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Horrible bass response

Discussion in 'Home Cinema Speakers' started by Daneel, Jun 9, 2003.

  1. Daneel

    Daneel
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    I'm starting to wish I hadn't bought AViA and a SPL meter. I already knew my system has problems with bass but I didn't realise quite how bad it was.

    Using the AViA test for a main speaker and sub which plays a test tone that starts at 200Hz and drops to 20Hz I get huge variations in volume (peaks that max the meter past +6 and dips that drop the meter to below -10). Despite changing crossover settings, messing with MCACC and just about anything else I can think of I still have 2 big problem areas.

    1. Repsonse between 50 and 60Hz is very low. It's like my room eats up anything in that range. Playing at -25 (should give me a constant 80dB output) when in this range the meter will drop to -10.

    2. With the crossover set to 50Hz, which gives me the best overall bass response, the sub kicks it at 50Hz and gives resonable output down to 40Hz, but by 35Hz I'm back to -10 and anything under 35Hz is very low indeed.

    Given that my main 602s are rated for +-3dB down to 49Hz and my CHT-10 is +-3dB to 28Hz I was hoping for better.

    There is little I can do as positions are pretty much fixed but I wonder just how much is down to my room/speaker placement and how much is due to my speakers not performing as their specification would suggest.

    Any suggestions are welcome but I don't really expect to be able to improve things much. I just wanted to moan a bit :zonked:
     
  2. Nic Rhodes

    Nic Rhodes
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    This actually seems quite normal, it is not the speakers / sub that are at fault but tmost likely the room. Why not have a play with the acoustics to improve things or equilisation of the bass?
     
  3. Jeff

    Jeff
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    Its quite normal to have these variations in bass response, you should consider room acoustic products or bass equalization using a Behringer Feedback Destroyer or both.
     
  4. Jeff

    Jeff
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    Sorry Beekeeper, you beat me to it.
     
  5. chris

    chris
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    What SPL are you useing......??

    The realistic analouge one, is known to not be the best bit of kit, but it is cheap and readily available...evern i have one.

    I did see a sub thread somewhere (might of been on here) that had a list of the values you should add or subtract for givern freqs with said meter readout.
     
  6. Daneel

    Daneel
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    The SPL meter is a standard analogue radio shack one, but most of the time it's just giving me a number for what my ears are telling me. I guessed before I got it that I had variations of about 15dB and that seems like a reasonable number.

    Where can I find out more about this BFD thing? Does it work? Suppliers in the UK?

    Beekeeper, how do I play with the acoustics?
     
  7. Jeff

    Jeff
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    There are plenty of threads here on the BFD, just do a search on BFD or Feedback.
     
  8. Paul Smith

    Paul Smith
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    Hi,
    I used to have a steep bump in my response around 60hz,:(
    but I found bunging up one of my subs two ports made it perfectly flat, lovely!!!.
    (running the sub through WinISD gave me the idea).
    It was obviously cheaper and much more satisfying than using a BFD as a band-aid to sort it.

    Paul.
     
  9. Steve.EX

    Steve.EX
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    Your Pioneer should carry all the software necessary to eleviate this.
    Can you not manually set the MACC for the sub, channel, you should only require 3-5 filters.

    Steve.
     
  10. BLACK_MAGIC

    BLACK_MAGIC
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    I would do things the old fashioned way and fill the room with lots of things wooden:)
     
  11. Daneel

    Daneel
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    Some searching and googling has brought me most of the information I need. One day I'm going to stop spending money on this stuff!!

    Steve, unfortunately MCACC has only 5 EQ bands which are wide and fixed so it cannot help me with this problem.

    The only thing I haven't workedout yet is how to connect this up. I assume I will need to buy some sort of converter to let me plug the RCA cable into the BFD and another one to get the signal out again and another length of 75 Ohm RCA to run between the BFD and the sub?

    So, 2 adaptors and another cable?

    Cheapest price I can find is £93 inc delivery from HW Audio, anyone used them before? Any good?
     
  12. Godfather

    Godfather
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    You need 2 RCA to 'headphone' adaptors, £1.50 each for good quality gold plated ones from Maplin. Any length of analogue interconnect cable will do to connect the subwoofer output of the amp to the BFD (e.g. QED Qunex, etc).
     
  13. nathan_silly

    nathan_silly
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    How do manage to measure Avia's tone if it's a sweep? I thought you use a constant tone to the subwoofer at various frequencies? I have Avia as well.
     
  14. avanzato

    avanzato
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    I know you say the positions are fixed but have you tried the sub in other parts of the room.

    A rough formula I was once given for standing waves was the rule of 1/3.
    The woofer of the speaker should be at the 1/3 distance of every wall h.w.d or as close to those points as you can get.

    My REL does sound more even out of the corner.

    Also have you tried changing the phase of the sub.

    Looking at the numbers you gave you're getting cancellation at 25-30 and double that at 50-60hz. Do you also lose volume at 100-120hz?
     
  15. Daneel

    Daneel
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    I haven't run the sub with a crossover above 100Hz so I don't know if anything happens at 120Hz. I have tried changing the phase, 0 is slightly better but there isn't a huge difference.

    The sub is in the only place it can go, it looks like the BFD is my best option.

    Nathan, I just watched the dial as the tone dropped in AViA, but I made a CD with specific tones to get more accurate results.

    Thanks a lot for the help guys.
     

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