall better speaker?
Are there out there better $1500/pair active speakers? If yes, which ones?

Peace.
 

Citizen

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I am not bothered by the noise TBH. There could be some kind of hacking involved perhaps.. taking the line level feed to the amp that could , perhaps, help in the noise department.
OTOH distortions set in pretty early IME. Around 90 dB, they start to shout and screech and ....
The Hypex runs about $350 each... The questions remain:
Would this mod results in an overall better speaker?
Are there out there better $1500/pair active speakers? If yes, which ones?

Peace.
To my ear the Mackie HR824 sound better, for some reason in my room they are the only speaker(in that price range) that is able to make it sound like the vocalist is in the center of the speakers, the pair I have are a very old and tired pair, these can be had for $300, represent huge value but parts and servicing can be a bit hard.
 

respice finem

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Would this mod results in an overall better speaker? Are there out there better $1500/pair active speakers? If yes, which ones?
Depends how to define "better". The ADAM T8V definitely has less noise, but not so much less THD, and the JBL may or may not be better suited for a given room, etc. If distortion is your main worry, adding a sub will help definitely more than any difference in amplification. Distortion from amplification is (at high but still sane levels) under 1%, while distortion from the woofers is an order of magnitude higher.

I wouldn't mod the amps, but rather get a matching sub to take the deep bass load off the woofers for less THD.


Or, said T8V tested here https://www.audiosciencereview.com/forum/index.php?threads/adam-t8v-studio-monitor-review.17118/ , and their matching sub.


 
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Buckster

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just for a comparison I also have a Genelec 8030C and I can't hear that at all normally - and I could only hear a faint hiss when I literally put my ear up to the drivers
 

Robbo99999

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My god the hiss is bad, my ears picked it up during low level listening from about 2m away, would not b able to use them in the near field at all, or maybe mine hiss a bit more, they were a second hand buy, other than that they seem to be a fantastic little speaker.

View attachment 311605
I'm surprised you can actually hear the hiss during low level music playing, because as soon as I play any kind of music through them it totally masks the hiss, I suppose if I listened to tracks where there were some moments of complete silence then I'd probably hear it (when used under 2m), but I can't recall any music that I listen to that has this characteristic. I agree with what @respice finem was saying, I think the hiss on these 308p is the same for everyone's and you can't change it by the input gain, as the hiss is constant regardless of volume knob position on back of speaker (unless it's at zero which is mute) - so I think all these different reports are down to how good people's hearing is & what their background noise level is in their room (& of course their listening distance). You're the first person that's mentioned that you can hear the hiss during low level music playback, no one has reported that, but yes almost everyone will hear the hiss when no music is playing (if they get close enough) depending on listening distance/hearing ability/room background noise.
 

Yorkshire Mouth

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Here’s the thing - Amir made a specific point of both noting the hiss and measuring the distance at which he could hear it. He definitely said c.60cm.

Now I know he’s not 18 anymore (are any of us), but I’d have thought he’d notice the difference between 200cm and 60cm.

Something’s going on. I struggle to believe that he either just got it wrong, or that his high frequency hearing is that shot.

And I certainly believe others’ comments, too.

As I say, something’s going on.
 

respice finem

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18? I am 18, three times so far :p But seriously - ears are not "calibrated instruments", and a little background noise (fans of the analyzer?) is sufficient to mask a little amp noise. We also get tired during the day, so we hear a bit worse in the evening, etc. The noise btw is not just in treble, it's similar to white noise to my ears (yes I know, ears...)

I might simply record it with my UMIK-1 and post it here. The only problem is, how do I get the .cal file of the mic into Audacity and such? How close is too close? Acoustic center or each driver separately? Never done this before. And uncalibrated, it remains more of a guess than an objective fact...

Subjectively, I'm sitting in front of them right now, 1,8m stereo triangle, and yes, I can hear the (midrange part of) their noise. I can also hear, at about the same subjective level, my fridge, which is about 10m away. Not really a problem IMHO. Oh, now they're silent. Standby mode.
 
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Buckster

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unit to unit variance ?

difference internal PSUs European vs US versions ?

I'm mid 40s so my ears are not perfect either ! I agree with one of the posters above too - it's not just high frequency noise there is a mid-range element to it too
 

LTig

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I might simply record it with my UMIK-1 and post it here. The only problem is, how do I get the .cal file of the mic into Audacity and such? How close is too close? Acoustic center or each driver separately? Never done this before. And uncalibrated, it remains more of a guess than an objective fact...
Use REW, you can add the cal file and should get the real SPL values.
 

TheWalkman

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This may open a can of worms (or judged as a really dumb idea) but has anyone hacked a pair of 308’s by bypassing the internal amps and driving these from a quality, external amp?

Based on Amir’s review, they show weakness with their bass performance at volume and he felt that a bit of additional horsepower would really make these speakers sing. Perhaps an external amp would also eliminate the hiss.

Granted, I’m guessing this hack would require a crossover to be installed to but it seems like the 308s start with, “good bones” and would make a good speaker great.

Considering their reasonable price point, it seems like this isn’t a huge risk.

I did a quick check over at diyaudio and a google search and didn’t find any 308 hacks to do this.

(I’d try this myself but it is a bit above my pay grade so I’m only throwing the idea out. I’ll now don my Nomex suit for the flamethrowers that may soon be coming my way!)
 

respice finem

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Use REW, you can add the cal file and should get the real SPL values.
I guess I still have a copy somewhere / but how do I avoid getting the sweeps as soon as I press record?
Did my measurements semi-automatically with Carma so far and am not proficient in REW.

For a valid comparison, we would need a large sample, with measurements using the same gear and the same conditions, difficult...
And even then, in the end everyone's perception would be be a little different.
 
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