Impressions of Salk SongTowers

Discussion in 'Loudspeakers' started by Swerd, Oct 19, 2007.

  1. Swerd Audioholic Ninja

    Swerd
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    I have been listening to my new SongTower QWT speakers for about a month. They are new MTM speakers in a floor standing transmission line cabinet, designed by Dennis Murphy, built and sold by Salk Signature Sound. Here are some photos.

    When describing the sound of new speakers, I should mention what speakers I previously used. This has an important influence on what I notice about the new speakers. My old speakers were vintage 3-ways, JBL L-100s that were greatly improved by new crossovers. The original L-100s were highly popular and highly flawed speakers from the 1970s. Aware of some of these flaws, I took them to Dennis Murphy for testing and redesign. Dennis kept the existing drivers and designed a totally new crossover that greatly improved the glaring bright sound of these speakers. If anyone is interested in more details about this, read the link in my signature line. It is a good illustration of just how important a crossover can be.

    The 14" wide JBL cabinet contains a 12" woofer, a 5" midrange, and 1½" cone tweeter. As modified, the crossovers are about 950 Hz and 5,000 Hz. As a result of these rather high crossover frequencies, there is considerable beaming by the woofer and midrange drivers, as well as the rather large tweeter.

    In contrast, the SongTowers come in a much narrower 8" wide cabinet, with two 5" midwoofers and a ¾" dome tweeter. The single crossover point is about 2.6 kHz. Dispersion is extremely wide and smooth. These speakers image beautifully.

    Imaging
    Although standard frequency response curves can’t directly show how wide a speaker’s dispersion is, several of these curves measured with the microphone placed at various off-axis positions can indicate this. The attached figure compares SongTower frequency response measured on axis and 60° off axis. Below 10 kHz, the two curves are very close to each other. This excellent off-axis performance means great dispersion and is a major reason why SongTowers create superb imaging. Most other speaker manufacturers don’t show off-axis response. Those few that do usually show response curves measured at 15° or 30° off-axis.

    Compare this to the on and off axis frequency response of the well received Ascend Sierra-1 speakers (scroll down to the 2nd graph). At 30° and 45° off axis, the response of its 5" woofer drops in the 1-2 kHz range, and the 1" tweeter response drops off well below 10 kHz. I’m don’t mean to unfairly single out the Sierra-1 – I only do this because Ascend Acoustics is one of the few speaker manufacturers that show these graphs in similar detail for its products.

    With my old JBL speakers, I was used to a sweet spot in the center of my sofa, about one sofa cushion wide. With the SongTowers, the sweet spot covers nearly the whole sofa!

    I often think of imaging for speakers as that “out of the box sound”. Instead of sounding like little musicians sitting inside speaker cabinets, speakers that image well create the illusion that the musicians have climbed out of the speaker cabinets and are sitting in your room. It reminds me of those impossibly tiny cars I saw at the circus as a kid, that would drive up and spew out 15 clowns. The last clown out usually leaned in the open door and said “we’ll meet up with the rest of you guys later”. So if you rate speakers’ imaging ability by how many clowns climb out, I’ll give the SongTowers a score of 30+ clowns. (Note, my clown/image rating scale has no upper limit.)

    Midrange & Treble
    I have so far focused on imaging, but the frequency response curves also make it clear that the SongTowers have essentially a flat response across the entire audio spectrum. The SongTowers sound neutral, clear, and transparent. They are neither laid back nor too bright, neither veiled nor etched sounding. They stand out by doing nothing wrong. To some, this may seem like faint praise, because many of us have heard speakers, with a flat frequency response, that sound lifeless. The SongTowers stand out because they do all this while maintaining a sense that the music is live in the room where I sit.

    Linear response refers to a speaker’s ability to respond to increasingly more powerful signals by generating louder tones in proportion to the original signals. Every speaker has an upper and lower limit to its linear response range. The SongTowers have an extremely wide linear response range which adds to their ability to image well at low volume as well as high. In my old speakers, high volume was required to hear good imaging. The more I listen to the SongTowers, the greater I appreciate this unexpected feature.

    Bass
    The SongTowers’ bass is startlingly good. I can’t say this enough. The SongTowers’ bass is startlingly good. And I’m comparing it to JBL speakers with 12" woofers that were famous (or infamous) for bass response. Just how do two 5" drivers keep up with one 12" woofer with a huge alnico magnet and 3" voice coil made with edgewound copper ribbon? The answer is the transmission line cabinet design.

    Properly designed transmission line cabinets allow significantly greater bass extension than either sealed or ported cabinets would allow for the same woofers. In the SongTowers, these 5" woofers produce bass down to below 40 Hz. In a smaller ported cabinet, one of these same 5" drivers can only deliver bass to 50 or 55 Hz. (This is the Dennis Murphy 2-way DIY design that I built about two years ago that started me on the quest for better sounding speakers.) The transient responses of small woofers (the speed at which they start and stop making sound) are much faster that those of larger heavier woofers. This difference is easily audible, and is often spoken of as “fast bass”. The air inside SongTower cabinets actively participates in producing bass from below 40 Hz to above 125 Hz. It is louder than a sealed or ported cabinet would be with the same woofers, and if suitable small woofers are used, as in the SongTowers, the bass transients are fast.

    Transmission lines create louder and deeper bass by coupling the rearward woofer motion to a large column of air inside the cabinet, and allowing this energized air to move freely out of large openings. An additional benefit of this is improved midrange clarity because eliminating internal back wave reflections results in less midrange interference. In most other cabinet designs, these woofer back waves are largely absorbed or suppressed. It makes me wonder how much low frequency energy is wasted by these designs. The only way they can generate good bass is by brute force.

    So, how do they sound? Jim Salk describes the SongTowers at his website as follows:

    • The driver dispersion and the slim cabinet combine to offer superb imaging
    • The soundstage is deep and wide with instruments and vocals precisely located.
    • The top end is lush and detailed – just what you'd expect from the exceptional Hiquphon OWII tweeter
    • Midrange is detailed and accurate. Voices are rendered with realism.
    • The TL cabinet results in very impressive bass extension considering the design uses 5" midwoofers.

    In my honest opinion as an owner, this isn’t just slick marketing language; it’s the best description I’ve seen of how the SongTowers sound. Considering the first rate quality of the cabinet construction and finish, I don’t know how he does this for $1,500. See this example of the Salk cabinet construction process. The speaker shown, the Salk HT-3, is much more complex to build than the SongTower, but the care and quality are similar.

    Some of you may have noticed a repeating theme here – that I have three pairs of speakers designed (at least in part) by Dennis Murphy: the CAOW1 2-ways, the rebuilt JBL L-100s, and the SongTowers. If you call me a Dennis Murphy fanboy, I’m guilty as charged. I have to wonder why everyone else doesn’t own speakers he has designed – they sound that good.

    Attached Files:

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  2. Seth=L Audioholic Overlord

    Seth=L
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    I notice you have one of those old school Sony DVD players.:)
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  3. Swerd Audioholic Ninja

    Swerd
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    Yeah my DVD player is old and I'm too busy listening to these speakers to replace it :D.

    Despite the irrelevance of your comment, we can always depend on you to bump a thread to the top of the list. Thanks.
  4. Seth=L Audioholic Overlord

    Seth=L
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    You don't get a post count like mine without irrelevant comments and eagerness to bump.:D

    I did forget to mention, nice review, very in depth.:)
  5. oldgoalie33 Audioholic Intern

    oldgoalie33
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    Swerd,
    As an owner of a pair of SongTowers I couldn't have said it any better! Excellent write-up. I would echo the comment about their bass response...simply outstanding. They are the best sounding speakers I have ever owned..hands down.
  6. Seth=L Audioholic Overlord

    Seth=L
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    I have a question. Where does one buy the Salk Song Towers. They don't appear to be listed on the site.:confused:
  7. Adam Audioholic Jedi

    Adam
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    Seth=L, just click on the first link that Swerd provided. That'll get you there.
    Adam,
  8. Dennis Murphy Audioholic Chief

    Dennis Murphy
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    I'm a little depressed you didn't see them on the home page. I'll have to tell Jim to blow up that pic 9 or 10 times. Sure you were at www.salksound.com?
  9. Seth=L Audioholic Overlord

    Seth=L
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    No I was here. I was using the link to the cabinet design or something.:confused:

    http://www.salksound.com/home.html

    I see it on the other link provided, thank you Dennis.:)
  10. Dennis Murphy Audioholic Chief

    Dennis Murphy
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    That explains it. Jim redid the site--that link somehow took you to the obsolete home page.
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  11. Tomorrow Audioholic Ninja

    Tomorrow
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    We know how Jim likes to tinker. ;)

    Great review, Swerd. Many thanks.
  12. Dan Full Audioholic

    Dan
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    I recently helped a neighbor of mine get a new 2 channel rig with Song Towers and the Outlaw 2 ch receiver. I have heard it quite a bit with both modern CDs and some of his excellent old jazz LPs on his new Thorens turntable. The room setup is less than ideal along the long wall of a 35 x 15' room.

    The feature I would like to emphasize is their forgiving nature and large sweet spot in less than ideal circumstances. Most of us don't have custom built rooms or if they do they have compromises which limit the sound somewhat. The Song Towers don't mind unlike say my beloved Vandersteens. I like mine better (at $2000 more!) but Vandy's are much more placement picky.

    Let me put my spin on Swerd's comments about bass succintly. I defy anyone to find better bass response with 5" woofers anywhere at any price.

    Finally, welcome Dennis. Your insights here will be truly welcome.
    Dan,
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  13. ChrisJam Full Audioholic

    ChrisJam
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    Welcome, Dennis! FYI, some of the Salk speakers are on my short list. :)

    Chris
  14. Dennis Murphy Audioholic Chief

    Dennis Murphy
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    Thanks for the welcome, Dan and Chris. I think I got all my posting problems straightened out--hopefully the p is back in my last name. As for sweet spots, those first order crossovers (on the Vandy's) giveth, and they taketh away. For me, whatever benefit they offer in the narrow sweet spot isn't worth the cost in listening flexibility, but I can see where others would disagree. It would also be a bad idea to try and implement them in an mtm due to comb filtering between the two woofers, and the complicated crossover that they require would blow the $1500 price limit I wanted to meet. I'm off to Iowa for the big DIY2007 meet at Grinnell College (my alma mater) this weekend. There are a couple of innovative designs being introduced, and I'll let you know if they pan out.
  15. Zar Audioholic Intern

    Zar
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    I'm very interested. Can they be placed fairly close to the rear wall? I have a narrow room and looking for speakers that can be further from my listening chair.
    Zar,
  16. Zar Audioholic Intern

    Zar
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    One more thing, do these have 4 terminals per for bi wiring?
    Zar,
  17. oldgoalie33 Audioholic Intern

    oldgoalie33
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    Zar,
    Jim recommended that I place mine about 18" to 24" from a wall. They are rear ported and need some room to 'breathe'. Only one set of speaker connections, but as each pair are custom made you only have to ask and Jim will add them if you wish to bi-wire. I believe there is an additional cost for that though.

    John
  18. Swerd Audioholic Ninja

    Swerd
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    You can ask Jim Salk to place the vent hole somewhere else instead of the rear, like on the front of the cabinets. It may cost extra. Remember that these speaker cabinets are technically a mass-loaded transmission line design and not a ported reflex. Breathing, and lack of bass, might be an issue if the hole was completely closed off. But what will really happen if you place these speakers much less than 18" to the wall behind them is that bass will sound louder. The closer they are to the rear wall the greater the reinforcement. It might make them sound bass heavy.

    You can also ask Jim Salk to add a pair of terminals for biamping or biwiring, although I don't think these speakers really need that. They are listed as having a sensitivity of 88 dB, but mine seem quite easy to drive, so I wouldn't be surprised if the sensitivity was higher.

    Come listen to mine if you live within easy driving distance to Gaithersburg, Maryland.
  19. Dennis Murphy Audioholic Chief

    Dennis Murphy
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    The wall-spacing question has come up before. I'll try and remember to experiment with mine tonight. No sense speculating on something as easy to check as this. Back at you.
  20. Dennis Murphy Audioholic Chief

    Dennis Murphy
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    Well, I just finished comparing one Songtower 8" from a rear wall with one about 2 feet out. I have a very high quality remote-controlled A-B box that allows me to make instant comparisons. Since I only have 2 ST's, I couldn't investigate how the closer rear-wall placement affects imaging. But I could check for any boominess in the bass, and there wasn't any. If anything, I prefered the closer spacing. The bass seemed a little more solid. So I don't think there's a problem unless you jam the speaker up against the wall and completely mess up the flow from the rear opening.
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