If you mount the driver similar to LXmini, you get a wrap around of the sound wave(hence a bump around 1-2Khz), if you mount it like yours there is little or no wrap around, the way it is mount will affect your driver equalization. I had done some measurements this was what I found.
Also if I mount it like your yours and if I don't damp the interior properly/adequately you get a honking effect/sound, it is not as easy to get the sound right even though I have seen many drivers mounted the same way as yours. I prefer the sound from LXmini and easier to damp. This I found experimentally.
I am currently performing experiments on the top section and bottom bass section comes later. I want to get the top section sound right first before I get to the bottom/woofer section.
Re:"I had done some measurements"- It'd be interesting to see them,
re: "damp the interior" - the pipe behind the top Sanyos is stuffed with damping (they've got a ridiculously high Qt, only good for OB, but actually sound quite good within their range)
re: "damp the interior" - the pipe behind the top Sanyos is stuffed with damping (they've got a ridiculously high Qt, only good for OB, but actually sound quite good within their range)
You don't believe me.... I did not store my results if I have time I will repeat it and show them here.
Really there must be is reason why SL mount the FR driver on the LXmini, it a combination of pure OB and attenuation of high frequency behind the driver.
Hey! I believe you... just askin'... meanwhile having fun trying all sorts of music on these monstrosities (my wife calls them 'ET' speakers...), unfortunately I've run out of beer...
Understanding the LX-mini
Just because a speaker looks vaguely like an LX-mini it is not going to perform like one unless you try to understand the original design. I do not have all the answers; but the directivity and the mechanisms giving rise to it need to be understood.
1 Low frequencies are omnidirectional.
2 In the crossover overlap region the radiation becomes cardiode. This has nothing to do with objects behind the "tweeter", but is a result of the monopole woofer and dipole (figure 8) tweeter interacting with one another. When the woofer cone moves upwards and the tweeter cone forwards the sounds sum in phase. While this is happening the dipole rear radiation is summing in antiphase causing a null.
3 Above crossover the tweeter is behaving as a dipole.
4 In the low kHz region the "dipole action" degrades due to the driver dimensions and the tweeter becomes a direct radiator. Normally we would be thinking of breakup modes, narrowing directivity, and how to avoid them.
It seems that the curv cone material comes to the rescue in that it is sufficiently lossey to make breakup modes relatively benign, and the radiating area shrinks towards higher frequencies broadening the pattern compared to other drivers. Someone on a forum suggested that the curv cone has some of the attributes of a bending wave transducer.
5 Finally, the tube behind the tweeter is a diffuser, and I would suggest the reason for the fibre filling is to damp the organ pipe resonance of it and that it has nothing to do with absorbing rear radiation.
Keith
Just because a speaker looks vaguely like an LX-mini it is not going to perform like one unless you try to understand the original design. I do not have all the answers; but the directivity and the mechanisms giving rise to it need to be understood.
1 Low frequencies are omnidirectional.
2 In the crossover overlap region the radiation becomes cardiode. This has nothing to do with objects behind the "tweeter", but is a result of the monopole woofer and dipole (figure 8) tweeter interacting with one another. When the woofer cone moves upwards and the tweeter cone forwards the sounds sum in phase. While this is happening the dipole rear radiation is summing in antiphase causing a null.
3 Above crossover the tweeter is behaving as a dipole.
4 In the low kHz region the "dipole action" degrades due to the driver dimensions and the tweeter becomes a direct radiator. Normally we would be thinking of breakup modes, narrowing directivity, and how to avoid them.
It seems that the curv cone material comes to the rescue in that it is sufficiently lossey to make breakup modes relatively benign, and the radiating area shrinks towards higher frequencies broadening the pattern compared to other drivers. Someone on a forum suggested that the curv cone has some of the attributes of a bending wave transducer.
5 Finally, the tube behind the tweeter is a diffuser, and I would suggest the reason for the fibre filling is to damp the organ pipe resonance of it and that it has nothing to do with absorbing rear radiation.
Keith
Circular radiator in circular baffle, concentrically is the worst scenario, above diffraction first null! As a dipole one should never let them go up there! However the ears are not as sensitive to this combing as a measurement mic.
http://www.mellowacoustics.com/articles/Disk_in_a_circular_baffle.pdf
And Linkwitz knows this very well! Electro-acoustic models
I've done actual measurements on "nude" drivers (unbaffled that is) and they look more like this:
The plot above is the predicted response for the case that the circular baffle radius (b) and the radius of the driver's cone (a) is the same. For a nude driver that is essentially the case, or perhaps b = 1.1*a which is very close to the model, so it's not all the surprising. If you go to SL's web page where these plots are located, you can see the effect of increasing the (circular) baffle radius, b. As b gets larger, dips and peaks develop in the response. This to me is very strong motivation for using a driver unbaffled, at least in a midrange application.
Before I did these measurements, I was very wary of trying to use a driver above the first dipole response peak. But now I realize that things are not always as bad as they seem. The real driver does not display the extreme peak and null on and off axis like the point source model, or even the plot you posted. As a result I know that I can effectively use my driver as high as its off-axis response tracks the on-axis response. In my case, instead of having to cross over below 1kHz I can use the driver up to almost 3kHz! That makes a huge difference in terms of the demands on the driver used above it in frequency (e.g. the "tweeter").
I did similar measurements on a range of drivers close in size to the one that I finally decided to use. For some of them, the response would break up off-axis around the frequency of the first dipole peak, and for others the on and off axis responses were relatively smooth. One problematic driver had a phase plug, so perhaps this is to be avoided - not sure, I only tested one like that.
The bottom line is that you need to take lots of measurements and then decide how to use the drivers, or whether the drivers used can support the application. Modeling can only take you so far, and does not capture things like the resonances behind the cone, reflections off of the magnet structure, etc., etc. Measure, measure, measure.
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Check this out... someone had kindly posted a youtube video of LXMini!
Sounds great. It does seem have that Pluto midbass signature.
www.youtube.com/watch?v=FunagvWi8jE
Sounds great. It does seem have that Pluto midbass signature.
www.youtube.com/watch?v=FunagvWi8jE
LXmini--round3 - YouTube
Love it .
I think YouTube is a great way to evaluate loudspeakers
Here's a link that works on mobile devices
Love it .
I think YouTube is a great way to evaluate loudspeakers
Here's a link that works on mobile devices
This particular sound rendition is not quite right(the sound seems to be choking) hence LXMini Round 3 which sounds much better.
BTW my LXmini "clone" doesn't sound like Round 1.
This is my polar measurement of a nude 3" alu-cone (cone diameter 75mm, frame 95mm). With some eq it sounds quite good as midtweeter, but is way off a real tweeter's sound.
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Indeed and there is round 004 too 🙂
They don't seem to exhibit the transparency that is proper OB + Tweeters? E.g. from the same house:
https://www.youtube.com/watch?v=hdbzRRTD3Ww#t=173
Even with all the impossibilities of showing sound on a Utube, it comes across like the resonant peaking of a speaker mounted in a tube.
While imperfect, I do think youtube is quite good for listening to speakers A compared to speakers B if you listen to both videos with the same pair of decent headphones*. I understand that's not to say listening to speakers on youtube through my headphones will give me a fair picture of how the speakers would sound in MY room 🙂
* - assuming both pairs of speakers are played under the same conditions (same room, mic recording position, levels, same song etc.).
Off-Topic Sorry - Help- Can't get on Orion/Pluto UG
I've to get on the Orion/Pluto Users' Group but can't because it says I'm blacklisted. I've tried from different computers, even other computers in the neighborhood and proxy IP's but no luck. I live in Ecuador. Can't email the admin w/o being registered. Tried running the recommended Norton a/v program - nada. Suspect O/P's spam detection software is at fault. Help!
Thanks!
Dan
I've to get on the Orion/Pluto Users' Group but can't because it says I'm blacklisted. I've tried from different computers, even other computers in the neighborhood and proxy IP's but no luck. I live in Ecuador. Can't email the admin w/o being registered. Tried running the recommended Norton a/v program - nada. Suspect O/P's spam detection software is at fault. Help!
Thanks!
Dan
Id also measure the frequency response of the rear emission. I can't imagine that that tube isn't creating a resonant cavity effect.
Email the admin: orionusers at gmail dot com. He will help you with your access problem.
I hear that the "virtual source" of a driver is at some distance in front of it. I searched around but could only find the term "virtual source" used with reference to driver arrays, not for a single driver. I'm wondering how to calculate it for a single driver.
I thought TA was calculated from the mounting flange? How did you determine the horizontal mounting distance of the Sanyo from the axis of the Akai?
I assume SL intended to TA the virtual sources of the drivers in the LXmini, but the distance of the virtual source of the HF driver seems to be out of proportion with that of the LF - 1/4" to 3".,,unless there is some TA going on in the miniDSP...?
Dan
If, with one speaker playing, the sound does not seem to come from where the speaker is, there is a phase issue between the drivers. Or bad diffraction.
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