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Thread: F3 versus F6 bass specs - is there a standard measurement?

  1. #1
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    Default F3 versus F6 bass specs - is there a standard measurement?

    Can these Spinorama.org bass extension numbers be in the right ballpark?

    eg 42Hz F6 for the Sierra-2 V2 on the Ascend specs page versus Spinorama 58.6Hz @ F3?

    And the original Sierra-2 Spinorama numbesr are an eye opening ~30Hz higher than V2? We knew the V2 improved on bass extension, but that gap seems more like a chasm? (I would have expected less than 10Hz difference).

    Ascend F3.jpg

    https://www.spinorama.org/scores.htm...d&reverse=true
    Last edited by jerryg; 04-27-2023 at 10:51 PM.

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    Default Re: F3 versus F6 bass specs - is there a standard measurement?

    Quote Originally Posted by jerryg View Post
    Can these Spinorama.org bass extension numbers be in the right ballpark?

    eg 42Hz F6 for the Sierra-2 V2 on the Ascend specs page versus Spinorama 58.6Hz @ F3?
    Hi Jerry,

    They look pretty darn close to me...

    I am not sure how Pierre (Spinorama.org) calculates bass extension. The site is completely automated and specifications are derived algorithmically.

    That stated, you do understand F3 and F6 are not the same thing, right? F3 is the -3dB point, F6 is the -6dB point.

    Quote Originally Posted by jerryg View Post
    And the original Sierra-2 Spinorama numbers are an eye opening ~30Hz higher than V2?
    There was never a V2 Sierra-2. Sierra-2 became Sierra-2EX with uses a much higher performance woofer that produces significantly deeper bass extension. That stated, Sierra-2 was amongst the first sets of speakers that were measured at ASR. The majority of these measurements on rear ported speakers and tower speakers produced wrong bass results. This was later corrected with assistance from Klippel engineers by changing the expansion point for lower frequencies. I experienced this same issue as well. It has been well documented and for the most part, resolved.

    https://www.audiosciencereview.com/f...rements.22493/

    It is rather unfair to many speakers tested in that first year but to ask Amir to go back and make changes is quite a bit of work.

    I am not concerned about it, Sierra-2 hasn't been manufactured for about 4 years now.

    We knew the V2 improved on bass extension, but that gap seems more like a chasm? (I would have expected less than 10Hz difference).
    From Sierra-2EX to Sierra-2EX V2, bass extension has not changed, but bass extension was significantly improved from Sierra-2 to Sierra-2EX, but not by as much as those numbers indicate due to what I stated above.
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    David Fabrikant
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    Default Re: F3 versus F6 bass specs - is there a standard measurement?

    Quote Originally Posted by davef View Post
    Hi Jerry,

    I am not concerned about it, Sierra-2 hasn't been manufactured for about 4 years now.
    Sorry I called the EX "V2". I'm aware of the HW changes and in my head I lose track of the nomenclature and just think of EX as version-two or generation-two. I understand the differences between Sierra-2/original and EX V1 (new woofer,xover) and EX V2 (Klippel optimized xover).

    I purchased my Sierra-2/originals during the clearance sale right before LX was announced so not that long ago. I'm trying to get a handle on how much (extension) ground was gained by the S2 EX since you've now explained that the S2/original Spinorama F3 number is not correct; ie it's not as bad as those numbers indicate (based on their numbers the same as the CBM-170)

    Or put another way, where would you estimate the S2/originals F3 (or F6) would wind up if they were Klippel measured as there is no "good" data out there AFAIK? That's why I inquired recently if you were going to do NFS scans on the Sierra-2/originals at some point. In this case, the correct absolute F3 may not be as informative as the relative numbers (ie comparing apples to apples).

    Sorry for the confusion on F3/F6. I was just pointing out that they (ASR) use F3 where you use (on your web short specs) F6 so obviously those two cannot be used for direct comparison.
    Last edited by jerryg; 04-28-2023 at 01:58 PM.

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    Default Re: F3 versus F6 bass specs - is there a standard measurement?

    Hi Jerry,

    Quote Originally Posted by jerryg View Post
    Sorry for the confusion on F3/F6. I was just pointing out that they (ASR) use F3 where you use (on your web short specs) F6 so obviously those two cannot be used for direct comparison.
    ASR does not post or list bass extension or any specifications for any speaker that I am aware of. Standard for anechoic bass extension is slowly moving towards F6. We also list F3 for all of our speakers, as well as average in-room bass extension.

    As far as NFS measurements for the Sierra-2, I would have to check so see if I ever took them. If I have not, I am sorry but I am not going to spend the necessary time to assemble a unit and run the tests. It is an entirely out of production model. If you want to determine bass extension in your room, simply download REW (Room EQ Wizard) - it is free, and you can purchase a decent calibrated mic very affordably. Then you will have the answers you are looking for.
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    David Fabrikant
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    Default Re: F3 versus F6 bass specs - is there a standard measurement?

    Quote Originally Posted by davef View Post
    ASR does not post or list bass extension or any specifications for any speaker that I am aware of. Standard for anechoic bass extension is slowly moving towards F6. We also list F3 for all of our speakers, as well as average in-room bass extension.
    I guess I should have said Spinorama.org which includes links to ASR reviews (and links to Ascend measurements, too). Spinorama.org lists all bass extension in the tabular format using F3 (without digging into it too much it's now not clear to me exactly where their measurement aggregations are originating from and, frankly, I no longer care).

    So, that was the crux of my question...why is F3 moving to F6 as the extension quick-spec? (if that is indeed the case). Perhaps there's a good reason for that.


    The practical take-away from all this is wondering whether the $800 to upgrade the S2/originals to EX would be worth it (and how much worth it). But, since I don't have much to make a comparison with but subjective comments I think I'll pass on that idea and just put that money toward new subs to better fill out the bottom-end of the S2/originals.


    Sierra-2 EX F6.jpg

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    Default Re: F3 versus F6 bass specs - is there a standard measurement?

    Hi Jerry,

    I am honestly doing my best to try and assist you.

    Quote Originally Posted by jerryg View Post
    Spinorama.org lists all bass extension in the tabular format using F3 (without digging into it too much it's now not clear to me exactly where their measurement aggregations are originating from and, frankly, I no longer care).
    No, Pierre (Spinorama.org) is very specific with regard to what he lists for each speaker as bass extension, and this closely follows Sean Olive's work.

    Here is our Sierra-2EXV2 as listed on Spinorama.org

    S2LFX.jpg

    You will note that it clearly lists "Bass Extension" as 42Hz. This is based on LFX "low frequency extension" LFX is a critical parameter in determining the preference score of a speaker. LFX = Log(F6). "Bass Extension" and LFX are the same thing, both represent the calculated bass extension of a speaker, just that LFX is logarithmically converted so that it can be used to help determine preference rating.

    The (-3dB) point you are seeing is not bass extension and is not listed as such. It is not used in any preference score calculations, my guess is that Pierre lists this just as a reference to speaker specs that still use this. There is no standard as to how -3dB is determined, -3dB from what? From the rated sensitivity of the speaker? From the measured sensitivity? -3dB from a specific frequency range? Or -3dB from where bass is flat? As I previously mentioned, I am not sure how Pierre is calculating this.

    So, that was the crux of my question...why is F3 moving to F6 as the extension quick-spec? (if that is indeed the case). Perhaps there's a good reason for that.
    It really isn't "moving"... As mentioned, LFX is low frequency extension - and always has been F6. This is becoming more standard because F3 (-3dB point) in determining the bass character of a speaker is rather useless.

    So why is F3 useless in describing the bass characteristic of a speaker? Depending on the design of the speaker, bass will roll off at a different rate. For example, take a typical acoustic suspension speaker vs a typical ported speaker. Let's say, for example, that the sealed speaker has an F3 of 60Hz while the ported speaker has an F3 of 50Hz. To the typical consumer, that ported speaker has the deeper bass extension but the reality is such that if directly comparing the 2 speakers, the sealed speaker with an F3 of 60Hz will produce much more bass, not just more bass, but deeper bass (assuming both speakers have relatively neutral responses).

    Why is this the case? Because the bass in a typical sealed speaker rolls off at a rate of 12dB / octave, while the ported rolls off at 24dB / octave.

    So to the typical consumer, the ported speaker with the F3 of 50Hz should have much deeper bass, but yet it actually doesn't, not even close. With the now standard LFX rating (F6), it better represents which speaker would sound like it has deeper bass, everything else being equal.

    This gets further complicated because of all the different bass alignments that are now possible (for typical sealed designs, Qtc of .5, or .7 or 1.2) and for ported, we have SBB4, SC4, QB3, B4, Be4 and many others)

    Frankly, I would prefer that F10 becomes the standard for "bass extension" as the lower down the roll off curve, referencing that to the -3dB point, one can easily determine the roll off rate and to a degree, the "Q" - which is extremely useful info if one does not have an accurate full range frequency response measurement.

    The practical take-away from all this is wondering whether the $800 to upgrade the S2/originals to EX would be worth it (and how much worth it). But, since I don't have much to make a comparison with but subjective comments I think I'll pass on that idea and just put that money toward new subs to better fill out the bottom-end of the S2/originals.
    Your decision on this should not be based on "Bass extension", especially a listed specification. The S2EXv2 is an entirely different speaker than the Sierra-2. It is simply a much better sounding speaker from top to bottom, with better directivity, a more neutral response, better dynamics, deeper bass extension and more midbass energy. You have plenty of info on hand to make this decision, including extremely detailed Klippel NFS measurements.
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    David Fabrikant
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    Default Re: F3 versus F6 bass specs - is there a standard measurement?

    Ok Jerry,

    Found a spin I did on the Sierra-2, went back in and adjusted the bass expansion point so that it matches what we currently use so this is a very fair comparison. (curves are adjusted to match sensitivity)

    s2EXv2 vs S2.png

    You will note Sierra-2EXV2 has quite a bit more energy in the range of 55Hz to about 120Hz. EXV2 also has more energy in the range from about 40Hz and lower, with the lower the frequency, the more output. Keep in mind there is nearly 6dB more output at 20Hz, which is 4 times the output, and 4dB more output at 70Hz (more than double the output)

    This is a good example of what I tried to describe to you regarding different bass roll off slopes and Q. If we were to simply rate either of these speakers using F3, F3 on Sierra-2 = 54Hz, Sierra-2EXV2 = 48Hz. Which makes them fairly close spec wise, but as you can see from the actual measurements, they aren't close at all as both the Q and roll off slope for the Sierra-2EXv2 is quite a bit different.
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    David Fabrikant
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    Default Re: F3 versus F6 bass specs - is there a standard measurement?

    Thanks for filling in the S2/original data. I agree that it's hard to plot a curve with one point.

    Spinorama Ascend S2 vx EX-2.jpg

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