Different sized drivers in a sub? - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #1 of 44 Old 07-18-2013, 12:48 PM - Thread Starter
Member
 
tknx's Avatar
 
Join Date: Dec 2009
Posts: 26
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I know too little about sound design to answer this, but is there a reason sub designers don't use different sized woofers that roll-off to each other to keep things tight and optimized across the bass spectrum? Is it just too difficult to cross-over without significant artifacts? Seems like you would get tight upper bass with an 8-10" and get the deeper stuff with a 15" or something like that.

I suppose the other alternative may be line arrays with different parts of the array assigned to different spectrums. 1 8" for one part, 2 8"s for further down, etc.

Denon 4520ci | Salk Veracity ST | OSD WPA-650 | Roku 3 | U-turn Orbit turntable | Roomie Remote | Heir Audio 4.A CIEM
tknx is offline  
Sponsored Links
Advertisement
 
post #2 of 44 Old 07-18-2013, 01:09 PM
AVS Special Member
 
braveheart123's Avatar
 
Join Date: Jul 2011
Location: Lone Wolf McQuade from Islamabad Pakistan
Posts: 1,814
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 115
I think it is very much doable. I dIYed something on the same lines but it was with two separate boxes. One housing a 10 inch driver and another a 12 inch both serving different pass bands and the results were amazing.

I would like to hear from some more knowledgeable lads on this forum regarding one box housing two subs using internal passive xo doing handshake between a 10" driver for upper bass and maybe a 15" or an 18" serving the ULF.

History is written by those who have hanged heroes ...

The best EQ is no EQ ...

Alpine SWR-1223D Slot Ported HT Sub

Dual Dayton RSS390HO-4 Reference 15 Build For HT

Main System: Klipsch RF-82 II, Klipsch RC-62 II, RS-52 II, Onkyo 5010, Rythmik FV15HP, PSB S300
braveheart123 is offline  
post #3 of 44 Old 07-18-2013, 01:46 PM
AVS Special Member
 
duc135's Avatar
 
Join Date: Apr 2009
Posts: 1,674
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Liked: 148
Bass "tightness" has nothing to do with driver size. A properly designed 21" sub driver is no less "tight sounding" than an 8" driver while playing within it's rated frequencies with the proper power behind it. Actually, it can be argued that the opposite would be true since the larger driver would have to move considerably less than the smaller driver to produce the same frequency at the same dB.

Mixing sub drivers in a single enclosure is not done because each driver has different T/S parameters which determine the box size and tuning in the case of ported, bandpass or horn loaded enclosures. You cannot simple throw two different drivers in a box and hope that crossovers give you a good response. The best you can do with multiple drivers sharing a common enclosure is to use the exact same drivers. Even two same sized drivers from different manufacturers or even the same manufacturer, but different models will not work. The only way to use multiple drivers in "one" enclosure is to separate the drivers from each other. Essentially you are building two separate boxes that share a common wall. Think of it like an apartment building. Two separate apartments sharing a common wall. Each does its own thing independent of the other. At that point you might as well build two individual boxes to take advantage of room modes.

Again, best thing to do is get a properly designed driver in the size and specifications you need and build a subwoofer enclosure around it. I can tell you my 18" LMS has a lot "tighter" bass than my cousin's 8" Pioneer. wink.gif
duc135 is offline  
post #4 of 44 Old 07-18-2013, 02:00 PM
AVS Special Member
 
braveheart123's Avatar
 
Join Date: Jul 2011
Location: Lone Wolf McQuade from Islamabad Pakistan
Posts: 1,814
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 115
Quote:
Bass "tightness" has nothing to do with driver size.

IMO the moving mass of an 18" cone is heavier than that of a 10" driver. A 10" driver will play the 80hz frequency quicker than an 18" driver keeping the input wattage equal.

History is written by those who have hanged heroes ...

The best EQ is no EQ ...

Alpine SWR-1223D Slot Ported HT Sub

Dual Dayton RSS390HO-4 Reference 15 Build For HT

Main System: Klipsch RF-82 II, Klipsch RC-62 II, RS-52 II, Onkyo 5010, Rythmik FV15HP, PSB S300
braveheart123 is offline  
post #5 of 44 Old 07-18-2013, 02:16 PM
AVS Special Member
 
steve nn's Avatar
 
Join Date: Aug 2003
Posts: 6,207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 425
Quote:
A 10" driver will play the 80hz frequency quicker than an 18" driver keeping the input wattage equal.

That's not what he said.. Might want to re-read, look for accordingly.

Klipsch RB-75
Klipsch C-7
Klipsch RB-35
On-going SW management class
Denon
PS3
steve nn is offline  
post #6 of 44 Old 07-18-2013, 02:40 PM
AVS Special Member
 
braveheart123's Avatar
 
Join Date: Jul 2011
Location: Lone Wolf McQuade from Islamabad Pakistan
Posts: 1,814
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 115
I think in a way it is the same thing. A 10" driver with lighter moving mass can be snappier at picking up recursive 80hz bass notes half a second apart than an 18" driver with heavier moving mass. The result is tight bass.

History is written by those who have hanged heroes ...

The best EQ is no EQ ...

Alpine SWR-1223D Slot Ported HT Sub

Dual Dayton RSS390HO-4 Reference 15 Build For HT

Main System: Klipsch RF-82 II, Klipsch RC-62 II, RS-52 II, Onkyo 5010, Rythmik FV15HP, PSB S300
braveheart123 is offline  
post #7 of 44 Old 07-18-2013, 03:01 PM
AVS Special Member
 
steve nn's Avatar
 
Join Date: Aug 2003
Posts: 6,207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 425
I don’t agree, we have seen this conversation over in DIY more than a few times. In my experience I have not noticed such and find the larger good drivers every bit as tight as a 10”. I equate it to design more than anything. I do hear what your saying though.

Klipsch RB-75
Klipsch C-7
Klipsch RB-35
On-going SW management class
Denon
PS3
steve nn is offline  
post #8 of 44 Old 07-18-2013, 03:46 PM
AVS Special Member
 
braveheart123's Avatar
 
Join Date: Jul 2011
Location: Lone Wolf McQuade from Islamabad Pakistan
Posts: 1,814
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 115
Quote:
I don’t agree

That's what this forum is all about.....arrive at an agreement after a lot of disagreements.

History is written by those who have hanged heroes ...

The best EQ is no EQ ...

Alpine SWR-1223D Slot Ported HT Sub

Dual Dayton RSS390HO-4 Reference 15 Build For HT

Main System: Klipsch RF-82 II, Klipsch RC-62 II, RS-52 II, Onkyo 5010, Rythmik FV15HP, PSB S300
braveheart123 is offline  
post #9 of 44 Old 07-18-2013, 04:24 PM
AVS Special Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 9,263
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1188
Quote:
Originally Posted by braveheart123 View Post

IMO the moving mass of an 18" cone is heavier than that of a 10" driver. A 10" driver will play the 80hz frequency quicker than an 18" driver keeping the input wattage equal.
Nope. It seems logical, but it simply is not the case.
Quote:
I think in a way it is the same thing. A 10" driver with lighter moving mass can be snappier at picking up recursive 80hz bass notes half a second apart than an 18" driver with heavier moving mass. The result is tight bass.
Also logical to assume that might be the case, but it isn't.
Quote:
That's what this forum is all about.....arrive at an agreement after a lot of disagreements.
In this case agreement or disagreement are moot, this is physics, very well known physics at that, and drivers simply do not behave that way.
steve nn likes this.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #10 of 44 Old 07-18-2013, 05:35 PM
AVS Special Member
 
steve nn's Avatar
 
Join Date: Aug 2003
Posts: 6,207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 425
Quote:
That's what this forum is all about.....arrive at an agreement after a lot of disagreements.
No not to me but if that's why you come here so-be-it!

I’m glad to see Bill step in, he has a way of correcting me from time to time also. wink.gif

Klipsch RB-75
Klipsch C-7
Klipsch RB-35
On-going SW management class
Denon
PS3
steve nn is offline  
post #11 of 44 Old 07-18-2013, 06:50 PM - Thread Starter
Member
 
tknx's Avatar
 
Join Date: Dec 2009
Posts: 26
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
So, skipping the "faster" discussion - what about using an array of subwoofers with different optimizations and roll-offs? Not that I have space for 4 subs or anything, but really just curious.

Denon 4520ci | Salk Veracity ST | OSD WPA-650 | Roku 3 | U-turn Orbit turntable | Roomie Remote | Heir Audio 4.A CIEM
tknx is offline  
post #12 of 44 Old 07-18-2013, 06:57 PM
AVS Special Member
 
bass addict's Avatar
 
Join Date: Dec 2003
Location: A padded room
Posts: 3,774
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Liked: 210
Quote:
Originally Posted by steve nn View Post

No not to me but if that's why you come here so-be-it!

I’m glad to see Bill step in, he has a way of correcting me from time to time also. wink.gif

LOL. Agreed.

It's amazing how long certain urban myths can hang around without being dispelled. I should have gone with 20 10" drivers instead of my 6 18's. What was I thinking? cool.gif

Achievement Unlocked

Psychotic Episode Averted

bass addict is offline  
post #13 of 44 Old 07-18-2013, 07:04 PM
AVS Addicted Member
 
sivadselim's Avatar
 
Join Date: Oct 2004
Location: CO
Posts: 16,058
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 38 Post(s)
Liked: 64
Velodyne 1812


"All men are frauds. The only difference between them is that some admit it. I myself deny it."
sivadselim is offline  
post #14 of 44 Old 07-18-2013, 07:13 PM
AVS Special Member
 
duc135's Avatar
 
Join Date: Apr 2009
Posts: 1,674
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Liked: 148
As Bill has stated, cone weight has nothing to do with it if the drivers are designed properly. A properly built 18" driver will have a motor capable of moving the cone at the required speed to produce the frequency it is given. Cone speed is a based on two factors, frequency and SPL. SPL is based on the amount of air the driver can move. An 18" driver will need to move considerably less to create the same SPL as a 10" driver at the same frequency. Look at it this way. I (18" driver) have to run 10' and back twenty times in one minute while you (10" driver) have to run 100' twenty times in one minute. Who needs to run faster?

Wattage has nothing to do with how fast a driver moves. Wattage affects how loud a driver will play given the enclosure and sensitivity of the driver. The driver will draw as much wattage as it needs to play the frequency at the SPL you set. If the amp cannot produce sufficient wattage then it will clip and the sub will not get any louder. Distortion not considered. Lets say all things being equal that a 10" driver has the same sensitivity as an 18" driver and their response curves are all the same. Now take the same wattage applied to both speakers you will see that the 10" driver will move much faster than the 18" driver. That's because the 10" driver has to move in and out a much greater distance than the 18" driver to produce the same SPL.
duc135 is offline  
post #15 of 44 Old 07-18-2013, 07:27 PM
AVS Special Member
 
duc135's Avatar
 
Join Date: Apr 2009
Posts: 1,674
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Liked: 148
Quote:
Originally Posted by sivadselim View Post

Velodyne 1812


Nice. If I had $15K in 2004 dollars with nothing better to use it for I might give it a try. Then again, I might need more than that because my old house might need the floors reinforced to support that beast. For now, my two 18"s and soon to be added four 15"s will suffice for the time being. Hopefully.
duc135 is offline  
post #16 of 44 Old 07-18-2013, 07:46 PM
AVS Special Member
 
steve nn's Avatar
 
Join Date: Aug 2003
Posts: 6,207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 425
Quote:
LOL. Agreed.

It's amazing how long certain urban myths can hang around without being dispelled. I should have gone with 20 10" drivers instead of my 6 18's. What was I thinking? cool.gif

LOL.. I hear yuh biggrin.gif


Quote:
So, skipping the "faster" discussion - what about using an array of subwoofers with different optimizations and roll-offs? Not that I have space for 4 subs or anything, but really just curious.

Now now! I notice from your post count that your new around here. We get off track all the time but we always seem to make it back to the subject at hand. I would give you my opinion regarding your question but I don’t want to. It’s going to start a big argument that I don’t feel like getting into. smile.gif There are many on both sides just like sealed v vented.

(imo) Very nice explanation duc!

Klipsch RB-75
Klipsch C-7
Klipsch RB-35
On-going SW management class
Denon
PS3
steve nn is offline  
post #17 of 44 Old 07-18-2013, 08:14 PM
AVS Special Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 9,263
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1188
Quote:
Originally Posted by tknx View Post

So, skipping the "faster" discussion - what about using an array of subwoofers with different optimizations and roll-offs?
Subwoofers have too small of a pass band for that to be of any advantage.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #18 of 44 Old 07-18-2013, 08:42 PM
AVS Special Member
 
steve nn's Avatar
 
Join Date: Aug 2003
Posts: 6,207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 425
Quote:
Subwoofers have too small of a pass band for that to be of any advantage.

If you make it back.. Do you perceive or know there to be any disadvantage?

Klipsch RB-75
Klipsch C-7
Klipsch RB-35
On-going SW management class
Denon
PS3
steve nn is offline  
post #19 of 44 Old 07-18-2013, 09:38 PM
AVS Special Member
 
braveheart123's Avatar
 
Join Date: Jul 2011
Location: Lone Wolf McQuade from Islamabad Pakistan
Posts: 1,814
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 115
BFM enlighten me with the Physics involved.

History is written by those who have hanged heroes ...

The best EQ is no EQ ...

Alpine SWR-1223D Slot Ported HT Sub

Dual Dayton RSS390HO-4 Reference 15 Build For HT

Main System: Klipsch RF-82 II, Klipsch RC-62 II, RS-52 II, Onkyo 5010, Rythmik FV15HP, PSB S300
braveheart123 is offline  
post #20 of 44 Old 07-18-2013, 09:41 PM
AVS Special Member
 
braveheart123's Avatar
 
Join Date: Jul 2011
Location: Lone Wolf McQuade from Islamabad Pakistan
Posts: 1,814
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 115
Quote:
I’m glad to see Bill step in, he has a way of correcting me from time to time also.

Stand up for yourself. Why do you need Bill all the time to fill in the blanks for you?

History is written by those who have hanged heroes ...

The best EQ is no EQ ...

Alpine SWR-1223D Slot Ported HT Sub

Dual Dayton RSS390HO-4 Reference 15 Build For HT

Main System: Klipsch RF-82 II, Klipsch RC-62 II, RS-52 II, Onkyo 5010, Rythmik FV15HP, PSB S300
braveheart123 is offline  
post #21 of 44 Old 07-18-2013, 10:28 PM
AVS Special Member
 
braveheart123's Avatar
 
Join Date: Jul 2011
Location: Lone Wolf McQuade from Islamabad Pakistan
Posts: 1,814
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 115
Quote:
It's amazing how long certain urban myths can hang around without being dispelled. I should have gone with 20 10" drivers instead of my 6 18's. What was I thinking? cool.gif

If you know something, best explain it than to create another urban myth. You having gazillion drivers doesn't mean they sound as good as they may look.

History is written by those who have hanged heroes ...

The best EQ is no EQ ...

Alpine SWR-1223D Slot Ported HT Sub

Dual Dayton RSS390HO-4 Reference 15 Build For HT

Main System: Klipsch RF-82 II, Klipsch RC-62 II, RS-52 II, Onkyo 5010, Rythmik FV15HP, PSB S300
braveheart123 is offline  
post #22 of 44 Old 07-18-2013, 10:46 PM
AVS Special Member
 
duc135's Avatar
 
Join Date: Apr 2009
Posts: 1,674
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Liked: 148
In very simplified terms, frequency is measured in cycles per second. A 20Hz frequency is 20 cycles per second. This means to produce a 20 Hz tone, a speaker must move in and out 20 times per second regardless of driver size. No more, no less. Anything other than 20 cycles per second then it is no longer producing a 20Hz tone. This means at 20Hz, a 21" driver is moves in and out 20 times per second. Same thing for the 8" driver. That is why driver size in itself has no bearing on the "tightness" or "speed" of the bass.

What determines the tightness of the perceived "tightness" is a combination of things like decay and secondary reflections of the sound waves. Decay is a function of how well the motor can control the movement of the cone as well as other things like enclosure design. Motor control of the cone is not dependent on the size of the cone, but the strength of the motor relative to the mass of the cone. Note I say mass and not size and I said the motor strength relative to that mass. As an analogy, consider me, a fairly fit person who can easily move around a 20lbs. weight with ease. I can move the weight around with control and stop and start it's motion with ease on command. Now take a five year old and ask him/her to move around a 10lbs. weight. Even though it is obviously lighter weight, the five year old will have trouble moving that 10lbs. weight around than I would with the 20lbs. weight. Speaker drivers operate in a very similar fashion in this respect.

I'm not Bill and I don't know the equations off the top of my head, but I'm sure they can be found online if you do a search for them.
duc135 is offline  
post #23 of 44 Old 07-18-2013, 11:09 PM
AVS Special Member
 
steve nn's Avatar
 
Join Date: Aug 2003
Posts: 6,207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 425
Quote:
Originally Posted by braveheart123 View Post

Stand up for yourself. Why do you need Bill all the time to fill in the blanks for you?

Mmm!.. I never have heard that said of me?.. all the time huh? Are you sure you’re not on the defensive for some reason? Anyway like said there has been a few times he has corrected me but never has backed me up. No I asked him the question (Do you perceive or know there to be any disadvantage?) regarding mixing SW's because I know he designs speakers and subwoofers and sometimes it’s best to listen rather than spout. Opinions, to a degree, are not what I’m looking for as I come to my final conclusion regarding the question asked. If my experience coupled with my opinion doesn't correlate with the physics involved, then I want to know.

Klipsch RB-75
Klipsch C-7
Klipsch RB-35
On-going SW management class
Denon
PS3
steve nn is offline  
post #24 of 44 Old 07-18-2013, 11:30 PM
AVS Special Member
 
braveheart123's Avatar
 
Join Date: Jul 2011
Location: Lone Wolf McQuade from Islamabad Pakistan
Posts: 1,814
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 115
Quote:
If my experience coupled with my opinion doesn't correlate with the physics involved, then I want to know.

So do I. Um not being defensive or offensive; just being logical. Whatever I'm saying is logical and does make sense; but according to more knowledgeable ppl on this forum I am wrong. That is perfectly fine, but leaving it open-ended and coming up things with things like "Urban Myth" or "It's Physics" and other crap and not explaining creates other so-called "Urban Myths".

History is written by those who have hanged heroes ...

The best EQ is no EQ ...

Alpine SWR-1223D Slot Ported HT Sub

Dual Dayton RSS390HO-4 Reference 15 Build For HT

Main System: Klipsch RF-82 II, Klipsch RC-62 II, RS-52 II, Onkyo 5010, Rythmik FV15HP, PSB S300
braveheart123 is offline  
post #25 of 44 Old 07-18-2013, 11:46 PM
AVS Special Member
 
steve nn's Avatar
 
Join Date: Aug 2003
Posts: 6,207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 425
Quote:
Originally Posted by braveheart123 View Post

So do I. Um not being defensive or offensive; just being logical. Whatever I'm saying is logical and does make sense; but according to more knowledgeable ppl on this forum I am wrong. That is perfectly fine, but leaving it open-ended and coming up things with things like "Urban Myth" or "It's Physics" and other crap and not explaining creates other so-called "Urban Myths".

If I could explain the physics in my posts I certainly would if called for, in all truth it’s beyond me. So I like to have them backed up and then explain to others in a manner like duc when it comes up. This mixing differently tuned subs thing has been coming up a long time, so I too wanted to rest the case in my mind regarding. I know what I think I know, but is it really so?

Klipsch RB-75
Klipsch C-7
Klipsch RB-35
On-going SW management class
Denon
PS3
steve nn is offline  
post #26 of 44 Old 07-19-2013, 12:35 AM
AVS Special Member
 
shadyJ's Avatar
 
Join Date: May 2009
Posts: 6,348
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 68 Post(s)
Liked: 446
I think a case might be able to be made for a two way subwoofer system, but not two different subs in one enclosure. For instance, the massive drivers that have great deep bass output like the RE XXX and the LMS Ultra are real energy hogs, and are relatively inefficient at upper bass frequencies. Other lighter drivers are very efficient at upper bass but you would not want them to go for lower bass. Also, as Hsu argues for its MBM-12, the subwoofer locations in a room that work that work great for deep bass can sometimes leave massive gaps in mid and upper bass frequencies, and vice versa, so two subs tackling different frequency ranges can work with the room and not against it. Furthermore, the narrower of a frequency band an amplifier has to deal with, the more headroom it has overall, since the amplified signal isn't being inflated by a other frequencies.
shadyJ is offline  
post #27 of 44 Old 07-19-2013, 12:58 AM
AVS Special Member
 
steve nn's Avatar
 
Join Date: Aug 2003
Posts: 6,207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 425
Quote:
Originally Posted by shadyJ View Post

I think a case might be able to be made for a two way subwoofer system, but not two different subs in one enclosure. For instance, the massive drivers that have great deep bass output like the RE XXX and the LMS Ultra are real energy hogs, and are relatively inefficient at upper bass frequencies. Other lighter drivers are very efficient at upper bass but you would not want them to go for lower bass. Also, as Hsu argues for its MBM-12, the subwoofer locations in a room that work that work great for deep bass can sometimes leave massive gaps in mid and upper bass frequencies, and vice versa, so two subs tackling different frequency ranges can work with the room and not against it. Furthermore, the narrower of a frequency band an amplifier has to deal with, the more headroom it has overall, since the amplified signal isn't being inflated by a other frequencies.

Thats not what I was alluding to though. You're referring to a mid bass mod. That’s a whole different subject/can of worms. wink.gif

Klipsch RB-75
Klipsch C-7
Klipsch RB-35
On-going SW management class
Denon
PS3
steve nn is offline  
post #28 of 44 Old 07-19-2013, 05:06 AM
AVS Special Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 9,263
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1188
Quote:
Originally Posted by steve nn View Post

If you make it back.. Do you perceive or know there to be any disadvantage?
The reason for using different size drivers in a system is dispersion, as that's the only factor that is determined by driver size alone. Dispersion is inversely proportional to the size of the radiating surface. In order to keep the angle of dispersion sufficiently wide as frequency goes higher and wavelengths grow shorter the radiating surface must be made smaller. That's the main reason why midranges are smaller than woofers, and tweeters are smaller than midranges. You can make a twelve inch driver that has useful axial response to 5kHz, but off-axis it's only going to be good to perhaps 1.5kHz at best.
Within the subwoofer pass band the wavelengths are far too long for the driver size to influence dispersion; even a 21 inch driver will have a 360 degree pattern to well above 100Hz. That means there's nothing to be gained by using different size drivers within the sub woofer pass band that justifies the added complexity involved.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #29 of 44 Old 07-19-2013, 06:00 AM
AVS Special Member
 
steve nn's Avatar
 
Join Date: Aug 2003
Posts: 6,207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 425
Quote:
Originally Posted by Bill Fitzmaurice View Post

The reason for using different size drivers in a system is dispersion, as that's the only factor that is determined by driver size alone. Dispersion is inversely proportional to the size of the radiating surface. In order to keep the angle of dispersion sufficiently wide as frequency goes higher and wavelengths grow shorter the radiating surface must be made smaller. That's the main reason why midranges are smaller than woofers, and tweeters are smaller than midranges. You can make a twelve inch driver that has useful axial response to 5kHz, but off-axis it's only going to be good to perhaps 1.5kHz at best.
Within the subwoofer pass band the wavelengths are far too long for the driver size to influence dispersion; even a 21 inch driver will have a 360 degree pattern to well above 100Hz. That means there's nothing to be gained by using different size drivers within the sub woofer pass band that justifies the added complexity involved.

Thanks Bill... Might you comment on using differently tuned subs in the same room at the same time and a sealed SW mixed with a vented SW in the same room, same time. This is what I was asking about.

Klipsch RB-75
Klipsch C-7
Klipsch RB-35
On-going SW management class
Denon
PS3
steve nn is offline  
post #30 of 44 Old 07-19-2013, 06:11 AM
AVS Special Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 9,263
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1188
Quote:
Originally Posted by steve nn View Post

Thanks Bill... Might you comment on using differently tuned subs in the same room at the same time and a sealed SW mixed with a vented SW in the same room, same time. This is what I was asking about.
I see nothing to be gained from that. It verges on voodoo engineering.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
Reply Subwoofers, Bass, and Transducers

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off