Axiom Home Page Forums General Discussion Technical Questions Subwoofer distance from listening position

In a different thread, I complained that the auto calibration in Denon 3805 is setting the distance of the subwoofer more than a meter further than it physically is. In that thread, JohnK pointed out that this is probably caused by delay in the Amp circuitry that causes a few microseconds delay in the sound coming from the sub and that this may be correct.

I decided to experiment in my setup. So I corrected the sub distanct to the actual distanct from the listening position and tested LotR RotK with that setup, then I increased the distance as per the Denon autocalibration and viewed the same scenes again.

With the increased distance, the setup that the Denon did in the autocalibration, I found that the sub sounds much more accurate and that the sub's blending with the mains was improved. The whole sound improved immensly with this setting.


This is my permanent setting now and I am extremely satisfied with it.


This is a hint for people to try (if people do not know about this already) and to check is anyone has a similar experience to me.

Nat:
I'm not sure I'm following you correctly, and I'm particularly interested because my Denon 3805's auto-setup gave an erroneous distance setting as well.

Are you saying that the sound was better with the Denon's auto-setup distance, or the sound was better when an actual, measured distance was manually entered into the 3805's setup?

Sorry- I'm bleary eyed after a lousy nights' sleep!

Go back to bed, Mark. The game doesn't start until 4:30 this afternoon.

If I understand him correctly. He feels the auto calibrate setting sounds better than the manual one.

I cant find my Denon manual at the time , but I know somewhere in the auto calibration section, an explanation is given as to why it sets that distance nearer or farer.

Maybe it's trying to get the right "phase" setting ?

Something I always wondered -- for subs with a continuously variable phase setting, that's going to be just for one frequency isn't it ? I can't imagine a non-DSP solution that could provide the same phase offset for an entire range of frequencies...

Mark, Nat is referring to my comment to him here . It isn't that our manual measurements are wrong, but the time differential(phase, as John B. commented)doesn't always coincide with what a tape measure would indicate. In general my view is that we should trust what receivers such as the 3805 come up with more than we trust our measurements or even(gasp!)our ears.

John, all frequencies travel at the same speed of sound, so a delay setting to compensate for different distances will affect all the frequencies sent out by that speaker equally.

Correct.

What I am saying is that the seemingly wrong distance set by the 3805 is actually CORRECT and results in better sound blending between sub and other speakers.

Let me see if I can describe what I think correctly (remember that my first language is Arabic and that English is my second language)...

Speaker distance in the 3805 is used by the 3805 to calculate the speaker delay. Since the sub is a 'slower' speaker, the 3805 sets more distance so that it can account for the slowness of the speaker.

Makes Sense ?

I had a look through the Denon 3805 Manual.

Page 26 says

- QUOTE -

When measurements have been made using the
measurement microphone, speakers with a builtin
filter such as subwoofers might be set with a
value that differs from the physical distance
because of the internal electrical delay.

- END QUOTE -

I think that confirms it...

Jeez Nat. If English is only your second language, you must be VERY articulate in Arabic, because you certainly do well with English. One of the great educational failings of this country is it's lack of emphasis on learning more than one language. Bravo! Apologies for the off topic comment.