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SVS 20-39 PC+ My Thoughts after a week.

Discussion in 'Subwoofers' started by Phil Hinton, Sep 11, 2003.

  1. Phil Hinton

    Phil Hinton
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    Ok I jumped onto the SVS bandwagon a while back to see what all the fuss was about. I was a fairly happy owner of a Velodyne CHT15 before making the switch (I have also had quite a number of Rel ST Subs in the past) and some will accuse me of jumping on the latest thing and hyping it just for the benefit of Tom and Ian. I will tell you now that any such comments or suggestions are rubbish, If I don't like something, I will tell all I'm not shy.

    And I am still undecided on the SVS thats for sure.

    I picked my sub up Last Saturday from Liams and he came with me back to my Cinema Room to help carry and set up the sub. The sub was placed in the alcove where the Velo sat firing out at the seating position. Obviously the SVS in a downward firing sub, but Tom and SVS recommend corner positioning. I quickly set it up using an spl meter and the tag tones, checking the other speakers as we went. Then put on Chp 4 of Moulin Rouge ("welcome to the moulin rouge") and sat back. "Wheres me bass gone!" I said looking at Liam. "Mmmm" said Liam.

    For whatever reason the bass had gone, especially in the mid band frequencies. So we put on Avia, and my worst fears were realised, I had a major dip from roughly 90hz down to 40hz, by about 9-11db. We moved the sub around, did the old walking around till you find the best spot, but the sub never produced any real spl in any location.

    Finally before Liam walked out the door, after i told him that a contract would indeed be taken out on him and Ian (Cheeky begger said I would know the right people as well;) ) I then found a placement where the bass returned in some volume, it was right behind the seating position. I continued to play around, and Liam went home to play with his.:eek:

    So after a week of use, how do I rate the SVS?
    It goes low, it is fast and accurate with music, but it also struggles with certain material. The dts "digital experience" intro makes it sound over loaded and bloaty at -12db. (the velo did this but not as bad). The intro to AOTC is just too much for it as well, and this is at normal sensible volumes -15db.
    It also doesn't seem to presurise the room in the right way or with any real spl. Move around the room and it disapears altogether. This is worring as Liams sounded rich and full balanced in his much larger room.

    With music this Sub is a dream to use, it is unnoticeable, yet switch it off and all the feeling goes from the track. Yet with movies it is very hit and miss. Maybe the velo was at fault, maybe what i was actually getting from it was just room induced boom, which made me think it was full bodied? I don't know, but in my room the spl levels were far higher than the SVS and the bass was fuller.

    What I really need to do is plot the room, but my skills with excel leave a lot to be desired, infact i just looked at it and thought ******** with this. When the shop downstairs closes tonight i will make my measurements, but i will need someone to plot the graph for me, any takers?

    Once i see what is happening, I then need to look carefully at how I am going to improve the dustbins performance. I know my room is not perfect and that some kind of EQ or room acoustical treatment is needed. I might have to pick Liam up and bring him over with his BFD and ply him with Beer.
    :laugh:

    At this moment in time, the jury is well and truely out. It works wonders with some material, and doesn't with others. That to me suggests a room problem, but i don't know where the spl is going as it never manages to fill the room, and to get the best performance I am literally sitting on top of the thing.

    Advice always greatly recieved.
     
  2. nathan_silly

    nathan_silly
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    Phil have you adjusted the Sub sonic filter to remove the frequencies below the standard port tune? - for example if yours is the 20hz model with all three ports open have you set the filter to 20hz?

    Have you tried blocking one port/two ports so it goes lower? (you'll need to re-adjust the SS to match)
     
  3. Phil Hinton

    Phil Hinton
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    Yes I have done and double checked everything on the sub, and double checked what the Tag was doing.
     
  4. dunkyboy

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    Do you have suspended wooden floors? Or an oddly shaped room? Maybe your room is just particularly unhappy with downfiring subs. I'm beginning to think mine is the same. I have a monster £2,000 ATC Concept 4 sub (650-watt amp, half-metre cube, 54kg!) which is designed for high SPL studio monitoring and by all rights should be able to handle anything I throw at it, but in my room I get very much the same effect as you describe with your SVS. With the response smoothed out by the BFD, I have to turn the gain on the sub WAY up to make it calibrate with Avia. Then when I play something like the AOTC intro (especially the THX bit beforehand... shudder) the thing just can't handle bits of it, and bottoms out quite worryingly. The response is also similarly very patchy throughout the room - move a few inches in one direction and it disappears.

    I have two theories for why this might be. One, that the suspended wooden floor is the culprit - instead of generating sound energy like it should, the down-firing sub ends up transferring the energy into the floor (which you can most definitely feel in the floorboards!) Two, that the room's odd shape (it has a big bay window pretty much taking the whole of one wall, which has wood panelling that "sings along" with the sub, and maybe absorbs energy in a similar way to the floorboards?) contributes to it.

    I really want to try out a decent front-firing sub - 'a la Velo CHT-15 or HGS, or Servo-15. But I have no cash so can't buy one myself for a while. :( Don't suppose anyone nearby to Edinburgh would be willing to drag their sub 'round for some fun experimentation? :)

    Another solution might be to get some sort of granite/marble/slate slab to place the sub on. This might decouple it from the floor enough to allow it to function properly... maybe? Problem is getting a stonemason to do such a thing for a sub the size of mine would cost in the neighbourhood of £50 - again, not something I can spare right now. THX, maybe you want to experiment with paving slabs or other solid surfaces to place under your sub? I'd be very interested to hear how you got on.

    Anyway, those are my thoughts at the moment. Any ideas?

    Dunc
     
  5. Phil Hinton

    Phil Hinton
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    Yes I have wooden floorboards and I was begining to think the same thing, will experiment later tonight.
     
  6. nathan_silly

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    I have the Storm on a large paving slab- it's defently improved the sound- before it was just causing boom...that's now reduced. Cost £6. Wooden floorboards on the 1st floor.. so space under my room.

    Oh if you decide to sell it I'll be interested in the SVS.. unless you wanna trade it for my Yammy 40? :p
     
  7. Phil Hinton

    Phil Hinton
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    Room Layout, very crude done in paint shop as I couldn't work out Room arranger.

    [​IMG]
     
  8. Phil Hinton

    Phil Hinton
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    Ha ha ha :)

    Looks like a kids drawing.
     
  9. nathan_silly

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    Phil convert them walls to cm and I'll do the room for ya.

    [edit] room arranger will convert to feet. Doing it now.
     
  10. Phil Hinton

    Phil Hinton
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    Nathan, my maths are as good as my drawings ;)
     
  11. chris

    chris
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    How have you got it connected.......???

    When i first got mine....i had the same thing as you (Where has my bass gone).
    I messed around with it for about a week and still could not get any thing out of it.
    I had loads of SPL but not a lot of bass....the only time i could hear/feel anything was when i put it in the kicthen.
    I had mine connected by a single run of coax into the left LFE input.
    I tried plugging the coax into the right LFE input and the thing came alive......there must of been a dodgy connection with the left one, but it does not matter what connection i use now, as they both work (For some strange reason).
    Have you tried changeing the input.....or maybe you have both hooked up anyway.
    I to was not totally impressed with the SVS in my room..........evern when Ian gave me a demo of his one, i was not totally blown away....(it will take a lot to impress me).
    I find the Servo just has the edge over the svs in my room (IMO).
     
  12. Phil Hinton

    Phil Hinton
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    Nathan, it wont let me unzip that file.

    Been to Jewsons and just bought a 50mm thick Paving slab, which is now under the sub, waiting for the shop downstairs to close and then try it out, nearly broke my back carrying the thing.
     
  13. nathan_silly

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    Rename the file extension (.ZIP) to .MST and open with Room Arranger.
     
  14. Phil Hinton

    Phil Hinton
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    No it wont let me do that
     
  15. nathan_silly

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    Ok try again.

    This time unzip it.
     

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  16. Mr Cat

    Mr Cat
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    so, whats your fave sub then, thx1138..?
     
  17. Phil Hinton

    Phil Hinton
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    [​IMG]

    Thats better, nearly everything to scale also.
     
  18. Apocalypse

    Apocalypse
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    If you give me your results I'll do a graph for you, just note the frequency and the actual db reading you got for it and email/pm me. You can tailor the graph to your liking (eg 20, 25, 30, 35, 40 etc) as long as there are 21 measurements.

    Email - apoc@lypse.eclipse.co.uk
     
  19. Phil Hinton

    Phil Hinton
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    Ok, done some sweep tests, but as well as being unable to work the room arranger, i can also not figure out the excel data sheet to graph this. but here are the figures, someone might be knid enough to post it as a graph.

    16hz = 81.7db
    18hz = 86.4db
    20hz = 90db
    22hz = 93.3db
    25hz = 92.0db
    28hz = 87.1db
    31.5hz = 79.0db
    36hz = 96.6db
    40hz = 95.1db
    45hz = 87.3db
    50hz = 81.4db
    56hz = 82.0db
    63hz = 94.7db
    71hz = 90.5db
    80hz = 77.0db
    89hz = 78.0db
    100hz = 82db
    111hz = 70db
    125hz = 68db
    142.5hz = 47db
    160hz = 32db

    Those were with the 5 speakers turned off via the rotel and just the sub working.
     
  20. Phil Hinton

    Phil Hinton
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    Edit. Thanks for your offer mate, looking forward to seeing what it looks like, at the moment i'm still not sure what the main problems are as the results don't look overly bad.
     
  21. Apocalypse

    Apocalypse
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    [​IMG]


    A BFD would drastically improve things, before I got mine I had a huge peak around the 50-60hz range which is what ultimately governed my sub's volume (I used to set the sub volume to the point just below boominess). Once the peak was removed I found that I could increase the sub's volume without any boom and this of course meant better LFE performance from the other previously neglected frequencies.
     
  22. HotblackDesiato

    HotblackDesiato
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    No expert...but...
    The overall dimensions of the room would suggest a potential peak at 37 and 40Hz, and i guess the ceiling height could be causing the blip at 63Hz if they're on the high side of normal say 8 and half feet.
     
  23. Phil Hinton

    Phil Hinton
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    That looks quite bad actually. So it would seem a BFD should be on the cards this payday, and some serious time needs to be spent on it.

    My ceiling height is 9ft.
     
  24. HotblackDesiato

    HotblackDesiato
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    My simplistic understanding is that 9ft might lead to problems, peak wise, around 60Hz.
    How did the CHT look in the same room?
     
  25. The Nightfly

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    Hi Phil,

    Have you heard of an equipment support manufacturer called Mana Acoustics ? Their products are focused mainly at the specialist/esoteric HiFi market (as opposed to AV per se) but they have a fanatical following who, in the main, regard these products as possibly more significant to getting a good result than the equipment they are supporting.

    Anyway, they manufacture what is essentially an isolation stand that normally goes under the speakers called a Sound-Base. This product has a great reputation for keeping the energy generated by a speaker in the air and not in the floor. I believe Sound-Bases have been used with Sub's with great success.

    This stuff is not cheap but they do offer a money back guarantee if you want to return it. They have a web-site and a support forum also.

    Try here:

    www.mana.co.uk

    Allan
     
  26. Phil Hinton

    Phil Hinton
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    Yes I had heard of them and thanks for your suggestions.

    I added my latest edition to the cinema room in the shape of a 600x600x50mm Concrete paving slab under the sub, and it has made a big difference to the performance with the floorboards no longer taking energy away from the sub. It has tightened up quite a bit and has surprised me. Was Only £2.49 as well.
     
  27. inzaman

    inzaman
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    THX Thanks for posting your thoughts the SVS was on my list of subs to upgrade to but couldnt just get over the cylinder shape but would probably have due to the praise heaped upon it. The room that i am going to rehouse my hc equipment sounds very similar to yours i.e wooden floor etc, so i will probably need a forward firing sub as opposed to downward firing sub.
     
  28. dunkyboy

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    Inzaman - don't assume I know what I'm talking about! The whole "downfiring subs don't like wooden floors" thang was just a theory! I haven't yet tried a forward-firing sub to compare, so I could just be talking out of my arse! :p

    Dunc
     
  29. nathan_silly

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    Don't you mean talking out of your back-firing port? :laugh:
     

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