Measuring data for D2 (2430k) on M2 waveguide wanted

[Kalle]

Still thinks it looks strange. It rolls of very fast. Any ideas?

Regards Karl

[sebackman]

Thank you both!

There seem to be more of a difference than expexted. Can you please check that any imposed delay in the dsp is turned off, no limters are active and if possible please use LR24 XO at 5-600Hz cut off to protect the driver. MTM/LR 36 filters may sometimes disturb the measuring algorithms. LR24 turns phase 360 degrees so that may help.

As both of you are using REW I expected the curves to be rather similar.

I don't know REW but if that is tricky to set up, maybe Holmimpulse could be an alternative.

Is there anyway to obtaing non equalised D2/M2 curves from JBL? They must have them...

kind regards and thank you
//RoB

[srm51555]

I set the Crown dci back to factory setting just in case turning off the filters wasn't enough and took another sweep with only LR36 crossover point added. This measurement was sent over to Karl for comparison to his.


Special Note: when resetting the Crown dci it will deliver a loud test tone during reset. Almost had to change my pants. I assume since it has a BSS processor inside this may be the case for all units.

Thanks,
Scott

[zeljkor]

Hi,
today I have measured my D2 on M2 horn. Serial capacitor of 47uF was added since I do not want to test my luck with DC component. Calibrated B&K mic was used.

Zeljko

[srm51555]

I had some missed steps with soundcard calibration when taking my measurements. Karl's sweep is in Blue and my sweep is in Red. The sudden drop off at 17khz also appears on the soundcard cal file. Smoothing is at 1/6

[sebackman]

Excellent !

That is what I was looking for. I will try to figure out a target curve for 2450sl and 2451be and post my findings here.

thank you
//RoB

[Kalle]

I had some missed steps with soundcard calibration when taking my measurements. Karl's sweep is in Blue and my sweep is in Red. The sudden drop off at 17khz also appears on the soundcard cal file. Smoothing is at 1/6

For me it would be extremely interesting to se your measurements and comparisation to mine curve with EQ. Can you do that? I will do new measurements on mine with a diffrent soundcard to se if there is any differences.

Regards
Karl

[srm51555]

For me it would be extremely interesting to se your measurements and comparisation to mine curve with EQ. Can you do that? I will do new measurements on mine with a diffrent soundcard to se if there is any differences.

Regards
Karl

Sure no problem, I'm hoping to have some time this weekend to do it.

Are you using a BSS Processor or MiniDSP or Other?

Thanks,
Scott

[Kalle]

Sure no problem, I'm hoping to have some time this weekend to do it.

Are you using a BSS Processor or MiniDSP or Other?

Thanks,
Scott

Fantastic

I use Crown CTs4200 with BSS DSP. I will do my measurements again with a analog soundcard to se if there is any difference. Maybe the reciver (and possible delay) interfere with the EQed measurement.

Regards
Karl

[srm51555]

Below shows Karl's measurement(Gold) with DSP and my measurement(Blue) with DSP.

[Zvuchniak]

.
Why they measure so bad ? Are your DSP settings as they should be ? Shouldn't they look more like this ?

[pos]

These measurements are flat +/- 2dB or so, quite similar to the on-axis measurement (the black one) in the spinorama.

The main difference is the rising response in the spinorama, mandatory for the flat "listening window average" curve (the green one).
It looks like JBL gave up on that one, probably for the better...

Another difference, that shows up constantly in nearly all real world M2 measurements I have seen, is that dip around 6.5kHz, and bump around 10kHz (although this one could be the only remaining sign of the HF boost of the original spinorama, resulting in a "listing window" curve that will be flat up to 10kHz)

[Zvuchniak]

I kinda disagree.

From JBL measurements you can easily see that SPL is virtually the same in the region 1-2KHz and 5-10KHz with maybe 1dB rise in SPL at 10KHz. That's not to say that from 2KHz to 5KHz it measures bad - it retains the same SPL with minor glitches in response.

Karls measurements clearly show great SPL difference. Very flat from 1-5KHz (that is expected) and then rise in level, +3dB hump from about 7.5KHz to at least 12KHz. I'm not concerned with the 6.5KHz dip... That hump looks awful and is worrying. Shouldn't that be dealth with DSP ? I'd really like to see gated measurements with gate set to at least 3ms which would make them valid to about 350Hz.

Cheers

[bubbleboy76]

Let's hope a former JBL-employee with a grudge or a former JBL-fan with a grudge can post the real unechoic data!

[srm51555]

Has anyone taken listening position measurements with the D2 they could post? I'm currently running another system for maintenance purposes.

Thanks,
Scott