My feeling is that the closer to the driver you measure, for example 3mm, the closer you measure the response before directivity come into play. So in effect what you measure is closer to power response.
No, I do not think room reflections should be integrated to give power response, that makes adding energy multiple times.
That's true if you meant "reflectivity", but directivity is there whether you're measuring it or not.
Correct me if you think I'm wrong here, soongsc, but isn't a piston's upper frequency lobing the result of the piston approaching virtually an infinite array of sources due to the wavelengths being smaller than the piston? This kind of behaviour would suggest some cancellation is going on.
By the way, I find power response sometimes resembles an off axis plot (say 30-40 degrees sometimes), I would only count on this if there was no other option though.
Just my opinion but I feel that any early and strong reflections ought to count for something if you can't eliminate them.
I'm really not the person to get into all this theoretical stuff. But what would make sense is to just do some measurements over the surface of the device to see what you get. It seems you are going to get some cancellation wherever you measure.
I recall earlier in this thread I measured a wave guide from inside to outside the mouth. The CSD characteristics seems to decay evenly, which is more well behaved than a direct radiating driver. At some point in time I'm going to see what EQing the the inner response will result in. I suspect very exceptional performance is possible.
I recall earlier in this thread I measured a wave guide from inside to outside the mouth. The CSD characteristics seems to decay evenly, which is more well behaved than a direct radiating driver. At some point in time I'm going to see what EQing the the inner response will result in. I suspect very exceptional performance is possible.
I am trying to do something about throat reactance, trying to damp it by stuffing the throat with dacron. I am not sure whether I'll like it, but this impedance plot seems to indicate something useful.
I noticed while I matched channels that they are fiddly to get right.
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The dacron extended part way towards the mouth but with a higher density in the throat region. Upon listening, all sounded ok. My attention was turned toward the upper bass, and I assumed the CD was now revealing a new level of woofer issues.
However after an hours listening and experimental EQing, I became stuck on the lower midrange and it seemed to become apparent that the dacron is improving performance in the area of HOM reduction, maybe indicating that my previous foam was not of an adequate density. At the same time the horn seems to be congested (mistuned?) near its bottom end.
However after an hours listening and experimental EQing, I became stuck on the lower midrange and it seemed to become apparent that the dacron is improving performance in the area of HOM reduction, maybe indicating that my previous foam was not of an adequate density. At the same time the horn seems to be congested (mistuned?) near its bottom end.
I may be misguided but when I think about the effect of not annulling the reactance on a regular horn, and the fact that my waveguides are not perfect and I have little control over the rear chamber I thought that turning the throat resistive would be worth trying. I wish I had a deeper mathematical understanding.
I am assuming that with the ideal OS, the point is moot. For myself, I have three issues of concern with my early contour....but I am now thinking I should let it all happen and then deal separately with the HOM.
I am assuming that with the ideal OS, the point is moot. For myself, I have three issues of concern with my early contour....but I am now thinking I should let it all happen and then deal separately with the HOM.
I think the MS-8 is great - IF you've a true smooth near-omni radiation of power response. It tones down a lot of the in car reflection stuff that's really offensive. Obviously a 12" OS Waveguide is a no go in car so it boils down to compromise. Then again I'm really skeptical on the possibility of ever getting "great" sound in a car... just "livable" sound is enough for me.
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To stay clear:
There is no (!) EQ that is capable of compensating reflections - reflections are CMP effects that are not treatable that way, some "tonal balancing" is the best you actually get from any (!) sort of EQ
simple physics, just not widely recognized.
Also - horns too are facing a specific CMP behaviour...
same simple physics, just not widely recognized too.
Best
Michael
I think Motors aren't a big deal... control the flux and you control the higher order distortion and subsequently IMD.
...but one thing I can't quite buy into, is the idea that a 1" compression driver operating through its diaphragm breakups, isn't audible??? I get that less rigid diaphrams don't have the same offensive breakups of metal/ceramic, but I can't imagine it being optimal. It'd in my mind, could be better than a silk dome tweeter (which can be "pretty good" but i believe limited by the delay off of the flat baffle unlike a CD in a waveguide which has a more optimal delay unless i'm mistaken?), but nowhere near the HF transparency of an aluminum RAAL which can operate much higher without any breakup.
.........but i'm not about to swing 1200 for a truextent diaphram to find out for myself
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I don't disagree with you, but in a car there's essentially not much else you can do about the reflections, except reduce the frequency intensity with EQ, or open the window (which has its own issues. A horn, while maybe possible, I think isn't very practical if it's larger than the steering wheel. I consider imaging in a car to be unattanable, and mostly just shoot for "doesn't make my ears bleed"... Unless you're aware of an alternative to the Omni + EQ approach ...??
As far as I can tell, getting great sound in a car is hopeless. But for an inoffensive sound, I think the MS-8 is a smart device.
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There is a wide variety of DSP bassed processors available for CAR at the moment - not the least to mention, you also can pimp a cheap DCX2496 for this app with a plug in SMPS
:endOT:
Best
Michael
There is a wide variety of DSP bassed processors available for CAR at the moment - not the least to mention, you also can pimp a cheap DCX2496 for this app with a plug in SMPS
:endOT:
Best
Michael
Yep ;P and I forgot to mention that the MS-8 is ridiculously overpriced for DIYers who like to do the legwork
...I've actually got a miniDSP waiting... I'm really fascinated by Patrick Bateman's idea of the aura 2" tweeter at ~800hz + tennis ball.
The DE2540 breaks up pretty badly about 16 kHz and then dies. But below this there are no notable resonances in the diaphragm. It is a mylar diaphragm which helps a lot. Breakups this high are not going to be serious problems and for most people not a problame at all.
I don't see how the rest of the discussion relates to the original topic.
I've always wondered, couldn't this be equalized? In the analog or perhaps digital domain?
I'm picturing the compression driver rolling off due to a mass corner in some kind of relatively smooth, controlled way.* Maybe that's a fantasy. I'd be curious to hear about anyone's experiences measuring larger-diameter drivers on CD horns.
*This would be like a Panasonic paper I read, where they achieved a truly remarkably controlled rolloff on and off axis. The response decreased I *think* about 6 dB per octave from 2 kHz or so. But that was using a dome tweeter + waveguide, not a compression driver.