1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Mission M35 drive units wired out of phase

Discussion in 'Home Cinema Speakers' started by r22flyer, Jan 14, 2005.

  1. r22flyer

    r22flyer
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Hello all,

    I discovered an interesting fact with my Mission M35 front speakers over the Xmas break. :confused:

    I changed my amplifier to a Yamaha DSPAX750, one of the new to me features being the auto setup. Interestingly, when I ran this, it reported that the front speakers were out of phase. I checked the bi-wiring and all was correct and ran the test again - same result. I then checked the speaker driver phases and found that the 2 bass drive units in each speaker cab are wired out of phase compared to the mid range and treble units.

    As an electronics engineer, this bothered me so I removed the crossover, worked out the circuit diagram and confirmed that indeed the woofers are wired out of phase. I took the plunge and wired them 'correctly' and then re-ran the Yamaha test. This time, of course, it passed all correct and setup nicely.

    Interestingly, the bass sound is now much tighter and defined and less boomy and the sub seems well integrated. Sounds great.

    I've had the M35's for about 8 months and I've thought something sounded a bit muffled, a bit indistinct (although I really do hate all these subjective descriptions) - it just sounds better to me now.

    However, I emailed Mission and they claim that the woofers are indeed wired out of phase on purpose because at a 1m listening distance, the frequency response was more correct (allowing for crossover phase changes) and that lengthy listening tests showed this was better. I find this truly remarkable - all my instincts and training says that all drive units should really drive forward at the same time. Just watch a bass drum in a kit and the initial driving thud is always outward and I want my bass speakers to do the same!
    Mission also suggested I reverse my sub too - oh dear!

    I also find Mission's reply a little contradictary and unrealistic. With such big speakers, who listens to them at 1m distance?! My listening position is 2.7m.
    Secondly, while quoting their listening tests as being the correct method to decide the phase, they then went on to use the arguement that their measuring equipment showed the best frequency response at 1m was with out of phase woofers, and then proceeded to slag off Yamaha's optimizer setup as being "more trouble than they are worth". I wonder what the measurement results are at 2m and 2.7m etc.

    They then go back to say that ears are the best instrument! It's a poor arguement to credit your own lab testing and then slag off an amplifier's own non subjective technical testing. Yamaha's system was clever enough to work out a phase error at 2.7m and now thinks its ok when the wiring has been 'corrected'. In my opinion, although ears will perceive the final results, they are not always best at deciding what is correct - ears are not consistent and the brain they are wired to rarely interprets the results the same as another similarly constructed brain! (hence all the great varied views on these forums).

    I fully realise that crossovers do cause phase changes but again my experience says 'up to 90 degree shift' and not 180. I also realise that front rooms are never ideal listening grounds compared to the tech lab, therefore there are bound to be phase changes, dips & troughs, all over the place and you'll never get an ideal frequency response. Its also worth pointing out that when a recording is made, although instrument sounds will all be different frequencies and all slightly out of phase depending on their position and distance from the listener, the recording mics will be the same phase (top & bottom snare mics excepted but for obvious reasons).

    Has anyone else had experience of Denon and Yamaha's optimizers finding errors with their speaker setup?

    Has anyone else spotted that their speaker drive units are wired out of phase?

    Regards
    Paul
     
  2. Beobloke

    Beobloke
    Active Member

    Joined:
    Aug 10, 2004
    Messages:
    1,312
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    51
    Location:
    Out in the Sticks!
    Ratings:
    +65
    It is more common than you might think to find drive units wired out of phase, although generally in my experience, the bass drivers are usually left in phase and the midrange or tweeters adjusted as required.

    Mostly this is done to offset phase shifts introduced by the crossover and cancellation between the drive units themselves at certain frequencies. It can also compensate to a certain extent for the speaker voice coils not being correctly time-aligned.

    It is even more common in car audio systems where phase can be reversed (either on the speaker itself, or in the amplifier) to accommodate the differing distances at which the speakers are placed from the driver.

    The differences on a hi-fi speaker are often quite subtle when listening, but can be quite noticeable when the speakers are measured, hence Mission's reason for reversing the phase.
    Ultimately, as always, though - your ears should be the judge of what sounds better!

    Adam.
     
  3. Dutchman01

    Dutchman01
    Standard Member

    Joined:
    Apr 16, 2008
    Messages:
    16
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Ratings:
    +0
    I know this is a old topic but after reading all over this and went back to my setup i do agree that the bas drive's could do a better job at a larger room.

    After dismantel a M35 and a M35i indeed a saw the wiring is reversed and the bas is out of phase.

    So i also change the wiring back to correct phase and can agree with a better bas reproduction in my room.

    I'm using a Denon AVR-4306 receiver on this set for almost 2.5 years now and finnaly i'm 100% happy with this setup.

    So i also can say to the user who do not listen very close on this speakers reverse the wire for the bas drivers.

    Dutchman01
     
  4. hifix

    hifix
    Distinguished Member AVForums Sponsor

    Joined:
    Mar 7, 2006
    Messages:
    12,283
    Products Owned:
    2
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Coventry, West Midlands
    Ratings:
    +2,426
    Yamaha's YPAO auto setup does have a tendancy to state that the front left is out of phase with many types of speakers. Just worth mentioning just in case.
     
  5. Dutchman01

    Dutchman01
    Standard Member

    Joined:
    Apr 16, 2008
    Messages:
    16
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Ratings:
    +0
    My denon did also report out of phase when bi-wired

    Denon use Audyssey,

    It is not a false report by the receivers with those speakers, unscrew the crossover and look
     
  6. flurapercussion

    flurapercussion
    Novice Member

    Joined:
    Jun 27, 2015
    Messages:
    3
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    4
    Location:
    Bucharest
    Ratings:
    +0
    hello! I will buy a pair of m35i tommorow,I just seen this topic right now,and I'm a bit concerned. Could you please explain to me(I'm kinda newbee) how can I see on the crossover the specific wires in,or out of phase? After reading your discussion I really want to check it out! Thanks!
     
  7. r22flyer

    r22flyer
    Member

    Joined:
    Sep 1, 2012
    Messages:
    430
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    31
    Location:
    Leeds
    Ratings:
    +74
    hi, the red wire or + on crossover should go to the + on the speaker terminals.
    Long time since I did mine but I seem to remember the terminals were different sizes so I had to cut the wires on the incorrect speaker (6 inch or so away from the speaker) and re-join them the opposite way round with a connector block.
     
  8. flurapercussion

    flurapercussion
    Novice Member

    Joined:
    Jun 27, 2015
    Messages:
    3
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    4
    Location:
    Bucharest
    Ratings:
    +0
    ok,I'll do the check ,thanks!
     

Share This Page

Loading...