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How to position your speakers perfectly

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26 minutes ago, MrC said:

The mathematical definition of an isosceles triangle is a triangle that has 2 sides of equal length.  Well ... an equilateral triangle has this property.  It is the same way we can say that a square is a rectangle (a special rectangle).

From a strict perspective an isosceles triangle two sides are of equal length  The third side is a different length.  With an equilateral triangle all three sides are of equal length.  Therefore the listening outcome could be different depending on the lengths of the triangle sides and the sitting position.

John

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24 minutes ago, Assisi said:

From a strict perspective an isosceles triangle two sides are of equal length  The third side is a different length.  With an equilateral triangle all three sides are of equal length.  Therefore the listening outcome could be different depending on the lengths of the triangle sides and the sitting position.

John

Venn diagram would separate and include both Isosceles and equilateral triangles. ( sub group).

 

Does having 2 equal side exclude having 3 equal sides? no, but having 3 equal sides does not include having 2 equal sides.

 

Therefore an Equilateral triangle is a special case of an Isosceles Triangle.

 

All Equilateral triangles are Isosceles, but all Isosceles are not Equilateral.

 

As I see it.

 

:)

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a373eaf4434467d8788795331986aa6d.jpg

For anyone in Victoria, you should come to our store to audition the well setup P3ESR.

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If you want to really learn something about room setups, try Jim Smith's "Get Better Sound" book - it's a direct 'on-line' purchase from "getbettersound.com" - it's still US$38 + postage - also available as a series of DVDs for those people who prefer this way
 

It also has some 'no-nonsense' introductions to "acoustics 101" (beginner acoustics) plus it has a list of specific music and how to listen well (excellent directions on what to listen for, etc)

 

Knowledge is the cheapest upgrade & the benefits last your lifetime.

 

It's great to see the acoustical control panels in use

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5 hours ago, MrC said:

The mathematical definition of an isosceles triangle is a triangle that has 2 sides of equal length.  Well ... an equilateral triangle has this property.  It is the same way we can say that a square is a rectangle (a special rectangle).

No. an Eq has three. An isosceles has two. Don't change the math to fit your assumption. Sounds like "WE" is you only. Not me.

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4 hours ago, Batty said:

 

All Equilateral triangles are Isosceles,

How? Isosceles has two equal sides. Not three. Seriously, where do you guys get this thinking from? Universities? Making me more and more worried about whats being taught theses days. But, I won't worry for long. Don't give a damn anymore actually.

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7 minutes ago, Wimbo said:

How? Isosceles has two equal sides. Not three. Seriously, where do you guys get this thinking from? Universities? Making me more and more worried about whats being taught theses days. But, I won't worry for long. Don't give a damn anymore actually.

Someone will be offended by your assumption, probs a vegan....

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21 minutes ago, Wimbo said:

How? Isosceles has two equal sides. Not three. Seriously, where do you guys get this thinking from? Universities? Making me more and more worried about whats being taught theses days. But, I won't worry for long. Don't give a damn anymore actually.

Quote the whole and it makes sense.

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3 hours ago, Wimbo said:

How? Isosceles has two equal sides. Not three. Seriously, where do you guys get this thinking from? Universities? Making me more and more worried about whats being taught theses days. But, I won't worry for long. Don't give a damn anymore actually.

You fail to grasp the idea that if there ARE two equal sides in an equilateral triangle then it is also isosceles too.   A Venn diagram that could be drawn has the equilateral triangle set contained completely within the isosceles triangle set.  If you don't get it then you just don't get it mate ... don't worry.

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My mrs just uses the vacuum cleaner as an alignment aid... :(

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On 02/11/2019 at 10:39 AM, bob_m_54 said:

My mrs just uses the vacuum cleaner as an alignment aid... :(

mis-alignment aid?

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On 01/11/2019 at 6:18 AM, Nigel said:

Yannakout, you left out an important item, the listening position. Just as the diagram above shows one particular freq or wavelength cancelling by the reflection from the wall behind the speaker, the same happens for many more freqs, especially the 3 wavelengths corresponding to the room W,L & Height. Various places in the room have primary and secondary cancellation points ("room modes") coinciding in clusters and you don't want to have your head there else you will be judging the overall sound falsely.

this diagram...

mu_2_channel_1.gif.8633f60bc9daf6b4246dcf1f4e5e87fb.gif

...is describing Speaker Boundary Interference Response (SBIR), which creates peaks and nulls in the response.

The issue Nigel describes above is room modal response, which is different to SBIR, but also creates peaks and nulls in the response.

 

As @Nigel points out, the listening position is just as important as the speaker position for both SBIR and Room Modes.

Changing speaker position and/or listening position can have a significant impact on both.

 

Room modes result from the room size - the room will have resonant behaviour based on its dimensions dominated by primary modes for length/width/height where each dimension of the room = wavelength/2, and then each multiple above ie wavelength/4 etc.

There are plenty of "room mode" calculators available on the interweb

Room modes in "normal" domestic rooms (ie small) have an impact below 250Hz or so, and create large peaks and dips in the room response below 250Hz or so depending on room size.

If your listening position is in a modal "null" you will hear reduced volume at that modal frequency.

Modal frequencies are set by your room size (with some qualification for lightly constructed rooms).

Changing the listening position will move you into/out of modal nulls (most rooms experience a significant change in bass response as you move around the room).

Changing the speaker position has a different effect on room modes - place them at a null and that room mode won't be energised - this is a technique Toole recommends.

 

As frequency increases, room modes and their multiples "bunch up" - large auditoriums don't have modal issues - their primary axial length/width/depth modes are well below 20Hz, and the modes are so bunched up by 20Hz it doesn't matter any more - very different to "domestic" listening rooms where modal behaviour with their peaks and troughs are smack in the middle of the room's bass response.

 

Room  modes can be treated with absorption etc, but below 150Hz or so the treatment gets too large and deep to be practical.

1 or more subs can help a lot to achieve a smooth bass response <100Hz or so.  

Below 150Hz or so I've also found EQ cut effective for room mode issues when the room response is "minimum phase" - the concept of minimum phase is a topic beyond the scope of this thread - suffice to say that IME EQ cut works well below 150Hz or so.

 

SBIR is a different beast than room modal behaviour - IMHO SBIR is a topic that doesn't receive the attention it deserves.

SBIR is based on path length differences between direct and reflected sounds creating peaks/troughs in the response.

An SBIR calculator is on Ken Tripp's site - an SNA member I haven't seen on SNA for ages...

http://tripp.com.au/sbir.htm

 

"Floor Bounce" is a term used to describe a specific type of SBIR, where the reflected sound from a woofer bouncing off the floor combines with the direct sound from the woofer to create a "null" at the listening position.

By mounting the woofer close to the floor you can ameliorate this SBIR effect.

 

The further a speaker or the listening position is from a boundary, the lower the dip/cancellation from SBIR is...

...unfortunately you need a truly massive room and speakers/listening position a long way from boundaries to push the SBIR dip below say 20Hz - muck with the calculators to see for yourself...

 

A bit contrary to the normal practise of having speakers as far from boundaries as possible, if you want to avoid SBIR dips/cancellations smack in the middle of the bass region you can push speakers closer to boundaries and raise the SBIR dip to a higher frequency where absorption may work effectively.

 

IME it's never a good idea to use EQ on SBIR issues - SBIR is never "minimum phase", and you will get sub optimal results by applying EQ - speaker/listening position adjustment and treatment are the best solutions for SBIR.

 

cheers,

Mike

 

Edited by almikel

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On 01/11/2019 at 6:34 PM, HdB said:

If you want to really learn something about room setups, try Jim Smith's "Get Better Sound" book - it's a direct 'on-line' purchase from "getbettersound.com" - it's still US$38 + postage - also available as a series of DVDs for those people who prefer this way
 

It also has some 'no-nonsense' introductions to "acoustics 101" (beginner acoustics) plus it has a list of specific music and how to listen well (excellent directions on what to listen for, etc)

 

Knowledge is the cheapest upgrade & the benefits last your lifetime.

 

It's great to see the acoustical control panels in use

I too am a member of the 'Jim Smith Get Better Sound' fan club. 

 

There seem to be two camps that I can identify.

1.  Sound stage lovers

2. Tonal colour lovers

 

Jim Smith is in the second camp and so am I. The guy in the Youtube video who says sound stage is the most important thing for him to listen to is missing out in my opinion.

I have a window that's over 6m wide, 2.7m high with a bar at 1.1m. In the building stage of the room, when the insulation was done and before the gyprock went up, I set up a pair of KEF LS50W on the bar. So there was nothing behind them and everything in the room they were pointing towards was super damped. It wasn't hard to get the most incredible sound stage I have ever heard in my life, from any system in any room. It was so good it was spooky. The music hang it the air like nothing else and even though I could see the speakers, I couldn't identify the sound coming out of them. 

 

You would think I was thrilled.

 

I was thrilled with the accomplishment of creating this incredible sound stage but there was something much more important missing; Tone. Nothing sounded like it's supposed to sound. There was no body to voice or instruments. It didn't sound real.

I'm sure this could be fixed by having much more powerful speakers with better bass. After all, outdoor concerts don't have walls to help out the speakers. But on average I would say setting up your speakers to get the best tone is more important than sound stage in a home setup. 

 

Jim Smith mentions he keep track of the triangle he ends up with after he has set up speakers for his customers and he's come to an average of I believe an 83% (could be 87%, I don't have the book here) width to distance ratio. So if the speakers are 10m away from you ears, they would be 8.3m apart tweeter to tweeter. This is an average, not a rule.

 

I've tried Jim's method in my old room (the new room has 'special' issues) and I found there actually was a point where the tone was best and the sound stage actually became pretty good too. But nothing like that time when I set the KEFs up in the window.

 

There's a lot more in Jims book and I urge everyone to give it a go. It changed my viewpoint of what can be accomplished with a system forever. Even to the point that whenever I listen to some other systems made up of much better equipment than mine I always conclude that mine sounds better, more natural and real.

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On 04/11/2019 at 2:00 PM, Pim said:

There seem to be two camps that I can identify.

1.  Sound stage lovers

2. Tonal colour lovers

at least one more camp :)  :

3. Bass nuts (which I'm one of) - those that enjoy smooth tight bass  - depending on taste from cavernous (<20Hz) up to 250Hz or so

 

IMHO if you get the room bass right, you're 80% done - not trivial to achieve - and usually requiring 1 or more subs, EQ and room treatment...

 

...I like sound stage and good tonal colour also...

IMHO both require a speaker with a smooth on and off axis frequency response - so reflections off room boundaries have the same spectral content as the direct sound.

I'm not familiar with the OP's Harbeth speakers so I can't comment on their sound stage or tonal colour...

 

Kudos to Harbeth for not overstating the low end capability of their 110mm driver in the P3ESR...but their cutoff at 75Hz would benefit from a sub or 2...even if their "in room" response reached lower...

 

I was amazed at the depth and weight a single sub added to my system - a well integrated capable sub added to the OP's system would make a big difference.

 

cheers

Mike

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On 01/11/2019 at 7:18 AM, Nigel said:

Yannakout, you left out an important item, the listening position. Just as the diagram above shows one particular freq or wavelength cancelling by the reflection from the wall behind the speaker, the same happens for many more freqs, especially the 3 wavelengths corresponding to the room W,L & Height. Various places in the room have primary and secondary cancellation points ("room modes") coinciding in clusters and you don't want to have your head there else you will be judging the overall sound falsely.

I did address it just not in detail before the numbers started ( avoid problem spots etc etc) I definitely could have been clearer but I thought it was damn long enough 

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On 05/11/2019 at 9:47 PM, yannakout said:

I did address it just not in detail before the numbers started ( avoid problem spots etc etc) I definitely could have been clearer but I thought it was damn long enough 

It was, but also very much appreciated!😍😘

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