Axiom Home Page Forums General Discussion Advice from Axiom Owners Speaker placement measurement question....

This may sound like a dumb question but it's a question that has popped into my head for quite some time now...

Whenever measuring speaker distances from the listening position, sidewall/back wall placement or even width placement, where are these speakers measured from, the back of the speaker (the rear ports affects the overall sonics) or the front of the speakers?

I've always made the center line of my measurements from the front edge of the grill, directly centered of the drivers for front, back (sometimes) and side placement ... basically disregarding the 17 inches these speakers are deep (I have lot's of room behind the 80s) but I know many of y'all have your speakers 6 inches or so from the back wall, telling me you measure from the back of the speaker.

Where do you all take your measurements from?

And if most of y'all don't understand my question, it's no biggie ... I'm on my fourth Heineken so give me a break, it's just a beverage induced, mind boggling question.

Rick, I usually measure from the center of the front edge of the speaker.

When I measure the back wall distance I measure perindicular from the wall to the center of the back of the speaker box

For me:

Back - from the wall to the rear of the cabinet and normal to the cabinet.

To sweet spot - from the front baffle to the spot diagonally

Width - centre to centre

Rick, the relevant distance should be measured from the center of the woofer cone, also counting the distance traveled along the front and/or side of the enclosure.

If this is the case it looks like I need to measure my distances again. I have always measured from the back of the cabinet to the wall.

Yeah, Rick Wid; it's the point where the sound is actually coming from that interacts with the nearby room surfaces.

John, could you post a link to your source for this information. I just read this article that shows something different.

Well, sure it's different; it pretty much ignores the point raised in this thread, i.e., what part of the speaker is relevant for determining distances. The sound waves reflecting off the boundaries obviously start at the driver cone, not at some part of the enclosure. As far as the different distances to the boundaries requirement goes, here's one brief discussion I found quickly.

In the article you referenced,"Tips For Speaker Placement", the author states "placed...angled in toward the listeing seat." I have not receive my m-80s yet, but when I call Axiom, they said you do not need to toe in Axioms.
What do most people do?

Mine are slightly toed in. Seeing how every room is different, as is individual hearing, I don't know how Axiom can come to that conclusion.

Dude:
Forget the measurements....instead look forward to having your own tap come March...

Whoa, now you're speaking my language Mark!


Measurements?? Who said anything about measuring anything anyway?

So if somebody states their 17" deep 80's are placed 6" from the back wall, in reality they are 23" from the back wall and should be stated as such?

My primary reason for asking the original question was due to the equidistant issue regarding back and sidewall placement, in my warped mind I view the rear port as a sonic source from the speaker and try to integrate that into the placement of the speakers, but with a 17" deep speaker one can understand where there could be confusion with just exactly where the reference line should be regarding back and side wall placement.

It has always been one of those little nagging questions that often comes to my mind whenever I get into the measuring mood.

I e-mailed Axiom on this topic. Here is my e-mail

Hello,

When measuring the front mains for positioning do you measure from the
back of the speaker cabinet or from the center of the front of the
speaker. I know it is said to have unequal distances from the back and
side walls but it will certainly vary if there is no set rule on where
this measurement is taken.

Here is their response

Hi Rick,

Thanks for your e-mail!

My name is Brent; I'm an expert audio advisor with Axiom.

I thank you for your interest in Axiom Award-winning audio speakers and
taking the time to send us in your request.

Measure from the back of the speaker.

The measurer should always give a reference to his/her measurements.

I used to have mine toed in and then I saw the light and straightened them. Toeing them in affects the response off of room surfaces.

That's why it is such an individual preference

Dang brother, you made it seem way too easy ... I suppose I *should* have emailed Axiom myself for the answer but then my personal post count here on the forums would not have increased, taking me just a little longer of reaching that all important goal of Axiomite.

I'm just sayin'.

Rick, that's about right, but another 4-5" can be added to that 23" to account for the width of the front baffle. If the purpose of giving a distance measurement is to indicate acoustic factors rather than simply describing general placement in the room, then the measurement has to made from the driver in question. Distance from the back of the enclosure to the wall behind or from the side of the enclosure to the side wall isn't meaningful in this context.

Wow. I'm inclined to agree with JohnK and am baffled (ha!) by Brent's response. I really needed to feel more confused today, so I want to thank all of you for increasing my anxiety and reducing my productivity. Help, JP!

Alan confirms that JohnK was right, as usual, with his advice on where the measurement should be taken from. He too was a little confused as to Brent’s reply.