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X15 measured

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Timber_MG View Drop Down
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    Posted: 22 April 2005 at 8:36pm
Alright, here are some fairly rough measurements done indoors. The dip around 800Hz is partly exaggerated by a floor-reflection. The divisions are 3dB (not 10 as many are used to) and as a whole the PAP VX1 passive x-over is well done. Perhaps one should make the ports a little shorter, as this X15 has a tuning requency in the mid-low 40s (nice for full-range use with eq)

Many thanks to Nexus for hosting. Let me know if you want me to remove img tags and replace with links.

Response on-axis


Response 20 degrees off-axis


LF response (free-air)


mic 3mm from dustcap


mic inside port


waterfall plot (NB: linear frequency scale!!!)


Good night

Martin
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JD01 Quote  Post ReplyReply Direct Link To This Post Posted: 23 April 2005 at 9:04am

@ Timber: Can't you set the waterfall to log frequency and longer time than 3ms? It's hard to say something about the decay in the lowmids...

Anyways, the resonance around 10kHz looks pretty bad.... and above 14kHz it just gets nasty. Maybe one should take the HF out at 14kHz. Seems there is no sense putting energy in that range into the driver...

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Timber_MG Quote  Post ReplyReply Direct Link To This Post Posted: 23 April 2005 at 9:28am
Heya

I will post some more measurements, but I am rather limited by the gating measuring indoors. Have to take it outdoors and put it on stands which I don't have here yet (I don't measure at home due to blessed family) and I don't intend to hoist it up a tree like i do with raw drive-units. Since I went passive I have switched compression driver back to the BM-D450 (will nicht Perlen vor dir Säue werfen)

The sound is a touch grainy up top, true, but not at all bad. For the intended application,they are well above average I must say, though a lower crossover (meaning diferent driver) would do them quite well. I have measureed "hi-fi" speakers that are much worse in all fairness.

Unfortunately ETF doesn't do Log scale waterfalls.

I will post some more measurements so that one can compare things when I get around to it (perhaps late today)


Edited by Timber_MG
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Timber_MG View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Timber_MG Quote  Post ReplyReply Direct Link To This Post Posted: 23 April 2005 at 10:47am
And some measurements of a 12"/1" I find good enough to listen to as a hi-fi (not perfect but show me the "hifi" that can do such dynamics short of a large-format studio monitor). Box resonance is very dificult to get rid off and is really evident at some lower frequencies as is evitent in a close-up measurement. The driver itself (Winner 12S) is quite well behaved up to 1.8kHz





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Post Options Post Options   Thanks (0) Thanks(0)   Quote JD01 Quote  Post ReplyReply Direct Link To This Post Posted: 23 April 2005 at 1:31pm

Well, I can't tell that much about the 12" from the waterfall. For that the resolution below 2kHz is to bad in linear scale.... Highs above 4kHz look pretty good. What driver/horn is it?

I can't believe that ETF can only do linear waterfall. Makes it pretty useless....

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Timber_MG View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Timber_MG Quote  Post ReplyReply Direct Link To This Post Posted: 23 April 2005 at 3:22pm
D2544 on H975. I can change the range to 200-2k, but I don't have enough clean impulse response to make that sensible to display at all. Another problem is getting enough s/n above computer noise in this place (3 PCs running, only one of them even nearly quiet)

Waterfalls don't tell you all that much, energy distribution like these might tell you a little something. Still getting to grips with what information is actually meaningfull and what is a result of windowing smearing artefacts in a waterfall plot (and rectangular windowing is much too grainy)

ETC for the Winner 12S post active crossover


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Timber_MG Quote  Post ReplyReply Direct Link To This Post Posted: 23 April 2005 at 3:30pm
Note the reflection just after 5ms. Windowing (except rectangular) effectively reduces that to 3.5 or so. So I could give you more than that, but the floor reflection would just about ruin any of that indoors. Outdors one coud get valid results up to somewhere (2kish) by doing a half-space measurement with the mic on the floor.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JD01 Quote  Post ReplyReply Direct Link To This Post Posted: 24 April 2005 at 11:55am
Waterfalls are good for checking resonances and decay times. That's all, not much, but important...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tb_mike Quote  Post ReplyReply Direct Link To This Post Posted: 18 August 2005 at 11:54pm

too bad about the linear scale and short time window.

We all want to measure stuff,but it takes software,gear,time,and effort! Its abit much for me right now! Il have to get an ecm8000 when the exchange rate is favourable.

 

martin perhaps you could get the DEMO 30day trial of praxis or similar and compare for a sanity check?

http://wiki16.parsimony.net/cgi-bin/wiki/program/db-view.cgi ?wiki27133;LoudspeakerMeasurement

 

You can go manual convolution with cooledit2000 + addon packs too.



Edited by tb_mike
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Timber_MG Quote  Post ReplyReply Direct Link To This Post Posted: 19 August 2005 at 1:47am
I will not be near my X15s for the next two odd months I'm affraid. I am using my 12"/1" Tops and my Achenbch 18s for a wedding of a friend this weekend but will not get around to measure anything I'm affraid.

I will update this thread with better measurements sometime in the future when I get around to it.
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