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New build of Linkwitz LXMini

dreite

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#21
At first I couldn't figure out if the price wasn't shown or if I was just missing the price do to the typically bad website design that is common with places selling audio gear. I guess it is a bit of both because there should definitely be a "login to see pricing" notice next to the items. Fortunately, that gave me time to think it over and I put my credit card away. Maybe someday... but not today.
You can build a set of kit speakers (a nice example in the post above) for cheap, and you don't even need your credit card.
I'm still not sure folks are appreciating what a value-speaker the LXmini is.

Dave.
 

AudioJester

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#22
You can build a set of kit speakers (a nice example in the post above) for cheap, and you don't even need your credit card.
I'm still not sure folks are appreciating what a value-speaker the LXmini is.

Dave.
Are there measurements to back this up?Genuinely interesed, have been caught too many times before by people raving about things.
 

AudioJester

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#23
For reference I built the LX521 after hearing the LXMini at a buddys place.
However, i have never seen proper measurements for either speaker.
 

suttondesign

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#24

dreite

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#25
For reference I built the LX521 after hearing the LXMini at a buddys place.
However, i have never seen proper measurements for either speaker.
What are "proper" measurements, in this context?
There are numerous measurements for both systems on the Linkwitz Lab website. You've built the LX521 system and you're not aware of those measurements??

Dave.
 

Hasse

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#27
What? Please explain to me in what way this post on LXmini is connected to "Midsommar".
Confused.
 

AudioJester

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#28
What are "proper" measurements, in this context?
There are numerous measurements for both systems on the Linkwitz Lab website. You've built the LX521 system and you're not aware of those measurements??

Dave.
Sorry, what i meant was are there any anechoic chamber or spinorama type measurements. This seems to be the benchmark allowing comparison to other speakers.
 

maxxevv

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#29
In my experience, 9ft wide should be fine for the lxmini since they are really best listened to up close. As long as they can an be 2-3 ft off the back wall and maybe 1+ off the sides your fine. My Orion's (full dipole similar to lx521) really need a good 5 ft off the back wall and 3 off the sides to sound best.
Looking at the design of the pipe being used as a radiator shell, would some of these issues be solved / reduced with a really stiff shielding plate forming a 90 degree arc around the rear face of the pipes or a specifically shaped shell to replace the pipes ? ?
 

dreite

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#30
Looking at the design of the pipe being used as a radiator shell, would some of these issues be solved / reduced with a really stiff shielding plate forming a 90 degree arc around the rear face of the pipes or a specifically shaped shell to replace the pipes ? ?
Radiator shell? It seems you're not understanding the design at all. The pipe itself does not re-radiate anything acoustically in this design.

Dave.
 

maxxevv

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#32
Radiator shell? It seems you're not understanding the design at all. The pipe itself does not re-radiate anything acoustically in this design.

Dave.
If it doesn't, replace those PVC pipes with 5mm thick steel pipes of the same internal diameter. Would the speakers sound the same after that ?
 

maxxevv

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#34
Radiator shell? It seems you're not understanding the design at all. The pipe itself does not re-radiate anything acoustically in this design.

Dave.
Is this the aspect of the design most interesting to you?

Dave.
Let me requote you again. As you have not assertively answered my question, since you claim to know.
 

dreite

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#35
Let me requote you again. As you have not assertively answered my question, since you claim to know.
Your question is a hypothetical. I made no claims of re-radiation characteristics from a steel-tubed version of an LXmini.
This sort of inane back and forth has no interest to me.

If you have any 'meaningful' questions about the as-designed LXmini system, I'll do my best to answer them.

Dave.
 

williamwally

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#36
Looking at the design of the pipe being used as a radiator shell, would some of these issues be solved / reduced with a really stiff shielding plate forming a 90 degree arc around the rear face of the pipes or a specifically shaped shell to replace the pipes ? ?
I would think that would mess with the radiation too much to be helpful (unless it could somehow attenuate all frequencies equally and delay all rear reflections by 6ms).

Nothing I said about setup was an issue or problem, but more so just how I like to set them up for best results (in my non scientific opinion of course).

... replace those PVC pipes with 5mm thick steel pipes of the same internal diameter. Would the speakers sound the same after that ?
Yes

The pipe came from both being strong enough to stop box resonances and to have no baffle reflections and measure flat in the listening plane:
(The driver doesn't vibrate the pipe like a box, only creates an internal standing wave which is dealt with by first stuffing the pipe, then by measuring the wave and equalizing for it in the active or digital eq/xo)
cylinder1.PNG

1581007208652.png


IMO I would contend that all speakers, outside of ones like a Klipsch cornerhorn (uses the walls as a horn extension) or DSL synergy horn (broadband, sharply controlled directivity) would benefit with some space off of the sidewalls.

SL was just very straightforward to ideal placement and why. There's a wealth of information on his site: http://www.linkwitzlab.com/index.htm going into all kinds of issues with speaker design, radiation, room response, hearing, and psychoacoustics etc, which I won't pretend to have a good enough understanding on to be able to speak at depth about. I can however copy and paste from his website :):

1581007304527.png


The above proposed/ideal setup is based on each speakers radiation pattern (dipole=lx521, monopole=lxMini) as it related to the listening position to get an ideal direct/reverb ratio:

1581007582959.png


So the LxMini would use the red line for listening distance vs the listening room's measured RT60. lt's interesting SL specified RT60/placement specs just like the Genelec and Nuemann figures someone posted in another thread; however he was a proponent of, and designed the speakers and setup for, a much more easy to achieve (IMO) RT60 of ~400-450ms. The 200ms that Nuemann (I think?) specs for listening distances is much more directed towards a dedicated studio with lots of absorption and treatment IMO, so the listening distances for each speaker listed would need to be brought in a bit to achieve the same direct/reverb sound ratio in normal listening room.

I apologize for the long post and all the copypasta; I can't say I have enough knowledge or experience do it any other way. Others here can expand these ideas/approaches and the trade off's way better than I can.
 

Attachments

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#37
Well, re-radiation in a speaker enclosure is related to the natural frequency of an enclosure that is excited by a forcing function applied to the enclosure. So in the case of the LXmini, the available frequency range of any significant forcing function lies in the range of frequencies produced by the LN-16SL driver plus maybe one octave above the crossover region and perhaps one octave at he max below the roll off point on the lower end of the frequency range.

One needs to calculate the first natural frequency of the enclosure, a function of the part geometry which for a cylinder is basically dependent on the diameter and wall thickness as well as material properties such as the modulus of elasticity. After doing this to see if any natural frequency falls within the range excited by the LN-16SL driver, one has to account for the damping effects of the material used. Damping in a plastic material such as PVC pipe is much greater than in steel.

Without doing the above calculations analysis,or any actual testing, it would be my hypothesis that the steel pipe would be have a greater likelihood of susceptibility to re-radiation. The proof is left to the student as an exercise. Knock yourself out.
 

suttondesign

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#39
What? Please explain to me in what way this post on LXmini is connected to "Midsommar".
Confused.
“I am a Swede,” said a post.
 

TimW

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#40
@suttondesign or anyone else who as built or at least researched building LXmini's, do you have any construction recommendations?

I plan to buy plans first and read through them, and was considering the Madisound kit with wood parts. But then I took a look at the magiclx521 kit and realized I want to make mine more like theirs. Screwless fullrange driver mount, capless lower tube mount, screwless upper tube support, hidden cabling, and use of speakON connectors. Much better! But then I started looking at all the inventive ways people make these things and realized I want to go even further in improving aesthetics. I don't like how the rubber coupler looks, and really don't like that it is just glued to the MDF support, which then requires that the woofer just be glued to the MDF without screws.

Does anyone know of alternative methods for mounting the woofer and upper tube to the lower tube? I can't seem to find any products or detailed plans for doing something like this, although I see lots of pictures of finished LXmini's with alternative or at least dressed up mounting methods. I would expect some of these builders to have posted about how they did what they did but I'm having a hard time finding these resources.
 
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