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My first attempt

Discussion in 'Home Cinema Speakers' started by stevegreen, Mar 26, 2004.

  1. stevegreen

    stevegreen
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    Here is a graph i produced tonight with the help of some test tones played through my XBox (my DVD wont play burnt CD's :rolleyes:) and my Rel Q200e sub.

    I have had a bit of a play with an AVIA disc and the picture on my RPTV is spot on :thumbsup:

    Speakers are balanced (fronts, centre and rears) but the sub seems to be all over the place for some reason. When i play the AVIA disc, the section where it switches tones between the sub and the left, then right etc the sub seems pretty balanced to the left speaker output level but is miles off on the right? How can this be when i have no control on my Yamaha amp to adjust outputs from the front two??

    Anyway, have a look and see what you think, let me know your thoughts.

    OOh look, 500 posts, sure i passed that ages ago :confused: :suicide: :laugh:
     

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  2. Smurfin

    Smurfin
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    Have you tried moving the sub around the room and taking a fresh set of readings? You're missing out on quite alot of "impact" bass there with that dip around 40hz.

    First I'd suggest trying different positions, if that doesn't work then buy a BFD (in fact buy one anyway as I've yet to hear any room/sub that wouldn't benefit from some EQ)
     
  3. Ian J

    Ian J
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    Are your speakers set to large or small ?

    I suspect that they may be set to large so try them at small which should get rid of the differences in output between your left and right speakers.
     
  4. stevegreen

    stevegreen
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    Both the fronts and the centre are set to large Ian. The centre was initially set to small but changing this seemed to have a positive effect.

    It occurred to me overnight that the dip at 40hz may be a crossover issue as the Polks lowest frequency is 40hz. I will adjust my crossover tonight and have another go.

    I also thought about moving my sub to the corner of the room which may improve performance, however, if i did this the fronts would have to be directly either side of the TV.
     
  5. Ian J

    Ian J
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    Try setting all of the speakers to small with all bass and LFE diverted to the sub.

    Also try putting the sub in the corner (not right in the corner though). It doesn't matter if your main speakers are closer to the TV as you may prefer the sound that way anyway.

    Don't judge speaker distances by my setup as my right hand speaker is much too far from the TV but there is nowhere else to put it and needs must. You don't have the problem of a fireplace to contend with.
     
  6. stevegreen

    stevegreen
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    After seeing Bob's set-up with his speakers directly next to the TV I am not that concerned about it. I may even see an improvement. I think moving the sub into the corner will be a good move though.

    I am a little wary of setting the mains to small as, being floorstanders, they have a fuller frequency range than sats would have and I am not sure about how much I want the sub to do in my setup. Bass Out is currently set to 'both'.

    I obviously have a lot of fiddling to do to get it better, but each time I change something that has an effect I will post the response graph to show progression.
     
  7. petrolhead

    petrolhead
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    Try setting to small steve, you never know ;)
     
  8. Ettepet

    Ettepet
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    Having all lower bass going to the sub will make it easier to cancel out room influences, which seem to be very prominent in your graph.

    Your main walls are 5.5 meters (=18 feet) apart, right? ;D
     
  9. stevegreen

    stevegreen
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    Right, I have had a further play this morning.

    I have re-balanced all of the speakers after moving the subwoofer more into the corner of the room and the main front speakers to either side of the TV.

    Unfortunately, due to an uneven floor in the corner I have had to remove the marble slab from under the sub and replace it with 4 20p coins, one under each spike. The sub is now perfectly stable.

    On the graph below, all the speakers are set to small and bass out is to the sub only. It has got rid of the dip at around the 40-45hz mark which should give me an overall better performance in respect of what Smurfin posted.

    Ettepet, my room is L shaped but with an 'open' kitchen area. The front wall where the TV is situated it around 12' wide, whereas the rear wall is approximately 2' wider.

    More thoughts would be appreciated :thumbsup:

    By the way, the pink line is the new reading.
     

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  10. stevegreen

    stevegreen
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    This is the graph with the fronts set to large and bass out to both :eek:

    Think i'll be leaving them as small although it looked quite promising initially. The blue line is the new reading now.
     

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  11. Dave H

    Dave H
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    Steve sorry to butt in but what sort of equipment are you using to get this graph if you don't mind me asking as I would love to know how my room performs.

    cheers Dave.
     
  12. stevegreen

    stevegreen
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    I have borrowed a test tone CD which has individual test tones from 16hz to 160hz. These can be downloaded from the internet and burnt onto a CD. I'm sure someone will post the link.

    Also an AVIA set up disc which will help you adjust the balance of speakers and phase etc etc

    You will also need a SPL meter to do the actual measurement.

    A pen, piece of paper and a bit of patience.

    The graph is a simple excel sheet which can also be found on the internet, again someone will no doubt post the link for you. If not, I can email to you :smashin:
     
  13. Dave H

    Dave H
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    When I get a SPL meter I will give you a shout.

    cheers Dave.
     
  14. Ettepet

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    stevegreen, great to see you come up with such nice and informative graphs. I am currently looking into a way to produce such graphs automatically, by using a pc-soundcart a microphone and some software. RMAA is a free software package that does this. I will need to use the line-in of the soundcart, since the mic-in is usually crap.
     
  15. stevegreen

    stevegreen
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    That sounds like a great idea and should give a more accurate graph. Some of the points in mine will be slightly off as they were mid way between a half and a full step.

    I don't really think that there is much more i can do to improve that unless i get an equaliser, but, to be completely honest the sound i am getting now isn't that much different to what it was before. Its an interesting exercise to carry out but at the end of the day it's about how it sounds to my ears, how the equipment looks in my room etc, not how it looks on a graph.

    I still have a hankering for a new, bigger sub and a new amp though :)
     
  16. Ettepet

    Ettepet
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    I also have an L-shaped room, and for me the best place for the sub is about half-way the opposite side to the wall with the open kitchen. This is next to my couch, and slightly in front, as I found out that I need to have "visual" contact with my subs bass-reflex port for best results.

    Moving the sub had me enjoying many more songs, that previously had seemed to have too much bass in them. (like Norah Jones' DVD)
     
  17. stevegreen

    stevegreen
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    Well, I have managed to have a serious listen tonight, and also watch Red Dragon.

    The sound is much better now that all of the speakers are balanced. The soundstage at the front is fantastic and the sub is much better integrated than I have ever had it before. I know I posted earlier that it hadn't made that much difference but having had a proper listen tonight I take that back.

    stevegreen is a happy lad :smashin:
     

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