speaker phasing

work out. Perhaps this is a mistake, so I thought I'd ask.

Experiment, but start with all 4 in phase. "Stereo everywhere" is when every chair is between a pair of speakers and was very popular in the pre-SQ 1970s.

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.

"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

There is no such thing as correct time of arrival type of phase coherence in modern electronic media. Everything is close-miked and smeared together with "pan pots" and any spatial sensation is created with DSP. In real life, the stereo "sweet spot" has room for one person at a time.

Put your speakers where they make sense to you. The floor reinforces the bass. The wall reinforces the bass. Too much bass get spkr off floor and away from wall, for more bass put speaker in corner. Usually you want the tweets at ear level, unless they are harsh.

** 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

Do you work with roustabouts or what? Modern electronic media like Pop Tunes and Rock tracks. I don't want to say CDs or downloads or whatever. I have worked behind the scenes and if you bring up time alignment outside the context of an electronic crossover for loudspeakers you get blank stares. Yes Pan Pots suck, almost as bad as graphic equalizers. The sound stage can only be preserved by recording live with no more than 1 directional microphone per channel, and both microphones as close to each other as possible. Then the sound stage is accurately preserved. Any other approach will degrade phase, time or whatever you like to call it. I learned this in the rigging at Jones Hall, recording the Symphony on Nagras.

In the situation you've suggested - if the two left-channel speakers are in phase, then their outputs will reinforce. You'll be doing something like moving the location of the left output to a point located half-way between the two left-channel speakers. Ditto on the right side. This may or may not give you an effect you like... it may "open up" the sound, but at the cost of creating a less-realistic "sound stage" stereo image between the left front and right front speakers.

You might want to experiment with a "phase difference" approach for your rear speakers... something akin to the old Dynaquad system. The simplest way to do this, is to wire the "-" inputs of the two rear-channel speakers together (and not back to the amp). Run the "+" inputs of the left rear and right rear speakers to the "+" terminals of the left and right amplifer outputs, respectively. You may wish to include a rheostat or pad somewhere in this wiring, so you can reduce the (relative) sound level from the rear speakers.

In this setup, the parts of the musical signal which are in phase and at the same volume, will be played only from the front speakers, and will appear to be "dead center". As an instrument or singer moves to the left or right, and the amplitude or phase of their music is different between the two channels, the rear speakers will begin to play it (in addition to one or both of the front speakers). Sounds which are very different in phase between the two channels (e.g. reflected "hall ambience" sounds) will be played most strongly from the rear speakers.

This is a simple and inexpensive setup to create, and it can sound surprisingly good. Compared to the "two left and two right" layout you suggested, it tends to leave you with a more realistic left/right stereo image.

If I recall correctly, the original Dynaquad setup works a bit differently. It requires four identical speakers (the above system works OK with two pairs that can be different from one another)... left, right, rear, and center... and the wiring is a bit more complex. Similar idea, though.

wrote in message news: snipped-for-privacy@googlegroups.com...

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 that it 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 about how this is going to work out. Perhaps this is a mistake, so I thought I'd ask.

If all four speakers are facing one another and are in phase, and by this I mean 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 explained this well. Thanks for any advice. Lenny

Back in the early 90's I was Sound Engineer in the Ministry of Sound Club, London. The main system was 6 stacks of a large PA system, all facing towards the centre of the oblong dance floor. One stack in each corner, and a stack half way down both long sides of the oblong.

I spent a long time trying all combinations of phase, assigning left and right to various stacks, and soon came to the conclusion that running 6 stacks this way in a large room pretty much produced such a chaotic/random sound, and that almost nothing I did produced an overall improvement, if you walked around the room and thus got an "average" assessment of the sound of the PA & room combined. It all sounded really good, actually, especially when the club was full and hot.

If you have a single preferred listening position, e.g. a comfy chair, then this might not apply so much to your situation, but even if it did, i would guess that moving your head a few centimetres would drastically alter the sound you observed, as the results from your 4 speakers are so random and dependent on listening position.

Here's an old photo - you can see 2 of the corner stacks either side of the podium, and one centre stack down one side of the long oblong.

(Stacks were 2 x 18" Y bins subs, 2 x 15" bass, 2 x 12" flared mids, 1 x huge horn compression driver, 1 array of bullet tweeters)

It sounded awesome, and any phase cancellations were totally ignored by a brain if it was pretty much constantly moving through the space covered by the speakers, as yours might when moving around your home.

Gareth.

On Friday, November 29, 2013 8:51:32 AM UTC-5, snipped-for-privacy@gmail.com wrote :

s 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 w indows. They are properly phased and sound very good. One of these existing speakers (left side speaker A system), is very slightly caddy corner so th at it projects into the room. I would like to connect the additional left s ide 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 counterp art from speaker A system,separated by about 15 feet. What I'm trying to ac complish 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 abo ut how this is going to work out. Perhaps this is a mistake, so I thought I 'd ask.

I mean before connecting to the receiver confirming that a small battery m akes all four cones move in the same direction, connected like this what ha ppens 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 p air 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 explain ed this well. Thanks for any advice. Lenny

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

I never mentioned that the receiver is an old Sansui QRX5500. That was a to p 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 pro ject.

This unit, although a quality piece of equipment was built like your typica l brick shit house, with circuit boards, harnesses, switch banks, etc. "lay ered" 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 mod e so that's how I use it.

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

I did notice that with the final setup, that is everything in phase, left a nd right rears facing fronts from across the room the bass seemed especiall y strong. In fact standing in the kitchen, two rooms away, I could feel Iro n 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 noti ced that I could hardly hear any scratches. Wow, ttis Stanton cartridge wit h the elliptical stylus tracking at 1.25 grams must be really something. Th en I remembered the results of my last hearing test, which pretty much show ed that essentially everything is down almost 40DB above eight KHZ, which e ssentially 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 like I remember it....Thanks to everyone for your advice and suggestions. Lenny

You have to analyze these "passive radiator" systems as resonant systems to see how they work.

At very low frequencies (below their cutoff) they do work in the way you think... the driver and passive-radiator outputs are out of phase (by angles approaching 180 degrees as you approach DC) and cancel out, and the acoustic output of the system drops off sharply.

At higher frequencies, the phase offset between the two diaphragms is different. The driver moves, and compresses the air inside the cabinet; the air presses on the passive radiator and accelerates it, and the passive radiator moves. Each of these "presses on" and "accelerates" steps takes time, and introduces some time delay and thus some phase delay... and this phase delay adds up, and has the effect of cancelling out part or all of the 180 degrees of phase shift between the two drivers.

So, at higher frequencies (above cutoff, but still down in the bass), the acoustic output of the driver and passive radiator are either in phase, or close to it... and their outputs reinforce.

The same thing occurs in a common "bass reflex" or "ported" speaker cabinet. At very low frequencies, the output of the port/vent is out of phase with that of the driver and there's no useful output from the system, while at higher frequencies, phase delay in the "back of the driver, through the air in the cabinet and port, to the port output" brings the driver and port outputs into phase, and they reinforce and you get stronger bass.

Both ported, and passive-radiator systems (and sealed "acoustic suspension" as well) can be modeled as electrical circuits. The compliance / springiness of the air and the driver surrounds "looks like" a capacitor, the mass/momentum of the driver and radiator and air "looks like" an inductor, and frictional and other losses "look like" a resistor. A speaker system ends up "looking like" an LCR high-pass filter, and the math for designing and tuning such filters can be applied to the physics of the speaker driver(s) and enclosure.

The development of this sort of electrical-equivalent modeling some decades ago was quite an innovation, and it's what enabled the development of predictable commercial ported speaker enclosures (as opposed to those which were worked out by trial and error, "by guess and by God", and tuned through listening tests until they sounded good to their creators).

David, Thanks to both you and William for your responses. I hadn't realized the complexity of the system. (Simple to look at in its physical form but requiring a complex model to analyse it at the frequencies involved).

Pat

"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