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Amp upgrade for JBL M2 (would be submitted for testing)

kiwiblair

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My advice? Buy a minidsp shd and put the nice apollon 2kw ncore in the bass and purify on the tweets, use the settings provided by pos and be happy
Thanks, I am later to the party but may just do that very thing @Absolute :)

Have you done this yourself by any chance? I see the M2 crossover settings talk about both input and output EQ, is this something that you have played with by any chance? I don't know if this can be done on the SHD (apologies for the newbie question).

I'm also curious how critical these are, given the SHD has Dirac Live, and that may do a lot of EQ automatically, taking the room into account? Thanks in advance for any thoughts you have!
 
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Absolute

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Thanks, I am later to the party but may just do that very thing @Absolute :)

Have you done this yourself by any chance? I see the M2 crossover settings talk about both input and output EQ, is this something that you have played with by any chance? I don't know if this can be done on the SHD (apologies for the newbie question).

I'm also curious how critical these are, given the SHD has Dirac Live, and that may do a lot of EQ automatically, taking the room into account? Thanks in advance for any thoughts you have!
Yes, I have. I used Minidsp 2x4 HD for those experiments. Knowing what I know now I wouldn't recommend the SHD as the Flex is better suited with input and output EQ. Here's the actual EQ settings for Itech amplifiers;

M2EQ.png


Here @pos have converted them to both constant Q peqs (most dsp use this) and proportional Q (minidsp);

The input peqs are not significant for the woofer, but can be somewhat audible for the tweeter. I tested with and without and thought I had measurements of it somewhere, but can't seem to find them. If using dsp with enough PEQs, like minidsp, you can just add them to each channel if you like.

As a general note I wouldn't stress too much with exact settings because the M2 is a bit bright in the original tuning, as shown and commented by Erin in his review. For amplifiers you need enough power to get the woofer to kick properly and a very silent tweeter amp to avoid that dreaded hiss. I ended up with icepower 1200as2 for the woofer and a custom built Neurochrome-based tweeter amp with 15w and that works brilliantly together with the rather archaic Hypex DLCP dsp/pre.

@synthetic also posted @pos 's minidsp settings that @hardisj was kind enough to also measure on the Klippel and compared to the Crown amp settings;

index.php


 

kiwiblair

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Wow, thanks for the detailed reply @Absolute - much appreciated.

I've just read elsewhere on these forums something from @jhaider saying :

If you use a different DSP do not expect an online “crack” to port over. BSS uses different math for certain filters. I have personally measured this compared to miniDSP, Storm/Bryston, and HTP-1.
Has anyone else had any first-hand experience with this? In particular, if the measurable differences equate to audible differences.

The Crown fan noise is a deal-breaker for me, and I've not yet ordered the M2's, so I am weighing up between
  1. M2's + MiniDSP, since I am already familiar with their great gear,
  2. M2's + BSS Blu-50 (fanless) DSP, or
  3. Taking the easy way out and going in the direction of the JBL 4367's, which apparently are comparable but more consumer-oriented with a passive XO design (a JBL M2 versus 4367 Shootout was in the works, but doesn't look like it eventuated)

Thoughts, anyone? Thank you!
 

jtwrace

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Wow, thanks for the detailed reply @Absolute - much appreciated.

I've just read elsewhere on these forums something from @jhaider saying :



  1. M2's + BSS Blu-50 (fanless) DSP, or
  2. Taking the easy way out and going in the direction of the JBL 4367's, which apparently are comparable but more consumer-oriented with a passive XO design (a JBL M2 versus 4367 Shootout was in the works, but doesn't look like it eventuated)

Thoughts, anyone? Thank you!
Yes, I used both of those configs. Audiolense is by far your best bet. 4367 isn't even close to the M2's.
 

kiwiblair

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Thank you @jwtrace. I'm definitely going for the M2's now. :)

Audiolense is not an easy option for me, as I don't have computers in my playback chain... and I'd ideally like a "set it and forget it" hardware-based approach.

So, my main options seem to be BSS versus the likes of MiniDSP.

It seems to me - from my admittedly new-to-all-this position - that BSS has the advantage of being designed exactly for this purpose, but the disadvantage of an extra set of ADCs/DACs, as it's analog-in, then DSP, then analog-out. There's no point in me using a fancy Weiss DAC, for example, if it's only going to be converted back to digital again.

MiniDSP has the advantage of being all in the digital domain, but in both cases, I expect we're talking some fairly entry-level DACs.

A "pure" solution - keeping everything in the digital domain - might be using something like the SHD, which has two digital outs, which then could be sent to two higher-quality outboard DACs. But - as @Absolute kindly points out - this lacks the input EQ required required for accurate modelling.

Hmm, not simple ... there seem to be trade-offs no matter which way I go. In a perfect world, there'd be a MiniDSP-type unit, with both input and output EQ, and twin digital outs, so everything can be kept in the digital domain until it gets to my HF/LF DACs.

So, any feedback much appreciated from those who have already been down this path!
 

jhaider

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Audiolense is not an easy option for me, as I don't have computers in my playback chain... and I'd ideally like a "set it and forget it" hardware-based approach.

I don’t get the obsession with poisoning audio signal chains with unnecessary general purpose computers.

So, my main options seem to be BSS versus the likes of MiniDSP.

I own, use, and like both miniDSP and BSS BLU (as well as Crown DCIn DSP-amps). I see no reason not to use the intended signal processor with JBL M2s. Keep in mind that if you have a single computer source you can avoid an A/D conversion with the BLU-USB. There’s also a BLU-DA for Dante to Blu-Link conversion. Or you could use a BLU-160 with AES cards if you insist on some fancy DAC. Or the BLU-806DA with a Dante input amp, etc. Lots of options using the correct processing.
 

kiwiblair

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I don’t get the obsession with poisoning audio signal chains with unnecessary general purpose computers.

Indeed. I became obsessed with getting general purpose computers out of my audio signal chain, so I am very reluctant to do a U-turn on this.

There’s also a BLU-DA for Dante to Blu-Link conversion. Or you could use a BLU-160 with AES cards if you insist on some fancy DAC. Or the BLU-806DA with a Dante input amp, etc.

Good suggestions, thank you ... I am clearly hard to please though, as I am almost as averse to fan noise as I am to general purpose computers ;-)
 

jhaider

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Good suggestions, thank you ... I am clearly hard to please though, as I am almost as averse to fan noise as I am to general purpose computers ;-)

Agree. I don’t think the separate BLU-DA box has a fan. I know BLU-USB does not (I own one).
 

Absolute

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Yes, I used both of those configs. Audiolense is by far your best bet. 4367 isn't even close to the M2's.
About that, how did you end up room-curve wise? After experimenting a whole lot I'm tempted to say that I believe constant directivity designs sounds a bit bright if they measure flat on-axis anechoically. I think the good sir @Duke also found this to be the case if I recall correctly.

In my case it doesn't really matter if I use Audiolense, Dirac or manual EQ, it sounds more neutral if there's a small tilt in the tweeter by about 0.5-1 dB octave from 1 kHz-20 khz as measured from 1 meter.

Wow, thanks for the detailed reply @Absolute - much appreciated.

I've just read elsewhere on these forums something from @jhaider saying :


Has anyone else had any first-hand experience with this? In particular, if the measurable differences equate to audible differences.

The Crown fan noise is a deal-breaker for me, and I've not yet ordered the M2's, so I am weighing up between
  1. M2's + MiniDSP, since I am already familiar with their great gear,
  2. M2's + BSS Blu-50 (fanless) DSP, or
  3. Taking the easy way out and going in the direction of the JBL 4367's, which apparently are comparable but more consumer-oriented with a passive XO design (a JBL M2 versus 4367 Shootout was in the works, but doesn't look like it eventuated)

Thoughts, anyone? Thank you!
Not a problem! BSS is the best out of the original dsp-solutions because it was the original, or so I'm told. Based on the test Erin did with Crown and Minidsp loaded with rephase copy of a BSS dsp output, I'm not sure if the difference is just a gain issue in the Crown or differences in the way the dsp calculates the shelving filter. Looks to be a gain-issue.
I've heard several people with M2's saying that the BSS sounds better in back to back testing than Crown, so might be something to it.

When I measured my Crown cdi 4/1200 drivecore (original M2 settings in the FIR section of the dsp) and compared it to the manual settings found on internet I found that the shelving in the FIR setting for the woofer was +8 dB low shelf centered at 135 hz and not -8dB high shelf as shown. The frequency response remained the same for the woofer isolated, but I got far too low output relative to the tweeter when I put in -8dB high shelf as told by the internet pictures. I installed the rephase settings into minidsp 2x4 hd and found the same issue, the settings there equaled a -8 db high shelf leading to way too low woofer output relative to the tweeter.
I can't explain this findings, but somewhere I should have the measurements to confirm if I ever went to trial for my statements.

Anyways, if I couldn't afford a Trinnov or similar all-in-one box, I would go for either a pure digital dsp like OpenDRC with the original M2 settings, a BSS, probably the BLU-50 since it's fanless or the Flex since it can (I believe) run the Rephase settings as provided by POS and have good SNR.
Audiolense requires a computer-based setup which is painfully difficult and cumbersome to make user-friendly in a real-life scenario where you might use the system as a home-entertainment set-up and it's not like you're guaranteed the best result as it combines room correction and speaker correction. In my case where the speakers are placed near front wall and one against a corner, all room correction systems over-compensate the SBIR problems between 100-400 hz and makes the sound very bloated. A simple MMM-measurement after the fact confirms this;

skjermbilde-11-png.667231


mmm-original-m2-bl%C3%A5-vs-mmm-etter-audiolense-r%C3%B8d-jpg.667228


Audiolense in red. As always, the results depends on the situation, so we still need to take basics into account.
 
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jtwrace

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About that, how did you end up room-curve wise? After experimenting a whole lot I'm tempted to say that I believe constant directivity designs sounds a bit bright if they measure flat on-axis anechoically. I think the good sir @Duke also found this to be the case if I recall correctly.

Here are some REW measurements post Audiolense. Audiolense is far above Dirac or any other product IMO.
Jason M2 digital XO with 2 Rythmik F18 and 2 FM8.jpg

Jason M2 digital XO with 2 Rythmik F18 and 2 FM8 step response.jpg

 

Absolute

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Thanks, looks like your ears have come to the same conclusion :)

I prefer Audiolense over Dirac because it's configurable, is faster to change settings and upload filters and gives better results with single-point measurements.
It's not for simpletons, though.

I've found that I'm a simpleton. Too much hassle to have it up and running as a main tv-centered entertainment system.
 

73hadd

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Two questions for the experts here:

1. BSS - When used with "quiet" amps, is there any hiss from the BLU? I heard an anecdote from a Harman installer that the BSS BLU introduced "hiss" as well, and tried to steer me to some of their new Cinema amps (that actually have worse specs than the I-Tech or DCI).
2. Audiolense - If using in a home theater setup, with an AV Preamp Processor analog output, how much delay is introduced in the ADC/Audiolense/DAC chain? I have never seen an AV Processor that has the ability to delay video to match a "slow" audio stream. I have only seen the abilty to add audio delay, not subtract for it.
 

73hadd

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A Harman rep strongly recommended the Crown DSi 2.0 amps as being quiet (chassis noise and through speakers) and also capable to import the M2 dsp tuning file. Has anyone tried them?

For the minidsp Flex, does it have "enough FIR taps" to render dsp similar to the original M2 tuning file?
 

pos

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When I measured my Crown cdi 4/1200 drivecore (original M2 settings in the FIR section of the dsp) and compared it to the manual settings found on internet I found that the shelving in the FIR setting for the woofer was +8 dB low shelf centered at 135 hz and not -8dB high shelf as shown. The frequency response remained the same for the woofer isolated, but I got far too low output relative to the tweeter when I put in -8dB high shelf as told by the internet pictures. I installed the rephase settings into minidsp 2x4 hd and found the same issue, the settings there equaled a -8 db high shelf leading to way too low woofer output relative to the tweeter.
The M2 rephase settings as found in this document should match the measured outputs of a BSS with factory M2 settings within a fraction of a dB.
 

Absolute

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The M2 rephase settings as found in this document should match the measured outputs of a BSS with factory M2 settings within a fraction of a dB.
Yes, the measurements Erin did with the rephase version seems to match perfectly (aside from a gain anomaly in the Crown he used).

m2-oem-vs-minidsp.jpg

 
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Check out Powersoft Quatrocanali 2404 and Armonia + DSP
Armonia is a free DSP down load from Powersoft . You can also use Smaart V8 to hone frequency response in the DSP.
 

Absolute

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Check out Powersoft Quatrocanali 2404 and Armonia + DSP
Armonia is a free DSP down load from Powersoft . You can also use Smaart V8 to hone frequency response in the DSP.
Hi Nigel, are you by any chance a representative of Powersoft?
Looking at your post history it would seem so. If that is the case you need to give @amirm a heads-up.

If not, never mind.
 

Molon_Labe

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A Harman rep strongly recommended the Crown DSi 2.0 amps as being quiet (chassis noise and through speakers) and also capable to import the M2 dsp tuning file. Has anyone tried them?

For the minidsp Flex, does it have "enough FIR taps" to render dsp similar to the original M2 tuning file?
Did you ever confirm if this was accurate?
 

al2002

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Erin’s testing showed a FR irregularity around 3-600 Hz due to surround issues. I vaguely recall reading somewhere that a later or different version (can’t exactly remember) of the JBL 15” driver did not have this problem. Anyone know more about this?
 
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