JBL 4365 Active Crossover settings

[hjames]

Hi
As known: "there is no better enhancement .... then displacement (volume)"

regards
ivica

Badly quoted ... among my brother and his car guy friends, the quote has always been:

"There is no substitute for cubic inches ..." (displacement)

[bubbleboy76]

"There is no replacement for displacement" is the one I have heard

[bubbleboy76]

Some more measurements today, with my current settings.

Stock passive filter on the horn.

Active dsp filter on the woofer:
24Db/oct Linkwitz-riley at 595.6Hz
-6Db notch 80Hz (the largest room mode reduced)
+8Db shelf at 136Hz with 6Db/oct slope
Delay 10cm

I measured 5cm and 1m from speaker elements, on axis and 60 degree off axis. Only one element at the time (the graphs are overlayed).

Sleeping baby at home, so I had to measure on lower SPL. I am on parental leave

[bubbleboy76]

I updated to the latest version of REW, and the latest usb soundcard drivers for my Oppo BDP-105.
Now, the measurements are in sync with my dbx. If I add the notch at 80Hz in the driverack, it takes effect at 80Hz in the measurements.

[bubbleboy76]

I should have even lower crossover point of the LF, should I not, judging from the measurements above?

[ivica]

"There is no replacement for displacement" is the one I have heard

Hi ,

You are right,
sorry for my bad English

regards
ivica

[ivica]

I should have even lower crossover point of the LF, should I not, judging from the measurements above?

Hi bubbleboy76,

1.LF
Looking at 1m distance measurements, the graph looks like (to me) very similar as on the "theoretical' shown on the:
http://www.audioheritage.org/vbullet...l=1#post375799

2.VHF
Looking at the VHF response, I think that You have to reduce "window time" in order to eliminate the reflection signal from the measurements, or to "lay down the box on the fore" with the face up, and then do the measurements, in order to reduce large surface reflections. Shown data are too bouncing, for me.

regards
ivica

[bubbleboy76]

Hi bubbleboy76,

1.LF
Looking at 1m distance measurements, the graph looks like (to me) very similar as on the "theoretical' shown on the:
http://www.audioheritage.org/vbullet...l=1#post375799

2.VHF
Looking at the VHF response, I think that You have to reduce "window time" in order to eliminate the reflection signal from the measurements, or to "lay down the box on the fore" with the face up, and then do the measurements, in order to reduce large surface reflections. Shown data are too bouncing, for me.

regards
ivica

Will do! I found this, describing how to do it in REW:

http://www.minidsp.com/applications/...r-measurements

[Mctwins]

Hallo!

Your measurement looks strange at least for the UHF. Strong Comb filtering even with mic close to the speaker. It looks the same at 5cm or 1meter.

You have take into account for your room modes when looking from 20Hz-500Hz.

Could you present a mdat file? I have REW also. I would like to see your waterfall graph?

In the link provided and the headline "Low-frequency measurement" is interesting to read.

[hjames]

Hi ,

You are right,
sorry for my bad English

regards
ivica

Hopefully that did not come across harshly,
it was not meant to be harsh ...
Growing up, my brother and some of his friends drag raced
and it was pretty well known in the hot rod crowd
(my brother raced a '64 with a Chevy big block V8 overbored .030)

I was more into british and italian sports cars

[ivica]

Hopefully that did not come across harshly,
it was not meant to be harsh ...
Growing up, my brother and some of his friends drag raced
and it was pretty well known in the hot rod crowd
(my brother raced a '64 with a Chevy big block V8 overbored .030)

I was more into british and italian sports cars

Hi hjames,

No, problem at all.
Many years ago, I have heard, the phrase, but can not remember at the moment,
but I think this one is very good: "There is no replacement for displacement"

regards
ivica

[bubbleboy76]

Hallo!

Your measurement looks strange at least for the UHF. Strong Comb filtering even with mic close to the speaker. It looks the same at 5cm or 1meter.

You have take into account for your room modes when looking from 20Hz-500Hz.

Could you present a mdat file? I have REW also. I would like to see your waterfall graph?

In the link provided and the headline "Low-frequency measurement" is interesting to read.

Yes it is strange for the high frequencies. I measured with the speaker very close to the concrete sidewall, I think that is why. I did not have time to move around the speaker this time. I played a little bit with time window now, but it did not help. The same hilly curve even with very low time-window.
Next time I will measure with the speaker more far away from the walls.

I have the .mdat files, but that is not a valid file-extension to attach to this forum. I can attach a full range waterfall from listening position next time I measure.

[bubbleboy76]

I also had the microphone taped to the top of chair because I have no tripod for it, yet.
I realise now this must have screwed it up

[bubbleboy76]

MiniDSP has some good instructions on my level, not only mathematical mumbo-jumbo:

http://www.minidsp.com/applications/...eo-2-way-xover

http://www.minidsp.com/applications/...time-alignment

[Jakob]

Reading the information in the link provided by bubbleboy76 it says:

"A good approach is to use the output channel Parametric EQ to correct for the response of the individual drivers, and the input channel Parametric EQ for overall response shaping and taming room issues"

Is this true in general or only apply to miniDSP units and if general, why is it better to use the EQ on the input for overall shaping and taming room issues? Is it to reduce work if some drivers are exchanged and you then only need to rework the output EQ?