My REW response - Comments welcome.

Discussion in 'Subwoofers' started by Morb, Jan 10, 2008.

  1. Morb

    Morb
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    Had my SVS for a while now but never got around to measuring my response as i was planning to move, the move has been hit with delays so i thought it was about time to have a look.

    The room is about 12' x 10' x 8' and contains all of the kit in my sig plus a computer, 2 monitors, a bunch of other av kit stuffed ontop of my wardrobe, some pictures on the wall, 2 shelfs with various books and magazines, cd and dvd rack that is full, more dvd's and cd's ontop of the rack and lying about, a mini fridge, bed side table and my double bed. I don't have any EQ device but i do have the small EQ on my SVS. :eek:

    Measuring was not perfect as it was only a quick test to try REW out and get a rough idea if i had problems or if i could make an improvment. It was quite a task to get the pc near enough to the av amp while being able to get the spl meter near to my listening position but i did my best. I must also mention i haven't made any adjustments to allow for my radioshack spl meter. So below is my response graph :

    [​IMG]

    In the end i didnt bother with any EQ from the sub as all i really managed to do was to get it roll off faster after 40Hz. I think the graph looks ok but im only starting to really dabble with this so would like any comments although there isn't alot i can currently do to adjust it at the moment. :)

    P.S. Thank good for the bag of cables making it possible for me to connect the av amp, pc and spl meter. :rotfl:
     

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  2. chrisgeary

    chrisgeary
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    thats nice as a starting point. i probably would want a house curve at the bottom end to compensate a little for our hearings natural roll off. but really a great response without EQ!
     
  3. suniil

    suniil
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    :) - would be much nicer with a pic of your room

    That's a very good response [-]curve[/-] graph without any adjustments, but IIRC, you need to load correction values for your SPL metre

     
  4. chrisgeary

    chrisgeary
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    oops, i didnt read that. the correction values will up the bottom end values of the response from 10 to 25hz or so. i think itll still need a bit of a house curve.
     
  5. Mr Incredible

    Mr Incredible
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    Is the graph with or without your mains?

    If it's with your mains I think your sub could do with be turned up a few DB, then retry.
     
  6. Morb

    Morb
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    Thanks for the response guys, i think i understand how to get the correction files loaded into rew now but it will have to wait before i can re run the tests with them. Still the graph is pretty close upto about 25HZ where it tails off pretty fast according to the numbers i have seen for the correction values.

    Im afraid no pictures as the room is a total mess. Hopefully i can get the move sorted now xmas and new year is over then i will provide all the photos you could ever want. Might have a tidy up when i redo the tests and post a couple shots.

    Think i have alot to learn here and by the looks of a BFD will be needed to get a house curve.

    Shame i was tired when i ran the test or i might have worked out how to apply the correction values then and been able to produce the actual response curve.

    Mr incredible if i set it up correctly it should have just been the sub without my mains. But again i am going to have to sit down properly and spend a decent amount of time with it.

    Seems i have a lot to learn, figured this would be the case. Luckily i have a week off sometime so should be able to dedicate a day to it then without upsetting the gf by explaining i want to spend the day measuring my subwoofer.
     
  7. chrisgeary

    chrisgeary
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    I quite often do an initial sweep with my mains off and EQ but do most of my sweeps with my mains on to make sure that i have phase right, overall balance right and to take into account frequencies where the two overlap.
     
  8. Mr Incredible

    Mr Incredible
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    Yeah, that's the best. But the curve above suggests the mains were on as you would not expect the roll off from a 80Hz crossover (as an example) to produce such SPLS at 200Hz. That being the case, the relative output of the sub below 80Hz in this instance, is too low compared to the mains. With mains in play the flatness should be right across the crossover area and as low as possible. The graph here shows the sub output to be about 5 db (perhaps a bit less) lower than the mains. If the AV amp has auto setup, perhaps a redoing of that may get the sub level nearer the mark.

    Additionally, raising the sub's output will give a better chance of a house curve < 60Hz and also filling that dip at 75Hz
     
  9. Morb

    Morb
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    Yes i would agree looking at the graph it seems mains were included. Will have a play tomorrow and really get my teeth into this. Learnt quite a bit already but a long way to go yet. Hopefully with some time patience and the help available i will get even more from my sub.

    Got to say i would be more than happy with it as it is now but fiddling to improve things is quite fun and will hopefully help me improve my subs performance.

    Might try and pick up a bfd before my week off as a little b'day pressie to myself.
     
  10. Mr Incredible

    Mr Incredible
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    Good luck with that:; they are no longer available in Europe and 2nd hand ones are as rare as rocking horse dung.
     
  11. mistygreenandbl

    mistygreenandbl
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    Luckily enough there seems to be a small amount of 'dung' on ebay at the mo...I've found 3 of the above offered for auction, and a further 1 in an ebay shop at b.i.n. :D
     
  12. Mr Incredible

    Mr Incredible
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    Yeah, dung usually ends up in a dung box. ;)

    EDIT: BTW, I Can only see 1 x DSP1124P (Pro) version. I think the processing improved on this model compared to the older models.
     

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