# Speaker or Sub Distance Adjust?



## allredp (Feb 7, 2007)

Just trying to use the distance adjusting for phase control (my SubMersive doesn't have a phase/polarity switch or dial). 

So, when you are trying to smooth out the x-over area (and other parts of the line), do you only adjust the sub's distance in the AVR or do/can you adjust the speaker's distance. 

Wondering what affect this will have on imaging, etc...

How do you calibrate the Center when you've already adjusted the mains? 

Thanks.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Moving to General Discussion, since the questions have nothing specifically to do with REW.

Regards,
Wayne


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## Wayne A. Pflughaupt (Apr 13, 2006)

Well, since no one else seems inclined to tackle this I’ll give it a go.

Basically an answer depends on what distance-setting capabilities your receiver has. The goal is to get all speakers’ signal arriving to the listen position at the same time, so utilize whatever settings you have available to accomplish that.

Regards,
Wayne


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## brucek (Apr 11, 2006)

> Just trying to use the distance adjusting for phase control


If you have no phase control, the distance adjust in the reciever for the sub is a decent proxy.

Set the distance of the sub to its measured distance as a starting point, then take a measure of the sub plus mains with REW and adjust the distance of the sub setting in the receiver to obtain the best, smoothest crossover region (as you would normally do with the phase control).

It's actually easier to do with the REW RTA feature rather than with successive measures.

brucek


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## allredp (Feb 7, 2007)

brucek said:


> If you have no phase control, the distance adjust in the reciever for the sub is a decent proxy.
> 
> Set the distance of the sub to its measured distance as a starting point, then take a measure of the sub plus mains with REW and adjust the distance of the sub setting in the receiver to obtain the best, smoothest crossover region (as you would normally do with the phase control).
> 
> ...


OK, that makes sense. I did do multiple measures just manipulating the sub's distance and it makes a rather impressive difference for sure. 

I'll have to read up on the RTA because I don't understand the simple "lines" it creates...

Thanks again.


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## brucek (Apr 11, 2006)

> I'll have to read up on the RTA


See here...

brucek


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## allredp (Feb 7, 2007)

brucek said:


> See here...
> 
> brucek


OK, that's very helpful! I'm going to go check that out and see how it works. 

BTW, how is RTA different from RT60? 

IIRC, RT60 is for measuring decay times in your room. This would help in measuring how well acoustic treatments are doing, right? Along with the waterfalls which are supposed to show you which frequencies are hanging around too long. 

Speaking of waterfalls, here's one from my last sub/mains (R&L) measurement.









Does that look right? 

Thanks again.


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## brucek (Apr 11, 2006)

> Does that look right?


You must switch to LOG mode rather than the LIN mode you're using. Click the button in the upper right hand corner of REW.

RT60 and RTA are completely different. RTA is like a dynamic frequency response, as opposed to taking a single static response check.

RT60 is only useful above 200Hz and is of limited use for small rooms such as in home HT's.

brucek


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## allredp (Feb 7, 2007)

Ahhh, like that, eh? 

OK, that's helpful. 

So, this shows me that I need some bass-trapping... What kind of "timing" are we shooting for, btw? 

Now I can re-check this waterfall against future measurments when I introduce/alter my room's acoustic treatment, correct? That way I can really see what each change is making sonically. 

Will EQ also affect this?


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## brucek (Apr 11, 2006)

The waterfall isn't bad at all. The 'room treatment/bass trapping' to counteract any ringing that low would be unrealistically large, so you must use EQ if you want to bring down the decay at 22Hz and 38Hz, but it's almost below room noise threshold by 300ms, so it's not bad at all.

brucek


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## allredp (Feb 7, 2007)

Really?! That's too cool--my wife will be ecstatic. 

Thanks much Brucek.


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