Subwoofer measurements

Discussion in 'Subwoofers' started by lmccauley, Apr 4, 2002.

  1. lmccauley

    lmccauley
    Well-known Member

    Joined:
    Oct 24, 2000
    Messages:
    3,553
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Newcastle
    Ratings:
    +340
    I just got a subwoofer today (traded with T_Strife), and quickly set it up using the high-level inputs (till I get a long enough phono lead).

    I then used the test tones and spreadsheet here along with my trusty SPL to measure the frequency response.

    I've attached a graph of the results (my sub is in dark blue - the pink line is for an EQ-ed sub from the snapbug page).

    Next step is to make up a long enough phono, calibrate it properly (I had to guesstimate by ear for the Volume and low-pass settings), move it around a bit till it sounds better, then take some more measurements and see if I've made it worse :rolleyes:.

    Cheers,
    Liam
     

    Attached Files:

  2. Jase

    Jase
    Distinguished Member

    Joined:
    Mar 16, 2001
    Messages:
    10,735
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    United Kingdom
    Ratings:
    +2,522
    Hi Liam

    Handy those test tones arent they??:)

    You need Ramius to comment on your results from what I can gather its the dips that cant be sorted out, you´ll have to move the sub, you can trim the peaks with an equaliser though.

    I´m a bit jammy with my placement as I get a pretty good response right throughout the subs range.:D

    Get some marble slabs on it!!!;)
     
  3. Ian J

    Ian J
    Banned

    Joined:
    Aug 6, 2001
    Messages:
    25,631
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Ratings:
    +4,906
    Liam,

    I read it three times but have to give up now as I still don't get the joke.
     
  4. lmccauley

    lmccauley
    Well-known Member

    Joined:
    Oct 24, 2000
    Messages:
    3,553
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Newcastle
    Ratings:
    +340
    Well, if you look at one of the tall peaks, it looks like a... you know... thingy :blush:
     
  5. lmccauley

    lmccauley
    Well-known Member

    Joined:
    Oct 24, 2000
    Messages:
    3,553
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Newcastle
    Ratings:
    +340
    Jase,

    Yeah, I saw your results - lucky b...er!

    I'm going to make up a long phono lead this morning (I have 10m of cable) and move it around this afternoon and do more measurements. Then I might PM Ramius and ask for some advice on what to do next.

    Cheers,
    Liam
     
  6. Couch Potato

    Couch Potato
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Liam, Jase,

    I too dowloaded the test tones and burnt them onto a CDR, but I've got lots of problems trying to replay them, 1stly my DVD player doesn't play CDR's :( 2ndly I tried it on my CD player on HiFi in another room and the replay quality was awful, lots of pops and crackles and then every track after 10 appeared to have an error.

    Did you guys have any problems?

    Steve
     
  7. Jase

    Jase
    Distinguished Member

    Joined:
    Mar 16, 2001
    Messages:
    10,735
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    United Kingdom
    Ratings:
    +2,522
    Steve

    Had no problems with mine, used them with a Toshiba 210 (plays cdr´s, mp3 etc). Didnt bother trying my cd players as it worked ok on the dvd. A few of the test tones from 70hz upwards didnt download properly first time but I´ve got them ok now.

    Didnt get any crackles or pops either.

    Not the perfect solution, but could you not borrow someones dvd player for a while??
     
  8. Couch Potato

    Couch Potato
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    I'll use my CD player, I'm re-burning the CD while we speak to try and get a better copy.

    Thanks.

    Steve
     
  9. lmccauley

    lmccauley
    Well-known Member

    Joined:
    Oct 24, 2000
    Messages:
    3,553
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Newcastle
    Ratings:
    +340
    Steve,

    I didn't have any problems at all - downloaded the 21 tones at work on a fast connection, burnt the MP3's along with some other files onto a CD-R, took it home, burnt the tones as a CD (which confused me - I assumed it would have left them as MP3) using Nero and they all worked fine.

    I've hooked up by low-level inputs, set the speaker size to small, set sub present, calibrated all speakers to 75db and taken some more measurements (see attached file).

    • Dark blue line = original measurements (high level only - speakers set to large);
    • Pink line = original measurements (low level only - speakers set to small);

    It looks like 19-56Hz is about 10db higher than 80Hz-. Think I'll listen to some films and music and see whether this rings true or not.

    Cheers,
    Liam
     

    Attached Files:

  10. Mark Grant

    Mark Grant
    Active Member

    Joined:
    Oct 27, 2000
    Messages:
    1,368
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    63
    Location:
    East Yorkshire, England
    Ratings:
    +171
    Liam,

    You could sell that Rollercoaster design to Alton Towers ;)

    Mark.
     
  11. Taz

    Taz
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Heres mine.......


    Taz.:cool:
     

    Attached Files:

  12. lmccauley

    lmccauley
    Well-known Member

    Joined:
    Oct 24, 2000
    Messages:
    3,553
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Newcastle
    Ratings:
    +340
    Taz - looks nice and flat from 18-50Hz. Very impressive.

    The SP level in that range seems to be about 20db higher than the 160Hz area, though. Do you not find the bass a bit to intrusive?

    I've played around with my bass level and reduced it by about 7db and that seems better with music, certainly. Will probably watch something like Pitch Black tonight, so that should give me an idea of the AV performance. I might try sticking it in the corner of the room and measuring that. See if it surpasses even Alton Towers ;).

    Cheers,
    Liam
     
  13. Ian J

    Ian J
    Banned

    Joined:
    Aug 6, 2001
    Messages:
    25,631
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Ratings:
    +4,906
    I thought that you were an intellectual !!
     
  14. lmccauley

    lmccauley
    Well-known Member

    Joined:
    Oct 24, 2000
    Messages:
    3,553
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Newcastle
    Ratings:
    +340
    Claudia Black in leather.

    What can I say :D.

    Anyway, it's a lads video night and the, er, material from DVD Box Office may have been delayed by customs... :eek:

    Cheers,
    Liam
     
  15. General Skanky

    General Skanky
    Active Member

    Joined:
    Jul 28, 2000
    Messages:
    4,253
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    71
    Location:
    Colchester
    Ratings:
    +44
    Been reading and reading and I think I've got it; the aim is to achieve a flat response across the freq range from 20Hz to say 100Hz for a sub at a ref level of 75db as used by Liam? Then, the same for all the other speakers so as all act in tandem with each other at the same frequencies?

    I know it won't be perfect due to many things like room shape, but that is the ideal?
     
  16. marcoeser

    marcoeser
    Standard Member

    Joined:
    Jul 17, 2000
    Messages:
    342
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    21
    Ratings:
    +1
    Hi,
    I was playing around with these tones last night. I found I have a mount everest of a peak at 40hz 20+ db higher than anything alse. I have some some small dips and peaks also but that 40hz mountain really worries me. :(

    The blue line is my sub and fronts (KEFs 55) and REL strata III connected at high level. The pink line is my kefs only.

    What advise do you give to flatten the peaks and smooth over the dips?

    marc :)
     

    Attached Files:

  17. Jase

    Jase
    Distinguished Member

    Joined:
    Mar 16, 2001
    Messages:
    10,735
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    United Kingdom
    Ratings:
    +2,522
    Hi Marc

    You either need to reposition the sub or buy something like the Feedback Destroyer Pro which acts as a Parametric Equaliser so can sort out problems. Just remember you can trim Peaks but you cant really do anything about Dips (Nulls), you´ll have to move the sub.

    Heres the Destroyer Pro

    http://www.behringer.com/02_products/prodindex.cfm?id=DSP1124P&lang=eng

    Cheers

    Jase
     
  18. lmccauley

    lmccauley
    Well-known Member

    Joined:
    Oct 24, 2000
    Messages:
    3,553
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Newcastle
    Ratings:
    +340
    Basically - yes.

    Ideally, you want a flat response from 20Hz-20kHz, but we're really just trying to sort out the sub here.

    A competently designed CD/DVD player, interconnects, amplifier and speaker cable will give almost ruler flat measurements over the complete 20Hz-20kHz range. Speakers and the room are the components that make by far the biggest difference to the frequency response.

    Cheers,
    Liam
     
  19. Ian J

    Ian J
    Banned

    Joined:
    Aug 6, 2001
    Messages:
    25,631
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Ratings:
    +4,906
    I set up my Q Bass originally using my Sound Pressure Ears then a couple of years later using a proper SPL.

    I now wish to set up my Storm properly and have carefully read the above and studied the pretty pictures and haven't a clue what you are talking about.

    I understood the first few words until I got to "burning MP3" then got completely lost as the only thing that I have burnt recently is the toast and I am not sure what Nero has to do with anything anyway.

    Perhaps if General Skanky has understood I will have a word with him as he tends to speak English not gobbledygook.
     
  20. lmccauley

    lmccauley
    Well-known Member

    Joined:
    Oct 24, 2000
    Messages:
    3,553
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Newcastle
    Ratings:
    +340
    Gobbledygook? I've spent the last week reading about accountancy, so I'm not going to take a comment like that from an accountant!

    Well, OK then, but only if you introduce me to Lucy - I've heard that you're close to her...
    Also, in protest against accountants, I'll structure my response like a Physics lab report :p.

    First of all, I am no expert - this is all stuff I've just picked up from these forums. Some of what I say may be slightly wrong, but hopefully it will be fit enough for purpose. Also, a lot of it is taken from here http://www.snapbug.ws/bfd.htm (especially the section entitled: "MEASURING SUB SPL LEVELS & USING MICROSOFT EXCEL WORKBOOK").

    Objective
    OK, as Skanky has said, our goal is to have the sound level at our listening position be identical no matter what note (frequency) is being played. This is known as a flat frequency response - if you make a graph of the frequency along the x-axis against the sound pressure level (SPL) up the y-axis and plot the measured SPL at each frequency you play, then the perfect frequency response will be a flat, horizontal line.

    Equipment
    1. CD with each track being 10 seconds of a single tone, or frequency. I made mine up by burning these http://www.snapbug.ws/sinewaves/ onto a CD.
    2. Tandy SPL meter.
    3. Spreadsheet from here http://www.snapbug.ws/subtestmodel.xls which has the corrections for the Tandy SPL (it becomes fairly inaccurate at low frequencies) built into it - you just need to fill in the readings you get at each frequency and it will produce those pretty graphs for you.
      [/list=1]

      Method
      1. Make sure the lead connecting your amp to subwoofer works correctly.
      2. Turn on the SPL meter. Set it to 70db, Slow, 'C' weighting (see manual if you want to know what this means).
      3. Put CD in CD/DVD player.
      4. Play final track (highest frequency) - use A-B repeat (explained in the manual of your CD/DVD player) until you've completed the next step.
      5. Hold (or ideally, place on tripod) the SPL meter at your listening position, facing up at 45 degrees angle. Adjust the volume on your amp until the SPL meter measures 75db (see the SPL manual to learn how to read it).
      6. Play each track on the CD, noting down the SPL measured.
        Type each SPL into the spreadsheet (the blue column marked RAW SPL).
      7. Look at the graph and cry "It's the Himalayas! What do I do now?"
      8. Move the subwoofer to a different location and repeat the previous steps. Type the results into the orange column marked RAW SPL and see if the graph is any flatter.
      9. Repeat until you've run out of places to put your sub.
      10. Put subwoofer back where the wife says that you can have it.
      11. Post graph here and wait for Jase to gloat...
        [/list=1]

        Conclusion
        Only Jase manages to get a flat frequency response - probably because he's allowed to put his sub wherever he fancies.
     
  21. Ian J

    Ian J
    Banned

    Joined:
    Aug 6, 2001
    Messages:
    25,631
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Ratings:
    +4,906
    Thanks for all that Liam, even a humble accountant can just about get to grips with that lot.

    Item 10 could be a problem as if I positioned the Storm where my wife wanted it, it would be back up the A1 on it's way to Phil's place.
     
  22. Jase

    Jase
    Distinguished Member

    Joined:
    Mar 16, 2001
    Messages:
    10,735
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    United Kingdom
    Ratings:
    +2,522
    :D

    Only measured up to 100hz.

    Heres mine:

    Probably have to click on the image to see it better.
     
  23. lmccauley

    lmccauley
    Well-known Member

    Joined:
    Oct 24, 2000
    Messages:
    3,553
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Newcastle
    Ratings:
    +340
    Why, is that where she watches most of her films? :eek:

    Jase, did I tell you I hate you?

    Cheers,
    Liam
    :D
     
  24. Jase

    Jase
    Distinguished Member

    Joined:
    Mar 16, 2001
    Messages:
    10,735
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    United Kingdom
    Ratings:
    +2,522
    :p ;) :D
     
  25. Stewart C

    Stewart C
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Excuse my being thick guys but how do I convert the MP3's to WAV files as my Tosh SD-200E will not play MP3's. At least I don't think it does?

    Thanks
     
  26. General Skanky

    General Skanky
    Active Member

    Joined:
    Jul 28, 2000
    Messages:
    4,253
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    71
    Location:
    Colchester
    Ratings:
    +44
    I use Nero 5 which does that for you automatically. You'll need a programme like it to do the same.
    Would you like a 'back up' of it?:D
     
  27. Ian J

    Ian J
    Banned

    Joined:
    Aug 6, 2001
    Messages:
    25,631
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Ratings:
    +4,906
    Guy,

    It didn't take you long to amend your signature. It must have only arrived a couple of hours ago.
     
  28. General Skanky

    General Skanky
    Active Member

    Joined:
    Jul 28, 2000
    Messages:
    4,253
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    71
    Location:
    Colchester
    Ratings:
    +44
    It was in my inbox. However, I've asked Encaser to do another one for me. It's something he should have a giggle with at least.;)
     
  29. Stewart C

    Stewart C
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Yes please.

    I have sent you a message with my e-mail address if that's ok.

    Regards
     
  30. marcoeser

    marcoeser
    Standard Member

    Joined:
    Jul 17, 2000
    Messages:
    342
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    21
    Ratings:
    +1
    moved things around with much snickering from the misses "just don't leave it in the middle of the room". I managed to flatten some of the peaks by quite alot, at least it sounds great now!!! :):) thats the main thing isn't it?

    JASE. You really are the dude... how the :devil: do you get it so flat. tell us please:D

    marc :)
     

    Attached Files:

Share This Page

Loading...
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice