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

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Originally Posted by 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

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That "hump" might look awful to you, but it is nothing compared to what happens in the 8kHz-20kHz in the on-axis curve from the spinorama.

Anyway, the on axis curve is only a (minor) part of the whole picture here, and the EQed curve was the listening window average.

Here are my gated measurements (correct settings in red, you can ignore the blue curve), 0° and 20°
http://www.audioheritage.org/vbullet...l=1#post393721

You can clearly see that the bump around 8-9kHz results in a flat curve at ~30° off axis (which is probably a good approximation of the listening window curve...)

8-20KHz on axis from spinorama does not look bad at all. It has gradual tilt starting from 8KHz to +3dB at 20KHz. I just don't see that as bad untill i hear it sounding bad.

You are totally right about on axis being just one part of the energy that is transmited into the room, but i was aiming at another thing. Measurements that are being made differs (a lot) from JBL measurements - yet they have the same DSP settings. There are few possibilities why.

JBL lying ? Possible but in that class of loudspeakers - very hardly.
Difference in drivers ? Isn't it possible that D2 ring radiators differ so much from one another that JBL pairs them up for M2 monitors and generates DSP curves for that particular pair of drivers ? That would explain the difference between two measurements provided by srm51555, and the difference between your measurements with theirs.

Your on axis measurements shows (6.5KHz dip excluded) +/-0.75dB variation from 1KHz-10KHz. Your drivers measures way better than the ones shown in smr51555 post because there is no bump.

Attachment 73540Attachment 73541

Quote:

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Originally Posted by pos

That "hump" might look awful to you, but it is nothing compared to what happens in the 8kHz-20kHz in the on-axis curve from the spinorama.

Anyway, the on axis curve is only a (minor) part of the whole picture here, and the EQed curve was the listening window average.

Here are my gated measurements (correct settings in red, you can ignore the blue curve), 0° and 20°
http://www.audioheritage.org/vbullet...l=1#post393721

You can clearly see that the bump around 8-9kHz results in a flat curve at ~30° off axis (which is probably a good approximation of the listening window curve...)

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Quote:

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Originally Posted by Zvuchniak

Isn't it possible that D2 ring radiators differ so much from one another that JBL pairs them up for M2 monitors and generates DSP curves for that particular pair of drivers ? That would explain the difference between two measurements provided by srm51555, and the difference between your measurements with theirs.

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I'm using the Crown DCI 4300 which has an analog DSP, I know Karl is using a BSS DSP but it may be digital, maybe this could explain the slight difference is measurements. As for Thomas's measurements not sure why its better in the 8-10 range.

Maybe...

I have no material or emotional involvement in this, i'm just trying to say that you should take JBL dsp curves like a good starting point for your speakers and adjust it yourself so that it suits your drivers. Do not hold on to it like it's a holy grail. Temper with it a little bit and then measure on and off axis.

Thomas's measurements do not look bad on axis nor off axis. Why wouldn't yours be like that with a little fiddling.

All 7 D2430K drivers I have measured measured pretty much the same.
5 came from ebay and were the VTX ones, and 2 were new and branded as M2 drivers.
Some ebay ones had serious distortion problems, but response curves were all very close.

The differences we see here are probably only measurement artifacts (mic response curve, distance, angle, smoothing, gating, etc.)

Will someone please post their room response with stock DSP M2 settings without any room EQ. I'm trying to figure out if my room measurements taken are correct or not. Final measurements would help a lot also if available.

Below shows a quick stereo measurement with 1/6 smoothing. The mic was placed at ear level by listening position and positioned at 90 degrees.


Attachment 73810

Thanks,
Scott

Got my M2 waveguides two days ago.

Hopfully i can do a proper anechoic measurement in about two weeks. The room is booked for the next 10 days.

I will do raw measurements without EQ. 5 degrees intervalls to 180 degrees without any box or baffle around the horn. Driver will be 2435 with Aquaplas (done by Guido)

If i find anything new i will post the results.


-Tim

Hi Tim,

Did you measure your driver/waveguide combo ?

I'd really like to see your measurements because D2 proves almost impossible to get.

Cheers

Dear all,

A little late to the party but for the record.

Attached is two D2 drivers on M2's. Measured indoor on workshop bench. Calibrated Earthworks mic, LSPCad MLS, 65 cm out, 4ms window, 33mfd in series, simple EQ as XO, two channel measurement (ie sound card, amp, EQ, tara), no smoothing, 65k samples, M-Audio Pro sound card.

Measurement files available for those who may be interested. PM me.

Attachment 74636

Kind regards
//RoB

Just looked at my data and saw that timing differs 2cm between D2 and 245x. That means that you need to reduce the delay with 2cm = 58 micro seconds from 270,8 to 212.8 when using an old 4" driver. Also worth noting is that the sound outlet is slightly larger on the D2 compared to the 245x.

Kind regards
//RoB

Dear all,

This is an average of 2pcs D2's (as per above) and an average of 3pcs 2451/475nd drivers on the same M2. No smoothing.

Pretty interesting as you clearly can see the waveguide notches albeit with some shift in frequency which may be due to driver geometry (the D2 is acoustically deeper). This may look worse than it is so please mind the scales here.

Kind regards
//RoB

Attachment 74661

Easier to look at.

Attachment 74662

Quote:

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Originally Posted by sebackman

Dear all,

This is an average of 2pcs D2's (as per above) and an average of 3pcs 2451/475nd drivers on the same M2. No smoothing.

Pretty interesting as you clearly can see the waveguide notches albeit with some shift in frequency which may be due to driver geometry (the D2 is acoustically deeper). This may look worse than it is so please mind the scales here.

Kind regards
//RoB

Attachment 74661

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Hi RoB,

Interesting that 2451&475dia seems to be much better either LF and UHF then D2430K on M2 horn ????
Is it possible to do a measurements about 1m or 2m from the M2 horn mouth?

regards
ivica

Quote:

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Originally Posted by sebackman

Dear all,

This is an average of 2pcs D2's (as per above) and an average of 3pcs 2451/475nd drivers on the same M2. No smoothing.

Pretty interesting as you clearly can see the waveguide notches albeit with some shift in frequency which may be due to driver geometry (the D2 is acoustically deeper). This may look worse than it is so please mind the scales here.

Kind regards
//RoB

Attachment 74661

Easier to look at.

Attachment 74662

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Is the average including off-axis as well? Maybe off-axis the D2 has an advantage up high?

Hi!

Nice work as always Robert:) Very interesting to compare with the SL-drivers.
Any measurements with EQ?

Regards
Karl

Quote:

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Originally Posted by sebackman

Dear all,

A little late to the party but for the record.

Attached is two D2 drivers on M2's. Measured indoor on workshop bench. Calibrated Earthworks mic, LSPCad MLS, 65 cm out, 4ms window, 33mfd in series, simple EQ as XO, two channel measurement (ie sound card, amp, EQ, tara), no smoothing, 65k samples, M-Audio Pro sound card.

Measurement files available for those who may be interested. PM me.

Attachment 74636

Kind regards
//RoB

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What is the difference between d2430h and d2430k. Lower frequency response for the d2430k?