LS50/70/90 - did Polk lie about bass specs?

Hi all, have been lurking here for quite awhile and enjoy everyone's posts and allegiance to Polk. I have at least 8 Polk speakers with the flagship being a pair of LS50 purchased in 1992 or '93. All I could afford at the time was the 50 but that's a post for a different day. Anyway I was thinking about upgrading them and so looking at specs again and the bass specs are, in a word, unbelievable: 30hz for two 6.5" drivers. You can spend hundreds of dollars for a subwoofer these days with that spec; and the ES60 and XT70 speakers today are beefier that are rated higher than that. So, my question is, did this series have magical properties, or was bass response measured differently then, or what explains it? I certainly don't want to give up anything at the low end if I upgrade them.... xqy0z842v4k1.jpg
LR: Polk R600, SVS SB-2000 Pro, Marantz NR1200 pre, Emotiva BASX A2 amp, Denon 600NE CD, JVC L-A11 turntable.FR: Polk TSI-400, Polk PSW110 center, Polk R1 surrounds, Onkyo TX-NR656 receiver.Home office: Polk LS50, Yamaha NR-602 receiver, JVC KD-V100 cassette, Sony TC-558 R2R.In reserve: Technics SA-203 receiver"Y'know? To truly love some silly little piece of music, or some band, so much that it ... hurts."

Comments

  • PS didn't mean to be so provocative with the title but it doesn't seem to add up....
    LR: Polk R600, SVS SB-2000 Pro, Marantz NR1200 pre, Emotiva BASX A2 amp, Denon 600NE CD, JVC L-A11 turntable.FR: Polk TSI-400, Polk PSW110 center, Polk R1 surrounds, Onkyo TX-NR656 receiver.Home office: Polk LS50, Yamaha NR-602 receiver, JVC KD-V100 cassette, Sony TC-558 R2R.In reserve: Technics SA-203 receiver"Y'know? To truly love some silly little piece of music, or some band, so much that it ... hurts."
  • mhardy6647
    mhardy6647 Posts: 33,786
    edited June 2022
    That 30 Hz 'spec' is probably at -10 dB relative to midrange output -- or it may just indicate there is some audible output at that frequency.

    Note the -3dB point is spec'd at 45 Hz.
  • nooshinjohn
    nooshinjohn Posts: 25,407
    PresidentPolk, most certainly you are not.
    The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD

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  • mhardy6647
    mhardy6647 Posts: 33,786
    PresidentPolk, most certainly you are not.

    Perhaps an homage to the late, great President James K. Polk...?
    vo9n6w6t46kz.png
  • xschop
    xschop Posts: 5,000
    Black lab-coat and all.
    Don't take experimental gene therapies from known eugenicists.
  • lightman1
    lightman1 Posts: 10,788
    From colonial North Carolina
  • mhardy6647 wrote: »
    PresidentPolk, most certainly you are not.

    Perhaps an homage to the late, great President James K. Polk...?
    vo9n6w6t46kz.png

    Bingo. Tho admittedly I didn't put much thought into it....
    LR: Polk R600, SVS SB-2000 Pro, Marantz NR1200 pre, Emotiva BASX A2 amp, Denon 600NE CD, JVC L-A11 turntable.FR: Polk TSI-400, Polk PSW110 center, Polk R1 surrounds, Onkyo TX-NR656 receiver.Home office: Polk LS50, Yamaha NR-602 receiver, JVC KD-V100 cassette, Sony TC-558 R2R.In reserve: Technics SA-203 receiver"Y'know? To truly love some silly little piece of music, or some band, so much that it ... hurts."
  • mhardy6647 wrote: »
    That 30 Hz 'spec' is probably at -10 dB relative to midrange output -- or it may just indicate there is some audible output at that frequency.

    Note the -3dB point is spec'd at 45 Hz.

    Thank you, this is a constructive response. The current specs for XT70 lists "Total Frequency Response" but doesn't include a "3dB" spec. So it's difficult (for me) to make an apples-to-apples comparison.
    LR: Polk R600, SVS SB-2000 Pro, Marantz NR1200 pre, Emotiva BASX A2 amp, Denon 600NE CD, JVC L-A11 turntable.FR: Polk TSI-400, Polk PSW110 center, Polk R1 surrounds, Onkyo TX-NR656 receiver.Home office: Polk LS50, Yamaha NR-602 receiver, JVC KD-V100 cassette, Sony TC-558 R2R.In reserve: Technics SA-203 receiver"Y'know? To truly love some silly little piece of music, or some band, so much that it ... hurts."
  • mhardy6647
    mhardy6647 Posts: 33,786
    xschop wrote: »
    Black lab-coat and all.

    That was excellent. :D
  • mhardy6647
    mhardy6647 Posts: 33,786
    edited June 2022
    mhardy6647 wrote: »
    That 30 Hz 'spec' is probably at -10 dB relative to midrange output -- or it may just indicate there is some audible output at that frequency.

    Note the -3dB point is spec'd at 45 Hz.

    Thank you, this is a constructive response. The current specs for XT70 lists "Total Frequency Response" but doesn't include a "3dB" spec. So it's difficult (for me) to make an apples-to-apples comparison.

    See if you can find tests of either or both loudspeakers on line. Stereophile, love 'em or hate 'em, does a pretty good job of quantitative assessment of loudspeaker performance (thanks to John Atkinson). Again, love 'em or hate 'em, audiosciencereview also provides data using a very consistent framework for the loudspeakers they test (i.e., he tests). Two other pretty good resources for frequency response data: https://www.erinsaudiocorner.com/ and https://www.soundstagenetwork.com/index.php?option=com_content&view=article&id=16&Itemid=140

    Remember that the actual in-room performance of any loudspeaker will vary from anechoic measurements.

    If you can find measurements of both speakers you're asking about made using the same approach, you'll get a pretty good apples to apples comparison of the two with respect to frequency response. Won't really tell you too much about how they sound, though.



  • mhardy6647
    mhardy6647 Posts: 33,786
    edited June 2022
    Here, for example, are some 'apples to apples' FR data for Polk's new(ish) R200 (shown with... umm... President Polk in the mash-up posted earlier) in comparison to a rather well-respected studio monitor (Genelec -- mislabled as "Genelect" in the graph).
    https://www.genelec.com/studio-monitors

    The -3dB point for the R200 looks like about 50 Hz, and the -10 dB point is about 37 Hz

    1mhi4rqdc7kb.png
    https://www.audiosciencereview.com/forum/index.php?threads/polk-reserve-r200-spinorama-and-measurements-a-really-nice-surprise.23502/

    51665522194_a5640772b2_b.jpg
  • mhardy6647
    mhardy6647 Posts: 33,786
    edited June 2022
    Oh -- and in terms of what's possible vs. what's practical when it comes to loudspeaker bass extension, there's an old saying known as Hoffman's Iron Law.
    Here's a paraphrase:
    When it comes to loudspeakers:
    • Small size
    • High sensitivity
    • Deep bass extension

    Pick two
    :)
  • MHardy, thanks so much and your first (or second) response led me to an older post (https://forum.polkaudio.com/discussion/189478/speaker-spec-question-3db-vs-other-measurement) that I couldn't find before and illustrates very well how the specs are slippery at best. I wish it were as easy to audition speakers as it used to be. So hard now to find a good listening room in retail.
    LR: Polk R600, SVS SB-2000 Pro, Marantz NR1200 pre, Emotiva BASX A2 amp, Denon 600NE CD, JVC L-A11 turntable.FR: Polk TSI-400, Polk PSW110 center, Polk R1 surrounds, Onkyo TX-NR656 receiver.Home office: Polk LS50, Yamaha NR-602 receiver, JVC KD-V100 cassette, Sony TC-558 R2R.In reserve: Technics SA-203 receiver"Y'know? To truly love some silly little piece of music, or some band, so much that it ... hurts."
  • VR3
    VR3 Posts: 28,636
    Ymmv, but when I see total frequency response I assume -10db.

    So like 30hz -10db is probably closer to like 45hz -3db
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • mhardy6647
    mhardy6647 Posts: 33,786
    VR3 wrote: »
    Ymmv, but when I see total frequency response I assume -10db.

    So like 30hz -10db is probably closer to like 45hz -3db

    Yup -- and good rule of thumb, I'd say.
  • Gardenstater
    Gardenstater Posts: 4,459
    edited June 2022
    I always forget his name but the Polk Marketing Manager (edit - Paul DiComo) RIP who wrote an article (which I can't find now) stated -9dB when they gave no qualifiers.

    Found it -

    How Polk Specifies Frequency Response
    Polk Audio publishes two frequency response specifications: “Overall” and “-3dB.” “Overall” describes the frequency range limits of the speaker within an amplitude drop off of 9dB. Any frequency reproduced more than 9dB down from the rest of the frequencies will contribute little to the sound. The “-3dB” spec describes the frequency range limits of the speaker within an amplitude drop off of 3dB.

    https://www.ecoustics.com/articles/understanding-speaker-frequency-response/
    George / NJ

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  • engie490
    engie490 Posts: 431
    Here's a review of the LS70 from Stereo Review:

    http://www.hifi-classic.net/review/polk-audio-ls-70-118.html

    A snippet about the bass response:

    "The close-miked response of the woofers from 20 to 500 Hz combined with the room curve to produce a composite frequency response of ± 5 dB from 42 to 20,000 Hz. Including the port radiation, the bass extended down to 20 Hz within the same limits, but under actual listening conditions the effective bass extension will depend on the speakers' environment. In our room, the audible response was clean and usable down to about 35 to 40 Hz."

    That tracks with Polk's "-3db Limits" vice the "Overall Frequency Response". YMMV.
    Alon Petite / Infinity 1.2S / Coda Continuum / Counterpoint SA5000 / Oppo BDP-105D / Technics SP-15 w/SAEC WE-308SX & Ortofon AS-309 arms / Ikeda 9C2 & Dynavector XX2 Mk II carts
  • Thanks for all the thoughtful comments and research!
    LR: Polk R600, SVS SB-2000 Pro, Marantz NR1200 pre, Emotiva BASX A2 amp, Denon 600NE CD, JVC L-A11 turntable.FR: Polk TSI-400, Polk PSW110 center, Polk R1 surrounds, Onkyo TX-NR656 receiver.Home office: Polk LS50, Yamaha NR-602 receiver, JVC KD-V100 cassette, Sony TC-558 R2R.In reserve: Technics SA-203 receiver"Y'know? To truly love some silly little piece of music, or some band, so much that it ... hurts."