Near field mains and far field subwoofers

[sbronf]

Hi everyone, I have a question about subwoofer placement.
I have a room about 5x4 meters. Normally, the Harbeth p3esr XD speakers are positioned about 3.5 meters apart and about 4 meters from the listening position, with two REL T zero mkIII subwoofers just behind and to the sides of the speakers. However, when I want to do serious listening, I move the speakers in near field at 1.5 meters apart and 1.5 meters from the listening position. My question is: can I leave the two subwoofers in their normal position, about 4 meters from the listening position, or should I move the subwoofers closer together as well?
Thanks!

 

[RayDunzl]

Can I leave the two subwoofers in their normal position

You already did.

Did it annoy you?

 

[sbronf]

I've only tried it once and I don't remember hearing any problems...but I've never tried moving the subwoofers closer together, so I have no comparison.
I also wanted to see if there are any theories or scientific evidence regarding the position of the subwoofers relative to the speakers.

 

[TheKoC]

How do you time/phase/gain align your subs with the main speakers? If you don't, I think both positions are wrong...

 

[sbronf]

Sorry, but I don't understand what you mean...it's my first experience with subwoofers

 

[Oddball]

Well, you should bring the subs closer. 4 m distance for such small subs is not great. Bigger subs or closer distance.

 

[TheKoC]

Sorry, but I don't understand what you mean...it's my first experience with subwoofers

Ok, i meant do you use some kind of DSP to integrate the system? Set time delay, crossovers, gain adjustment, etc. I personally wouldn't use subwoofers without that anymore, but that doesn't mean you can't.

 

[sbronf]

Well, you should bring the subs closer. 4 m distance for such small subs is not great. Bigger subs or closer distance.

ok i could try with rel tx5, just one for the moment

 

[sbronf]

Ok, i meant do you use some kind of DSP to integrate the system? Set time delay, crossovers, gain adjustment, etc. I personally wouldn't use subwoofers without that anymore, but that doesn't mean you can't.

I just measured the frequency response with umik-1 and rew, adjusting the crossover and the volume of the subs until the response seemed correct to me...

 

[DVDdoug]

It could theoretically be a problem...

137Hz has a wavelength of 2.5M. So at about 68Hz that's 1/2 a wavelength and the waves will be 180 degrees out-of-phase and they will cancel.... IF that happens to the crossover frequency where the main speakers and subwoofer are putting-out equal signals.

 

[TheKoC]

I just measured the frequency response with umik-1 and rew, adjusting the crossover and the volume of the subs until the response seemed correct to me...

I would tend to keep the subwoofers close to the mains then, although the response will still change, for example if you move the subs away from the walls/corners you will loose the boundary gain. Remeasuring for the new position would be a good idea.

 

[RayDunzl]

I also wanted to see if there are any theories or scientific evidence regarding the position of the subwoofers relative to the speakers.

Sound travels 1 meter in 2.92 milliseconds.

So, if you move the mains a meter closer to you than the subs, the subs will be 1.92 milliseconds late - or later than they are now, that being an unknown.

If it sounds good I wouldn't worry about it.

Of course it could all be measured and modified and corrected if it causes an audible problem.

 

[Keith_W]

If you have a microphone, you can measure and see the difference for yourself. There WILL be a difference, but whether that difference is better or worse, nobody knows until you measure.

 

[Cote Dazur]

My question is: can I leave the two subwoofers in their normal position, about 4 meters from the listening position

Since you already done it and did not noticed anything wrong, I would leave well enough alone.
I too listen near field with sub far away, I like it better that way.
I have to add that I like my near field listening even better without sub, as the bass of my speaker in near field is more than adequate.
Have you tried that?