Basic stereo setup, how do you do it, what is important to you?

[terryj]

Ok, stereo is an artificial construct as we all know, and at it's most basic depends on the relative positions of the speakers and listener.

So, how much care do you take? How do you go about it? Do you pay more attention in one area of that setup than another?

At a guess, what would you think your potential error is between the left listener distance vs the right listener distance?? How would you know??

Where would you place it on the relative levels of importance, maybe you feel the amp speaker 'synergy' (oh how I hate that word!) is more important, or sumthin else. Whatever.

 

[Steve Williams]

I am very anal as to placement of my speakers as well as listening position. Wilson formula is

1-1.3 X distance from tweeter to tweeter=listening position

presently my sitting position = 1.1X distance from tweeter to tweeter

 

[DonH50]

My order:

1. Speaker/room interactions.
2. Everything else.
3. What my dog thinks. Sometimes elevated in status to (2), never to (1) unless she has to go out then all other priorities drop.

I do take great care in speaker placement, but then I am an engineer so tend to overdesign everything. (Hey Steve, how's that for getting around the word "anal"? )

 

[terryj]

hah, bet they are not lightweight speakers either!!

So HOW did you get that exact ratio? Get the left (say) in one position, then physically move the other? Using what, tape measure? You're not prone to long posts! so I doubt you'd explain more fully, but that is kinda what I am curious about, the methodology used to get the job done, and the error bars the person suspects they have in those physical measurements.

Would you think your left and right are the same distance from your forehead to 1 inch, 1/2 an inch, you know that sort of stuff. And then, again, how do you know it is as accurate as you think? (not you steve in particular, the general 'you')

What level of accuracy do people strive for? 1 inch close enough? Beyond which level of accuracy is there no further benefit? If not why not, if so why so. How would a one inch difference manifest?

Oh hi don, thanks. about sums up my order of importance, tho I suspect the missus might be a tad miffed if I described her that way as in your point three (haha, joke).

Ok, if the speaker and room is so important, how much care do you take, how do you do it? Being an engineer, you'd know what I mean about error bars!!

 

[Steve Williams]

Terry

I agree with Don that speaker placement comes first and then the room. As far as placement I can tell you that I am accurate within 1-2 mm. I can say with 100% certainty that the distance from back of each side of my speakers to the front wall is identical to the other speaker. As well the distance from the front and back corners of each speaker to the side wall is absolutely identical. It took great trial and error as each speaker weighs 720 lbs. As to how they were moved,Wilson delivers the speakers on rollers which are used to place the speaker before they are spiked. As to toe in the Wilson formula re ommends that from the sitting position you should only be able to slightly see the inside wall of each speaker. Finally as to placement of speakers Wilson recommends the Slap Echo method.
A laser light is also used by me.

 

[DonH50]

Well, the formula is a standard rule-of-thumb for roughly equilateral placement. The other formula worth remembering is that ___ (drew a blank, sorry) says optimal viewing distance is about 1.5 to 2 times the screen diagonal. This can make for some interesting set-up situations... I got lucky and my range of optimum listening and viewing distances overlap quite a bit.

I am not quite as exacting as Steve, but I use a tape rule to get the speakers within a fraction of an inch. I don't recall our time resolution capabilities, but 1 ms is about 1 foot so under an inch means less than 0.1 ms delay difference between the two speakers. I suspect that is good enough. Toe-in is a function of the speakers; my Magnepan panels probably like a bit different toe-in than Steve's Wilsons with their drivers lined up. Magnepan suggests aligning them pointing at the listener but toed so the bass panel is a bit "ahead" or closer to time-align the wavefront. For my current placement, with my tweeters on the outside, that means they are actually aimed a little behind the listener's head.

As for the room, I start with a scale drawing of the room, including speakers, equipment, and furniture. The listening spot is a close guess based upon where my ears are when sitting on the chair or couch, but since I want to cover a fairly wide area of listening spots super precision is not required. i do accurately (with a tape rule) determine the center listening position to use as a reference. I use triangles in the drawing program to establish the range of early reflection points on the walls and ceiling with respect to the listening position(s); I can change the size of the triangles without messing up the angles. That determines where and how many panels to put up. Since I use dipole speakers, I also deaden the front wall, and I tend to place additional absorption on the back wall and ceiling to help suppress early reflections from the rears and secondary reflections from the mains. Having fairly tall and wide speakers, I probably end up with an extra row of panels compared to most folk. I also have enough of a recording background (not that much, but enough) that a room on the dead side does not bother me.

I usually calculate room modes (I have my own program, but there are numerous mode calculators on the web) so I have an idea what I am starting with. That tells me what to expect when doing my measurements, and helps decide what sort and how many/big traps I need.

I take lots of measurements while going back and forth between the plots and listening to get the widest, bestest sweet spot I can.

I should note the dipole panels like Maggies and electrostats are more room-sensitive than conventional speakers due to their back wave. However, thinking regular speakers are insensitive to the room is a big mistake. I have seen a lot of people paying thousands for equipment upgrades when a fraction of that in room treatment would make a much larger difference sonicly.

FWIWFM - Don

 

[terryj]

steve, mm?? don't you guys use inches!

1-2 mm, that is impressive. (and I suspected your buggers would be hard to move!) How do you use the laser?? what can that tell you.

Hi don, have never heard maggies, but the people that have them swear by them.

Not that I wanted this thread to particularly go in the direction of a survey on what ratio you have, but mine are setup diagonally within the room (a decware reference)..it worked for me.

What I am wondering is 'just how accurate CAN you be with a tape measure'?? At least two people, the tape can sag differently, the spot on the couch used as a reference can vary ever so slightly, yada yada. I mean we do it to one of two points (I think), to the limit of our measurement (tape example) or to the 'that should be sufficient' level, which includes the limit of measurement with the tape with the added layer of 'point of diminishing returns'.

(from recent comments thought I'd better make this clear steve, not directed at you specifically)..so we think we are accurate to 2mm say, how do we know?? How can we confirm?

What IS the sonic difference between 5mm and two mm?? How would we perceive that difference? For example, I doubt we'd say 'oh, the left is later than the right', but if it has a sonic consequence, how do we hear that consequence?

I'll fess up and say this all has to do with the imaging stuff I was going to post about, but have changed it to a more general curiosity thing, mostly to do with 'how do we know it is as accurate as we think it is', limits of the techniques used.

For example, toe in. For most it would be the final tweaking in this process?? With that, what do you use it to tune for? Don uses it to get the widest sweet spot he can, I imagine another might use it to get the sharpest focus of the centre image, I use it to get the most enveloping ambience I can...willing to sacrifice pinpoint imaging for that....BUT I now suspect it can be a final way to get the speakers equal distance to the listener??

We do the best we can with a tape measure, then by rotating around one spike we can fine tune the distance that way (even if this is being done unconsciously)???

One last thing don, fwiw I understand, but what is fwiwfm???

 

[Robh3606]

Hello Terry

I am very careful about placement and matching driver pairs when I put a set of speakers together. I like to match the actual driver pairs withing a Db of two. I usually get a couple of pairs of drivers and measure and match the drivers in pairs. If I can't get them close I will tweak the crossovers to get the match. I like to have the speakers pair matched as best as I can.

 

[Bruce B]

The one thing that can't be stressed enough is symmetry. Every acoustician will say symmetry in a room is critical for spatial cues. We built our room perfectly symmetrical +/- 1/16"
As with Steve, our speakers are within 1mm of being symmetrical. When we had the Wilsons in here, we used the Wilson formula. Now we have the Evolutions and we followed the guidelines in their manual. According to what project I'm working on, either stereo or 5.1, the listening position moves a couple of inches front/back, so that I can get the 110 degree angle for the surrounds. I've just reached 1000hr. on the speakers and now have started to do my fine tweaking of the controls in the back. They're still sitting flat on the floor and will eventually use the spikes or Wave Kinetics footers.

 

[DonH50]

My tape rule is laid on the floor to prevent sag. I also use marked wooden measuring sticks to make life easier (and faster).

FWIWFM = for what it's worth from me (not bloody much)

My room is not symmetric, unfortunately, but OTOH it's a HT/media room, not a studio, so I have to work with what I have.

 

[Robh3606]

My room is not symmetric, unfortunately, but OTOH it's a HT/media room, not a studio, so I have to work with what I have.

Mine isn't either and I think It works in our favor. Symmetry is nice from the visual aspect but it also reinforces room modes when a stereo pair is placed in the exact same positions in a rectangular room.

Rob

 

[RBFC]

Mine isn't either and I think It works in our favor. Symmetry is nice from the visual aspect but it also reinforces room modes when a stereo pair is placed in the exact same positions in a rectangular room.

Rob

While symmetry does increase the effect of room nodes and nulls, those nodes and nulls are more predictable and less complex to deal with if I recall correctly. With the advent of DRC and various implementations of bass EQ, I agree with others that symmetrical placement (carefully measured) and reasonable treatment of primary reflections are the initial goals for setup.

My current room is hopelessly asymmetrical, so speaker placement and some acoustic treatment are all I can reasonably do, along with the JL's ARO.

Lee

 

[terryj]

thanks guys, keep em coming.

It's good to hear that accuracy IS striven for. I admit I have a little tale to tell, which has very much rammed home how important all this can be, but will wait for a day or two. Hah!, I may as well post my measurements bit I 'threatened' you all with in the other thread haha, it would be interesting to see if others can duplicate it.

Anyway, will tell that little story soon.

(thanks don, thought it may have been along those lines)

On to the symmetry, not all of us have a symmetrical room, and even less so the luxury of building one! Well I have already mentioned that my system is set up 'to the corner', and I DO have a symmetrical room!

The only real symmetrical layout this room presents necessitates that I have a bay window behind me. It is rather a large bay, but on hindsight (I think) it acted as a lens, and reflected everything back to me (the focal point). As they are all tall windows, I cannot really blot them out with absorption or anything.

This may or may not be useful to others, often we just like reading stuff relating to audio, but here is the link that I decided to try http://www.decware.com/paper14.htm

It really lightened up the midrange and vocals.

Anyway, it's there if you're interested, if not then ignore.

 

[terryj]

grrr lost my edit! grrr

any thoughts on how any discrepancy here will manifest aurally? How different will 5mm be from 1mm.

rob, what do you do with the drivers you discard from your matching process?? how much DO they vary??

and, build thread??

 

[Gregadd]

Re:measuring distances- For the really lazy and anal you can get a range finder or laser masuring device. I'm not sure of the dgree of accuracy. Available on the internet, large sporting goods store and home improvement center.

 

[DonH50]

Greagadd, Steve said he uses one. Not sure if he's lazy, anal, or both... OTOH it can be argued that perfection of the whole comes from doing a lot of little things right...

I think ones with mm accuracy are not cheap but I have not priced them for a while. Of course, you probably don't actually need that much accuracy if you are simply trying to place things symmetrically, just repeatability. Probably still expensive.

terryj, I doubt anyone could hear a difference between 1 mm and 5 mm but I've been wrong before. The speed of sound is about 1127 ft/s. The wavelength at 20 kHz is about 17 mm (0.676"), so arguably you could hear the difference with a 5 mm shift since that's over 1/4 wavelength. Assuming you can hear to 20 kHz (I no longer can). At 10 kHz, double those numbers. There's also the time delay issue, but I don't recall how finely we can resolve time deltas (anybody remember? one of those things I should know but have forgotten). I would expect a small shift to move the image slightly; whether that causes imaging issues depends upon how linear the delay is with frequency from your speakers and room interactions.

I would guess I am within about 1/4" or less using my various rules (tape and wooden) and that's good enough for me. I am pretty sure my head moves well over 1 mm over the course of listening to a song or three... I remember adverts years ago for chairs with small pads to keep your head in one position, but my fear of dental tools kept me from ever getting one.

 

[Steve Williams]

not lazy but definitely anal

I use the laser light having someone aiming the light from the inside wall of each speaker aimed to the ipsilateral ear at the sitting position. This allows for very precise toe-in

 

[Robh3606]

I agree with others that symmetrical placement (carefully measured) and reasonable treatment of primary reflections are the initial goals for setup.

Yes I agree. My set-up is symmetrical however the room positions are not. You are right about room modes being much easier to predict in a rectangular room. That said as long as you have a way to measure what's going on there is no reason why you can't get acceptable results in rooms that are more complex for the simulators to deal with.

Rob

 

[RBFC]

The ability to deal with multiple room modes in the bass region will depend on which EQ program you employ. JL's ARO program only corrects the largest bass anomaly in the room. More sophisticated DRC is necessary for handling multiple peaks/valleys. I understand that one may not choose to integrate a subwoofer into a straightforward stereo setup, but the JL "room correction" is used as an example of an EQ scheme that may not be sufficient for more complex rooms.

Lee

 

[FrantzM]

Hi

I use a laser to have toe-in as precisely as possible. Measure to inches etc. My former room was symmetric. I do now know and have experienced that in the very low bass , say under 50 Hz, it is good to use multiple subwoofer (more than 2 ) and in asymmetrical positions a la Geddes. Works marvelously and will provide a level and quality of bass that few would suspect their system capable of, everything else being equal, i-e adequate subwoofer with variable phase, crossover and level controls, good source, amps and speakers.

I have come to understand that the most important thing is to place the mains where they stage and sound the best in the upper range, i-e over 500 Hz, then bring the bass with subwoofers. I hasten to say that I am not a fan of mini-monitors plus subs. I'd rather use full range mains plus subs. The way I have witnessed what subs can do in term of bringing a system to a superior level of quality, I would recommend to always use subs, at least three...