Multi-sub using full range speakers - how to measure.

[sfdoddsy]

A little while ago I side-graded by swapping an excellent bookshelf speaker with great bass extension (KEF R3) for excellent floor-standers (Davone Solos - think Revel F208 with prettier cabinets).

Thanks to generous boundary reinforcement, the Davones (via a few EQ peak cuts) are flat to below 30Hz.

Aesthetics aside, one of my reasons for buying them was to try a multi-sub approach using the mains as extra bass sources.

I have a Rythmik sub which goes below 20Hz and extends, theoretically, beyond 300Hz. Plus a couple of spare subs but the point is to not use them for the same aesthetic reasons that lead me to buy the Davones.

My processor (Anthem) doesn't have an Extra Bass setting that allows you to run the mains full range and the sub as well, but the Rythmik does.

What I am having trouble with is working out how to measure the various permutations.

Normally I would use REW and a single speaker (plus sub) measurement to find the best crossover point, phase and level.

But, assuming there is a benefit, it should be with all of the bass sources playing at once. So L+R.

Should I adjust each speaker (plus sub) to be flattest and then measure L+R? And then EQ?

Or EQ each set to be flat, then measure together?

 

[AnalogSteph]

That's a good question, actually. Bass is often (though not always) mixed together, so I would tend towards L+R+Sub optimization as well.

 

[daftcombo]

I am not sure that you need to measure each channel separately as bass naturally melt. I would measure L+R.

 

[Duke]

Imo in the bass region the frequency responses of the individual pieces of the puzzle are of academic interest only. All that really matters is what their summed in-room response is, so that's what I'd focus on.

 

[sfdoddsy]

Yep, that's pretty much what I was thinking.

Where it would get tricky is EQ. Although I could use one of my MiniDSPs, normally I use Anthem ARC.

And it, like the other automatic EQs I am aware of, measures and corrects one speaker at a time.

 

[Chromatischism]

Imo in the bass region the frequency responses of the individual pieces of the puzzle are of academic interest only. All that really matters is what their summed in-room response is, so that's what I'd focus on.

And it's going to get complex as without bass management, source material will put some bass up front and not share it with the subs.

 

[Absolute]

@Duke Would you recommend EQ for individual speakers down to say 100 hz and then EQ of the combined response from there? Or are you thinking lower/higher than that?

 

[Duke]

@Duke Would you recommend EQ for individual speakers down to say 100 hz and then EQ of the combined response from there? Or are you thinking lower/higher than that?

Assuming the subs are coming in below 100 Hz, I'd EQ the combined response from there on down.

 

[BullBuchanan]

@sfdoddsy Did you end up going this route? I'd like to do the exact same thing. I have Tekton DI's running through a Pioneer SC-27 with a Polk HTS 12 amp. Given that the Tekton's far outclass the polk it seems to me I should let the tektons do all that they can, and let the polk exist to try to flatten out the response.

EQing together seems like it might take away some of the benefit of having multi-sub as the peaks of one speaker can help offset the troughs of another. In my case my left speaker has a 15db trough at 50hz, but my right speaker measures pretty well. I'm thinking that if I start applying EQ universally, it's going to screw up the natural compensation.

How do you handle the additional SPL that a subwoofer is going to add? How do you match the overall bass volume to the rest of the frequencies given you have 3 drivers for bass and just the two mains for everything else?

Do you have separate EQ configs for mains only and mains+sub, or do you sum it all together and use the sub 100% of the time?

 

[Chromatischism]

EQing together seems like it might take away some of the benefit of having multi-sub as the peaks of one speaker can help offset the troughs of another. In my case my left speaker has a 15db trough at 50hz, but my right speaker measures pretty well. I'm thinking that if I start applying EQ universally, it's going to screw up the natural compensation.

It doesn't though; it improves it.

How do you handle the additional SPL that a subwoofer is going to add? How do you match the overall bass volume to the rest of the frequencies given you have 3 drivers for bass and just the two mains for everything else?

This is automatically handled by the bass management system of all AVR's, however most people adjust sub levels to taste after setup.

Do you have separate EQ configs for mains only and mains+sub, or do you sum it all together and use the sub 100% of the time?

I personally only have one configuration and that includes the subwoofers for all content because that is the only way to get the best frequency response and sound quality in the room.