Subwoofer Discussion

[Timber_MG]

@RR....you may hold that opinion but my experience is counter to that and I have played with multiple subs lots (once added two 10" sealed units 8dB down in output to two large subs and was gobsmacked at a 60Hz massive room mode evening out beautifully. I am yet to fail to be astounded by the improvement multiple subs make.

If the sub isn't rattling or pulling untoward attention to itself I assert that it would improve the bass region (seemingly a secondary concern in the actual problem so I suggest moving this to another thread if you whish to continue). I would also recommend playing with the roll-offs and levels of the subs (and a measurement system and EQ helps too)

Google search for for Dan Wiggin's excellent dissertation of Woofer speed.

[RR]

I still have no problem with what you're saying, but the Mission sub and REL sub is too different. Its like using the center channel speaker from an LG HT in the box system with Sonus Faber Extrema's as main stereo speakers. (OK, greatly exaggerated example but makes the point).

I think we both agree that two subs can be magic, I feel he might then consider getting a second REL Q-series sub (If this sort of requirement is part of his system fix obviously)

[Timber_MG]

@Moderator: please move to a new thread.

@RR: Wave propagation where there room dimention is acoustically small compared to the wavelength is a totally different case.

This is off topic.

[Hennie]

........... I am yet to fail to be astounded by the improvement multiple subs make.

If the sub isn't rattling or pulling untoward attention to itself ...........

I support the multiple sub idea, IME in most cases it really gives a significant improvement w.r.t. room modes. But who knows, if one sub is really low quality.........

I suggest: Let the reader experiment and decide.

[Andrew]

Hey, so here I can expose my ignorance and ask for advice on my set-up. Yamaha receiver plus Yamaha sub. Used the auto set-up feature, and generally the thing works great, but sometimes the bass comes out and pretty much wipes out everything else in the room. It doesn't add to the experience because the 'boom' is too false. Is the sub's volume too high or is it a problem with the frequency setting I have it at?

[Hennie]

Tell us more about the auto setup feature. Does it match the sub level to the speaker level, or does it attempt to do some equalization or correction for acoustics?

If it does EQ then my feeling is the effect you describe should be minimized or eliminated but at one listening position only.

If it does not do EQ or acoustics correction then I would say the effect you describe is mostly due to room modes (standing waves) causing ripple in your sub's response.

I think to solve that:

Use an EQ or room correction unit, but it will really help at one position only. Units like Audissey (built into some HT receivers too) attempt to do multiple position correction, but IMHO this is still a compromise.

Use multiple subs to reduce the effect of room modes. Four subs can almost eliminate room modes and give you a very smooth bass response. Hard to get past the wife though, but two subs can give a meaningful improvement without alienating her...

[Timber_MG]

Perhaps I should make some measurements to display the problems a bit more graphically. I have a room with a very pronounced ~60Hz boom. LF is at the mercy of resonances (the smaller the room and the more equal its dimentions the worse) and this causes certain frequencies to be much louder than others. Graphically this is representable on a frequency response measurement and in many rooms variances of 20dB are nothing out of the ordinary.

Sometimes EQ can help and Statesside the behringer feedback destroyer (and similar equipment) employed as a high-Q parametric EQ to take care of resonances that are not taken care of effectively by placement.

[Timber_MG]

With many subs one can use smaller units as well, but then one usually looks at an amplifier and multiple passive subs.

[Hennie]

Perhaps I should make some measurements to display the problems a bit more graphically.

Show the people how bad a typical room can be. It is much worse than most people think it is.

Good plots would indeed be most welcome.

[Roelof]

A late response to the subwoofer feature in the AV mag August issue. I was very exited to see there was a feature on subwoofers, but once I finished the article, I was abit dissapointed. Why was there no Sonor Audio subs in this article? I beleive Roy designs and buildt great subs and would have like to see a review/comparison within this article.
     

[Vaughan]

Does anyone here have the Velodyne SMS-1 ? It is a real-time analysis tool that corrects frequency response errors with an 8 band parametric equalizer. I had a huge peak centered at 43 hz and at 65 hz and it nailed it down beautifully.

However I'm in the process of ditching the SMS-1 and using Room EQ Wizard software with a dedicated parametric EQ (BFD) to get even more accurate results. I, too, have dual subwoofers and the results are amazing.

Regards,
Vaughan

[joel]

Roy does indeed design some great subs, and one was featured in our last sub feature.

Time issues meant that we couldnt get all the subs we wanted in time for the the feature.