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Multi-Way Conventional loudspeakers with crossovers

KEF Q500 new crossover
KEF Q500 new crossover
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Old 17th April 2019, 03:01 PM   #61
wtnsmk is offline wtnsmk  United Kingdom
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At least finally I could measure with 4.2ms gate:

freq3 - Google Drive

The issue was the speaker was too close to the ground. With this measurement the speaker is from 120cm from the ground.
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Old 17th April 2019, 06:18 PM   #62
Zvu is offline Zvu  Serbia
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Try to set this offsets just for test:

For tweeter all offsets are 0
For midrange there is only Z offset and it is -11mm
For woofer we have Y offset of -300mm and Z offset at -50mm

All of this is just for test purposes and aren't real offsets.


Offsets are entered with microphone as a reference point.

Now, since you haven't used ARTA, you have to derive Z offsets yourself. If microphone was pointed to the tweeter, all offsets for it are 0. Since you have concentric driver for mid-hi you only have to derive the Z offset for midrange and since i have LS50 which is almost the same as your concentric it is safe to say that Z offset for your midrange is around -11mm (as is with mine concentric driver). For woofer, based on your cabinet and driver placement sketch, woofer is 30cm below microphone position so we have X offset 0 and Y offset is -300mm.

To derive acoustic Z offsets for drivers you have to place the mic on axis to the tweeter at 1m distance. Don't touch the volume of the amplifier (or any other volume control in chain for that matter) and set start frequency of the sweep at 300Hz. Measure the tweeter and name it say Q500TW. Then you connect the midrange in parallel with the tweeter and make another sweep. Name it Q500MID.TW. Then you set start frequency of the sweep at 20Hz. Disconnect tweeter and measure just midrange. Name it Q500MID. Then connect the woofer in parallel to the mid and make another sweep, you get it, name it Q500MID.WF. Then disconnect the midrange and measure the woofer, name it Q500WF.

Now you have everything that is necessary to derive Z acoustic offsets yourself.

Set listening distance in VituixCAD at 1m. Make the tweeter in sim and upload the tweeter Q500TW and impedance. Then make a midrange in sim, and import Q500MID file. Import Q500MID.TW file as Reference (that's what it's called in LspCAD that i use) and compare it to the combined curve. Add Z offset in mm until they overlap. Then disconnect the tweeter and make a woofer in sim and upload Q500WF and impedance. Now upload as a Reference Q500MID.WF and compare it to combined curve. Set X offset at 300mm and add Z offset (usually negative value) until the curves overlap. Now connect the tweeter again and you can begin to simulate your crossover.
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Old 17th April 2019, 07:08 PM   #63
wtnsmk is offline wtnsmk  United Kingdom
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Thanks I will do these measurements.

The weird thing, in Xsim, I'm already really close to the measured response (brown measured, black simulated), if I DON'T invert the mid speaker...:
Click the image to open in full size.
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Old 17th April 2019, 07:27 PM   #64
Zvu is offline Zvu  Serbia
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I'd, again, advise you to use Holmimpulse or Arta. I'm not sure that rew is good for modeling frequency response. It has few different types of smoothing that all give slightly different results. I'm not saying that's bad but it takes knowledge to know when and what to use. With Holm and Arta it is much simpler.

As for differences in Xsim, maybe it is optimized to work with rew measurements like Vituix is for ARTA.

Last edited by Zvu; 17th April 2019 at 07:29 PM.
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Old 17th April 2019, 09:53 PM   #65
wtnsmk is offline wtnsmk  United Kingdom
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I'm doing the measurement in HOLMImpulse and I can't change the freq range. There is a start freq in device & signal, but if I put that up to 3-400Hz my measurement is just completely useless. I see some crazy curve. Also which sign I should use? Log or chirp? They look different in the low range
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Old 17th April 2019, 10:15 PM   #66
wtnsmk is offline wtnsmk  United Kingdom
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Looks like this:

Click the image to open in full size.
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Old 17th April 2019, 10:48 PM   #67
Zvu is offline Zvu  Serbia
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Red Spade Audio: How to measure your crossover with Holm Impulse
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Old 18th April 2019, 11:08 AM   #68
wtnsmk is offline wtnsmk  United Kingdom
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Thanks for the link, it was really useful, but unfortunately doesn't understand my questions.

These are my tweeter responses if I start the measurement from 400Hz:

Click the image to open in full size.
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Old 18th April 2019, 11:18 AM   #69
wtnsmk is offline wtnsmk  United Kingdom
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Could you please have a look on the file? Maybe it just a problem with my visualisation...

holmimpulse - Google Drive

Thank you very much!
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Old 18th April 2019, 01:18 PM   #70
wtnsmk is offline wtnsmk  United Kingdom
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Ok I think I found the issue, I tried to change the start freq on the first (device & signal) tab rather than the highpass on the measurement tab... really confusing

Here are the measurements:

correct.zip: holmimpulse - Google Drive

you will see these measurements:
LF - woofer
LF MF - woofer with midrange (normal polarity) - 20-20
LF MF 2 - woofer with midrange (reversed polarity) - 20-20
MF - midrange - 20-20
MF HF - midrange + tweeter (reversed polarity) - 300-20
MF HF 2 - midrange + tweeter (normal polarity) - 300 - 20
HF - tweeter - 300-20

Last edited by wtnsmk; 18th April 2019 at 01:27 PM.
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