LS50/70/90 - did Polk lie about bass specs?
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PresidentPolk
Posts: 11
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.... 
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."
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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."
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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.
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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
“When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson -
nooshinjohn wrote: »PresidentPolk, most certainly you are not.
Perhaps an homage to the late, great President James K. Polk...?
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Black lab-coat and all.Don't take experimental gene therapies from known eugenicists.
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From colonial North Carolina
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mhardy6647 wrote: »nooshinjohn wrote: »PresidentPolk, most certainly you are not.
Perhaps an homage to the late, great President James K. Polk...?
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." -
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PresidentPolk wrote: »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.
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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
https://www.audiosciencereview.com/forum/index.php?threads/polk-reserve-r200-spinorama-and-measurements-a-really-nice-surprise.23502/
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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
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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."
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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. -
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. -
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
Polk 7B main speakers, std. mods+ (1979, orig owner)
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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.Sonus Faber Liuto / Coda Continuum / Anthem STR Preamplifier / 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."
