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Hardware Review Definitive Technology Mythos ST-L SuperTower Review

Discussion in 'Speakers & Subwoofers' started by Dave Upton, Dec 26, 2014.

  1. Dave Upton

    Dave Upton Audiophile
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    Definitive Technology Mythos ST-L SuperTower Review
    [​IMG]
    As I was walking the halls of CEDIA Expo 2013, I chanced upon Definitive Technology’s booth, where they had a pretty long line of folks waiting to hear their new flagship loudspeaker. At the time I had no idea that this was the Mythos ST-L, and had no interest in hearing it because I’d generally been rather unawed by Definitive Technology products in the past. It wasn’t that Definitive Tech speakers I had heard in the past sounded bad, but rather that they either weren’t set up properly or the particular model wasn’t well suited to my listening tastes.

    Since my feet hurt, I decided to walk into the demo room and was treated to a 10-minute demo of the Mythos ST-L in a seriously challenging acoustic environment. I was extremely impressed by how well the ST-L imaged and by its bass response, which was extremely tight. Walking out of the demo, I was impressed enough that I wanted to review this speaker in my own room and see just what it could do.

    [imgr]http://www.hometheaterforum.com/uploads/gallery/album_37/gallery_383964_37_18476.jpg[/IMGR]The Design

    Definitive Technology had a hit on their hands with the 2007 Mythos ST, yet here we stand some seven years later – and technology has come a long way. One of the major changes from the Mythos ST is that the driver design has changed pretty radically. In large part, the changes in the design of the drivers for the Mythos ST-L are due to the addition of a new measurement and analysis method at Definitive Technology’s secret lab in [redacted] called the Klippel System. Sounding appropriately Germanic, the Klippel System utilizes laser mapping, and a host of other advanced technologies with a combination of high and low amplitude signals to better approximate “real world performance” during loudspeaker and transducer development. For the layman, this is just polite Definitive Tech PR speak for “it’s designed to handle the punishment you wackos will dish out on your speakers”. At its most basic level, Klippel analysis is all about eliminating distortion, and distortion is a large part of what makes one speaker sound worse than another.
    Some of the interesting design decisions made by Definitive Technology as a result of this system include a parabolic speaker cabinet made of extruded aluminum with ribs for stiffening and a baffle made of Polystone, a very dense mineral rich polymer. This extends to the completely separate driver enclosure which isolates the MTM drivers from the subwoofers, again a decision designed to reduce intermodulation distortion. Another interesting feature of the ST-L is that it is remarkably narrow as shown above, with the total face of the speaker being just fractionally wider than the drivers. This is all in pursuit of lowering diffraction and increasing the ability to image.

    Technical Details - The Components

    Public Service Announcement: If you find the "geeky stuff" behind speaker design boring, please skip ahead to the section titled "The Sound"

    The Mythos ST-L utilizes a D’Appolito array with two 5.25” drivers on either side of a 1” dome tweeter. This is called an MTM (Midrange/Tweeter/Midrange) arrangement and is extremely common in loudspeaker design. The primary reason for this MTM design is in principle that the midrange surrounds the tweeter, allowing the sound waves to combine in such a way that it sounds like a single point source of sound and improves imaging.

    [imgl]http://www.hometheaterforum.com/uploads/gallery/album_37/gallery_383964_37_13983.jpg[/IMGL]Mid-Range

    The mid-range drivers in the ST-L utilize a technology called BDSS (Balanced Double Surround System) which surrounds the midrange driver in two separate soft rubber surrounds, one on the inner edge, and one on the outer. This increases excursion for each cone without raising distortion as much as a single surround would – allowing a smaller driver to play louder, necessary for the narrow baffle of the Mythos ST-L. According to Definitive Technology’s product brief, the BDSS driver utilized in the Mythos ST-L has a larger magnet, pole piece and motor assembly which increases the magnetic power of the driver and again reduces distortion.

    The electrical design of the ST-L’s drivers also includes a shorting ring to result in lower inductance and a more linear inductance curve as the driver moves. The net result of all these improvements is a mid-range with much lower distortion than the previous generation.

    As you can see in the close-up picture below, the mid-range drivers of the Mythos ST-L are actually inverses of each other. One has a surround structure that is concave, while the other driver’s surround is convex. The idea behind this is to produce destructive interference that lowers distortion.
    Tweeter
    The tweeter in the Mythos ST-L is a Magnesium/Aluminum Alloy design or M/AA that weighs 59% more than its predecessor, this is all in pursuit of greater motor strength which enables some other design changes that cuts both harmonic and intermodulation distortion significantly over the previous generation. The crossover the of MTM portion of the Mythos ST-L is a simple network using air-core inductors and Mylar capacitors. The high and low pass filters between each midrange and tweeter are 12dB/octave slopes to reduce phase shift.

    The Subwoofer

    The Mythos ST-L includes a subwoofer system that includes a 6”x10” racetrack shaped driver and two passive radiators of the same size on either side. The driver is powered by a 1200-watt Class HD amplifier. The entire subwoofer is a new design for Definitive Technology and was produced using the Klippel System. The net improvements over the Mythos ST are about 25% greater driver excursion and reduced harmonic distortion.

    Definitive states that behind each subwoofer section is a 56-bit DSP performing parametric equalization and protection when it’s being driven too hard. The inputs of the Mythos ST-L include an LFE input which allows the subwoofer gain to be controlled by your receiver’s LFE signal if you are primarily watching movies.

    I could probably go on for at least a few more paragraphs with engineer speak, technobabble and details that I find fascinating and probably make you want to close your browser. Suffice to say, the Mythos ST-L is all about lower distortion and better sound than its predecessor – so how does it sound?


    The Sound

    All the technology and improvements that have gone into the Mythos ST-L look impressive on any press release, however the only thing that really matters is whether these advancements translate into improved real-world sound quality.

    [imgr]http://www.hometheaterforum.com/uploads/gallery/album_37/gallery_383964_37_17768.jpg[/IMGR]Setup and Positioning

    I spent a good two hours fine tuning the positioning of the ST-L’s, playing with toe-in, position relative to front and side walls, and trying to find the best location for the built-in subs to give a smooth response. In the case of my theater, it ended up being about the same spot my Paradigm Studio 100’s sit, with the exception of being a touch further in from the side walls. The final positioning was 25 inches from the side wall to the closest corner of the speaker, and about 40 inches from the rear wall to the back of the cabinet. I settled on about an inch of toe-in, which gave a sound-stage broad enough for my entire seating area.
    Definitive Technology’s Dave Peet made a stop at my house while he was in town to ensure I had any questions answered and to assist with integration, but mostly we just sat around like a couple of bums and listened to music.

    After proper set up, the ST-L’s truly shone in 2-channel mode, offering some of the best imaging I’ve heard from a sub $10K speaker. I played through my standard demo list including B-Tribe’s Volume 5, Acoustic Alchemy’s The Very Best of Acoustic Alchemy, and several albums from Mickey Hart including Planet Drum and Supralingua. The combination of percussion elements and world music is a real sonic treat and gives any speaker a workout. Dave from Definitive Tech also commented on several occasions that he wanted to pick up these albums, since they sounded seriously amazing on the ST-L’s. The built in subwoofer outputs extremely tight and solid bass which is fantastic for 2 channel listening. Since the MTM and Sub portions of the speaker are in separate enclosures the mids and highs remained extremely delicate and controlled no matter how hard the sub was working, especially important for many of the tracks I use in my reviews.

    It bears mentioning again that these speakers image really well, portraying the artists wherever they are relative to the mic with pinpoint accuracy. While the level of holography isn’t quite up to the standard of a benchmark speaker like the Legacy Audio Focus SE, for less than half the price, it is truly astonishing how well the Mythos ST-L performs. The vocal in Sophie Milman’s In The Moonlight was rich, velvety and projected about 12 feet in front of the listener on center stage. On AIX Records Blu-ray release, the piano in Bryan Pezzone’s performance of Berceuse suffused the entire room just as one would expect from a close-mic recording.

    Movies & TV

    As much as the ST-L’s impressed me for music listening, it should come as no surprise that they are fantastic performers for home theater use as well. The built in subs allow a great degree of flexibility, enabling a very low crossover to be set, double bass configurations where bass comes from both sub and mains, or even extending the LFE channel to both ST-L’s via their LFE input and overcoming some pesky room modes. I played with all three of these options, and settled on crossing the ST-L’s over at 80Hz as my room is a real pain to get LFE right in. Since it is easy enough to switch to full-range mode prior to a 2-channel listening session, this delivered the best of both worlds for me.

    Over the course of the review period, the ST-L’s were used to watch many films, including The Edge of Tomorrow (Live, Die, Repeat), TMNT, Transformers: Age of Extinction, Frozen and many other films that have excellent lossless audio tracks. The ST-L’s did a great job anchoring my system and their excellent dynamic range really impressed me.

    Closing Thoughts[imgl]http://www.hometheaterforum.com/uploads/gallery/album_37/gallery_383964_37_4615.jpg[/IMGL]

    If I were to level a complaint at Definitive Technology, it would be for launching a speaker as well rounded as the Mythos ST-L without a center channel that can truly measure up. I was sent the Mythos Ten center channel to go with the review, and while it was a very decent performer, it really is not in the same league as the ST-L.

    Priced at almost $5000 a pair the Mythos ST-L is not a cheap speaker, in fact it’s close to the territory of being an expensive speaker. Despite that, it performs in every way a speaker needs to. While I haven’t had the chance to hear the Golden Ear Technology Triton One outside of a CEDIA demo, I suspect that the two speakers are very serious competitors and would suggest you audition both if you are considering a purchase.

    For myself, the performance, looks and overall package of the Mythos ST-L make it an easy candidate for one of the best products I’ve reviewed in the past two years. I enjoyed my time with the ST-L’s so much, I have actually decided to keep my review pair as my new 2-channel system in the living room. The Mythos ST-L is a transparent, beautiful speaker that provided me more “Holy $&!#” moments than anything I’ve reviewed in a long time. It is a fantastic two channel performer in addition to being one hell of a home theater speaker. Highly Recommended.

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  2. schan1269

    schan1269 HTF Expert
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    I just read the manual...Like all preceding Super Tower, LFE is gain control only. Not outside bass management. (And that is a common misconception with these. However, this one...the "subs" are really subs...as the crossover point is 111hz. Most ST, the crossover is 350-500hz)
     
  3. Dave Upton

    Dave Upton Audiophile
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    Sam - I have read the manual also and don't know if our interpretations are different or not. Here is the section of the manual I am referencing. This sounds like bass management IS working on your receiver. My read is that this is a typical "double bass" setup where you are just feeding both. What makes you think otherwise?
    [​IMG]
     

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