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speaker phasing

Discussion in 'Electronic Repair' started by [email protected], Nov 29, 2013.

  1. Guest

    I'm making some additions to my stereo system and I'll try to explain this as concise as possible. I have two additional speakers which I'd like to connect to the receiver in the living room. The room is about 15 X 22 feet. The existing two speakers are situated against an inside wall facing the windows. They are properly phased and sound very good. One of these existing speakers (left side speaker A system), is very slightly caddy corner so thatit projects into the room. I would like to connect the additional left side counterpart on the opposite window wall so that it's speaker, (proposed speaker B system) is doing the same thing from the corner it's in. The new right speaker from proposed system B will essentially facing it's counterpart from speaker A system,separated by about 15 feet. What I'm trying to accomplish is more sound filling the room from more directions and hopefully simulating a sort of pseudo "surround" type of effect. But I'm not sure abouthow this is going to work out. Perhaps this is a mistake, so I thought I'dask.

    If all four speakers are facing one another and are in phase, and by this Imean before connecting to the receiver confirming that a small battery makes all four cones move in the same direction, connected like this what happens when the two lefts for instance are outputting the same signal. With the cones facing each other, will the projected sound buck and effectively try to cancel? Or should both cones in proposed B system be in phase as a pair but out of phase with respect to A system? Or should I forget the whole thing and just stick with my two existing A speakers? I hope I've explainedthis well. Thanks for any advice. Lenny
     
  2. This is a common source of confusion. "Same direction" means "outward or
    inward", /not/ same direction viewed from overhead. The same signal should
    produce compression or rarefaction from all speakers.

    Other than a sore back from moving your speakers, it costs nothing to
    experiment. As dave says, start with them in phase, then play around.
     
  3. Phil Allison

    Phil Allison Guest

    "William Sommerwerck"

    ** Correct.

    Phasing similar speakers is all about making the low frequency output from
    each *reinforce* the others rather than cancel.

    Compared to the wavelengths of low frequency sound, woofers are a point (
    hence omnidirectional ) source of sound pressure - so it is irrelevant
    which way the cone faces.

    Ideally, a listener should be seated at the same distance from each speaker
    so all time ( of arrival ) delays are identical and do NOT create phase
    changes.


    .... Phil
     
  4. Phil Allison

    Phil Allison Guest

    "dave the dickhead"
    ** WTF is meant by "modern electronic media " ??

    Got nothing to do with my comments, what ever this idiot says.


    ** Pan pots do not "smear" .

    ** Laughably stupid and wrong.


    ** Correct.

    Due to the criteria I just mentioned.

    " Ideally, a listener should be seated at the same distance from each
    speaker
    so all time ( of arrival ) delays are identical and do NOT create phase
    changes."



    .... Phil
     
  5. Phil Allison

    Phil Allison Guest

    "dave"
    ** So any popular music recording made in the last 50 years.

    ** But do not smear - you fucking nutter.

    ** Your hobby horse - not mine.



    ..... Phil
     
  6. Phil Allison

    Phil Allison Guest

    "dave dickhead"
    ** Your the one preaching strange religion - fuckwit.
     
  7. Guest

    Well I tried a few different scenarios and eventually I ended up with all four speakers in phase connected to both A and B front outputs. It would have been really nice if I could have used the rear speaker circuit of the receiver as it was intended, but unfortunately that was not possible.

    I never mentioned that the receiver is an old Sansui QRX5500. That was a top of the line 4 channel SQ unit circa 1975. Sadly neither the four channel or the SQ circuit no longer is functioning, and after spending a gret deal of time trying to repair this several years ago I finally abandoned the project.

    This unit, although a quality piece of equipment was built like your typical brick shit house, with circuit boards, harnesses, switch banks, etc. "layered" on top of one another. It makes signal tracing, not to mention parts replacement an absolute nightmare. But it does work well on two channel mode so that's how I use it.

    I have to say the sound quality assessment of this project was really difficult. As was mentioned by others in the discussion, depending upon where you stand in the room certainly influences the way this sounds. The fact is that every arrangement seemed to sound fairly good. However lacking the proper equipment to scientifically do this, (and if I had wanted to get that technical anyway), the final decision was at best a good guess.

    I did notice that with the final setup, that is everything in phase, left and right rears facing fronts from across the room the bass seemed especially strong. In fact standing in the kitchen, two rooms away, I could feel Iron butterfly pounding in my chest. I've never heard sound like this from my system before so I must have done something right.

    In fact I was thinking about how good some of my old records were actually sounding. I haven't listened to many of these in quite some time and I noticed that I could hardly hear any scratches. Wow, ttis Stanton cartridge with the elliptical stylus tracking at 1.25 grams must be really something. Then I remembered the results of my last hearing test, which pretty much showed that essentially everything is down almost 40DB above eight KHZ, which essentially translates to "deaf as a doorknob", and I realized that yes they're still scratched. The difference is, I just can't hear it anymore.

    Now if I could only upgrade that, so that music could once again sound likeI remember it....Thanks to everyone for your advice and suggestions. Lenny
     
  8. "Pat" wrote in message
    I was away for a while, so this thread is new to me today. Your
    comments above make sense, but bring up a question I have had for many
    years. I own a pair of ESS AMT Monitor speakers that I purchased new
    back in the 80's. Each has a pair of 12" woofers - one active (ie, a
    normal speaker) and the other passive. I would think that when the
    active one is compressing the air in the cabinet, the passive one
    would be pushed out thereby appearing to be out of phase to a
    listener. That doesn't appear to be the case because these speaker
    have a great low end sound. Can you explain why they work? (I am
    just picking you because you seem to know something about the subject,
    but others are welcome to explain my misunderstanding as well.)

    The passive radiator is not a radiator in the conventional. It "looks like" a
    a volume of air with the same mass. In other words, it's used to create a
    ducted-port speaker without the tube. (I think this is the correct
    explanation.)
     
  9. Phil Allison

    Phil Allison Guest

    "Pat"

    ** Using a "passive radiator" is just a variation of the ported enclosure -
    it allows a small box to be tuned to a lower frequency and with a larger
    radiating surface area than is possible with a conventional port.

    Drawbacks are increased cost and non-linearity in the radiator's suspension.

    The radiator and the driven cone operate essentially in phase over the
    octave above radiator resonance.


    ..... Phil
     
  10. "dave" wrote in message
    It's been done. William Michael Watson Dayton-Wright built conventional
    dynamic speakers with bags of SF6 in the woofer box. He got clean bass to
    below 16Hz from a small cabinet.
     
  11. "dave" wrote in message
    When I put 16Hz through the Watson woofers in my concrete-slab apartment...
    //nothing// audible came out of the woofers. But everything in the room
    rattled.
     
  12. Phil Allison

    Phil Allison Guest

    "William Sommerwerck"
    ** For what advantage ?

    The speed of sound is about half in SF6 but that is no help in a sealed box
    where resonance depends only on the stiffness of the volume of gas trapped
    behind the woofer.

    The smaller the volume or the larger the woofer, the stiffer it becomes.
    ** Really ?



    ..... Phi
     
  13. "Phil Allison" wrote in message "William Sommerwerck"
    ** For what advantage ?
    The lower speed of sound makes the bag appear to have a larger acoustic volume
    than the air it replaces.

    ** Really?

    Really. The bass cabinet was about 20" by 20" by 12". At 16Hz, there was no
    /audible/ output from the speaker, but everything loose in the room was
    rattling.

    The spec sheet for these speakers included a harmonic distortion curve. If I
    recall correctly, the speaker had something like 5% harmonic distortion at
    20Hz at 90dB output. (Don't hold me to the exact numbers, but the distortion
    was very low.)

    He also claimed that aluminum wool was a better damping material than
    Fibreglas, fiberfill, or foam. He said the linearity of the driver's movement
    depended in part on the thermal linearity of the damping material, and that
    aluminum wool did a better job. I didn't fully understand this, so don't jump
    on me.

    Ever heard his SF6-filled electrostatics? We sold a pair to a man with a
    large, dead basement. With each speaker powered by bridged Crown M300 amps,
    the system could play at ear-splitting levels with no strain.
     
  14. gregz

    gregz Guest

    I used to rattle things in my old basement. It resonated around 30 hz, but
    16 hz will shake things. With 30 hz in the basement, you had to be in the
    right spots to hear or not hear 30 hz.

    Greg
     
  15. Phil Allison

    Phil Allison Guest

    "William Sommerwanker"

    ** You have simply ignored question, which is the stiffness of a fixed
    volume of gas.

    Take a look at Boyle's Law ( PV = k )


    ** That is not a "small cabinet" at circa 50 litres internal volume.

    Had an 15 inch woofer fitted - did it ?


    ** Standing waves are a real bitch........

    ** Now that was done for an entirely different reason.



    ..... Phil
     
  16. I'm giving a respectful response, despite being called Sommerwanker. Shall I
    start calling you Anuson?

    ** You have simply ignored the question, which is the stiffness of a fixed
    volume of gas.

    Take a look at Boyle's Law (PV = k)

    As Michael Flanders put it... "The greater the pressure, the larger the volume
    of hot air."

    I found the spec sheet. He describes the SF6 as performing a linearizing
    function. He says nothing about increasing the cabinet's "apparent" volume.
    I'll call a friend who designs speakers and have him put me right -- if such
    needs be done.
    ** That is not a "small cabinet" at circa 50 litres internal volume.

    I consider it "small", as it was the bottom structure of a floor-standing
    speaker. That's not a large enclosure for a speaker that gets to 20Hz and
    lower with low distortion.

    Nope. Two oddball 10" drivers -- with pie plates glued to them! See the photo.

    ** Standing waves are a real bitch...

    Oh, I walked around to see if I could hear any subsonic output. There was
    none. Assuming you believe the spec sheet, note the ridiculously low LF
    distortion.

    ** Now that was done for an entirely different reason.
     
  17. I just found the following quote:

    "Only the woofer/subwoofer were not bipolar. These relied in the use of SF6
    (sulfur hexafluoride) gas (which is inert), to increase the virtual volume of
    the enclosure. As SF6 is an 'ideal gas', it operates as an 'isothermal'
    spring, thus avoiding the problems with 'acoustic-suspension' loudspeakers
    that operated partially as an isothermal and partially as an adiabatic system.
    Some designers seemed to lave little knowledge of Boyles Law or the Laws of
    Thermodynamics.

    "In effect, the use of SF6, increases the virtual volume of the enclosure by a
    factor of 27! As can be appreciated, this both lowers the distortion as well
    as permitting a lower resonant frequency of the woofer."

    It's here...

    http://www.dayton-wright.com/WATSONLABS_.html

    I should point out that the bass cabinet is not completely filled with SF6. If
    I recall correctly, the gas bags were separated with foam sheets.
     
  18. Phil Allison

    Phil Allison Guest

    "William Sommerwerck"

    ** You have ignored the question AGAIN !!!!!

    ** Pure marketing hype.


    ** Yawnnnnnnnnnnnnnnnnn....

    It is not small - a 10 litre box is small.

    And Boyle's law makes all the claims re SF6 all wrong.



    ..... Phil
     
  19. Phil Allison

    Phil Allison Guest

    "William Sommerwerck"

    ** I found it two days ago and roared laughing.

    It is the greatest pile of * bullshit * I have ever seen about woofers.


    ** Marketing hype - not engineering fact.

    The very next line is soooo telling:

    " But to use this, a larger cone mass is needed and the suspension has to be
    much more compliant."

    Cos it contradicts the rest of the hype.

    If SF6 worked as claimed, standard woofers would be all that was needed.

    It doesn't.



    ..... Phil
     
  20. Unfortunately, Mr Anuson, I owned these speakers and can vouch for their
    performance.

    Mr Anuson, name a brand and model of woofer, of the volume given, that can get
    down to 16Hz with such low distortion. I'm waiting...

    It's impossible to have any kind of a discussion -- you know everything.
    You're polite when people agree with you, and a vicious -- I can't think of
    anything bad enough -- when they don't.
     
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