Hi there,
I've read stuff about sound cancellation and such for bass, but never for the whole audio band. Hence my request for help.
In my room with all speakers I have had, and the one I use now, the stereo image was unstable. If you are slightly in front of one speaker then you think the other is faulty and not playing. The sweet spot is very unstable, toe in and out, closer or not. Same feeling as a speaker out of phase.
So I've played pure sine waves, at frequencies where each driver should play alone. And it made me almost sick, I mean physically.
With low frequencies if I move slightly myself backward or forward the sound goes from center to left only, but not speaker left but almost on my very side at 90° and in the same time no sound at all to right! This was close to pain :'( Going up in frequencies gave the same result, but with faster change in the "center/left/a touch of right" cycle with less movement from me, I guess proportional to wavelength. And in highs I can also with very slow moves get complete cancellation, no sound at all! That's funny and scary at the same time, there is sound playing I know it but I can't hear it...
No wonder I don't get a stereo image...
I've never read that kind of issue, do I have an ear in reverse phase? The amp does fine as with oscilloscope both channel are in phase (higher freq as my scope is slow and don't cope well with LF). Don't have a clue on how to understand and solve.
Any ideas?
I've read stuff about sound cancellation and such for bass, but never for the whole audio band. Hence my request for help.
In my room with all speakers I have had, and the one I use now, the stereo image was unstable. If you are slightly in front of one speaker then you think the other is faulty and not playing. The sweet spot is very unstable, toe in and out, closer or not. Same feeling as a speaker out of phase.
So I've played pure sine waves, at frequencies where each driver should play alone. And it made me almost sick, I mean physically.
With low frequencies if I move slightly myself backward or forward the sound goes from center to left only, but not speaker left but almost on my very side at 90° and in the same time no sound at all to right! This was close to pain :'( Going up in frequencies gave the same result, but with faster change in the "center/left/a touch of right" cycle with less movement from me, I guess proportional to wavelength. And in highs I can also with very slow moves get complete cancellation, no sound at all! That's funny and scary at the same time, there is sound playing I know it but I can't hear it...
No wonder I don't get a stereo image...
I've never read that kind of issue, do I have an ear in reverse phase? The amp does fine as with oscilloscope both channel are in phase (higher freq as my scope is slow and don't cope well with LF). Don't have a clue on how to understand and solve.
Any ideas?
Invite a friend over: does he/she hear the same thing?
Try with a headphone set - still the same?
Try with a headphone set - still the same?
It might help if you describe the equipment used, and post a photo of your room.
Variables must be eliminated, to redress your problem.
http://www.cardas.com/room_setup_main.php
Sent from my Nexus 6 using Tapatalk
Variables must be eliminated, to redress your problem.
http://www.cardas.com/room_setup_main.php
Sent from my Nexus 6 using Tapatalk
You might just hear the room more than your speakers. Have you heard real Stereo before? Just asking because there are people who are insensitive to a phantom centre stereo image.
Get the speakers away from all walls, sit up close at 1 M in a typical stereo triangle and check.
Draki, yes it's obvious to everyone as when I've sold my B&W DM4 the two young guys listening to them each complained the opposite speaker was faulty as almost silent until I told them to listen in the middle for them to conclude that something weird was going on.
As for headphones I can only say the sources are stereo compliant. Guess that confirms a problem 😉
Anji and Wesayno, I'll make pictures from four corners and a list of the gear. Btw I must say my freedom of placement is limited by the fact wires must be hidden as a rabbit is roaming the room, bunny owners know what I mean.
What is the phantom centre stereo image? The name of the perfect stereo illusion effect? I have to be honnest and say I don't know, I have experienced voices in center, drummer hitting from side to side, but each time on a very unstable spot wich is never sweet. If depth is part of the phantom I only experienced that once with my no more used OBs.
I can go downtown to ask the kind seller of the last audio shop to set me a very good and rock solid stereo imaging system -to his ears- and see if I experience it.
As for headphones I can only say the sources are stereo compliant. Guess that confirms a problem 😉
Anji and Wesayno, I'll make pictures from four corners and a list of the gear. Btw I must say my freedom of placement is limited by the fact wires must be hidden as a rabbit is roaming the room, bunny owners know what I mean.
What is the phantom centre stereo image? The name of the perfect stereo illusion effect? I have to be honnest and say I don't know, I have experienced voices in center, drummer hitting from side to side, but each time on a very unstable spot wich is never sweet. If depth is part of the phantom I only experienced that once with my no more used OBs.
I can go downtown to ask the kind seller of the last audio shop to set me a very good and rock solid stereo imaging system -to his ears- and see if I experience it.
And yes, placing them in similar places is important. I.e. one of them in a corner and the other one freestanding is definitly detrimental to imaging for instance.
Do they have large differences in frequency response maybe (like one driver defective or outr of specs or wired out of phase) ? There is an easy test for that: Place them face to face very closely spaced, one of them wired out of phase. Now run noise from an FM receiver through them. It is important that it is a MONO signal with equal level on both channels that you feed them. There should be a definitive drop in loudness throughout the whole audio spectrum when both are playing, compared to only one playing. But don't expect to have full cancellation. A difference of just 1 dB, which is not that bad at all, reduces the cancellation to just - 20db.
Regards
Charles
Could one of the speakers be wired in reverse? Try flipping the red/black terminals on one of them.
Good to have: a Stereophile or similar test CD. There are spoken voice Left/Right, In-Phase, Out-of-phase tracks which are very useful for this purpose. Voice is much more natural and intuitive than pure tones/sinewaves.
Tested as that was my first tought. No issue there, DMM beeped and scope tested.
Good tip!
Michael and fellows, will play with placement after pictures.
Thanks guys for helping!
Matthieu
1) Find a source of noise (white-noise or pink-noise) or steady applause. Hit the "play" button and adjust volume to a comfortable level. Not too loud, not too soft. A little above conversation level is correct.
2) Listen to the pair of speakers in the "normal" connection in a central seating position. Note sensation. Press "pause" and return to beginning of track. Do not adjust volume.
3) Reverse the "hot (red)" and "cold (white)" speaker wires to ONE speaker only. Leave the other speaker alone. Press "play" again. Return to the central seating position.
4) How does it sound different? The connection with the most bass, and most solid center image, is the correct connection.
It is possible to have speakers internally miswired (this even happens with commercial speakers every now and then). That would result in the woofers being in-phase, but the mids out of phase, which would result in really weird imaging.
If you notice the speaker-wire connection (steps 1 through 4) that results in the most bass also results in poor center-imaging, that could be the case. This can be confirmed by reversing the speaker-wire, as described above, and noticing if the bass gets worse but the imaging gets better.
If this is the problem, you have to open up the speakers and carefully check the phase of all the wires from driver to crossover, as well as the wires from the crossover to the speaker terminals on the back of the enclosure.
Correct phasing, along with matched-pair drivers for each part of the spectrum (woofer, mids, tweeter) is absolutely essential for a stable stereo image. If the drivers are mismatched, or the wiring wrong, then stable stereo is impossible.
The other requirement is symmetric placement in the listening room and a spacing angle of 40 to 50 degrees apart (as seen from the listening position). I usually aim the drivers at a point about 0.5 meter or 20 inches in front of the listening position.
P.S. There is an iPhone/iPad app called "Theodolite" which is very convenient for precisely measuring the angle between the stereo pair. I thought my speakers were pretty widely spaced but it turned out they were exactly 45 degrees apart.
2) Listen to the pair of speakers in the "normal" connection in a central seating position. Note sensation. Press "pause" and return to beginning of track. Do not adjust volume.
3) Reverse the "hot (red)" and "cold (white)" speaker wires to ONE speaker only. Leave the other speaker alone. Press "play" again. Return to the central seating position.
4) How does it sound different? The connection with the most bass, and most solid center image, is the correct connection.
It is possible to have speakers internally miswired (this even happens with commercial speakers every now and then). That would result in the woofers being in-phase, but the mids out of phase, which would result in really weird imaging.
If you notice the speaker-wire connection (steps 1 through 4) that results in the most bass also results in poor center-imaging, that could be the case. This can be confirmed by reversing the speaker-wire, as described above, and noticing if the bass gets worse but the imaging gets better.
If this is the problem, you have to open up the speakers and carefully check the phase of all the wires from driver to crossover, as well as the wires from the crossover to the speaker terminals on the back of the enclosure.
Correct phasing, along with matched-pair drivers for each part of the spectrum (woofer, mids, tweeter) is absolutely essential for a stable stereo image. If the drivers are mismatched, or the wiring wrong, then stable stereo is impossible.
The other requirement is symmetric placement in the listening room and a spacing angle of 40 to 50 degrees apart (as seen from the listening position). I usually aim the drivers at a point about 0.5 meter or 20 inches in front of the listening position.
P.S. There is an iPhone/iPad app called "Theodolite" which is very convenient for precisely measuring the angle between the stereo pair. I thought my speakers were pretty widely spaced but it turned out they were exactly 45 degrees apart.
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First things requested first, pictures. Each corner and a kind of wide angle photoshop wich was taken from the wall which is almost in full the bay window. And this is all but symmetrical...
List is easy, Tuner/Transport&Dac/Turntable, then a pair of UcD400 and finally speakers being JBL 4313B...
Close 1m and more off the wall test and reversed phase on one speaker are next.
List is easy, Tuner/Transport&Dac/Turntable, then a pair of UcD400 and finally speakers being JBL 4313B...
Close 1m and more off the wall test and reversed phase on one speaker are next.
Attachments
I guess it is that Bjork Cover on the wall. She can be quite detrimental to listening pleasure ! 😉
Fun aside: That might not be the perfect setup but it should definitely give at least some imaging. For that listening distance the speakers are a little closely spaced IMO. You don't have a equally sided triangle if I estimate the distances properly. You might have a hole somewhere in the upper bass however due to floor bounce. And did you ever try any toe-in ?
Regards
Charles
Fun aside: That might not be the perfect setup but it should definitely give at least some imaging. For that listening distance the speakers are a little closely spaced IMO. You don't have a equally sided triangle if I estimate the distances properly. You might have a hole somewhere in the upper bass however due to floor bounce. And did you ever try any toe-in ?
Regards
Charles
You have a big reflective surface (glass) one side, and a diffuser (bookcase) the other side. Could affect the off axis performance. I'd try removing the hifi rack and chest from between the speakers and toeing them in to cross a foot or so in front of the couch. Also the table in front of the couch probably doesn't help.
Rob.
Rob.
I've seen worse set ups that sounded fine. I'm suspicious of a wiring problem, as mentioned above.
If there us another pair of loudspeakers available, substitute those to verify the problem.
If the interference persists, the problem is not the speakers.
Mechanical parts are the most common (and likely) sources of playback errors.
I suspect there is a midrange driver, or woofer connected with reverse polarity, or one of the interconnects is intermittent.
It looks like a nice room. I do hope the OP gets it sorted.
Sent from my Nexus 6 using Tapatalk
If there us another pair of loudspeakers available, substitute those to verify the problem.
If the interference persists, the problem is not the speakers.
Mechanical parts are the most common (and likely) sources of playback errors.
I suspect there is a midrange driver, or woofer connected with reverse polarity, or one of the interconnects is intermittent.
It looks like a nice room. I do hope the OP gets it sorted.
Sent from my Nexus 6 using Tapatalk
From post #1
Ralf
This should leave out the speakers as the culprit. This is a perfect case of problem determination, you have first to find where the problem is, and only then try to find a solution. You need to understand if the problem is the room or the amp/cdp, as the probability that several speakers have had the same problem is quite zero. You need to perform two or three tests: move the whole setup to another room, have another amp/cdp in the same room and optionally in another room. Those tests will sort out where the problem is.
Ralf
For this to be systematic, only a single variable can be changed to find the source. I fear the description is incomplete, as the photos show a room no worse than most.
I wonder if it's something obvious we've missed, such as the dimensions of the "listening triangle"?
http://www.cardas.com/room_setup_horizontal_and_square.php
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I wonder if it's something obvious we've missed, such as the dimensions of the "listening triangle"?
http://www.cardas.com/room_setup_horizontal_and_square.php
Sent from my Nexus 6 using Tapatalk
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