LX mini quest

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Would like to share my recent toys with all of you.

Speakers are based entirely on Mr. S.Linkwitz LXmini speakers design and all royalty's belong to him.

Reading on a web a god bunch energetically charged reviews and even leaving Don Keele`s masterpiece in a dust .

I decided to build a pair of LX mini`s and take a look closer to that original Mr. Linkwitz design.
The first build of LXmini`s was with in mine opinion improved drivers - woofer is Dayton Audio 6" reference paper woofer RS150P4 and full range is Markaudio Alpair 5.

Don't get me wrong it is a huge amount of beautiful things about that design and most of them way above average, but…..6 inch woofer just can't do it ...it is just not enough space in those drivers for musical instruments. Real woofers with such driver configuration is just a must.

Second version was more grown up ...woofer - Philips AD8066-W4-8 inch and speakers pipe volume has changed from 8 liters to 25 liters, full range driver is Markaudio Alpair 7A Gen. 3A.

And what a difference it was !!! Sound became relaxed and natural, sound stage huge, live recordings became a live, no one was “raping” violins and cellos any more .

It is enough bass to shake glass in windows frame.

It is possible to live with such speaker configuration happily ever after but….. It is a lots to ask from one driver to behave nicely and in civilised manner from 30 Hz to 700 Hz alone.
 

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And know is time for complete LXmini quest with all your help and advise.
I have laid hand on huge PVC pipes O.D. 315 mm.

Volume it can be from 49 to 66 liters and can accommodate 12.00’’ driver easily.

Mine plan is :

  • Incorporate Zobel network for woofer
  • Can be used 2 woofers in same pipe.
  • Woofer choice is Eminence BETA-12A-2 (good spec,reasonable price)
 

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I have a few questions about your LXmini with either 6" or 8" woofer. I use an 8" Silverflute woofer in an Omni design.

The FR graphs are too coarse to see whats going on. They are 50db/div and its easier to see whats happening with 5db/div. I'm assuming the measurement is at 1m.

How are you doing the XO and EQ ?

What did you stuff the woofer pipe with, typically there would be a standing wave or resonance in a long chamber behind a driver ?
 
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Dear DonVK,
Mine mic is not the best in a world but does same ruff job witch is god enough what our ears can hear, mic is UMIK-1 by minidsp. 1/12 smoothing represents that mic pretty god for getting same understanding. But not even best measurement in a world with the best mic. in the world will represent ...how it sounds .
I do XO and EQ like this:
1. Take a speaker reading from 1 m using REW. Letting REW generate first EQ.
2. Take a speaker reading one more time ( with first EQ imported to minidsp) and result send to re Phase software and make corrections with it.
3. Import re Phase results to miniDSP FIR filter.
4. Erase first EQ and take a reading and again with REW and generate second set EQ.
After all that you should be god to go.

Pipe stuffing.....I have used Hawaphon sound insulation panels glued to PVC pipe and later polyester wool damping MDM-4. Self physical pipe size (length) will not allow for
standing wave to form...pipe is just not long enough.
 
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Hej ven,
I can`t do that ...use the same xo/eq filters as Mr. Linkwitz' because he is using different drivers for his design,but....I have original xo/eq filters ( no miracle in those).
But my Xover has the same`ish cross point. Same times I'm enjoying 400 Hz crosspoint for drivers. Mr. Linkwitz' is genius to use full range driver and that makes all differences.
 
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Does any one have tray such woofer configurations ( like in a drawing) ?
Wiring in phase and out of phase ?
How it affects sound ,specially out of phase wiring ?
I have used in phase wiring with back to back woofers and it gives force cancellation. If they were wired out of phase I would imagine you would get some kind of a vertical dipole effect and so some 360 degree cancellation. It would be simple and interesting to try both ways and tell us your results.
 
Thanks scottjoplin,
Agree would be really interesting. Same how out of phase configuration makes me think about pipe volume as well ...volume at least will increase as one drivers Sd.
I don't remember where I red, but same one with such configuration ended up with half of speakers volume needed for driver.
Drivers are same how helping each other do a job as well .
 

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And know is time for complete LXmini quest with all your help and advise.
I have laid hand on huge PVC pipes O.D. 315 mm.

Volume it can be from 49 to 66 liters and can accommodate 12.00’’ driver easily.

Mine plan is :

  • Incorporate Zobel network for woofer
  • Can be used 2 woofers in same pipe.
  • Woofer choice is Eminence BETA-12A-2 (good spec,reasonable price)


I'm assuming this is a subwoofer design, so you don't need a Zobel comp as the freq will always be very low and limited range.

What freq range are you expecting to cover (ie. 30-120Hz) ??

Why 2 drivers in a single pipe?
 
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Thanks guys, with a design (incorporating second mid range woofer ) to the pipe,a goal is to get even more natural and relaxed bass with god musical definition of musical instruments...
to charge and move more air....I would describe as a "musical" bass (not a booming bass for car stereo) but bass where you can hear musician touching contrabass string.
At the same time would like to find physical drivers limit ( mine opinion is 12 ") where driver will reproduce musical instruments with minimum colouration.
Lets say one woofer will do 30 - 120 Hz range ( simple 1 order crossover) and second woofer do 120 - 1500 Hz range.
To make job easy for amplifiers incorporate Zobel network . I think BETA-12A-2 driver will benefit a lot from it.
All that is only mine thoughts and not based on practical experience.
Main reason behind starting this thread is to get practical experience from you. I'm sure same one was playing with such speaker configuration.

If I personally must choose subwoofer deferentially is will be RIPOL design.
Actually going build one after all festivity in a new year.
 

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If you want good bass you need to go down to 40Hz.

Why not have 2 chambers in your main 12" pipe. The top chamber would have your 8" woofer (>120Hz) and the bottom chamber has your 12" woofer (40-120Hz). You could make the bottom chamber a BassReflex or Bandpass. The low freq is omnidirectional anyways. SonoTube and SewerPipe BP6 Subwoofer

Alternatively, even with a single 12" you could get 40-400Hz and let the FullRange take >400Hz, keeping it a 2way system.
 
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