SVS 16-46 PC+ freq response

Discussion in 'Speakers' started by MingL, Mar 26, 2003.

  1. MingL

    MingL Stunt Coordinator

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    I recently got hold of a 16-46PC+ from the nice guys at SVS. Paired up with a BFD, and this graph is what I got using warble tones from 10 to 1kHz.

    [​IMG]

    Green = mains alone
    magenta = 16-46 alone
    Cyan = system response before bfd
    Gold = system with bfd

    There's lotsa lows, but is there anything else I should do to improve? Or did I miss or do anything wrong?
     
  2. Edward J M

    Edward J M Cinematographer

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    Are you running your mains on large or small? If they are being run on small, what is your high pass / low pass filter point?

    Also, what connection method are you using for the sub? Is your sub filter switch disabled if you are filtering at the AVR or pre/pro and connecting with a line level sub cable?

    Ed
     
  3. Lee Bailey

    Lee Bailey Second Unit

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    Your before BFD graph is actually better than the after. You boosted your frequencies. The real trick is to bring down the higher levels, so as not to add unneeded boost which takes headroom out of your amp.
     
  4. Keith Shaw

    Keith Shaw Agent

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    I assume he confused the "before" and "after" labels on the graph. Otherwise, it doesn't make much sense.
     
  5. MingL

    MingL Stunt Coordinator

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    The legends are correct, but I'm sure something isn't right somewhere too. I was pretty darn surprised to see the SVS almost flat with the bfd bypassed.

    I'm using a yammy Z1, all speakers to small, but LFE/bass to both sub and mains. Because of the lfe/bass setting, the mains remain full range. The SVS is connected to the bfd and to the amp via line-level. SVS filter disabled, gain at 11 o'clock

    I do prefer a slightly exaggerated lower bass(below 25hz), but am I forgetting anything?

    Agree with the before BFD is flatter than after BFD, but the bfd can still be programmed. If I could program multiple bass profiles on the BFD, any suggestions to how I could change things?

    BTW, my room is a small 12ft x 11ft x8ft.


    The warble tones used are spaced at 1/6 octave. Its generated by cool-edit and burnt on CD.
     
  6. Edward J M

    Edward J M Cinematographer

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    Have your tried running your mains on a true "Small" setting without the "LFE/bass" option enabled? You might be experiencing a phase problem between the mains and the sub.

    The PC+ has more than enough power to fill that room with prodigious amounts of bass. There is no need to run the mains full range and it may be causing more problems than it is solving.

    If you want an exaggerated bass response below 25 Hz, the BFD could cetainly do that for you.

    That size room may cause standing waves and peaks/nulls, regardless. But try the mains to small and just the sub for bass first. Try an 80 Hz filter point.

    Ed
     
  7. JimmyK

    JimmyK Second Unit

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  8. MingL

    MingL Stunt Coordinator

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    I believe you can get it on-line.

    But If you wish, I can mail you the CD-R with the warble tones. Its 1/6 octave warble so...

    10,11,12,14,16,18,20,22,25,28,32,36,40......etc

    So a warble at say 28 would start centred at 28hz but deviate quickly between 26hz and 31Hz. This "warbling would be about 5 times a second.
     
  9. JimmyK

    JimmyK Second Unit

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    Thanks MingL!

    You've got e-mail!

    JimmyK
     
  10. MingL

    MingL Stunt Coordinator

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    [​IMG]

    I had some spare time over the weekend and decided to re-tune my BFD and this is what I got.

    The above is from a port-plugged 16-46PC+, SS set to 12Hz, Phase 0deg.

    Any idea how I could futher improve on this curve?
     
  11. Frank Carter

    Frank Carter Screenwriter

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    Ming,

    I think that looks good. Man does that sub go loooooooow!
     
  12. Edward J M

    Edward J M Cinematographer

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    Ming:

    It looks as if you set your mains to small based on the plunging straight lines for the mains and the sub starting at 80 Hz.

    That curve looks really great. It appears your room provides some significant gain down low, as evidenced by the gently rising response starting below 30 Hz.

    I see no reason to leave a port plugged with the 16-46 model. You are losing some air flow and SPL. Also by plugging a port, you have moved that nice hump in the curve down to 16 Hz - well into the subsonic range. Pulling a plug will move that 16 Hz peak back up the scale to around 20 Hz, where it will really lend some superb foundation to the ultra low stuff on DVDs without sounding boomy at all.

    Regards,

    Ed
     
  13. MingL

    MingL Stunt Coordinator

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    The curve looks good to me too.[​IMG] I was suspecting that I am actually loosing a bit of headroom with that port plugged. I'm afraid that the loss of headroom will increase the chances of bottoming out the fella.

    Damn, I wish I had a way to find out how much head room is left. I was wondering what should I compromise on........ extension to 12hz, or loudness at 16hz?

    Does anybody want to see the FR for a port plugged 16-46 as compared to a non-plugged 16-46?
    [​IMG] [​IMG]

    Again, I'm using warble tones at 1/6oct spacing. Warble tones are warbling at 5hz and deviate 1/6oct from centre freq.
     
  14. Lynn Little

    Lynn Little Stunt Coordinator

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    If you ever get the time, I'd love to see a FR chart of an NON-port-plugged 16-46PC+ against the various settings of the SS filter, with and without the BFM...

    I have twin 16-46PC+s, placed about 2" apart.

    If you ever get the $$$, I'd love to see a FR chart of twin NON-port-plugged 16-46PC+s against the various settings of the SS filter, with and without the BFM...
     
  15. Edward J M

    Edward J M Cinematographer

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    Ming:

    The possibility of bottoming really only increases when you leave all the ports open and set the SS filter to 12 Hz.

    Since any ported sub will "unload" below it's tuning point, SVS wisely includes an adjustable SS filter on the PC+ model to help protect the driver at very high playback levels.

    At moderate playback volumes, setting the SS filter to 12 Hz with all three ports open will be perfectly safe, and might allow a smidge more extension than the 16 Hz setting.

    If you run the 16-46 really hard, then keeping the SS filter set to 16 Hz with all three ports open, or 12 Hz with one port plugged is the safest route.

    BTW, in your size room (1,000 ft3), I'm sure you will have headroom galore in either tuning mode. I would estimate a 16-46PC+ with all three ports open could safely hit 113-115 dB peaks in your size room at the listening position. Plug a port, and you might lose 2 dB off that.

    Finally, please do me a favor and let me know what software you are using to generate these graphs. I would like to have the same capability - it's much nicer than posting just the numbers in a column format.

    Thanks,

    Ed
     
  16. Zack_R

    Zack_R Stunt Coordinator

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  17. MingL

    MingL Stunt Coordinator

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    Yes, its an excel spreadsheet.

    Here is the link to download the spreadsheet I'm using. The one I'm using goes on from 10hz to 1khz, so its easy to see how well the sub integrates with the mains.

    Here the link to download : http://hometown.aol.com.au/jag947845...e+by+MingL.xls

    All you need to do is to take readings from the radioshack SPL meter and key it into the spreadsheet while playing the appropriate warble tone.

    There's the original spreadsheet from Sonnie Parker's webby that measures up to 160hz. I just merely spruced things up and stretched the graph till 1khz.
     
  18. Greg Bright

    Greg Bright Second Unit

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    My only question, and I'm sure it's been discussed somewhere else before, is why use warble tones instead of straight sine waves? Seems to me that sine waves will zero in on peaks and nulls much more accurately than warble tones. Then the BFD can be utilized in a much more precise manner, right? Am I reading this wrong?

    Greg Bright
     
  19. MingL

    MingL Stunt Coordinator

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    Perhaps I'll plot a couple of graphs that uses warble versus another that uses pure tones.

    I previously used to utilise pure sine tones to do my calibration, but I realise there are some issues that might produce flawed results.

    1) Sine tones tend to set up and reveal room modes too easily. I remember using sine tones only to give me nulls at my listening point. It seemed pretty weird that the same tone sounded real loud at the seat next to me, but I couldn't hear a thing at the next seat. Walking around the room with a pure tone really illustrated the effects of room modes and standing waves. with a SPL in hand, the needle swayed further than the scale allowed with just a step to the left or right. Warble tones didn't do this, supposed thanks to the averaging effect.

    2) Sine tones are potentially fatal to speaker drivers, esp subs as I've read somewhere.

    3) sine tones jump from freq to freq. I figured using warble tones, they swept across the octave boundaries and the reading on the meter gave me the averaged reading from the sweep.

    4) Sine tones just weren't that reproduceable. I could have measured a particular response today, but tomorrow when I re-did the same measurement, the results were never the same. I think that has got something to related with the position of the meter with the magnitude of the room mode at that particular spot. With warble tones, things appeared to more reproduceable and predictable.

    I tried to steer away from pure tones for the reasons above, and thus ventured onto filtered noise and warble tones.

    Warble tones were easy for me to generate, but I'll try 1/6 oct filter noise later on.
     
  20. Edward J M

    Edward J M Cinematographer

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    Sorry guys - I should have been more specific. I've already got a ton of Excel spreadsheets plotted for my 20-39PC+ in various states of tune and phase, etc.

    I just don't know how to save the spreadsheet as a .jpg file and post it on HTF - that's where I need the help.

    Thanks,

    Ed
     

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