Measure/eq with or without mains

1969 Views 9 Replies 4 Participants Last post by Sonnie, May 15, 2006

Discussion Starter · Apr 24, 2006

Which is preferred when eqing?

My thinking is the mains and probably all the speakers would interact with the sub and affect the response?

Thanks

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brucek

· #2 · Apr 24, 2006

It's best to eq with the sub only. You want to first establish and reach your target response, after which you add the mains to check for interaction.

Using the phasing on your sub combined with possibly repositioning of the mains can somewhat reduce the interaction.

Once that's complete, you can often tweak the upper frequency filtering to further help. The effectiveness of the equalization on the overall curve is reduced at higher frequencies but can certainly help around the crossover frequency.

brucek

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Discussion Starter · #3 · Apr 24, 2006

Cool

I know from previous testing I was getting some help by the mains to bring up a null or two in the subs response which was missing in the sub only graph.

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Wayne A. Pflughaupt

· #4 · Apr 25, 2006

To elaborate a little on what brucek wrote:

The effectiveness of the equalization on the overall curve is reduced at higher frequencies but can certainly help around the crossover frequency.

When you add the mains, you might see some response problems around the crossover frequency that are caused by phase issues. Often filters can be added to address these.

Regards,
Wayne

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Discussion Starter · #5 · Apr 25, 2006

When you add the mains, you might see some response problems around the crossover frequency that are caused by phase issues. Often filters can be added to address these.

Do you mean like peaks and nulls? or something different

When you say phasing do you mean 0/180 and speaker distance controls?

What should I be looking for in REW with regards the mains and the sub being in phase? A flat response in the crossover region?

Thanks

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brucek

· #6 · Apr 25, 2006

Do you mean like peaks and nulls?

Yep

When you say phasing do you mean 0/180

Yep, some subs have a switch and some have a nice continuously variable control from 0 to 180.

A flat response in the crossover region?

Yep.......

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Discussion Starter · #7 · Apr 25, 2006

I think Wayne answered this on the AVS forum. I have a Denon 3805 with crossover set to 80hz and speakers set to small. Sub is SVS PB12-Plus. System is calibrated to 85db (82db sub) with Avia.

Denon's have a 4th order crossover? So sub should sound best with phase at 180?

Also as far as speaker/sub distance settings, should I let the receiver auto setup the distances or put them in manually? For some reason I get the best response with the sub distance set to 1m when it's really about 2-2.5m.

Is the distance setting the same as the phase control on the sub?

Thanks

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Wayne A. Pflughaupt

· #8 · Apr 25, 2006

Do you mean like peaks and nulls? or something different

Correct. In my experience, they’ll look something like a saw tooth – sharp, narrow peaks and valleys, often back to back. Typically you’ll find them in the range of about an octave above and below the crossover frequency.

Is the distance setting the same as the phase control on the sub?

Essentially, yes. A variable phase control functions like an analog delay, as I understand it.

I think Wayne answered this on the AVS forum.
Denon's have a 4th order crossover? So sub should sound best with phase at 180?

If you’re referring to the phase figures for various crossover slopes, that is correct, for subs at the front of the room with the mains. However...

As far as speaker/sub distance settings, should I let the receiver auto setup the distances or put them in manually? For some reason I get the best response with the sub distance set to 1m when it's really about 2-2.5m.

Yes, I’d let the receiver do it (although you could double check it by doing it manually and taking readings both ways). The receiver’s distance setting pretty much replaces a sub’s phase control – I’m confident the automatic ones are much more accurate, as they adjust for both crossover phase and distance.

Regards,
Wayne

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mike c

· #9 · May 15, 2006

In my experience, they’ll look something like a saw tooth – sharp, narrow peaks and valleys, often back to back. Typically you’ll find them in the range of about an octave above and below the crossover frequency.

ok, so I have this ... narrow deep dips.

what do I do now? I tried the 0-180 phase thing, the dips above and below the crossover disappeared but a new one appeared higher up the frequency.

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Sonnie

· #10 · May 15, 2006

Hey Mike... you might want to start a new thread and post your REW graph so we can analyze it. We drool over graphs! :yes:

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