Forums

How to tell speaker + from -?

Started by Unknown September 5, 2018
In my shop I have a a Pioneer SX-434 radio/amp  for my listening
pleasure. The speakers are mounted high up, screwed to the wall, and
are not easy to get at. I had to disconnect the speaker wires
temporarily from the stereo and stupidly didn't mark the wires for
positive and negative. Is there a way to tell which wires are which
that doesn't involve ladders and me unscrewing the speakers from the
wall?
Thanks,
Eric
Turn up the bass, put it in mono and try it both ways. Whichever way has more bass is the right way. 
On Wed, 5 Sep 2018 09:41:51 -0700 (PDT), jurb6006@gmail.com wrote:

>Turn up the bass, put it in mono and try it both ways. Whichever way has more bass is the right way.
With the speakers facing each other...
On 2018-09-05, etpm@whidbey.com <etpm@whidbey.com> wrote:
> In my shop I have a a Pioneer SX-434 radio/amp for my listening > pleasure. The speakers are mounted high up, screwed to the wall, and > are not easy to get at. I had to disconnect the speaker wires > temporarily from the stereo and stupidly didn't mark the wires for > positive and negative. Is there a way to tell which wires are which > that doesn't involve ladders and me unscrewing the speakers from the > wall?
Play an asymetical signal. One that does not have glide reflection symmetery, eg: 33% PWM use a low low frequency so that the cross-over doesn't mess it up too much. view the sound on an oscilloscope (or audacity etc) -- &#1578;
On Thu, 6 Sep 2018 05:46:55 -0000 (UTC), Jasen Betts
<jasen@xnet.co.nz> wrote:

>On 2018-09-05, etpm@whidbey.com <etpm@whidbey.com> wrote: >> In my shop I have a a Pioneer SX-434 radio/amp for my listening >> pleasure. The speakers are mounted high up, screwed to the wall, and >> are not easy to get at. I had to disconnect the speaker wires >> temporarily from the stereo and stupidly didn't mark the wires for >> positive and negative. Is there a way to tell which wires are which >> that doesn't involve ladders and me unscrewing the speakers from the >> wall? > >Play an asymetical signal. One that does not have glide reflection >symmetery, eg: 33% PWM use a low low frequency so that the cross-over >doesn't mess it up too much. > >view the sound on an oscilloscope (or audacity etc)
O'scope, separate mics, two channels? I wonder how speaker phase affects our perception of sound. Assume both speakers are phased to each other. Now can human hearing discern when they are phased correctly for the program material? I can't, but maybe there are people who can. And what happens in a orchestra... the wind section, for instance, takes great pains to see that they are all playing the same note frequency-wise before the concert starts, but surely some slight variations on timing must cause one or the other to be phased slightly different from the rest of the section. Damn, back to Google for me.
>"O'scope, separate mics, two channels? "
Seems like a bit much.
>"I wonder how speaker phase affects our perception of sound. Assume both speakers are phased to each other. Now can human hearing discern when they are phased correctly for the program material? I can't, but maybe there are people who can. "
Very few people can. They did pay attention to phasing on AM radio because they would rather "up" modulate than "down" modulate. There is also a difference in some speaker systems. Some. Also amps with single ended output.
>"And what happens in a orchestra... the wind section, for instance,
takes great pains to see that they are all playing the same note frequency-wise before the concert starts, but surely some slight variations on timing must cause one or the other to be phased slightly different from the rest of the section. " Part of the confusion there is that those fucking stupid schools used to teach that a 180 phase shift is the same as inversion. That only applies to symmetrical waveforms like a sine or 50 % duty square, or triangle. (not a sawtooth) Anything that has a mirror positive and negative side. Many instruments do not, and I mena really do not. How much of that you can actually hear is a question. For example to reproduce a muted trumpet to real levels requires thousands of watts because of crest factor and whatever. It is definitely non symmetrical. So is the human voice, which may explain the fact that people will tolerate low even order distortion to higher levels than other types. So when they talk abut speakers being out of phase they don't REALLY know what they're talking about. what that is when the speaker wires are reversed on one is INVERTED. Many people can tell when speakers are out of phase with each other. I can, and on fact have been called upon to phase multiple or "stacked" speaker systems. This is needed because speaker polarity is not standard between manufacturers nor even among models of one manufacturer. Some are more sensitive. Many years ago I sis audio at Wellman & Griffith. In was a Sansui receiver with DC coupling but no DC protection. One of the transistor sockets went intermittent and blew both woofers in an EPI. It had a switch for 4 or 16 ohms and of course it was set to 4, so both woofers went. I had some used ones and sold them to the guy and installed them at the company. There was another audio guy there and he listened and said "There is no center". Sounded fine to me, but when you work at a high end place thing need to be done right, so I got the customer to bring in the other speaker. Sure as shit, the woofers were out of polarity and that guy could hear the difference. When I hooked up both speakers they definitely sounded out to me, but I couldn't tell woofer from tweeter he could. I had observed polarity at all times and the woofers were actually wired the other way. I reversed the wires internally and all was well. Not only did the speaker we fixed sound fine to me, I couldn't hear the difference between it and the one that was right. Some people can't hear the difference at all unless they are right next to each other, or on the same cabinet. One place you could really tell was in old cars that had a pair of speakers (6X9) in the rear deck. I have literally insisted someone STOP THE CAR, GIVE ME THE TRUNK KEY. Why ? Just do it. I crawled in the trunk and reversed the wire son one speaker, got back in and said go ahead. They turned the stereo back on and said "Damn, what did you do ?". Even for me, if the speakers are far apart it can be hard to tell. The bass is not mixing so if it is out of polarity it makes so little difference sometimes it just isn't worth the trouble. Absolute polarity is a difficult thing. You must be sure, for example, that the microphone(s) put out positive voltage when air is PUSHED to it/them. Then EVERY step in the process, this means tape heads, the cutting lathe for the master recording to the phono cartridge to the pre amps and amps and the speaker all must not reverse the polarity. That is damn hard to guarantee. In digital, if the OP AMPs in the filters invert, it must be reinverted. It's a big pain in the ass.
On Thu, 6 Sep 2018 04:40:53 -0700 (PDT), jurb6006@gmail.com wrote:

>>"O'scope, separate mics, two channels? " > >Seems like a bit much. > >>"I wonder how speaker phase affects our perception of sound. Assume both speakers are phased to each other. Now can human hearing discern when they are phased correctly for the program material? I can't, but maybe there are people who can. " > >Very few people can. They did pay attention to phasing on AM radio because they would rather "up" modulate than "down" modulate. There is also a difference in some speaker systems. Some. Also amps with single ended output. > >>"And what happens in a orchestra... the wind section, for instance, >takes great pains to see that they are all playing the same note >frequency-wise before the concert starts, but surely some slight >variations on timing must cause one or the other to be phased slightly different from the rest of the section. " > >Part of the confusion there is that those fucking stupid schools used to teach that a 180 phase shift is the same as inversion. That only applies to symmetrical waveforms like a sine or 50 % duty square, or triangle. (not a sawtooth) Anything that has a mirror positive and negative side. Many instruments do not, and I mena really do not. > >How much of that you can actually hear is a question. For example to reproduce a muted trumpet to real levels requires thousands of watts because of crest factor and whatever. It is definitely non symmetrical. So is the human voice, which may explain the fact that people will tolerate low even order distortion to higher levels than other types. > >So when they talk abut speakers being out of phase they don't REALLY know what they're talking about. what that is when the speaker wires are reversed on one is INVERTED. > >Many people can tell when speakers are out of phase with each other. I can, and on fact have been called upon to phase multiple or "stacked" speaker systems. This is needed because speaker polarity is not standard between manufacturers nor even among models of one manufacturer. > >Some are more sensitive. Many years ago I sis audio at Wellman & Griffith. In was a Sansui receiver with DC coupling but no DC protection. One of the transistor sockets went intermittent and blew both woofers in an EPI. It had a switch for 4 or 16 ohms and of course it was set to 4, so both woofers went. I had some used ones and sold them to the guy and installed them at the company. There was another audio guy there and he listened and said "There is no center". Sounded fine to me, but when you work at a high end place thing need to be done right, so I got the customer to bring in the other speaker. Sure as shit, the woofers were out of polarity and that guy could hear the difference. When I hooked up both speakers they definitely sounded out to me, but I couldn't tell woofer from tweeter he could. I had observed polarity at all times and the woofers were actually wired the other way. I reversed the wires internally and all was well. > >Not only did the speaker we fixed sound fine to me, I couldn't hear the difference between it and the one that was right. > >Some people can't hear the difference at all unless they are right next to each other, or on the same cabinet. One place you could really tell was in old cars that had a pair of speakers (6X9) in the rear deck. I have literally insisted someone STOP THE CAR, GIVE ME THE TRUNK KEY. Why ? Just do it. I crawled in the trunk and reversed the wire son one speaker, got back in and said go ahead. They turned the stereo back on and said "Damn, what did you do ?". > >Even for me, if the speakers are far apart it can be hard to tell. The bass is not mixing so if it is out of polarity it makes so little difference sometimes it just isn't worth the trouble. > >Absolute polarity is a difficult thing. You must be sure, for example, that the microphone(s) put out positive voltage when air is PUSHED to it/them. Then EVERY step in the process, this means tape heads, the cutting lathe for the master recording to the phono cartridge to the pre amps and amps and the speaker all must not reverse the polarity. That is damn hard to guarantee. In digital, if the OP AMPs in the filters invert, it must be reinverted. > >It's a big pain in the ass.
I'll try your first suggestion but it seems like there is a good chance I won't even be able to tell. Especially since the speakers are high up on a wall and the building interior is mostly exposed metal that is deeply corrugated, like a quonset hut. Thanks, Eric
Jasen Betts wrote:

> > > Play an asymetical signal. One that does not have glide reflection > symmetery, eg: 33% PWM use a low low frequency so that the cross-over > doesn't mess it up too much. > > view the sound on an oscilloscope (or audacity etc) >
** Make current pulses in each speaker using a battery, 1.5 V to 6V. Use a mic or small speaker attached to a pole and view output on a scope. The resulting asymmetrical sound pulses will be the same polarity when the wiring is correct. .... Phil
On Sat, 8 Sep 2018 18:13:28 -0700 (PDT), Phil Allison
<pallison49@gmail.com> wrote:

>Jasen Betts wrote: > >> >> >> Play an asymetical signal. One that does not have glide reflection >> symmetery, eg: 33% PWM use a low low frequency so that the cross-over >> doesn't mess it up too much. >> >> view the sound on an oscilloscope (or audacity etc) >> > >** Make current pulses in each speaker using a battery, 1.5 V to 6V. > >Use a mic or small speaker attached to a pole and view output on a scope. > >The resulting asymmetrical sound pulses will be the same polarity when the wiring is correct. > > >.... Phil
How about connecting the speaker leads to a dual-trace scope and making a pressure pulse in the room. Slam a door. Pop a balloon. Firecracker. -- John Larkin Highland Technology, Inc trk jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On Wednesday, September 5, 2018 at 9:41:54 AM UTC-7, jurb...@gmail.com wrote:
> Turn up the bass, put it in mono and try it both ways. Whichever way has more bass is the right way.
I second this. When I was in college a friend helped me install new speakers in my car. After installing the first speaker, the bass was impressive. When we installed the second one the bass was much less impressive; my friend said I was "getting used to it." Then even later when I switched to JUST left OR right channel, the bass was louder. Dad finally told me one of the speakers was wired backwards. Yep. Michael