Hi all,
Has anyone here listened to both of them?
I've only listened to the LX521's. I was very impressed; I'm convinced I don't want point-source speakers any more.
I'm aware of their respective strengths on paper.. I was hoping someone here could describe their subjective differences.
The CBT36 is intriguing... but I wonder if it has weaknesses from using lower-cost drivers than the LX521 (having dozens of them to reduce distortion when playing loudly notwithstanding).
Do the CBT36's have a significantly wider sweet spot due to their slow falloff in SPL with distance? Do they also tend to sound better when far away from the sweet spot (e.g. from the kitchen in an open plan house)? How does their imaging compare? "Cleanness" when played relatively loudly?
I'm not concerned about the CBT's need for subs. I already have dipole subs. I got them to integrate very nicely with my current monopole speakers.
I'm also not terrible concerned about voicing and other mild easy-to-fix frequency response errors - that's easy to fix with the DSPs I plan to use.
TIA
Has anyone here listened to both of them?
I've only listened to the LX521's. I was very impressed; I'm convinced I don't want point-source speakers any more.
I'm aware of their respective strengths on paper.. I was hoping someone here could describe their subjective differences.
The CBT36 is intriguing... but I wonder if it has weaknesses from using lower-cost drivers than the LX521 (having dozens of them to reduce distortion when playing loudly notwithstanding).
Do the CBT36's have a significantly wider sweet spot due to their slow falloff in SPL with distance? Do they also tend to sound better when far away from the sweet spot (e.g. from the kitchen in an open plan house)? How does their imaging compare? "Cleanness" when played relatively loudly?
I'm not concerned about the CBT's need for subs. I already have dipole subs. I got them to integrate very nicely with my current monopole speakers.
I'm also not terrible concerned about voicing and other mild easy-to-fix frequency response errors - that's easy to fix with the DSPs I plan to use.
TIA
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I've listened to both and much prefer the lx 521. Better bass, more spacious, better tone. This was at burning amp 2012 or 2013 and I was only able to listen to my own music on the lx521's, so I would not consider this the word.
It should not be hard to find someone willing to have you over for a listen to the lx521's, I'm not sure about the cbt's.
It should not be hard to find someone willing to have you over for a listen to the lx521's, I'm not sure about the cbt's.
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I've listened to both but a much shorter time with the LX521. Very different designs of course and I think it depends on what your priorities are. I use another CBT design in my own system and like them the best of any format. With the CBT36 the coverage is very wide and you can listen at a greater range of distances than most other speakers and still have very uniform sound.
Tonally the LX521 might be a little better but I think with some attention to the equalization and response curve for the CBT36 that would be minimized. I've done some crossovers different than the suggested settings in the CBT36 manual and received good feedback on the results. With the smaller 3" woofers a subwoofer with good upper end bandwidth helps.
Tonally the LX521 might be a little better but I think with some attention to the equalization and response curve for the CBT36 that would be minimized. I've done some crossovers different than the suggested settings in the CBT36 manual and received good feedback on the results. With the smaller 3" woofers a subwoofer with good upper end bandwidth helps.
I do not recall if the Cbt's had a sub or not. The lx521's have very real and natural sounding bass, not home theater bass but plenty powerful for most music. The spaciousness and soundstage presented goes far beyond the speakers especially in depth. I really only listened in the sweet spot, that's my spot. 
I really think you need to listen for yourself. I mean either these or any number of other speakers can provide a very satisfactory listening experience. A lot of great sound is working on your setup, from placement, room treatment, subwoofer integration, eq etc.
I really think you need to listen for yourself. I mean either these or any number of other speakers can provide a very satisfactory listening experience. A lot of great sound is working on your setup, from placement, room treatment, subwoofer integration, eq etc.
I've never compared the two but if I built a floor-to-ceiling array I would include active delay and amplitude shading. You can read Don Keele's AES papers for a good overview of the differences between the various array formats.
AES Papers -- Official website of D.B.Keele
I haven't been able to find analysis of infinite lines. If I am not mistaken, infinite lines don't have the issues amplitude and delay tapering are supposed to fix.
I haven't been able to find analysis of infinite lines. If I am not mistaken, infinite lines don't have the issues amplitude and delay tapering are supposed to fix.
I've a pair of CBT36 (also Geddes Abbey) and have listened to LX521 in another home quite recently. Both with same power amps (Hypex Ncore).
First listening impressions CBT36 vs LX521:
Let me just mention here that I heard the system with Audiolense where I believe both speaker and room correction had been utilized. With full Audiolense correction the sound becomes somewhat strange and awkward to me. I believe this is because EQ is used where it's not minimum phase. In other words, I probably haven't heard the best of LX521. So keep that in mind.
With subs crossed over at 80 Hz or higher I found the CBT36 sound much more "dynamic" (despite a low sensitivity in the highs), more open with better clarity and resembles real sound to a greater degree. It also sounds a bit more coherent and the sound is great everywhere in the room because of the very uniform and wide response.
Differences in design:
- The LX521 will suffer from vertical lobing. Using two high cross overs will also be detrimental to coherency. Active cross over doesn't overcome this.
- CBT avoids the floor bounce and reflections completely, and ceiling reflections are also highly attenuated without any treatment. Thus, there will be far less early vertical reflections with the CBT. And the vertical response is text book.
- The LX521 has a narrower horizontal response. I don't know how uniform it is, would need to see a polar. The CBT has a very wide dispersion which leads to more sidewall reflections. However, the horizontal is very uniform till about 300 Hz, thus it sounds great and natural even without any sidewall treatment. This is because the reflective energy highly resembles the direct sound. For great pin pointing and accuracy, sidewall reflections need to be treated in a small room. So it is with LX521 but they may need an absorbent panel or an half of a panel less.
Because the CBT is so uniform and also avoids floor bounce, I'm quite confident that they will have a flatter freq. response in almost every room compared to LX521.
First listening impressions CBT36 vs LX521:
Let me just mention here that I heard the system with Audiolense where I believe both speaker and room correction had been utilized. With full Audiolense correction the sound becomes somewhat strange and awkward to me. I believe this is because EQ is used where it's not minimum phase. In other words, I probably haven't heard the best of LX521. So keep that in mind.
With subs crossed over at 80 Hz or higher I found the CBT36 sound much more "dynamic" (despite a low sensitivity in the highs), more open with better clarity and resembles real sound to a greater degree. It also sounds a bit more coherent and the sound is great everywhere in the room because of the very uniform and wide response.
Differences in design:
- The LX521 will suffer from vertical lobing. Using two high cross overs will also be detrimental to coherency. Active cross over doesn't overcome this.
- CBT avoids the floor bounce and reflections completely, and ceiling reflections are also highly attenuated without any treatment. Thus, there will be far less early vertical reflections with the CBT. And the vertical response is text book.
- The LX521 has a narrower horizontal response. I don't know how uniform it is, would need to see a polar. The CBT has a very wide dispersion which leads to more sidewall reflections. However, the horizontal is very uniform till about 300 Hz, thus it sounds great and natural even without any sidewall treatment. This is because the reflective energy highly resembles the direct sound. For great pin pointing and accuracy, sidewall reflections need to be treated in a small room. So it is with LX521 but they may need an absorbent panel or an half of a panel less.
Because the CBT is so uniform and also avoids floor bounce, I'm quite confident that they will have a flatter freq. response in almost every room compared to LX521.
Same, though worth noting that neither was in a particularly good "room" for evaluation at burning amp. The LX521 nevertheless impressed, while the CBT, though more "punchy" (like a good "venue" sound system) did not. I later heard the LX521 at SL's house, where it impressed even more. I can see preferring the CBT as a "HT" speaker, but for classical or other "acoustic" source reproduction the LX521 is just . . . better . . .
There will be some more information coming out in the next few months. Stay tuned!
Two links to summaries of Don Keele's presentations on CBTs at the 2015 AES meeting:
AES New York 2015 Engineering Brief EB3: Transducers—Part 2
AES New York 2015 Paper Session P6: Transducers—Part 2: Loudspeakers
AES New York 2015 Engineering Brief EB3: Transducers—Part 2
AES New York 2015 Paper Session P6: Transducers—Part 2: Loudspeakers
Copied from AES page:
P6-2 Time/Phase Behavior of Constant Beamwidth Transducer (CBT) Circular-Arc Loudspeaker Line Arrays—D.B. (Don) Keele, Jr., DBK Associates and Labs - Bloomington, IN, USA
This paper explores the time and phase response of circular-arc CBT arrays through simulation and measurement. Although the impulse response of the CBT array is spread out in time, it’s phase response is found to be minimum phase at all locations in front of the array: up-down, side-to-side, and near-far. When the magnitude response is equalized flat with a minimum-phase filter, the resultant phase is substantially linear phase over a broad frequency range at all these diverse locations. This means that the CBT array is essentially time aligned and linear phase and as a result will accurately reproduce square waves anywhere within its coverage. Accurate reproduction of square waves is not necessarily audible but many people believe that it is an important loudspeaker characteristic. The CBT array essentially forms a virtual point-source but with the extremely-uniform broadband directional coverage of the CBT array itself. When the CBT array is implemented with discrete sources, the impulse response mimics a FIR filter but with non-linear sample spacing and with a shape that looks like a roller coaster track viewed laterally. An analysis of the constant-phase wave fronts generated by a CBT array reveals that the sound waves essentially radiate from a point that is located at the center of curvature of the array’s circular arc and are essentially circular at all distances, mimicking a point source.
Convention Paper 9387
P6-2 Time/Phase Behavior of Constant Beamwidth Transducer (CBT) Circular-Arc Loudspeaker Line Arrays—D.B. (Don) Keele, Jr., DBK Associates and Labs - Bloomington, IN, USA
This paper explores the time and phase response of circular-arc CBT arrays through simulation and measurement. Although the impulse response of the CBT array is spread out in time, it’s phase response is found to be minimum phase at all locations in front of the array: up-down, side-to-side, and near-far. When the magnitude response is equalized flat with a minimum-phase filter, the resultant phase is substantially linear phase over a broad frequency range at all these diverse locations. This means that the CBT array is essentially time aligned and linear phase and as a result will accurately reproduce square waves anywhere within its coverage. Accurate reproduction of square waves is not necessarily audible but many people believe that it is an important loudspeaker characteristic. The CBT array essentially forms a virtual point-source but with the extremely-uniform broadband directional coverage of the CBT array itself. When the CBT array is implemented with discrete sources, the impulse response mimics a FIR filter but with non-linear sample spacing and with a shape that looks like a roller coaster track viewed laterally. An analysis of the constant-phase wave fronts generated by a CBT array reveals that the sound waves essentially radiate from a point that is located at the center of curvature of the array’s circular arc and are essentially circular at all distances, mimicking a point source.
Convention Paper 9387
My pair of Audio Artistry CBT36 speakers
I just completed my pair of CBT36 speakers. I was lucky enough to get a pair of Outlaw 10" subs used for a good price. I can say I've never heard "better bass" from any other speaker.
Some comments:
The speakers took about a week to break in, playing just a couple to a few hours a day.
The speakers have a rating of 50-150 wpc for the tweeters and 50-500 for the midbass drivers, but I found the tweeters need a minimum of equal power given to them in order to have them sound integrated.If you run lower power to the tweeters and don't compensate the db's via the crossover this will not sound amazing.
I purchased my speakers without having heard them before based upon a friends recommendation who had heard them at a show. However, I heard these speakers at burning amp last year (2015) and was very unimpressed with the sound. In fact, I thought their sound lacked any dynamic quality's that make music listening engaging.
Maybe those speakers were just completed the day before Burning amp, as that's the way my speakers sounded when first assembled before being broken in.
t may also be that as a friend suggested, the tweeters be run at lower power than the mids. Doing so in my system produce a very hard to listen to sound with a grey quality to vocals. I was rather amazed when my pair- completed this month- actually sounded great.
I'd love to post some pictures but there seems to be no way to insert them here.
Thank you Don Keel for putting these kit speakers out there.
I just completed my pair of CBT36 speakers. I was lucky enough to get a pair of Outlaw 10" subs used for a good price. I can say I've never heard "better bass" from any other speaker.
Some comments:
The speakers took about a week to break in, playing just a couple to a few hours a day.
The speakers have a rating of 50-150 wpc for the tweeters and 50-500 for the midbass drivers, but I found the tweeters need a minimum of equal power given to them in order to have them sound integrated.If you run lower power to the tweeters and don't compensate the db's via the crossover this will not sound amazing.
I purchased my speakers without having heard them before based upon a friends recommendation who had heard them at a show. However, I heard these speakers at burning amp last year (2015) and was very unimpressed with the sound. In fact, I thought their sound lacked any dynamic quality's that make music listening engaging.
Maybe those speakers were just completed the day before Burning amp, as that's the way my speakers sounded when first assembled before being broken in.
t may also be that as a friend suggested, the tweeters be run at lower power than the mids. Doing so in my system produce a very hard to listen to sound with a grey quality to vocals. I was rather amazed when my pair- completed this month- actually sounded great.
I'd love to post some pictures but there seems to be no way to insert them here.
Thank you Don Keel for putting these kit speakers out there.
seriously, you do relize what the word "dipole" means?
lx521 emits far less energy to the room than cbt or most other speakers for that matter.
cbt is wider in the high end and as you suggest it will be omni down low (300hz is extra ordinary generous btw) where linkwitz is directional. what part of figure 8 pattern do people not understand?
http://www.thesciencemill.com/Research/edm/img/charge_dipole.png
iv listened to both and lx521 is by far the best speaker. cbt would be suitable for home theater though.
I'm well aware of how dipole dispersion works.
It emitts less energy towards sidewalls, but don't completely avoid sidewall reflections. Therefore, like I mentioned previously:
"So it is with LX521 but they may need an absorbent panel or an half of a panel less."
In other words, they need less sidewall treatment than CBT if one desires the best imaging.
However, contrary to CBT they also send all the energy toward the front wall and measure quite poorly vertically.
So all together the CBT will have less early reflective energy in most small rooms, plus they avoid the floor bounce/cancellation.
The CBT isn't omni. The beamwidth is 90 degrees to each side or 180 degrees total.
I've listened to LX-521 but haven't compared them directly to CBT36 which is needed for a proper judgement. Based on what I've heard though, I find (subjectively) the CBT36 being a better design.
For owners out there with a MiniDSP unit - I recently reworked the CBT-36 crossover. Let me know if you would like any information on the results.
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