Subs and x-overs...am I missing something?

Why is it that I don’t see anyone adding a highpass crossover to their mains after adding subs? Wouldn’t it make sense to relieve the mid/bass units of reproducing the lowest frequencies as there are subs to do that? Wouldn’t the mid/bass units perform much better when relieved of such duties?

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It is certainly an option - but most find that running the mains full range and supplementing them with the subs crossed over quite low is the way to go. Running everything through processing has negative effects such as phase distortion, along with the desired ones.

If your mains have ports, you can plug them with foam, which has the effect of creating a steeper crossover curve on their low end.

“Running everything through processing has negative effects such as phase distortion”

I know we want to distort the signal as little as possible…but! What’s the point of keeping the signal clean if the device which is reproducing it (in this case the mid/bass units) is straining (and therefore distorting) more than it needs to?

For me personally I don’t like the way that makes my main speakers sound. Adding that HP filter robs the main speakers of acoustic space and realism. A better approach is to buy speakers that are designed to be full range.

And here is the crux of the matter. To me, a speaker designed to be full range shouldn’t require an additional sub - it should have no problem properly reproducing the low region. I’ll use an extreme example to make the point - pretty much any decent bookshelf speaker is designed to be full range. But those 5.25" or 6" or whatever mid/bass drivers are not really reproducing anything useful below say 100Hz. So the design has no bearing on the real world.

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Or perhaps my logic is flawed due to an incorrect basic assumption (which maybe you can clear up?). My base assumption is that there is more cone breakup as a driver reproduces lower frequencies. Therefore if alleviated of that duty by a sub, it will be more accurate. Or is that just wrong?

I agree in principal but not in practice. Problem is, what’s full range? Most passive speakers cannot reach into subwoofer territory though they claim they can. They just don’t.

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A common response to subs plus full range mains is that the mains are positioned for the best performance, usually upper mid to hi and it is not the best placement for bass - therefore the need for subs. I am looking into trying subs for this reason even though my mains are designed for bass, i.e. a 15" and 13" speakers in each.

I like to use Paul’s philosophy of using your ears to make a decision. I’ve heard plenty of systems that are using ‘full range’ speakers. Is the bass response there? Absolutely. Do I sit there wishing there was more bass? Maybe for a few tracks. But 10 times out of 10 when a sub is added to the system, the sound becomes much more full and believable. Full range speakers tend to match extremely well with a sub because the sub is easier to integrate with the system. With a full range speaker, there is less of a gap between the speaker and sub’s roll off. This gap CAN be extremely noticeable in a system using bookshelf speakers and a sub.

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Exactly what I experienced when I added a pair of subs recently to my ‘full range’ speakers.

What are the speakers you’re using and which subs did you get?

Speakers are Focal Chorus 826V (they are decent speakers) and REL S/3 SHO subs.

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Something I had not considered. Thanks.

Yeah, those are great! Certainly can’t go wrong with two RELs. I’m sure it’s a really good sounding system.

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My full range speakers have two 15" woofers each. I use a pair of Rythmik servo controlled 15" subs from 18-40Hz.

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I’m looking at Rhythmiks as well.

I’m running E15HP2s. Tight and deep. Very solid subs!

I’m thinking 2 12s per side. Haven’t decided yet.

Very good!
Asking: Did they add substantially and, just generally, where/how?
How/where did you position them relative to mains and the room, i.e. adjacent to mains, side wall, back wall? This only because of reading the opinions of offsetting subs to counter bass nodes.
Thanks for your input/experience.
Dave

I would never classify myself as a “bass head”. I used to have a single sub to go with my full range speakers. When I switched to monoblock amps I bought a new pair of REL subs. I have adjusted them to supply bass below 60 Hz. I am very pleased with the results. My wife and daughter, not so much. So it is not a question of adding A sub, it’s which pair of subs should you get. I am happy with REL.

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