Sub driver to the "Next in line"

[kgveteran]

Do you think that the next driver in line after the sub needs to be the same displacement to blend well at high SPL. I've been listening to movies at 0db.I think Audyssey calibrates to 75db at 0dbMV. The dual 8" RS225's seem to blend well with my quad sub setup.

Why is it so easy for a mid to roll off to the tweeter, or a woofer to a mid. I just don't the same school of thought pertains to the sub/woofer transition.

Kg

[ThomasW]

As frequencies go higher it takes less displacement to play them equally loud...

So no you don't need 15" woofers to match up with 15" subs.

[kgveteran]

Its becoming a bigger issue these days when subwoofer systems are as large as the ones we have, to blend them with our mains.

Midbass is a big issue.There has to be at least an 80% match in displacement to avoid the "hole in the midbass". I'm not talking about bloated midbass or over EQ'd either. There is just a bigger problem blending sub/woofer than mid/tweeter.

At MV -20db isn't an issue.Heck, that low and you can blend RS150's with 15's. It's when you get up to 0db MV where it becomes an issue. I'm not saying you have to match 15's with 15's to get the 100% match, but I don't think 75-80% displacement matching isn't out of the question.

KG

[Mazeroth]

Not many people have four Tumults filling in their lowest octaves. Also, not many people that do have that much displacement use it all.

I still can't see how dual RS225s, per side, would have trouble filling in the midbass for those, unless you're playing levels above 105 dB? If that is the case then that's a problem you're going to have to figure out yourself because most sane people don't listen that loud :B

[Dennis H]

Its becoming a bigger issue these days when subwoofer systems are as large as the ones we have, to blend them with our mains.

Midbass is a big issue.There has to be at least an 80% match in displacement to avoid the "hole in the midbass". I'm not talking about bloated midbass or over EQ'd either. There is just a bigger problem blending sub/woofer than mid/tweeter.

At MV -20db isn't an issue.Heck, that low and you can blend RS150's with 15's. It's when you get up to 0db MV where it becomes an issue. I'm not saying you have to match 15's with 15's to get the 100% match, but I don't think 75-80% displacement matching isn't out of the question.

KG

That's not correct. Every time you go an octave lower, you need 4x the Vd for the same SPL. Let's say your sub plays from 20-80 and crosses to the mains at 80. Your mains only need 1/16 the Vd (2 octaves -- 4x4) to keep up with the sub. Probably much less than that considering the sub has to play the LFE channel plus all the redirected bass from the mains.

[kgveteran]

Not many people have four Tumults filling in their lowest octaves. Also, not many people that do have that much displacement use it all.

I still can't see how dual RS225s, per side, would have trouble filling in the midbass for those, unless you're playing levels above 105 dB? If that is the case then that's a problem you're going to have to figure out yourself because most sane people don't listen that loud :B

I hear ya. I'm just wondering how a pair of 8" drivers can keep up with the 15's. Dennis answered that for me. It's probably my lack in real engineering and math that limits my real knowledge. I'm not having any real issues with my system. I watched Iron Man this weekend and boy did it give my system a workout.

I guess Dennis said it. I usually listen at or near 0db MV. I don't think it's that loud.There is no distortion or clipping.

[---k---]

This is the theoretical output of a pair of RS225-8 in a 65L sealed box. It is a bit different than in room listening where you have multiple speakers all summing together, in room reflections, and room gain.


But, you can see at your 100hz crossover, your pair of RS225 should be able to produce 113.5 db from 200W. With more power, the excursion limit is 116db. At an 80hz crossover, the pair should be able to produce 112.5 db and is at it's excursion limit.

In general, I doubt you're listening at levels anywhere near the excursion limits. I'm not smart enough to know when compression and other forms of distortion might be kicking in. Maybe someone like Dennis, Zaph, Jed or CJD can speak up and answer that.

[kgveteran]

Smashing.Love the graphs.Those RS225's are amazing.