JBL 4365 Active Crossover settings

[bubbleboy76]

A little update. I have been waiting for some XLR to 1/4" TRS adapters, so I could use the same soundcard (focusrite 2i2) for both input and output.
Previously, I have had the focusrite for input and the oppo for output, and POS advised me strongly against this.
Hopefully, this was the cause of the comb filtering in my measurements.
Now the adapters have arrived, so I will have better quality measurements as soon as I get the time to do it.
I also used 4 sweeps for every measurement before, and that can under some circumstances cause spikes in the curve according to the REW helpfile. So I will use 1 sweep from now on.
I will also use ASIO drivers instead of Java. It was not possible in REW when choosing different input/output soundcard.

[bubbleboy76]

New measurements done today and sent to POS for analysis.
No more comb filtering

[bubbleboy76]

1Audiohack, I have the anechoic 4365 horn/driver measurement curve in REW-format if you want it. POS did some magic and extracted it from the picture.

[bubbleboy76]

Measurements ongoing.
110cm to side walls. The longest my cables allows.

[Ed Zeppeli]

Funky looking room! Nice Les Paul too.

Cheers,

Warren

[Jonas_h]

Interesting thread! I fiddled around with active crossover (without known presets) with my last speakers and the process I ended up with which gave the best result:

1. Create two target curves in REW with 24db/oct LR filters at the desired crossover frequency. I.e. one target curve with a high-pass filter and one target curve with a low-pass filter.
2. Measure the drivers and assign filters so each driver follows this slope.
3. Do time-alignment on both drivers. (Either use RTA and adjust delay which is the easiest or compare the phase trace for both drivers and adjust accordingly).

The above procedure gave me really good results.

But the lack of free-field measurements and the constant thought about "Have I done it correctly" lead me to sell the speakers and buy speakers with passive crossover. Then I am doing "passive bi-amping" with known JBL presets to time-align the drivers.

[bubbleboy76]

Interesting thread! I fiddled around with active crossover (without known presets) with my last speakers and the process I ended up with which gave the best result:

1. Create two target curves in REW with 24db/oct LR filters at the desired crossover frequency. I.e. one target curve with a high-pass filter and one target curve with a low-pass filter.
2. Measure the drivers and assign filters so each driver follows this slope.
3. Do time-alignment on both drivers. (Either use RTA and adjust delay which is the easiest or compare the phase trace for both drivers and adjust accordingly).

The above procedure gave me really good results.

But the lack of free-field measurements and the constant thought about "Have I done it correctly" lead me to sell the speakers and buy speakers with passive crossover. Then I am doing "passive bi-amping" with known JBL presets to time-align the drivers.

Another way of achieving this, POS told me, is to first EQ each driver acoustically flat one octave past crossoverpoint, and then apply the electrical crossover slope of choice. But my dsp is to limited in number of PEQs to be able to do this.

Today, we measured delay properly, and 16-17cm delay of the woofer it should be. This also is consistent with the physical distance of the drivers, that I have estimated to be about 20cm.

We now have a pretty decent acoustical linkwitz-riley 36Db/oct at 800Hz (using electrical BW24db/oct). But the work is ongoing.

I would like to have a properly calibrated mic. The soundcard is now calibrated with loopback.

[bubbleboy76]

I just ordered a calibrated microphone from Cross-Spectrum Acoustics.
It feels pointless to have a meaurement system that can not be fully trusted.

[bubbleboy76]

I once voted for 4313B as president, but in the next election I have to put my vote on POS!

[Jonas_h]

Another way of achieving this, POS told me, is to first EQ each driver acoustically flat one octave past crossoverpoint, and then apply the electrical crossover slope of choice. But my dsp is to limited in number of PEQs to be able to do this.

Today, we measured delay properly, and 16-17cm delay of the woofer it should be. This also is consistent with the physical distance of the drivers, that I have estimated to be about 20cm.

We now have a pretty decent acoustical linkwitz-riley 36Db/oct at 800Hz (using electrical BW24db/oct). But the work is ongoing.

I would like to have a properly calibrated mic. The soundcard is now calibrated with loopback.

That is a solution as well. But I would feel that I added way too many filters and "reverting" them afterwards without utilizing the natual response of the driver. I am no expert though, so maybe my worries are not significant.

Congrats with your microphone. I bought an EarthWorks M30 for the same purpose to be sure that I had reliable measurements - it measured identical to a Behringer microphone in the 100-2000hz area and slight variations below and above...

[bubbleboy76]

This is marketing, but still shows how it can look.

[Jonas_h]

This is marketing, but still shows how it can look.

I bought 8 Behringer mics which measured identical. I could have been lucky though. But no matter what, I understand the need to "be sure". Thats why I bought the Earthworks myself.

[bubbleboy76]

I will calibrate my old mic with the new one as reference, then I can duct tape them to my head by the ears and do the perfect listening position measurement!

[Mctwins]

I will calibrate my old mic with the new one as reference, then I can duct tape them to my head by the ears and do the perfect listening position measurement!

Why do you want to do this?

[bubbleboy76]

Why do you want to do this?

It was a joke.