Ok, here goes.
Basically I want to add more bass without adding an active crossover.
So I was to run a “midbass module” with (running in parallel) what I currently have (both would be ported at same freq too).
So question is, if the speaker already has an 18db crossover (say at 1.2khz) to the tweet, can I run a bass module (in parallel) but also with an 18db at a lower frequency (say 200hz) ?
Based on phase and all that, it would have better blending ?
Basically I want to add more bass without adding an active crossover.
So I was to run a “midbass module” with (running in parallel) what I currently have (both would be ported at same freq too).
So question is, if the speaker already has an 18db crossover (say at 1.2khz) to the tweet, can I run a bass module (in parallel) but also with an 18db at a lower frequency (say 200hz) ?
Based on phase and all that, it would have better blending ?
What you're describing is a '0.5 way' helper woofer. Usually 6db/Oct is OK (i.e. a single low DCR inductor), I'd cross over at your baffle step frequency (115/baffle width in metres). You'll need extra box volume for the extra mid/woofer, and you'll need to check that your amp can handle the combined parallel impedance of both woofers.
yup.
I figure a 6db rolled low alongside of a 18db crossed woof (up high), they wouldn't mesh...………….
I figure a 6db rolled low alongside of a 18db crossed woof (up high), they wouldn't mesh...………….
I doubt there'll be any problem, they're a long way apart. You could up the lower xover to 2nd order & reverse the tweeter phase if you think that would help, it would only be an extra cap
I'm worried about the midbass module "fighting" against the woofer in the 2-way.
Or canceling out.
The phase would be way off unless also electrical 18db (say using the same woofs) to me.
Or canceling out.
The phase would be way off unless also electrical 18db (say using the same woofs) to me.
In theory (for now), you shouldn't worry about trying to match 6dB and 18dB. The 18dB crossover is at a higher frequency and you don't reach it until the helper woofer is down and crossed where it doesn't matter any more.
So the 6dB is not about the upper woofer's crossover region, it's about the upper woofer's passband. In a 2.5 way, the 6dB crossover allows the two woofers to work together until one is reduced in level. If you used an 18dB crossover on the helper woofer in a 2.5 way, you'd get a notch due to phase on the way down.
So the 6dB is not about the upper woofer's crossover region, it's about the upper woofer's passband. In a 2.5 way, the 6dB crossover allows the two woofers to work together until one is reduced in level. If you used an 18dB crossover on the helper woofer in a 2.5 way, you'd get a notch due to phase on the way down.
I think i see what you mean.
At an 18db way up at 1.2khz, the 12" woofer's phase would be way different than down at say 200hz.
And a 6db baffle step woof crossed in (not through the 2-way's crossover) run alongside maybe 200hz, the phase would not be too far off, combining with the 2-way's woofer, close anyway.
Is this right ?
At an 18db way up at 1.2khz, the 12" woofer's phase would be way different than down at say 200hz.
And a 6db baffle step woof crossed in (not through the 2-way's crossover) run alongside maybe 200hz, the phase would not be too far off, combining with the 2-way's woofer, close anyway.
Is this right ?
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Also keep in mind that the .5 woofer doesn't need to be the same as the other driver.
Midrange performance isn't what you need here so you can choose a woofer that does bass better and you mention using a 12"; I would think a 12" would normally have much better bass
Midrange performance isn't what you need here so you can choose a woofer that does bass better and you mention using a 12"; I would think a 12" would normally have much better bass
True.
I'm using 12" in jbl 2-way.
F9 is probably 50hz (fs=50 and qts .3).
I have my eye on some 12's or 15's.
I don't regret moving from 2 x 15" with 2384 to this smaller 2 way.
I prefer the 1.2khz crossover point over 750 (maybe) but i think my preference is the better horn.
Granted, 750hz is a lot to ask of a horn running all the way up.
I'm trying to add more versus active crossover, eq, etc, etc.
I like the simplicity of receiver / speakers.
I just miss the tactile bass from 20' away !!!
I'm using 12" in jbl 2-way.
F9 is probably 50hz (fs=50 and qts .3).
I have my eye on some 12's or 15's.
I don't regret moving from 2 x 15" with 2384 to this smaller 2 way.
I prefer the 1.2khz crossover point over 750 (maybe) but i think my preference is the better horn.
Granted, 750hz is a lot to ask of a horn running all the way up.
I'm trying to add more versus active crossover, eq, etc, etc.
I like the simplicity of receiver / speakers.
I just miss the tactile bass from 20' away !!!
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Would a plate amp work for you?
My budget won't allow the drivers I lust after but I certainly get the need for tactile bass and I concur that 15 beats 12 any day of the week for bass and perhaps 18" even better again.
No personal experience with JBL drivers tho
My budget won't allow the drivers I lust after but I certainly get the need for tactile bass and I concur that 15 beats 12 any day of the week for bass and perhaps 18" even better again.
No personal experience with JBL drivers tho
I think you have it. I have an example of rolling off slowly vs fast, showing the notch I mentioned.
Attachments
Here's the basic example where 6dB for the lower rolloff doesn't cause a notch even when the 18dB cross is there. (Although real drivers are different, most of this is relative so you should find that it works if all else is the same.)
Attachments
Only way to just add more bass capability is to wire the extra woofer in series with the first woofer and have a shunt capacitor in parallell over the poles of the extra woofer. Then you will not mess with sensitivity or phase isssues. The capacitor needa to be quite big though.
Read this paper by Jeff Bagby, it will steer you in the right direction: The Kairos and Continuum Three-Ways