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

[Bugal1998]

@amirm

I tried to send a PM but I keep getting blocked as spam...

Many thanks for the wonderful forum you've created and the testing service you're providing for the audio community!

If you're interested in testing the amps below, then I'd be interested in learning how the process works and the turnaround time. Feel free to PM me.

I have a Crown DCi 8|300N powering JBL M2s that needs repair (one channel's output drifts up and down by +/- 6db), and after Harman completes the repair I could have it shipped to you for testing.

In the meantime, I will be buying another amp to power the M2s while the amp above is in for repairs... Probably a b-stock Crown DCi 4/1250N (unless you or the forum members would strongly recommend an I-tech or some other amp solution). I could have that amp sent to you from the seller, and then you could forward to me as long as the testing could be completed within any return window. Once I receive the new amp from you I would send my current 8|300N in for repair.

Are these amps of interest to you?

 

[TheHighContemplator]

I really hope this happens!

 

[Frank Dernie]

@amirm

I tried to send a PM but I keep getting blocked as spam...

Many thanks for the wonderful forum you've created and the testing service you're providing for the audio community!

If you're interested in testing the amps below, then I'd be interested in learning how the process works and the turnaround time. Feel free to PM me.

I have a Crown DCi 8|300N powering JBL M2s that needs repair (one channel's output drifts up and down by +/- 6db), and after Harman completes the repair I could have it shipped to you for testing.

In the meantime, I will be buying another amp to power the M2s while the amp above is in for repairs... Probably a b-stock Crown DCi 4/1250N (unless you or the forum members would strongly recommend an I-tech or some other amp solution). I could have that amp sent to you from the seller, and then you could forward to me as long as the testing could be completed within any return window. Once I receive the new amp from you I would send my current 8|300N in for repair.

Are these amps of interest to you?

Don't the Crown amps supplied with the M2 have a DSP correction curve built in to match?
As I understood it the only amps supplied with matching correction curves for the M2 are the Crown and a much, much more expensive but fan-free Levinson option.
Or you do it yourself like some others here have done.
Would you be intending to generate the appropriate correction files yourself for any alternative amp and, if so, which DSP box would you be using?

 

[Bugal1998]

Don't the Crown amps supplied with the M2 have a DSP correction curve built in to match?
As I understood it the only amps supplied with matching correction curves for the M2 are the Crown and a much, much more expensive but fan-free Levinson option.
Or you do it yourself like some others here have done.
Would you be intending to generate the appropriate correction files yourself for any alternative amp and, if so, which DSP box would you be using?

Yes, the crown network amps have the option to load the crossover and EQ tuning files into the on board DSP. And yes, I use JBL's tuning files with the Crown amp.

If there's a compelling reason to pursue an alternate DSP solution I'm certainly willing to consider the potential benefits.

 

[Frank Dernie]

Yes, the crown network amps have the option to load the crossover and EQ tuning files into the on board DSP. And yes, I use JBL's tuning files with the Crown amp.

If there's a compelling reason to pursue an alternate DSP solution I'm certainly willing to consider the potential benefits.

I don't know if there would be any advantage except, perhaps, not having fan noise if that is distracting.
IMO amps are audibly transparent and I am sure JBL wouldn't supply the one they do if it was audibly compromised.
OTOH sota amps and some sort of DSP box may make a theoretical performance gain that I wouldn't be able to hear.

 

[Dialectic]

Member @dallasjustice used computer-based DSP and a Benchmark stack with his M2s.

https://www.audiosciencereview.com/...m2-audiolense-digital-crossovers-w-subs.2369/

https://www.audiosciencereview.com/forum/index.php?threads/benchmark-stack.2283/

Measured performance (particularly impulse response) looks better than what can be attained with the Crown amps.

Is the improvement audible? I doubt it, but I imagine that there is peace of mind in knowing that your system measures that well.

 

[jtwrace]

I personally use the below with my M2's and happy I got away from the fan noise from my DCi 4/1250n. And yes, measuring them with the DSP is another hurdle for Amir which he's probably aware of. I thought about sending mine before selling it but figured it wasn't worth the effort for me or Amir since it's such a specialized use case and what I was replacing it with was a known objective performer.

 

[Absolute]

I have M2 clones with Crown dci 4/1200 Drivecore that replaced 4x hypex nc400.

The fan problem was easily fixed by changing the fans inside with some that runs slower. Now I can't hear the amp, but it runs at about 65 degrees celcius with these fans that's running at 1500 rpm.

Other than that, there's some hiss audible that's a little louder than nc400, especially the low gain version where I didn't hear anything at the lp. Not really a problem unless you're very sensitive for it, because the Crown will disconnect the channels after 3 minutes of silence, removing all hiss when idling.

I bought the Crown due to my stupid ass not thinking straight about gain structure with low gain versions of nc400 + hypex dlcp resulting in about 15w of power. And I wanted to use the built-in M2 settings just to compare against the manual ones I used in the Hypex DLCP, but for the life of me I can't get it to work so I had to find the exact settings from a hacked Itech online to install into the Crown.

Turns out it's exactly the same as the settings I used for Hypex DLCP as provided by @pos - too bright due to a bump between 6-10 khz. Sounds far more authoritative in the bass due to far more power than the 15w I had, but otherwise the same.

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

 

[jtwrace]

Just use the BSS BLU 50 (with JBL tuning) and be done and use silent amps of choice. Perhaps too simple for most.

 

[Absolute]

The Bss blu 50 doesn't have so good snr numbers, so I would expect the Minidsp to be less noisy than that one?

 

[jtwrace]

The Bss blu 50 doesn't have so good snr numbers, so I would expect the Minidsp to be less noisy than that one?

Perhaps. I didn't want to program a miniDSP as I was told when I was at Harman that they do something special to the I-Tech and DCi that isn't clear when people try to extract it out. It became not worth my effort and constant wonder if it was correct so I opted for the BSS. In the end, it sounds and measures as expected so I'm good. But hey, if the miniDSP works for you and others go for it. I've never seen the "official" miniDSP settings though. I'm still hopeful for the fully active M2 though.

 

[Frank Dernie]

Perhaps. I didn't want to program a miniDSP as I was told when I was at Harman that they do something special to the I-Tech and DCi that isn't clear when people try to extract it out. It became not worth my effort and constant wonder if it was correct so I opted for the BSS. In the end, it sounds and measures as expected so I'm good. But hey, if the miniDSP works for you and others go for it. I've never seen the "official" miniDSP settings though. I'm still hopeful for the fully active M2 though.

I like what you have done, I would do the same if M2s were available in the UK.

 

[jtwrace]

I like what you have done, I would do the same if M2s were available in the UK.

You can import them for sure.

 

[Frank Dernie]

You can import them for sure.

I have imported speakers before (active Apogee Divas) but now would prefer a local(ish) dealer and JBL treat the UK market with contempt so it would be a problem if anything went wrong. I decided against buying anything JBL after great frustration a number of years ago.
Anyway I am an old bloke and really pleased with the SQ I am getting now, so no need to ever change again!

 

[Bugal1998]

I don't know if there would be any advantage except, perhaps, not having fan noise if that is distracting.
IMO amps are audibly transparent and I am sure JBL wouldn't supply the one they do if it was audibly compromised.
OTOH sota amps and some sort of DSP box may make a theoretical performance gain that I wouldn't be able to hear.

The amps will be going into an equipment closet located outside the listening room, so I’m not overly concerned about noise. The I-tech series seems to have increased DSP capacity, but I haven’t heard definitively if there’s a cross-over/correction difference between the DCI series and the I-tech series for the M2. I don‘t have any issue with the signal to noise and distortion of the current DCI amp I’m running, so I don’t think I would find that improvement in the i-tech series alone to be compelling for me.

Absent a difference in DSP implementation, I’m not looking to throw money at improvements I likely won’t hear, either.

 

[Bugal1998]

Member @dallasjustice used computer-based DSP and a Benchmark stack with his M2s.

https://www.audiosciencereview.com/...m2-audiolense-digital-crossovers-w-subs.2369/

https://www.audiosciencereview.com/forum/index.php?threads/benchmark-stack.2283/

Measured performance (particularly impulse response) looks better than what can be attained with the Crown amps.

Is the improvement audible? I doubt it, but I imagine that there is peace of mind in knowing that your system measures that well.

I followed his experience closely, but I would prefer to use a black box solution as opposed to a PC solution. However, I‘m truly curious if the soundstage and dimensionality of playback is audibly improved for the typical listener going from the JBL tuning to his custom implementation. If there was a verifiable improvement with the same amps (i.e. using crown amp with internal tuning, vs crown amp with custom external crossover) I might find that compelling.

Otherwise, I get plenty of peace of mind from spending money on things I can hear, and not spending money on things I can‘t hear.

 

[Bugal1998]

I personally use the below with my M2's and happy I got away from the fan noise from my DCi 4/1250n. And yes, measuring them with the DSP is another hurdle for Amir which he's probably aware of. I thought about sending mine before selling it but figured it wasn't worth the effort for me or Amir since it's such a specialized use case and what I was replacing it with was a known objective performer.

I don‘t know if DSP can be fully deactivated for an analog only test of the amp, or if the DA/AD step always happens in the Crown. No matter, the tunings could be removed so there’s no additional manipulation of the signal beyond the DA/AD step. Though Totally possible Amir isn’t interested in testing the amp for the reasons you mentioned.

Beyond the fan noise, do you believe there was an audible improvement in SQ going to the Hypex amps? Any issues with the performance or reliability of the BSS Blu50?

 

[jtwrace]

Beyond the fan noise, do you believe there was an audible improvement in SQ going to the Hypex amps? Any issues with the performance or reliability of the BSS Blu50?

Subjectively? Sure. Realistically? Who knows. I did it to mitigate fan noise. No, BSS has been on 24/7 since I got it. I do keep all of my gear plugged into a Zero Surge (TSC) as well.

 

[Absolute]

Perhaps. I didn't want to program a miniDSP as I was told when I was at Harman that they do something special to the I-Tech and DCi that isn't clear when people try to extract it out. It became not worth my effort and constant wonder if it was correct so I opted for the BSS. In the end, it sounds and measures as expected so I'm good. But hey, if the miniDSP works for you and others go for it. I've never seen the "official" miniDSP settings though. I'm still hopeful for the fully active M2 though.

As far as I can see in the hacked files directly from an I-tech there's a -1,2 dB bandpass on the low channels, but every other EQ point is exactly the same as shown by @pos.
He measured the output of a BSS and matched the output with minidsp in rephase and published the settings so it should be the same.

There's no secret ingredient possible to hide when you measure the outputs of a dsp directly. All settings I've tried through minidsp, DLCP and with Crown have all shown the same rising on-axis plateau between 6-10 khz and it sounds better if you correct for that, imo.

I will call Harman (again) to get help with the included M2 settings in the Crown because that would certainly end all doubts forever for me.

 

[jtwrace]

As far as I can see in the hacked files directly from an I-tech there's a -1,2 dB bandpass on the low channels, but every other EQ point is exactly the same as shown by @pos.
He measured the output of a BSS and matched the output with minidsp in rephase and published the settings so it should be the same.

There's no secret ingredient possible to hide when you measure the outputs of a dsp directly. All settings I've tried through minidsp, DLCP and with Crown have all shown the same rising on-axis plateau between 6-10 khz and it sounds better if you correct for that, imo.

I will call Harman (again) to get help with the included M2 settings in the Crown because that would certainly end all doubts forever for me.

The only way to know for sure is to measure the speaker though which "pos" hasn't done.