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Can you hear below 30Hz?

Discussion in 'Home Cinema Speakers' started by Godfather, Feb 1, 2003.

  1. Godfather

    Godfather
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    I did a frequency sweep with AVIA the other day and found that my Velo CHT 15 stops making any audible sound below about 30Hz. Is that because it's outside the audible range?
     
  2. Apocalypse

    Apocalypse
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    The human ear is supposed to be able to hear sounds right down to 20Hz.

    The AVIA tone changes to more of a rumble below 30Hz and is not really heard as such, you should be ok down to the low 20s with the CHT-15.

    What volume was the amp at, at low levels you definitely won't hear anything below 30Hz even with a top of the line sub.
     
  3. Godfather

    Godfather
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    Thanks for the quick reply.

    Amp was on reasonaly high (don't have a sound meter so can't tell you exact levels) but I'll turn it up a bit more to see if I can hear anything.
     
  4. JSW

    JSW
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    I had the same problem, and after chatting with Eric and carrying out a few tests It turned out to be the tosh 900 !!!!!!

    When tested through my HTPC I could clearly hear down to 23Hz but on the Tosh only down to 30Hz.

    Bry
     
  5. tk2001

    tk2001
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    I have my speakers and sub all calibrated to 85dB at 00dB on my amp using a SPL meter and I did the exact same frequency sweep as you did using Avia.

    As I played the frequency sweep at reference level, I had my SPL meter handy and found that between 20hz - 30hz, the CHT-15 gave an output of 75dB - 85dB. Even though the low frequencies aren't that audible, trust me its there.

    Incidently, between 35hz to 40hz, the sub gave a clean output of 105dB:eek:
     
  6. tk2001

    tk2001
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    You mean the Tosh that I now own? :)

    Does this mean that the Tosh stops frequencies below 30hz from being heard?
     
  7. JSW

    JSW
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    Yes the one you now own ;)

    I couldn't explain why it does it.

    Maybe try emailing Tosh and asking them why there doesn't seem to be any output below 30Hz.

    Bry
     
  8. tk2001

    tk2001
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    Between 20hz - 30hz, I get between 75dB - 85dB on the SPL meter.

    Does this mean that I am getting some kind of output below 30hz?
     
  9. JSW

    JSW
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    Yes but its over -10db lower than 30Hz and up which is half the volume !!!
     
  10. tk2001

    tk2001
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    I've just double checked the frequency sweep again and can gladly report back that I can indeed hear sound from 30hz all the way down to 23hz.:) Below 23hz, the sound becomes completely in-audible.

    I tried the frequency sweep on another dvd-player can report the results being exactly the same. So I guess my Tosh is ok then. ;)
     
  11. Steve.EX

    Steve.EX
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    Can i say that when using my Tosh 900 with a Stryke test tone cd (full scale 16bit pcm) there is "audible" presence down to around 12hz. I woud humbly suggest that it is not a Tosh problem.

    Steve.
     
  12. Jase

    Jase
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    As is mine.:smashin: Maybe JSW had a problem with his:confused:
     
  13. tk2001

    tk2001
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    The Tosh that JSW use to own IS NOW mine!:laugh:

    Still, don't seem to have the same problem that JSW had - not hearing anything below 30hz.

    Jase, have you ever measured the Avia frequency sweep on your CHT-15 using a SPL meter? I only seem to be able to get around 75dB at 20hz and a peak of 105dB at 38hz setting at the listening position - which is 12 feet away from the sub.
     
  14. Jase

    Jase
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    Not tried it, used the sweeps but never bothered to measure them. I´ll give it a go this weekend and let you know.:)
     
  15. greenthumb

    greenthumb
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    Would it have anything to do with the AVIA dvd being reg1.
    Does the Tosh give the same readings with region 2 test dvd?
    Just a stab in the dark, probably miles off, just an idea.
     
  16. Jase

    Jase
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    Unlikely. You´d need to compare an R2 AVIA disc (which doesn´t exist!) to do a true comparison.
     
  17. JSW

    JSW
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    Jase,

    listen @ 75db and then tell me you don't think youv'e gone deaf when the sweep gets to 30Hz and you stop hearing ;)

    Bry
     
  18. Godfather

    Godfather
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    I really hope there isn't a problem with my Tosh 900. JSW and tk2001 were you using the coaxial or optical output? In case that makes a difference?
     
  19. JSW

    JSW
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    I was using the multichannel analogue outputs.

    Test was made using Denon's Sonic Boom DVD Audio setup Disc.

    The sweep on this disc goes down to 1Hz and has over 31 other test tones.

    Bry
     
  20. tk2001

    tk2001
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    I have my Tosh pluged into my amp via a Ixos digital coaxial cable.

    Don't worry Godfather , the Tosh does give out an audible output level below 30hz but in order to hear it, you need to have the frequency sweep running at reference level.
     
  21. Godfather

    Godfather
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    Thanks for the reassurance. I feel a bit better now. :)
     
  22. tk2001

    tk2001
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    Jase, did you manage to get time to do some measurements for the frequency sweeps?
     
  23. Jase

    Jase
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    Yes. All channels balanced to 85db with amp set to 0db. Connected to amp via digital coaxial output.

    75hz - 80db
    70hz - 80db
    65hz - 88db
    60hz - 94db
    65hz - 95db
    50hz - 97db
    45hz - 97db
    40hz - 99db
    35hz - 100db
    30hz - 95db
    25hz - 86db
    20hz - 85db

    Also tried it with the THX Ultra 2 Boundary Gain Compensation switched ON.

    75hz - 80db
    70hz - 80db
    65hz - 86db
    60hz - 92db
    55hz - 93db
    50hz - 94db
    45hz - 95db
    40hz - 93db
    35hz - 92db
    30hz - 89db
    25hz - 80db
    20hz - 75db

    Make of that what you will.:)
     
  24. tk2001

    tk2001
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    Thanks Jase. If I get the chance, I'll do the same and post the results when I have time.:)

    BTW, how do you have your sub calibrated? I have mine calibrated at 85dB to the center speaker, which is balanced with with rest of the speakers.

    Now you know that you are losing 10dB at 20hz and a few dB at the rest of the frequency range with the THX Ultra 2 Boundary Gain Compensation switched ON, are you going to avoid using it in the future? (assuming you do use it now and again).
     
  25. Jase

    Jase
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    Sub is calibrated to 85db as well, same as all the other channels. I don´t usually have the Boundary Gain Compensation switched on, I just wondered what effect it had on the response. Listened to couple of films with it ON and then OFF. I prefer it left OFF as it reduces the bass you "feel" too much when its ON.
     
  26. tk2001

    tk2001
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    Well, here are my frequency sweep readings:
    I've stuck your figures next to mine for comparative sakes - mine is on the left:

    95hz - 82dB ------------------
    90hz - 84dB ------------------
    85hz - 81dB ------------------
    80hz - 75dB ------------------
    75hz - 81db ------------------ 75hz - 80db
    70hz - 90db ------------------ 70hz - 80db
    65hz - 89db ------------------ 65hz - 88db
    60hz - 87db ------------------ 60hz - 94db
    65hz - 92db ------------------ 65hz - 95db
    50hz - 95db ------------------ 50hz - 97db
    45hz - 98db ------------------ 45hz - 97db
    40hz - 105db ---------------- 40hz - 99db
    35hz - 100db ---------------- 35hz - 100db
    30hz - 94db ------------------ 30hz - 95db
    25hz - 84db ------------------ 25hz - 86db
    20hz - 75db ------------------ 20hz - 85db


    I'm a bit envious that you are getting 10dB more than me at 20hz. :rolleyes:
     
  27. Jase

    Jase
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    They´re pretty similar. Its probably Room Gain thats giving me the higher output at 20hz. It was the same when I measured my old Rel Q200 last year.
     
  28. tk2001

    tk2001
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    Now all we need is for Smurfin to post a frequency sweep reading for his servo-15. :)
     
  29. sinister_stu

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    A difference of 3dB is actually quite a big difference. 3dB difference between two signals means that one is twice the magnitude of the other. However, due to the sensitivity of the human ear, a difference of 10dB is perceived as being twice as loud. So there really is quite a big difference.
     
  30. HotblackDesiato

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    I'm a bit envious your're both getting 10-20dB more than me!

    Hz--------dB
    80--------81.4
    71--------82.7
    63--------80.1
    56--------88.8
    50--------97.4
    45--------91.5
    40--------88.9
    36--------86.2
    31.5-----73.4
    28--------68.9
    25--------69.3
    20--------67.7
    18--------62.3
    16--------58.1

    Background 48.2dB, sub calibrated at 75dB flat with the rest of the speakers.

    spence
     

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