Martin Logan CLX Review
I purchased these speakers after being exposed to them at the 2009 Montreal Audio Show in the Bryston/Martin Logan Room hosted by our dealer Son Ideal. They sounded terrific at the show and I already own the Quad 2905's and felt it would be a great time to compare two of the best of the current electrostatic speakers out there. I will not bore you with all the descriptive technical stuff - suffice it to say it's all available online -
http://www.us.martinlogan.com/speaker_intro/clx.htmlFirst off, different speaker technologies sound different to me. Line Sources, Point Sources, Omni, Planar, etc. all present a different perspective due to their specific radiation pattern and room interface issues. Also I find that the specific driver material used in a speaker imparts a particular sound characteristic that rides on the music. I set the speakers up in listening room 3, which is a 16 by 23 by 8-foot room. I have listened to the Quad 2905's, the Magneplaner MG20's, the Thiel 3.7's, the JBL 1400 Array's, the Magneplaner MG3.6 and 1.6's and the PMC IB2's and MB2's in this room over the last few years.
The CLX's needs serious break in time. The manufacturer suggests a minimum of 100 hours at 90dB (which is fairly loud). I assume it is to allow the compliance of the panels to acclimatize and the crossover components to settle in. I found the sound changed a lot during this burn in period and I would not recommend any critical listening or positioning efforts before hand. In fact I am in to 200 plus hours now and they're still changing!
The CLX's are a 'dipole' design that radiate in a figure '8' (eight) pattern. The CLX though has a small twist on this because the midrange/tweeter panel is curved so its radiate pattern deviates a little from the traditional dipole polar response. Large planer speakers tend to suffer from what is call the 'venetian blind' effect which is to say there are holes in the sound-field created by the fact that the different size drivers in the planer speaker start to constrict their polar response as the frequency goes up. So in other words, as the woofer driver in the panel gets near the top of its frequency range - lets say 300Hz - the on and off axis response starts to 'beam' a little. That's why the goal with any multi-driver speaker is to try and prevent these changes in polar response from interacting in a negative way as one specific driver transitions to another (woofer to mid --- mid to tweeter etc.).
In the CLX the curved mid/tweeter driver, which operates from 360Hz and up, does not exhibit the typical beaming that most panel speakers have and acts more like a line-source than a dipole. In fact I measured the polar response of the mid/tweeter panel and it is very flat and uniform over about a 60-degree arc. So the side wall reflection becomes more of an issue with the curved mid/tweeter than it would be with a typical dipole but the smooth dispersion available from the cylindrical mid/tweeter driver is a big plus. The bass panel measured down to about 40Hz in my room with reasonable output - which is very good for a full range electrostatic speaker.
Set-up:OK let's get to the set-up. Being a dipole over most of its range means the back wave from the speaker has to be taken seriously. The manufacturer recommends placing the speaker 4 feet from the front wall and 2 feet from the sidewalls with the mid/tweeter panels on the inside and angled so that you're listening to the inner 1/3rd of the mid/tweeter panel. I tried them on the outside but the image was way to diffuse. I suspect the reason placement 4 to 5 feet from the front wall is recommended is because it nulls out a front wall boundary frequency bump.
Also one of the main issues with the back wave from any dipole is the dreaded 'haas effect'. The ear will 'integrate' the first arriving sound with an early arriving sound if the early arriving sound is within 10-15ms from the first arriving sound. This prevents the ability of the ear/brain to differentiate which is the first arriving sound and which is the first reflection. In a good concert hall in row 12 center the arrival time of the first reflection will exceed 100ms. So if your early reflection in your listening room falls below 8-10ms your soundstage goes to pot. Also early arriving sounds can affect the level of the perceived sound as well. Some people are bothered by this 'hass effect' more than others but generally most audio people feel a delay of somewhere around 8ms or more is a good place to start when setting up your speakers if image placement and focus is important to you. So in the case of the CLX's the 4 foot distance from the rear wall means about 8ms of delay in the sound bouncing of the rear wall and reaching your ears at the listening position. Sound travels at approximately 1 foot per ms so 4 feet back and 4 feet forward means a delay of 8 milliseconds from your listening position. 5 Feet would give you 10 milliseconds and so on.
I had been using point source speakers in my room prior to getting the CLX's so I had to fiddle around a fair bit to get the soundstage dialled in. I added some absorption ( 4 inch foam) on the front wall (not too much though). Relative to a point source the CLX's image is still more diffused and images are a little larger and less defined. An important point to remember here is that all of these observations are in MY ROOM (16x23x8). A different room will exhibit different results but I think the comparison between a point source and a dipole/linesource would still apply in a relative sense. I ended up sitting 10 feet from the speakers with the speakers 8 feet apart (edge to edge) 4.5 feet from the front wall and 2 feet from the side wall and angled in about 15-degrees. This gave me the best soundstage with the maximum amount of width.
SEE BELOW
