Page 1 of 2 12 LastLast
Results 1 to 10 of 18

Thread: Phase shifts from using full range bridged amps?

  1. Back To Top    #1
    Noob KillerBox's Avatar
    Location
    Mobile, Alabama
    Vehicle
    Lexus LX 470 (Land Cruiser)
    Posts
    55
    Join Date
    Aug 2016

    Phase shifts from using full range bridged amps?

    Last night a well known car audio guy said:


    “You do not want to bridge two channels into one mono channel for broadband use, there are multiple phase shifts through the bandwidth. You don’t have this issue when bridging an amp for sub use when your bandwidth is set the less than 100 hz. When using amp amp in bridged (mono) for bandwidths that cover broader ranges you will encounter phase shifts between the two channels at certain frequencies. This tends to destabilize image and stage as the phase changes.


    You will be having phase shifts, it happens in ALL 2 channel amps when bridged to mono use over broad frequency ranges. It’s the inter-reaction between the two channels.”


    I am neither agreeing nor disagreeing with him because in my +35 years of being an amateur car stereo guy this is the first time that I have ever heard that.


    To put this in context the discussion was about using bridged (or monoblock) full range amplifiers on door speakers. So I wanted to see if anyone has anymore information on Phase shifts from using full range bridged amps?

  2. Back To Top    #2
    Senior Member jrwalte's Avatar
    Location
    Atlanta
    Vehicle
    2007 Corolla
    Posts
    275
    Join Date
    Oct 2019

    Re: Phase shifts from using full range bridged amps?

    I've never heard that either and had bridged an A/B 4ch amp for >80Hz range for years. But I didn't RTA at the time so would never have known if it did cause anything.

  3. Back To Top    #3
    Owner BigAl205's Avatar
    Real Name
    Alan
    Location
    Hayden, AL
    Vehicle
    2018 Chevy Silverado Z-71
    Posts
    5,395
    Join Date
    Feb 2013

    Re: Phase shifts from using full range bridged amps?

    I think he means don't run a stereo signal to an amp that's been bridged, the two channels will want to fight each other. A single channel amp needs to see a mono signal.

  4. Back To Top    #4

    Re: Phase shifts from using full range bridged amps?

    seems like the statement needs more context

  5. Back To Top    #5

    Re: Phase shifts from using full range bridged amps?

    I've never heard of this, and don't see how it is possible. If it was, then running amps in stereo would have phase shifts too between the channels, and it would still screw up the stereo image.

  6. Back To Top    #6
    Noob KillerBox's Avatar
    Location
    Mobile, Alabama
    Vehicle
    Lexus LX 470 (Land Cruiser)
    Posts
    55
    Join Date
    Aug 2016

    Re: Phase shifts from using full range bridged amps?

    The comments are from Sound Quality Competitors

    https://www.facebook.com/groups/sqco...omment_mention

  7. Back To Top    #7
    Senior Member Euphonic's Avatar
    Location
    SOSIQUIL
    Vehicle
    1991 Mercury Capri, 2016 Ford Escape SE, & 2017 Nissan Altima SR
    Posts
    2,713
    Join Date
    Feb 2015

    Re: Phase shifts from using full range bridged amps?

    Quote Originally Posted by BigAl205 View Post
    I think he means don't run a stereo signal to an amp that's been bridged, the two channels will want to fight each other. A single channel amp needs to see a mono signal.
    This seems to be the most accurate explanation. Back in the day (only because I don't see it much anymore), several amps had a Stereo/Mono switch. When switched to Mono, both channels would be driven from a single RCA input. I'm not sure how you'd get phase shift with a single input.

  8. Back To Top    #8
    Senior Member jrwalte's Avatar
    Location
    Atlanta
    Vehicle
    2007 Corolla
    Posts
    275
    Join Date
    Oct 2019

    Re: Phase shifts from using full range bridged amps?

    Quote Originally Posted by BigAl205 View Post
    I think he means don't run a stereo signal to an amp that's been bridged, the two channels will want to fight each other. A single channel amp needs to see a mono signal.
    That makes more sense. But then why would you ever merge a L and R signal for a single speaker playing high frequencies. But I guess people could make that mistake. But wouldn't most amps just ignore the other input anyway because it's only taking the one input it identifies for bridged?

  9. Back To Top    #9
    Wave Shepherd - aka Jazzi Justin Zazzi's Avatar
    Location
    Tempe, AZ
    Posts
    496
    Join Date
    Aug 2018

    Re: Phase shifts from using full range bridged amps?

    Never heard that one before.
    I'm also kinda doubtful.

    If the phase between channels was bad enough to be heard in bridged mode, then it should also be audible if you use those two channels in a stereo pair right?
    Measure with mics, mark with chalk, cut with torch, grind to fit, sand to finish, paint to match.
    Justin Zazzi's tuning companion for room eq wizard
    Do it for them.

  10. Back To Top    #10

    Re: Phase shifts from using full range bridged amps?

    Quote Originally Posted by Justin Zazzi View Post
    Never heard that one before.
    I'm also kinda doubtful.

    If the phase between channels was bad enough to be heard in bridged mode, then it should also be audible if you use those two channels in a stereo pair right?
    I am a responder on that Facebook post, the guy who made the statement is an ex phase linear tech

    i did respond by stating I have never measured any difference in phase (which would effect timing also) between a stereo channel and then when I bridged the same amp onto the mids also, so I stated I didn’t see how it could be an issue

    he wasn’t talking about a stereo input, he specifically was saying it in response to someone who wanted to bridge an amp to run various drivers (not subs)

    I got told I didn’t know who he was or words to that effect, I replied with when I’ve done exactly this I have never seen any difference in phase at the speakers actual output when measured at the listening position

    he does definitely know his onions and has pedigree, but I dismissed it as a none entity

    as in theory at least if one pair of channels induces some kind of phase shift then the other pair of channels would, and so the phase would still match if anything changed at all

    i understand that when bridging the phase is inverted on one channel of a pair to be bridged as it’s driven from the negative vs the first channels positive so when combined there is a push pull effect occurring, but that won’t effect the phase of the output as it just makes a bigger sine wave with twice the voltage effectively

    curious as to what he’s speaking about… but I haven’t measured it in any case where I’ve been using stereo channels and then swapped to bridged channels and I do like measuring phase

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Back To Top