• 11-13-2009, 05:38 AM
    audio amateur
    Just ordered a Radio Shack SPL meter
    ...from a UK subwoofer maker. Good price too. I'm well excited! Have never owned one and will finally be able to have an idea of SPLs that are hitting my ears. I'll probably be taking it everywhere with me, organ recitals, clubs, etc etc... More importantly I will be able to fine tune my HT and eventually EQ my sub when get around to purchasing a BFD (most likely).

    I know some of you own one and perhaps you can tell me of your experience with it (accuracy, problems, settings, recommendations for using it etc)

    AA.
  • 11-13-2009, 06:58 AM
    E-Stat
    Quote:

    Originally Posted by audio amateur
    More importantly I will be able to fine tune my HT and eventually EQ my sub when get around to purchasing a BFD (most likely).

    Congrats. It is indeed a very useful tool. It's Achilles heel is in the high frequency response where its accuracy is poor. The low end, however, is pretty close but you still need to find the correction curves for your particular model.

    I find it works wonderfully for optimizing bass response. It seems many folks like boosted bass over a more neutral response. You can determine where the truth lies. What you need now is two more things:

    1) Test tones. I have a set of Stereophile test CDs and use freebee tones found here.
    2) Correction curve for your unit. I have the current digital version and plugged the values into this Excel spreadsheet which provides a visual outcome. Note that this supports third octave response figures only and the actual response one hertz at a time will necessarily be more jagged. :)

    Good luck!

    rw
  • 11-13-2009, 07:07 AM
    Geoffcin
    Quote:

    Originally Posted by audio amateur
    ...from a UK subwoofer maker. Good price too. I'm well excited! Have never owned one and will finally be able to have an idea of SPLs that are hitting my ears. I'll probably be taking it everywhere with me, organ recitals, clubs, etc etc... More importantly I will be able to fine tune my HT and eventually EQ my sub when get around to purchasing a BFD (most likely).

    I know some of you own one and perhaps you can tell me of your experience with it (accuracy, problems, settings, recommendations for using it etc)

    AA.

    Best money you ever invested in audio-wise!

    Like E-Stat said, the unit looses some accuracy in the upper treble, but for finding and adjusting your speakers for proper placement it is the bomb.

    Wait till you see how room nodes affect bass performance!
  • 11-13-2009, 07:41 AM
    audio amateur
    Quote:

    Originally Posted by E-Stat
    Congrats. It is indeed a very useful tool. It's Achilles heel is in the high frequency response where its accuracy is poor. The low end, however, is pretty close but you still need to find the correction curves for your particular model.

    I find it works wonderfully for optimizing bass response. It seems many folks like boosted bass over a more neutral response. You can determine where the truth lies. What you need now is two more things:

    1) Test tones. I have a set of Stereophile test CDs and use freebee tones found here.
    2) Correction curve for your unit. I have the current digital version and plugged the values into this Excel spreadsheet which provides a visual outcome. Note that this supports third octave response figures only and the actual response one hertz at a time will necessarily be more jagged. :)

    Good luck!

    rw

    I have indeed read about some inacurracy in the lower octaves (which is something that will be crucial for sub EQing), and have a correction list already. I'll have a look at the spreadsheet.

    As for test tones, will any test tones generator program suffice? I have one on my winISD pro program which is used to model subwoofer enclosures as you probably know. I actually have several of these test tone generators. Will they do?
  • 11-13-2009, 07:46 AM
    audio amateur
    Quote:

    Originally Posted by Geoffcin
    Best money you ever invested in audio-wise!

    Like E-Stat said, the unit looses some accuracy in the upper treble, but for finding and adjusting your speakers for proper placement it is the bomb.

    Wait till you see how room nodes affect bass performance!

    Thanks, I hear they do come in handy.
    I've no doubt that room acoustics affect bass performance a lot, I can clearly hear it.

    Have either of you used the REW software? http://www.hometheatershack.com/roomeq/
    I can't say I remember anyone at AR mentioning it, but I do on AVforums.co.uk which is UK based.
  • 11-13-2009, 08:30 AM
    E-Stat
    Quote:

    Originally Posted by audio amateur
    As for test tones, will any test tones generator program suffice? I have one on my winISD pro program which is used to model subwoofer enclosures as you probably know. I actually have several of these test tone generators. Will they do?

    Should do fine. Haven't tried the Room Wizard setup yet. Looks pretty cool! Apparently, you wire the SPL meter to your laptop soundcard and pipe it back through preamp / processor. Might have to try that.

    rw
  • 11-13-2009, 08:31 AM
    GMichael
    Congrats. It's a very useful tool. I bought the test CD from Rives. It has been, "calibrated to compensate for the non-linearity (particularly in the lower octaves) of the Radio Shack SPL meter." http://www.rivesaudio.com/software/softframes.html

    Just don't play it too loud above 4 kHz. Sine waves are brutal on tweeters. (don't ask)
  • 11-13-2009, 12:00 PM
    Woochifer
    Now that you have the SPL meter, it's time to put the thing to good use. The most basic function is simply verifying the level settings on your home theater system.

    The more advanced function, as everybody else has pointed out, is using it for your subwoofer. Might as well order the BFD now, because once you look at those peaks and dips in your lower frequency measurements, you'll be itching to fix them ASAP.

    Quote:

    Originally Posted by audio amateur
    Thanks, I hear they do come in handy.
    I've no doubt that room acoustics affect bass performance a lot, I can clearly hear it.

    Have either of you used the REW software? http://www.hometheatershack.com/roomeq/
    I can't say I remember anyone at AR mentioning it, but I do on AVforums.co.uk which is UK based.

    I've tried it before. It has a lot of functionality built into it and definitely shortens the amount of time needed to do a parametric EQ calibration. But, I liked the bass settings better doing manual measurements and setting the EQ filters myself. The REW application prescribed three EQ adjustments, and I found that the resultant bass sounded a bit hollow compared to my previous settings. But, it's still a huge improvement over the sub's sound out-of-the-box.

    The experts over at HT Shack recommend using the calibrated Behringer mic with the REW app. I simply plugged the mic output from my Radio Shack SPL meter into a laptop sound card, and used the REW's frequency adjustment chart. So, my results might differ quite a bit with a more accurate mic.

    I'd already taken the time to do the measurements and EQ adjustments manually, so the REW app wasn't especially helpful in my case. But, if you've never done any of this before, the REW app will save you about 90 minutes.

    The BFD thread below has a few comments on the REW application.

    http://forums.audioreview.com/home-theater-video/bfd-installation-setup-help-29673.html
  • 11-13-2009, 12:37 PM
    E-Stat
    Quote:

    Originally Posted by Woochifer
    But, it's still a huge improvement over the sub's sound out-of-the-box.

    The more time consuming task for me was finding the optimum high pass setting for the satellites in my HT. Since the room modes are beyond the normal range of subs (up to 160 hz), I experimented with different settings on the receiver: 80, 120, and 200 hz. I ended up using the 200 hz setting and running the subs wide open to meet them. This in contrast to the usual practice of limiting the sub somewhere between 50 hz and 80 hz. That enabled the EQ to encompass a wider range and participate in correcting more of the room's issues. That is why I am a fan of using stereo subs. It also provided more headroom for the satellites.

    Upstairs where I have no need for a sub with the stats, the SPL meter helped me position the speakers and the bass traps for the most neutral response.

    rw
  • 11-13-2009, 12:38 PM
    JoeE SP9
    Below is an Excel spreadsheet with the corrections for the TRS SPL meter.

    I have the REW software but haven't used it yet.


    http://i615.photobucket.com/albums/t...ESP9/excel.jpg
  • 11-13-2009, 12:53 PM
    E-Stat
    Quote:

    Originally Posted by JoeE SP9
    Below is an Excel spreadsheet with the corrections for the TRS SPL meter.

    As I indicated, there is no ONE Radio Shack meter. I've found three different calibrations for the old analog, new analog and new digital. The corrections for the new digital are quite different. Your table reflects the "old analog".

    Various correction curves

    rw
  • 11-13-2009, 12:53 PM
    Geoffcin
    Quote:

    Originally Posted by E-Stat
    That is why I am a fan of using stereo subs.


    rw

    Stereo subs? Natch!

    (although the maggies are now "stand alone" )
  • 11-13-2009, 01:28 PM
    audio amateur
    Quote:

    Originally Posted by Woochifer
    The more advanced function, as everybody else has pointed out, is using it for your subwoofer. Might as well order the BFD now, because once you look at those peaks and dips in your lower frequency measurements, you'll be itching to fix them ASAP.

    I've tried it before. It has a lot of functionality built into it and definitely shortens the amount of time needed to do a parametric EQ calibration. But, I liked the bass settings better doing manual measurements and setting the EQ filters myself.

    Same here, I like doing things manually and will probably not use the REW.

    I would buy a BFD now, however, I am not home (France) during term time as I am studying abroad (England), and I cannot do much until I'm home during the holidays. I will most likely have everything ready by next summer at which point I will hopefully be tweaking the heck out of a sonosub which I plan to make around that time.
  • 11-13-2009, 01:52 PM
    JoeE SP9
    Quote:

    Originally Posted by E-Stat
    As I indicated, there is no ONE Radio Shack meter. I've found three different calibrations for the old analog, new analog and new digital. The corrections for the new digital are quite different. Your table reflects the "old analog".

    Various correction curves

    rw

    Thanks E-Stat. I forgot about that. I have one of the old analog ones. I've had it more than twenty years.
  • 11-13-2009, 03:32 PM
    E-Stat
    Quote:

    Originally Posted by JoeE SP9
    Thanks E-Stat. I forgot about that. I have one of the old analog ones. I've had it more than twenty years.

    No problemo. I was late to the party and only got mine a couple years back where I did a fair amount of research on them. It was indispensable for positioning the stats in my current house.

    rw
  • 11-13-2009, 03:35 PM
    audio amateur
    Quote:

    Originally Posted by GMichael
    Congrats. It's a very useful tool. I bought the test CD from Rives. It has been, "calibrated to compensate for the non-linearity (particularly in the lower octaves) of the Radio Shack SPL meter." http://www.rivesaudio.com/software/softframes.html

    Just don't play it too loud above 4 kHz. Sine waves are brutal on tweeters. (don't ask)

    Thanks. I think Ill save the money and make the compensation myself:)