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JBL 308P MKII Studio Monitor Review

Blumlein 88

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Just picked up a pair of these to play with while in COVID QT and have a question related to the limiter. I was hitting one of the speakers pretty hard (didn't measure the actual input voltage or output SPL) to see if I could duplicate the limiter symptoms Amir got...which I thought I did. I didn't leave it at that level for long - just enough to say, "Yeah, OK, that's what the limiter sounds like." However, when I backed off to normal levels, I was still getting what I had thought were the limiter artifacts. Powered off, unplugged, waited a couple minutes, powered back on, artifacts still there. Powered off, unplugged, waited about 6 hours, powered back on, artifacts gone. Speaker is completely clean and normal. I'm curious if anyone else has experienced this behavior?
I've some 308 II's and haven't seen this. Only rarely and briefly got into limiting. Though I might tonight listening to Creed as I type this. Deep Purple and Godsmack on the way.
 
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I wonder if there is an internal temperature sensor involved?
That's kind of what I was thinking, but I'd never heard it mentioned in conjunction with this model. My other thought was some kind of limiter malfunction. I can check the other unit, but it's still in the box.
 

CerealKiller

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Just picked up a pair of these to play with while in COVID QT and have a question related to the limiter. I was hitting one of the speakers pretty hard (didn't measure the actual input voltage or output SPL) to see if I could duplicate the limiter symptoms Amir got...which I thought I did. I didn't leave it at that level for long - just enough to say, "Yeah, OK, that's what the limiter sounds like." However, when I backed off to normal levels, I was still getting what I had thought were the limiter artifacts. Powered off, unplugged, waited a couple minutes, powered back on, artifacts still there. Powered off, unplugged, waited about 6 hours, powered back on, artifacts gone. Speaker is completely clean and normal. I'm curious if anyone else has experienced this behavior?
Wonder if its just a psycho acoustic perception, manny times I thought had done permanent damage to some of my speakers or headphones just to "try them" again another day and coud not hear the same distortion at similar levels.
 
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Wonder if its just a psycho acoustic perception, manny times I thought had done permanent damage to some of my speakers or headphones just to "try them" again another day and coud not hear the same distortion at similar levels.
:D So have I. In fact, since it is kind of my job to find problems with sound system-related things, I have been known to hear a lot of things that weren't really there. ;) I have also found a lot of problems that other people missed!

Since this doesn't (so far) appear to be a known thing with this speaker, I'm going to hit mine again and see if I can get it to do the same thing again or something different. The circumstances were well documented, so I can duplicate them exactly.
 

Robbo99999

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:D So have I. In fact, since it is kind of my job to find problems with sound system-related things, I have been known to hear a lot of things that weren't really there. ;) I have also found a lot of problems that other people missed!

Since this doesn't (so far) appear to be a known thing with this speaker, I'm going to hit mine again and see if I can get it to do the same thing again or something different. The circumstances were well documented, so I can duplicate them exactly.
If you do the testing, can you let us know at what voltage input the distortion occurs, and in relation to the DIP sensitivity setting on the back of the speaker too? Amir reported that the 308p didn't do well in this regard where he said: "Setting the gain low and them pumping up the source generates severe distortion.". It's a pity he didn't make a note of what (theoretical) voltage he was inputting to the speaker to cause the distortion, because it would be extremely useful to know if it was above or below the 2V input that the specs say this speaker can handle when on the consumer DIP switch sensitivity on the back of the speaker. I'm assuming your testing is to work out this phenomenon re Input Voltage causing distortion that Amir mentioned?
 

Buckster

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would I be right in thinking (as I have connected to an AV amp) that a pair of A130s would provide more volume with lower distortion that my current 308 MKIIs.

I love the sound of the 308 MKIIs - but at very high home cinema volumes that can sound a bit shouty/like horn speakers - which I can only guess is a bit of distortion creeping in - I'm thinking A130s would almost as good but would go to higher volumes more easily ?
 

FrantzM

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would I be right in thinking (as I have connected to an AV amp) that a pair of A130s would provide more volume with lower distortion that my current 308 MKIIs.

I love the sound of the 308 MKIIs - but at very high home cinema volumes that can sound a bit shouty/like horn speakers - which I can only guess is a bit of distortion creeping in - I'm thinking A130s would almost as good but would go to higher volumes more easily ?
I am where you are. It seems that to go past this, is to invest in the 708p. Perhaps my next step...
 

Robbo99999

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would I be right in thinking (as I have connected to an AV amp) that a pair of A130s would provide more volume with lower distortion that my current 308 MKIIs.

I love the sound of the 308 MKIIs - but at very high home cinema volumes that can sound a bit shouty/like horn speakers - which I can only guess is a bit of distortion creeping in - I'm thinking A130s would almost as good but would go to higher volumes more easily ?
If you've not EQ'd the JBL 308p Mkii's to flat then they will sound a bit shrill due to the general elevations from about 800Hz onwards. This is my Anechoic Listening Window EQ if you want to try it. EqualiserAPO file attached at end of post.

Effect on Listening Window:
index.php


Effect on the On-Axis:

index.php


That totally sorts out any shrillness for me.
 

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  • JBL 308p Anechoic LW EQ v2.txt
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Buckster

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thankyou - I'll give that a try. Not sure its shrillness though - but I'll try it.

I'm limited in my PEQ bands though so I'll see how I can translate your kindly given EQs into what I have to use.

This is as my Denon 7200WA amp only has either Audyssey XT or Manual PEQ - I just can't get on with XT - I've tried and tried. Even with several different speaker setups - I don't like the seemingly recessed area around 1k and then the boosted very high uppers. If I had a newer amp with the adjustable Audyssey and I could set a max frequency for the Audyssey I'm sure it would sound great.

I do have a UMIK - if I have time I will try REW on them at weekend.
 

Robbo99999

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thankyou - I'll give that a try. Not sure its shrillness though - but I'll try it.

I'm limited in my PEQ bands though so I'll see how I can translate your kindly given EQs into what I have to use.

This is as my Denon 7200WA amp only has either Audyssey XT or Manual PEQ - I just can't get on with XT - I've tried and tried. Even with several different speaker setups - I don't like the seemingly recessed area around 1k and then the boosted very high uppers. If I had a newer amp with the adjustable Audyssey and I could set a max frequency for the Audyssey I'm sure it would sound great.

I do have a UMIK - if I have time I will try REW on them at weekend.
How many PEQ bands do you have? I'll recommend you which ones to use for best effect.
 

Robbo99999

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Thankyou very much - manual EQ has 9 bands

63, 125, 250, 500, 1k, 2k, 4k, 8k, 16k
Oh sh*t, right! That's Graphic EQ, not Parametric EQ (PEQ). That's really quite coarse, I don't think you'd be able to totally sort it out with those rigid restrictions, but I'll have a look at it. I'll have a look at it over the weekend & come back to you with any suggestions.
 

Buckster

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Oh sh*t, right! That's Graphic EQ, not Parametric EQ (PEQ). That's really quite coarse, I don't think you'd be able to totally sort it out with those rigid restrictions, but I'll have a look at it. I'll have a look at it over the weekend & come back to you with any suggestions.
Oh yeah sorry I got my terms muddled up yes it's Graphic EQ not PEQ. It's annoying as I could do with a lot more bands. And any suggestions much appreciated so thanks very much
 

Robbo99999

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Oh yeah sorry I got my terms muddled up yes it's Graphic EQ not PEQ. It's annoying as I could do with a lot more bands. And any suggestions much appreciated so thanks very much
Ok, I had a look at this in REW today to create an Anechoic Fixed Band Graphic EQ, and I've tested it out on my speakers and I think it's pretty good, I think it will for sure cure the "shoutiness" aspect you mentioned.

Find the following graphs showing the effect of the Graphic EQ on the Listening Window as well as on the On-Axis response:

Graphic EQ Effect on Listening Window:
308p Mkii Graphic EQ Listening Window v2.jpg


Graphic EQ Effect on On-Axis Response:
308p Mkii Graphic EQ On Axis v2.jpg


So as you can see Filter #1 in the pics is exactly equivalent to you flipping the HF Trim Switch that is on the back of the speaker to (minus) -2dB, so you'll want to flip that to (minus) -2dB, following is pic showing HF Trim Switch (it's not in the correct position in this pic, but at least you can see the switch I'm talking about):
HF Trim Switch.jpg

And then really the only filters you need to activate are the following:
1000Hz -1dB
2000Hz -1.5dB

for the 16000Hz filter probably keep that deactivated, but you can try setting that to -2.2dB to see how you like it, I recommend leaving it deactivated.

Yes, so I've listened to these settings, pretty good, I think you'll like it and it should at least fix the "shoutiness".

EDIT: see the annotated note I make about the 2000Hz filter in the pics for further tweaking during your experimentation.
 
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Buckster

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Robbo99999 - thank you so very very much - I'll give those EQ suggestions a try.

Very kind of you to take the time to do that - its much appreciated

I have to say I think I'd miss-interpreted the review results on here as I found I'd added a boost to 1K and 2K

I was thinking earlier - how much difference to the overall SQ of active speakers (those with digital EQ) - does the ADC to DAC conversion make ?

after reading tonnes of the reviews on here on USB audio interfaces and picking a Motu M4 for my music playing/production (in loose sense!) and thinking how good it sounds through my JBL 305s (and headphones), and likewise my Denon 7200WA into the 308 MKIIs for my home cinema setup which I think uses pretty decent AKM 4490s - I wonder how much of that "high-end" DAC conversion is "lost" (if any) once going through the (assumingly) relatively cheap ADC/DAC on the 305/308s or other non high end active speakers

they sound pretty transparent to me - but does make me wonder

my Genelec 8030C which I use a centre uses analogue EQ/etc but is still active which seems to be the best of both worlds.

Say if the 308 MKII and the Stage A130 passive measured similarly - presumably any SQ advantage of not going through another 2 analogue to digital stages (as in the passive only has one DAC stage on the amp, the active chain as an ADC and another DAC also in the chain) wouldn't be shown in the graphs etc in the reviews on here as I'm not sure would show up in distortions/frequency output etc ? would only be in the "how it sounds" part which is obviously subjective

thanks again Robbo99999 for the EQs - and I'll report back with how I get on
 
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Robbo99999

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Robbo99999 - thank you so very very much - I'll give those EQ suggestions a try.

Very kind of you to take the time to do that - its much appreciated

I have to say I think I'd miss-interpreted the review results on here as I found I'd added a boost to 1K and 2K

I was thinking earlier - how much difference to the overall SQ of active speakers (those with digital EQ) - does the ADC to DAC conversion make ?

after reading tonnes of the reviews on here on USB audio interfaces and picking a Motu M4 for my music playing/production (in loose sense!) and thinking how good it sounds through my JBL 305s (and headphones), and likewise my Denon 7200WA into the 308 MKIIs for my home cinema setup which I think uses pretty decent AKM 4490s - I wonder how much of that "high-end" DAC conversion is "lost" (if any) once going through the (assumingly) relatively cheap ADC/DAC on the 305/308s or other non high end active speakers

they sound pretty transparent to me - but does make me wonder

my Genelec 8030C which I use a centre uses analogue EQ/etc but is still active which seems to be the best of both worlds.

Say if the 308 MKII and the Stage A130 passive measured similarly - presumably any SQ advantage of not going through another 2 analogue to digital stages (as in the passive only has one DAC stage on the amp, the active chain as an ADC and another DAC also in the chain) wouldn't be shown in the graphs etc in the reviews on here as I'm not sure would show up in distortions/frequency output etc ? would only be in the "how it sounds" part which is obviously subjective

thanks again Robbo99999 for the EQs - and I'll report back with how I get on
I think the most fundamental think to get right with audio equipment is Frequency Response (which has been scientifically proven), so I don't think you should worry too much about active speakers doing their ADC-DAC conversions. Your "shoutiness" you noticed would be all about the frequency response, and that's what EQ tackles - manipulating the frequency response to the most neutral result, which is well understood for speakers......in fact the EQ I did for you is using the basis of that understanding - anechoic flat on-axis tonality combined with as smooth a Listening Window curve as possible. Setting the HF Trim Switch on the back of the speaker to -2dB does the majority of the heavy lifting to bring the on-axis to flat tonality, and and the other two filters I created for you at 1000Hz & 2000Hz bring down some broad elevations that would specifically be related to "shoutiness" - this "shoutiness" variable occurs around 2kHz, those 2 filters bring it down so it's flat in that area for the on-axis.

Yeah, it would good to hear how you get on with the EQ I did for you & if it helps at all. Let me know if you're unsure whether or not you've entered the EQ correctly. I've listened to that Graphic EQ I did for you on my speakers and it's good......it's not quite as good as the parametric EQ I showed you to start with, the parametric EQ contains a bit more clarity and detail which might be due to the 1.5kHz dip being filled combined with the subtle elevation of a broad but very shallow depression between 4-6kHz and the substantial depression between 10-14kHz which can also be lifted with Parametric EQ, but you can't tackle those areas just using coarse Graphic EQ, that's the beauty of the flexiblity of Parametric EQ.
 
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richard12511

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thankyou - I'll give that a try. Not sure its shrillness though - but I'll try it.

I'm limited in my PEQ bands though so I'll see how I can translate your kindly given EQs into what I have to use.

This is as my Denon 7200WA amp only has either Audyssey XT or Manual PEQ - I just can't get on with XT - I've tried and tried. Even with several different speaker setups - I don't like the seemingly recessed area around 1k and then the boosted very high uppers. If I had a newer amp with the adjustable Audyssey and I could set a max frequency for the Audyssey I'm sure it would sound great.

I do have a UMIK - if I have time I will try REW on them at weekend.

To use Aydyssey, you have to use the phone app to really make it decent. The phone app allows you to remove that recession and highs(or bass boost).
 

Buckster

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I think the most fundamental think to get right with audio equipment is Frequency Response (which has been scientifically proven), so I don't think you should worry too much about active speakers doing their ADC-DAC conversions. Your "shoutiness" you noticed would be all about the frequency response, and that's what EQ tackles - manipulating the frequency response to the most neutral result, which is well understood for speakers......in fact the EQ I did for you is using the basis of that understanding - anechoic flat on-axis tonality combined with as smooth a Listening Window curve as possible. Setting the HF Trim Switch on the back of the speaker to -2dB does the majority of the heavy lifting to bring the on-axis to flat tonality, and and the other two filters I created for you at 1000Hz & 2000Hz bring down some broad elevations that would specifically be related to "shoutiness" - this "shoutiness" variable occurs around 2kHz, those 2 filters bring it down so it's flat in that area for the on-axis.

Yeah, it would good to hear how you get on with the EQ I did for you & if it helps at all. Let me know if you're unsure whether or not you've entered the EQ correctly. I've listened to that Graphic EQ I did for you on my speakers and it's good......it's not quite as good as the parametric EQ I showed you to start with, the parametric EQ contains a bit more clarity and detail which might be due to the 1.5kHz dip being filled combined with the subtle elevation of a broad but very shallow depression between 4-6kHz and the substantial depression between 10-14kHz which can also be lifted with Parametric EQ, but you can't tackle those areas just using coarse Graphic EQ, that's the beauty of the flexiblity of Parametric EQ.

I gave EQ a try - and definitely has improved things thanks very much.

I have done a whole load of experimentation at weekend - as I moved one of my desktop pcs into lounge, and finally got REW up and running to see results. I will write much more when I work out exactly what I did - I think I kept broadly what you kindly suggested - with a few minor tweaks just can't remember right now what I ended up with.

I also received a new amp plate for my SVS sub as my old one failed - so whilst frustrating had to spend a load of money - the new amp has much better EQ - still only three EQ filters (on top of the room gain compensation etc features) - but now those three EQs can accurately set the Q, Frequency (to 1hz resolution) and gain (in something like 0.1dB steps) - this has allowed for much better sub EQ being possible
 

FTB

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Hello there,

I have a question for people who own these speakers.
I would like to go for these 308P mkii because of their qualities and their price (I'm on a budget now but for sure I could go for Genelec 8351B).

I am used to passive speakers with class AB amp using passive components (MOSFETS or LM3886...) and non SMD stuff, so I wonder about these active speakers and their class D integrated amplifier.

I believe in class D because of its efficiency (heat is the enemy about distortion and reliability, isn't it ?) and it seems well executed now (low-pass filtering and intermodulation distortion).

What about in case of failure ? I guess class D amp are less prone to failure as it runs cold but if so, is it as easy to repair as a passive components amplifier or we do as we do nowadays, replacing all the board ?
When I look to an amplifier as the Allo Volt, it is full of SMD components, can we repair this kind of stuff at home ?

Please note I'm not an engineer, only a passionate, if some of my statements are false don't hesitate to correct me.

Thank you
 
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