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New Linkwitz LXmini building during COVID-19

suttondesign

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Decided to ditch the cat-coffins in the living room bookshelf (those are for sale in the "For Sale" forum, BTW) and build a second pair of LXmini, this time without purchasing any kit parts. The living room is part of the open-plan first floor with dining and kitchen, so the acoustics are terrific -- few noticeable nodes, lots of things to break up nodes, and lots of space around behind the listeners.

Finished the last bit yesterday after fully testing everything for a few days -- and finding an out-of-phase driver using the 9-volt battery test. The errant phase was making the system sound strange. Now, it sounds incredible. It's hard to explain the change from a box -- esp. one in a bookshelf -- to an open-type speaker like this except to say, Wow.

This particular build is using a 4-channel Adcom amp I picked up from Craigslist for $250 and a MiniDSP 2x4HD for the time being. I'm building a passive, downward-firing subwoofer which will sit in the bookshelf behind one of these. I found a tremendous 9" subwoofer driver for it, requiring only a .7 cu. ft. sealed enclosure. If the sub works well, I'll build another.

I'm buying some cheap books at goodwill and cutting off the spines, which I will glue to the face of the subwoofer box to make it look like books. It will be driven by some spare amp I can find, and I'll switch out the 2x4HD for a 4x10HD to have total control over the sub integration. Since the amp(s) sit under the main stairs behind a removable panel, I have no particular heat or space issues for amplification, which is nice.

I control all this through a Matrix Element i which directly feeds the amp. The interface is Roon, connected to a computer server elsewhere on the first floor. Anyone can use the system by just picking up an iPad which sits in the living room.

Oh, and 3 of the NKS behind the one speaker are signed first editions. Eat your hearts out, skeptics of the universe-as-computer theory.
 

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muad

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Yeah, it would be amazing to see some measurements from the LP. Or even some MMM. Really curious to see how the compare to harmans research, since people seem to love them.
 

Gatordaddy

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I really like the bookwoofer idea!

Glad you like their sound. I'm hoping these are tested at ASR soon.
 

muad

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LXmini in-room measurements and compared with Accourate dsp "room correction". Terrible, just terrible :cool::
https://oplug-support.org/viewtopic.php?f=33&t=4272
Looks pretty damn good. I'm flip flipping between lxmini and the KEF R3, to be used with sub. But I've read that the lxmini isn't kind to bad recording material. I find the stones, Beatles and various other bands a little difficult to listen to on most HiFi gear.
 

pozz

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@suttondesign Did you machine the wood yourself? What material did you use for the tubes?
 
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suttondesign

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Yes, I used a hole saw, jigsaw, router w/ rabbeting bit, and leftover walnut from a cabinet project to make the wood parts. The tubes are just the PVC, spray-painted. I wanted to do something more adventurous, but honestly the PVC build, when painted, looks as good as anything else, particularly when there's a huge rubber coupler attached to its top. It has its own design integrity, you know? In the room, these little guys really disappear, unlike any other stand + cat-coffin I tried.
 

pozz

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Yes, I used a hole saw, jigsaw, router w/ rabbeting bit, and leftover walnut from a cabinet project to make the wood parts. The tubes are just the PVC, spray-painted. I wanted to do something more adventurous, but honestly the PVC build, when painted, looks as good as anything else, particularly when there's a huge rubber coupler attached to its top. It has its own design integrity, you know? In the room, these little guys really disappear, unlike any other stand + cat-coffin I tried.
I think I'd like to build a pair myself. Any particular kind of spray paint? Looks really good in the pictures, as does the walnut.
 

Severian

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How many times have you read A New Kind of Science?
 
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suttondesign

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Proof-of-concept for hiding bottom-firing subwoofer in bookcase using book spines attached to front and sides of box. The second iteration will feature spines plus top of books so that the top of the woofer box is also covered. But I need to find a bunch of 14" tall books!
 

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suttondesign

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testing it out. waiting on the plate amp, then i will use REW to integrate the sub. probably below 60hz. i may need to open more space in the cavity around the sub. we shall see.
 

kaka89

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Looks pretty damn good. I'm flip flipping between lxmini and the KEF R3, to be used with sub. But I've read that the lxmini isn't kind to bad recording material. I find the stones, Beatles and various other bands a little difficult to listen to on most HiFi gear.

are they? it is +- 5 dB before correction
It is the scale of the graph makes them look flat
 

rvsixer

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Found another LXmini in-room measurement (@1m, 1/12 smoothing):
https://www.hifisentralen.no/forumet/threads/linkwitz-lxmini-diy-og-byggetråd.75552/post-2070661
https://www.hifisentralen.no/forumet/threads/linkwitz-lxmini-diy-og-byggetråd.75552/post-2071591
https://www.hifisentralen.no/forumet/threads/linkwitz-lxmini-diy-og-byggetråd.75552/post-2077516

I'd really like to see the LXmini go for a spin(orama) on the ASR Klippel tester. I've got a hint out on the SL OPLUG forum for a local to do that, but if that does not happen and I do build these; I have friends on the Olympic peninsula that I need to visit, and could drive one up for testing.
 
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rvsixer

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are they? it is +- 5 dB before correction
It is the scale of the graph makes them look flat
There are speakers out there don't achieve that without the room. I think its a great result for a pair of $400 speakers, without any EQ applied, better than most initial in-room response graphs I have seen (that usually have far more and far deeper peaks and dips), and who knows if LP/speaker positioning could tighten up the response any further.

What is unknown is where in room the measurement was taken, and what if any smoothing is applied...that could skew results. But judging by the other in-room measurement above, the results correlate.
 
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