How much driver movement is bad?

Discussion in 'Home Cinema Speakers' started by Daneel, Jun 12, 2004.

  1. Daneel

    Daneel
    Active Member

    Joined:
    Dec 5, 2002
    Messages:
    2,843
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    68
    Location:
    London
    Ratings:
    +8
    As I finally have a tv setup here I thought I'd try some more films to see what my Electras are capable of for movies. I'm just using the front two, nothing else.

    I grabbed The Haunting DTS and set volume to -15 to play the "coming mother" scene. The bass was very strong and managed to get a fair bit of movement from the bass drivers on my speakers. The last thing I want to do is damage them but I thought -15 would be safe enough.

    The speakers are supposed to be used with a 50-175W amp with a max of 200W. I'm biamping them with the Parasound which is rated at 140W x 5 but will deliver a bit more.

    So am I going to damage my speakers watching things like that at high volume? I had hoped they would be fine at reference but I dare not test it. I got enough of a fright at -15!
     
  2. karkus30

    karkus30
    Banned

    Joined:
    Jul 29, 2002
    Messages:
    13,997
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Ratings:
    +1,236
    Are they showing audible signs of distress ? Clipping, bottoming or sounding really harsh? I dont know the drive units, but if you can touch the pole piece, see if its getting hot.


    If the speakers are sounding fine, then the amount of cone excursion is unimportant, however, a word of warning, most domestic speakers are not designed to be driven to pa levels. Theres a lot of talk about reference levels on these forums and I have to admit to having no idea what ref level sounds like. I just turn the sound up till it sounds realistic. Whatever, thats pretty loud in my 16' x 16' front room (you have to shout to make yourself heard during most of the film and would probably give up during action sequences).

    Would have thought the Parasounds would be well up to driving the majority of speakers with good control (not sure what your using for a pre). So unless your intending to play pa levels ie pain threshold or in a very large room you should be OK.
     
  3. Daneel

    Daneel
    Active Member

    Joined:
    Dec 5, 2002
    Messages:
    2,843
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    68
    Location:
    London
    Ratings:
    +8
    Well, they are on a wooden floor and don't have the spikes on and I'm sure I saw movement from them. They weigh 36kg each. It didn't sound bad, but distorition in sound effect bass is very hard to detect.

    They are domestic speakers of course but they are 91 dB / W / m sensitivity, so taking 175W into a musical program so at a distance of 1m (seating position is about 2.8m away)

    dB W
    91 1
    94 2
    97 4
    100 8
    103 16
    105 32
    108 64

    At -15 I should have been around 90 dB with peaks to less than 100 which should be well within the limits of the speaker. The thing is I've at them at -5 on music and never had such driver movement. Obviously they were being fed very low frequency sound which was causing the movement.

    They do look pretty mean though, have a look. They don't exactly look delicate and easy to damage do they?
     
  4. russraff

    russraff
    Active Member

    Joined:
    Aug 1, 2000
    Messages:
    2,444
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    51
    Location:
    Newcastle
    Ratings:
    +73
    One thing that I would do if I had bought some new speakers: I certainly wouldn't be playing excessivly loud material through them untill at least 24 hours had passed of moderate volumes.

    The amount of driver movement shouldn't be too important, within reason. Whether or not your speakers are distorting because of overly high SPL's, is. Certainly your amplification is good enough to not be clipping at even very high volumes.

    Believe me, if your sepaker's drive units are at their limits, you'll know about it! They will fart and splutter and the sound will be very degraded. Bear in mind that It won't just be the bass that will distort; by the looks of things your speakers are 3 way with the slightly larger bass cones crossing over at ~230 to 300Hz. This is not really bass per se and if distortion is occuring at these frequencies, then it will certainly be audiable. You will also be able to detect an increase in harshness and loss in control before the speakers hit their endstops, however, as karkus30 pointed out.

    The other thing is The Haunting has material that goes way down. Someone said single figures at one point on these forums. Since your speakers are unlikely to go down that low, perhaps you are trying to get them to reproduce bass frequencies that are beyond the scope of the speaker's frequency response?

    Russell
     
  5. Daneel

    Daneel
    Active Member

    Joined:
    Dec 5, 2002
    Messages:
    2,843
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    68
    Location:
    London
    Ratings:
    +8
    The speakers are -6 @ 33Hz from the spec so yes, I would guess that some of the signal being sent to the speakers is going to come out very quiet, but then the speaker will have a natural roll-off, helped by room gain so that shouldn't be a problem; or should it?

    It is a 3-way design with cross-over at 200 Hz and 2,500Hz. The two lower units do the bass with the top driver being the midrange.

    The speakers aren't new, I've had them for a little over a month and they are well run in. The fart and splutter bit would be easy to hear on music, but in this case, it's all rumbling and banging which practically sounds like distortion to begin with!

    I can't say I detected any harshness, although Kill Bill the other night at -10 did sound a little harsh. That was all high frequency stuff though and I put it down to movie sound tracks being a little bright to start with. It was the Tokyo fight scene with the ball and chain. Very impressive, amazingly realistic but that chain sound could get a little hard on the ears. But then, wouldn't it in real life?

    Speaker detail are here.
     
  6. karkus30

    karkus30
    Banned

    Joined:
    Jul 29, 2002
    Messages:
    13,997
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Ratings:
    +1,236
    That very low frequency bass is the reason Im getting a sub for the H/C system and will be using bookshelf speakers set to small.

    Slightly off topic:

    I think this really identifies the difference between hifi and h/c. If your using a sub for music, it doesnt need to go very low, but above all, it must be very musical. H/C is a different ball game, who knows what an explosion sounds like, but it will contain multiple frequencies, some of which will be subsonic and it will be very loud. In other words a different style of subwoofer. This is probably the reason for so many arguments over which is the best sub (how the hell do you compare subs when your programme material contains everything from low synth, full orchestra, missile attacks, bullets, explosions).

    In a perfect world all speakers would be able to handle any material perfectly, but in most cases a compromise exists. I dont really think that full range speakers are the way forward for h/c. Pinpoint imaging through multi speaker arrays is IMO best handled by smaller speakers (after all the best imaging for hifi is almost always by way of small bookshelf speakers not large floorstanders) Its also easier to produce a small two way design which handles the human voice for the dialogue. This leaves dedicated subs to deal with the low frequency effects that are rarely heard in music.

    IMO the opposite is true for hifi, rarely does a sub integrate perfectly with any speakers. REL claimed they had the technology years ago, but Ive heard several systems and Im yet to be convinced. When your talking very low frequencies from a chuch organ, maybe then you might swing to a sub, but that would still compromise the other music.

    So, in a nutshell, I would'nt use full range floorstanding hifi speakers for full on h/c work, without some care for ultimate volume levels. Its akin to taking you gorgeous sounding hifi set up to your local arena and expecting it to perform.

    No doubt many will have opposite opinions, but thats my $0.02 worth.
     
  7. Daneel

    Daneel
    Active Member

    Joined:
    Dec 5, 2002
    Messages:
    2,843
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    68
    Location:
    London
    Ratings:
    +8
    Well, I'd think that just adding a sub will solve the problem. Or maybe using the 2 channel sound track. ATM I'm using the DTS or DD 5.1/6.1 track and downmixing to 2 channel, so all the LFE in the .1 is being sent to my fronts. I take your point though. Now where do I get £900 for an ultra? Anyone need a manslave? :D
     

Share This Page

Loading...
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice