ETC and determining speaker alignment

[Drudge]

I'm trying to determine through the ETC graphs if my front 3 speakers are positioned equally to the listening position by looking at the impulse response.Do all 3 responses have to mirror each other through a majority of the response or do just the initial spikes have to align with each other if the speakers are equal in distance to the mic?

Here are 2 ETC graphs of my 3 LCR speakers.


ETC dBFS graph



ETC %FS graph

[brucek]

Do all 3 responses have to mirror each other through a majority of the response or do just the initial spikes have to align with each other if the speakers are equal in distance to the mic?

Yeah, the initial spikes should align. After that, the reflections can be dealt with by looking at each speaker if you wish.

BTW, the %FS is the best graph to use for the alignment...

brucek

[Drudge]

Thanks again Brucek

[JohnM]

You cannot tell distances by making individual measurements, REW automatically aligns the impulse responses. To make distance measurements you need to either use the "left channel loopback" option in the REW soundcard settings and read the distance from the measurement details or (my favourite and quite reliable ) use a tape measure.

[brucek]

You cannot tell distances by making individual measurements

Yeah, I forgot that. I failed to notice the different colors on your plot "drudge". I did try and use REW in the past to determine if my main speakers are aligned at the listening position (after someone asked about it) and it works quite well, and you do indeed need to be using the "left channel as cal reference" option.

But as John says, why not just get out a tape measure....

brucek

[Drudge]

I've measured them with a tape measure within +/- 1/8".

Just thought it would be cool(and little more accurate)with the ETC graphs.

I'll have to try REW's distance measurement for sure.


Thanks again guys

[tenzip]

I don't know about your pre/pro or AVR, but I believe the best I can do in mine is .5' increments, so it's not all that critical, as you can't adjust any closer than +/- 3 inches, at best.

I guess you could actually move the speaker(s) themselves an inch or two for fine adjustment, unless they're mounted, but then I think we've gone around the bend from sanity. (More than we already are, that is.)