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Living With Linkwitz

xarkkon

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#61
I can compare them to box-based speakers of similar design and quality: Aerial Acoustics, KEF, and Dutch & Dutch. There is something very different about the mid- and lower-bass area, and all I can say is that you can tell that there is no box. Rather than a punchy-type sound, the Linkwitz designs make it impossible to locate a box in space. The Dutch have a buttery-smooth response, but I still hear the box. That's even more true with any B&W, including high-end lines, which to my ears sound very "damped."
given it's kind-of open baffle for the tweeter, any issues with comb filtering?
 
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#62
I have question that I know will be largely frowned upon here, but I want to ask anyways: do you think the LX- Mini would run OK on a 35wpc tube amp for the full range and a 60wpc tube amp for the bass? I know tubes are frowned upon here, but I like building and playing with them and might build this kit, but am worried about having different output amps.
 
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suttondesign

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Thread Starter #63
I have question that I know will be largely frowned upon here, but I want to ask anyways: do you think the LX- Mini would run OK on a 35wpc tube amp for the full range and a 60wpc tube amp for the bass? I know tubes are frowned upon here, but I like building and playing with them and might build this kit, but am worried about having different output amps.
go to linkwitzlab.com. all your questions answered.
 
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#65
I have question that I know will be largely frowned upon here, but I want to ask anyways: do you think the LX- Mini would run OK on a 35wpc tube amp for the full range and a 60wpc tube amp for the bass? I know tubes are frowned upon here, but I like building and playing with them and might build this kit, but am worried about having different output amps.
Tube amps should work if you like. Linkwitz suggested a minimum of 20 W into 8 ohms for the full range speaker. But the FR driver is 4 ohms, so you need the capability of 40 watts into 4 ohms. Using amps with equal voltage gain is very important. if they don't match in gain then you need to adjust relative output level in your solid state miniDSP 2x4 or 2x4HD. Tubes would not be my cup of tea, but Siegfried always wanted people who built his speakers to experiment and to, most of all, have fun.
 

dreite

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#66
I think it depends on what tube amps you're talking about. They can have significant output impedance, which can skew the frequency response of many speakers when interacting with the system impedance. In this case, there's no passive crossover and the impedance of the drivers is fairly benign, so the effects would be reduced, but not zero.

Dave.
 

xarkkon

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#67
go to linkwitzlab.com. all your questions answered
alas, all references to comb filtering on that site have been theoretical and the topic isn't covered in the lxmini design documentation

regardless, i'm more interested in your view :) was it something that you'd encountered during your review? or just utter hogwash i shouldn't be too concerned about?
 

dreite

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#68
given it's kind-of open baffle for the tweeter, any issues with comb filtering?
All speakers that aren't true point-sources would exhibit that effect, to some degree.

Relative to other speaker designs the LXmini would exhibit much less of this effect with measurements. And it works for normal listening as well, as the character of the speaker sounds much the same when you walk around the listening room.

The tweeter in the LXmini is a dipole, but with a diffused rear radiation. The LXmini system, as a whole, is primarily an omni-directional design.

Dave.
 
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suttondesign

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Thread Starter #69
My unqualified opinion is that there are so many different reflections that any destructive interactions are either unlikely or lost in the mix. The stuffing behind the full-range driver eliminates or vastly reduces destructive rear interferences.
 

xarkkon

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#70
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#72
I'm OK at woodwork, but never was very good at getting a good paint finish - especially on plastic. So with my LXMinis I used 3M "carbon fibre" wrap - it's tough and goes on quite easily - minute air holes make it easy to get any bubbles out. It might not be to everyone's taste, but I find the "high tech" look suits the LXMini.

View attachment 50614
what did you use to strap the cones. Is it just the regular stuff but painted black?
 

Lbstyling

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#73
Do you have any issues with the MiniDSP 2x4 such as audible noise or hum? It doesn't measure well compared to most recent DAC's, but is it good enough?
Just L pad it. You loose power of course, but it solves the problem.:)
 
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#74
While sitting around in lockdown, I decided to take an in depth look at toe in angle of dipole speakers. The goal was to determine the optimum toe in angle for a generic rectangular room with lateral symmetry. Consistent with this type of room, the primary listening position is located on the centerline of the room.

The work was based on Richard Taylor's 2013 paper "Delaying Room Reflections: Constraints on Room Size and Loudspeaker Placement". This paper is linked in the " LX521 Reference" web page on www.linkwitz.lab.com. A diagram showing room setup from this page is attached below.

Linkwitz suggested spacing dipole speakers a minimum of 1 meter from room side wall to allow the reflected sound to reach the listener position 6 ms after the direct sound to create phantom source and realistic sound sources. For the case where the speakers and listener form an equilateral triangle with the speakers 1 meter from the side walls, I found that the reflected sound level is about 45 dB below the direct path sound level. However, I discovered that the 1 meter spacing does NOT delay the arrival time of the reflected sound by his recommended 6 milliseconds. Linkwitz also suggested using speaker toe in an alternate method to improve the phantom sources and the sound spaces in front of the listener by minimizing side wall reflections sound levels.

In Taylor's paper, he shows the basic geometry of a side wall reflection (diagram below) As a dipole radiates sound minimally at 90 degrees from the speaker axis, the optimum speaker toe in angle is achieved at an angle parallel to angle ACB in the Taylor diagram. This points the minimum sound radiation from the dipole directly at point O. Therefore, Angle ACB becomes the optimum toe in angle for the speaker axis relative to the side wall. This angle can be found by the equation below, written in an Excel type of equation format.

Angle ACB = Toe in angle = SQRT(v^2+(x+x-u)^2)

where: v = distance parallel to side wall from speaker to listener
x= distance from listener to side wall
x-u = distance from speaker to side wall

If you have a Linkwitz design dipole system, you might want to give this a try and evaluate it for yourself.
. Dipole toe-in diagram.png Side Wall Reflection Geometry.jpg
 

anmpr1

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#75
Linkwitz suggested spacing dipole speakers a minimum of 1 meter from room side wall...
Years ago I owned Acoustat speakers--tall and slender. Electrostatic dipoles. At least three feet from any wall and angled in toward the listener was about right for best sound. Space behind the speaker was most critical. I always suspected that they would have sounded best with no back wall. Although both are dipoles, the radiation pattern of Acoustat panels is no doubt much different than that of the multiple cone drivers in Linkwitz's design.
 
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#77
what did you use to strap the cones. Is it just the regular stuff but painted black?
Mine are built from a MagicLX (basic) kit which comes with some black plastic shims that hold the upper driver in place so you don't need to drill the tube and insert screws as in SL's original plans. They are a very tight fit, so I used a small dab of clear silicone on the edges of the shims to ease them in and help hold them in place. Works very well.
 
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#78
I've just come across this thread and it's my first post on this forum.

Siegfried's Plutos were my first ever DIY audio project and there were many occasions when I wished I hadn't started! I did eventually finish them and added subs based on the Pluto + design. I was lucky enough to happen upon some workmen laying gas pipe, the wall of which was about an inch thick (the pipe itself being about a foot in diameter). Ideal, thought I, for subwoofers to match the Plutos. I asked if they had any offcuts and they let me have a couple. I had few power tools at the time, so I had to cut them with a hacksaw which took some doing! I think they worked well though - each one driven by a Hypex UCD400.
They're the best speakers I've ever heard, but then again, I don't know anyone with the money to buy decent speakers, so have little to compare them to. To my ears though, they do sound excellent.
 
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#79
I have one report regarding using Pass amps with the LXmini and a couple of other comments on other posts in the thread.

I bought a pair of First Watt F7’s to try with my LXmini’s and they were not acceptable. Soft, mushy, and muted is how I would put it. Not a comment on Pass in general. I’m certain they sound great with many speakers, but they didn’t have enough muscle to push sound out of even the small dipoles. Luckily, the amp is in demand so I was able to sell them rapidly with no loss.

For any who may be curious, I’ll attach a photo of where I ended up after having two years of free time to tinker with the Linkwitz designs. I started by buying an Orion system. My goal after that was to integrate the other two last designs but leave the Orion’s untouched so I could always go back. No cutting, sawing, screws, de-soldering etc. I ended up adding a DIY LXmini, two LX subs, and two DIY LX521 baffles (no LX521 woofer boxes). It looks like it could be a hot mess but it’s not. The room isn’t large (10ft wide) but it looks even smaller in the photo with the large speakers. It has a high ceiling (10ft.) and a waist high partition in the back with a far wall that extends the listening depth to 25ft.

I use the Orion analog crossover/EQ and a miniDSP 4x10. As one user mentioned above, I had to use the analog input on the miniDSP downstream of my chosen DAC (Schiit Yggdrasil) but the miniDSP A/D/A section measures very well according to Amir and the SQ doesn’t suffer from the second D/A conversion to my ear. I am using 2 ATI 6012’s and one ATI528c and REW for room correction in the 4x10. I probably don’t strictly need the 3rd amp but I bought it just in case I set up in a larger room someday and build the LX521 woofer boxes.

I can mute any of the three pairs of speakers and I do depending on the track I’m playing. The gains and delays are different for each pair (except for the Orion which has no delay - it's the reference). With everything engaged, the sound image shifts up (imagine sitting in the mid-orchestra section) and is wider with the LX521 baffle imaging better than the Orion and the LXmini’s at a much lower gain on the perimeter. The LX521 baffle sounds crisper and faster than the upper half of the Orion but the Orion adds something magical in the upper mid-range that I love. The combination works well for me.

I was going to add grilles to the LX521 baffles but my wife likes the shape exposed so there it is.
 

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rvsixer

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#80
I use the Orion analog crossover/EQ and a miniDSP 4x10. As one user mentioned above, I had to use the analog input on the miniDSP downstream of my chosen DAC (Schiit Yggdrasil) but the miniDSP A/D/A section measures very well according to Amir and the SQ doesn’t suffer from the second D/A conversion to my ear.
Thanks for the report, nice.
I am not aware of Amir having tested the miniDSP 4x10, can you provide a link? miniDSP's tested here at ASR, do not test that great in regards to A/D/A conversion (one exception being the SHD unit).
 
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