# Thoughts on 6.5 midrange



## T3mpest

Looking for a high output 6.5 midrange. I may be able to do an 8 in the location I'm planning, but a 6.5 woudl fit WAY easier so I'm trying to simplify my life..

My two options I've found are:

Audax PR170M0 6.5" Midrange - 
The Madisound Speaker Store

From what I can tell it's not 100db/1w/1m, unless we include the breakup at like
3khz as "output". Other than that though it has somewhat low xmax, but good subjective reviews as very dynamic sounding and still clocks in at the mid 90's.. 

Other option is the JBL 165H. From what I can tell this is the updated driver JBL used on theirCMCD-61H. 
CMCD Cone Midrange Compression Driver

I can get these mids for about 150 each, so 50% more than the Audax.. The other good 6.5 I've seen reviews on is the PHL 6.5, but I can't find them for sale anywhere and PHL is going or is out of business, so that's no bueno 

These will be run from 300hz or so on a steep crossover up to a pair of mini horns, so between 1-2khz depending on how it all actually sounds.

Edit: Some more reading seems to indicate the JBL driver MAY just be a rebadged audax, hence the lack of info on the driver itself online.. Powerhandling is 25 watts different, not sure if that's JBL being optimistic or Audax underrating, maybe the arent' the exact same, IDK...

The idea of horn loading a midrange is also interesting, especially if the their CMCD-61H is just an audax mid with a horn and optimized rear enclosure..


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## Eric Stevens

What frequency range are you looking to cover?

If you want it to play to 80 or 90 Hz on the bottom you are limited to about a 91/92 dB type of driver.


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## T3mpest

Eric Stevens said:


> What frequency range are you looking to cover?
> 
> If you want it to play to 80 or 90 Hz on the bottom you are limited to about a 91/92 dB type of driver.


Nothing that low. True midrange around 300hz and up.


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## thehatedguy

The Audax is nice, one of my favorites of all time. It's really about 96-97 dB range.

The JBL is really designed to go on a horn...and I don't know how low it would play as a direct radiator. However there is a huge horn guy on DIY Audio who is using the 8s and he says it's the best midrange that he has ever had in any of his systems. The 6 is 106dB loaded on JBL's horn and they are using it from 500 to 2.8k on one model cabinet. On the horn it the -3 is 400 and -10 at 350.

Oh...I forgot...

The B&C 6MD38 and 6MDN44 are worth looking at too. The 6MD38 is supposed to be a drop in replacement for the PHL 1120. Both are supposed to be very nice. And PE has them.


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## T3mpest

thehatedguy said:


> The Audax is nice, one of my favorites of all time. It's really about 96-97 dB range.
> 
> The JBL is really designed to go on a horn...and I don't know how low it would play as a direct radiator. However there is a huge horn guy on DIY Audio who is using the 8s and he says it's the best midrange that he has ever had in any of his systems. The 6 is 106dB loaded on JBL's horn and they are using it from 500 to 2.8k on one model cabinet. On the horn it the -3 is 400 and -10 at 350.
> 
> Oh...I forgot...
> 
> The B&C 6MD38 and 6MDN44 are worth looking at too. The 6MD38 is supposed to be a drop in replacement for the PHL 1120. Both are supposed to be very nice. And PE has them.


That's good to know because the PHL 1120 was made by the designer of the audax 6.5 and is basically a improved version what what he learned doing the audax. I saw that post on the JBL 8 being the best midrange ever. That's what sparked my interest. John finally has his td8m ready but it's pretty deep.


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## thehatedguy

And it is pretty damned expensive- the td8 is.

If you wanted an 8, you would have a lot more choices..maybe, I haven't looked in a while.


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## T3mpest

thehatedguy said:


> And it is pretty damned expensive- the td8 is.
> 
> If you wanted an 8, you would have a lot more choices..maybe, I haven't looked in a while.


I may be able to do an 8 when I start getting in their and doing fab work.. I'll have to see, but I'm planning for the easier of the two options to start.


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## Patrick Bateman

T3mpest said:


> Looking for a high output 6.5 midrange. I may be able to do an 8 in the location I'm planning, but a 6.5 woudl fit WAY easier so I'm trying to simplify my life..
> 
> My two options I've found are:
> 
> Audax PR170M0 6.5" Midrange -
> The Madisound Speaker Store
> 
> From what I can tell it's not 100db/1w/1m, unless we include the breakup at like
> 3khz as "output". Other than that though it has somewhat low xmax, but good subjective reviews as very dynamic sounding and still clocks in at the mid 90's..
> 
> Other option is the JBL 165H. From what I can tell this is the updated driver JBL used on theirCMCD-61H.
> CMCD Cone Midrange Compression Driver
> 
> I can get these mids for about 150 each, so 50% more than the Audax.. The other good 6.5 I've seen reviews on is the PHL 6.5, but I can't find them for sale anywhere and PHL is going or is out of business, so that's no bueno
> 
> These will be run from 300hz or so on a steep crossover up to a pair of mini horns, so between 1-2khz depending on how it all actually sounds.
> 
> Edit: Some more reading seems to indicate the JBL driver MAY just be a rebadged audax, hence the lack of info on the driver itself online.. Powerhandling is 25 watts different, not sure if that's JBL being optimistic or Audax underrating, maybe the arent' the exact same, IDK...
> 
> The idea of horn loading a midrange is also interesting, especially if the their CMCD-61H is just an audax mid with a horn and optimized rear enclosure..


What's your F3? I horn loaded some Dayton ND91s and the efficiency went up by about 10dB:

Ikea Midbass Horn - diyAudio

I know I'm a broken record here, but output trumps efficiency. An ND91 has an efficiency in the low 80s but stick it on a horn and efficiency goes through the roof.


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## edzyy

The audax is the best midrange I've played with so far

And the output is out of this world.

Edit:

Isn't there a b&c midrange that is almost identical to the PHL?


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## thehatedguy

6PEV13 looks a lot like the Audax. 

Either the 6MD38 or the 6MDN44 is a drop in replacement for the PHL 1120.

The Audax is just wonderful. You would never know it had 1/2mm of excursion.


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## Jesus Christ

Patrick Bateman said:


> I know I'm a broken record here, but output trumps efficiency.


If you're looking for output though it's easier if you start with efficient drivers.


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## mikey7182

Are you using these in a 3-way front with horns like I've done? As far as 6-7" drivers go, I've used the B&C and several others and the Audax is by far the best. Depending on application and HPF, I would say it rivals the 2118. The 8" obviously has better bottom end, but the Audax is the best 6-7" high efficiency midrange out there that I've found, hands down. If your plan is 300hz for a HPF, run a 24db slope and you're gold. I've run them as low as 220hz, but they started to roll off below 300 and a midbass should be able to get up that high with no problem so it's not really worth overdriving the midrange. As hated said, the PHL is basically a beefed up version of the Audax, but they're near impossible to find and I don't know that the marginal gains would be worth the hunt/additional cost. If you can fit an 8", I would recommend either the JBL 2118H or the BMS 8S215. Take it from a guy who's tried a few.


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## mikey7182

Patrick Bateman said:


> I know I'm a broken record here, but output trumps efficiency. An ND91 has an efficiency in the low 80s but stick it on a horn and efficiency goes through the roof.




If output trumps efficiency, why place a low efficiency driver on a horn to increase... efficiency?  Seems a bit contradictory. We've had this discussion, and I've read a lot of your thoughts regarding this, but nothing trumps efficiency, because in essence what you're doing by coupling tons of little inefficient drivers or strapping them to a horn is _increasing net efficiency_. Sure, you're increasing output, but isn't that what efficiency is? Output IS efficiency. And yeah, you can take an array of ten 3" drivers with an efficiency of 78db, strap them to a horn and end up with an output of [email protected]/m (I didn't actually do the math on that- just being rhetorical), but what's the point? What's the advantage over running a single driver whose voice coils won't have to be pushed to the brink of going thermal, creating distortion and other unwanted side effects? 

Output doesn't trump efficiency; Output is dictated BY efficiency. There is a reason why you don't see cabs at shows full of 12" midrange with efficiencies in the mid 80s. They use 2206H or a variety of other high efficiency drivers, then port them for added gain. Why? Because even in an array, efficiency trumps inefficiency.


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## T3mpest

mikey7182 said:


> Are you using these in a 3-way front with horns like I've done? As far as 6-7" drivers go, I've used the B&C and several others and the Audax is by far the best. Depending on application and HPF, I would say it rivals the 2118. The 8" obviously has better bottom end, but the Audax is the best 6-7" high efficiency midrange out there that I've found, hands down. If your plan is 300hz for a HPF, run a 24db slope and you're gold. I've run them as low as 220hz, but they started to roll off below 300 and a midbass should be able to get up that high with no problem so it's not really worth overdriving the midrange. As hated said, the PHL is basically a beefed up version of the Audax, but they're near impossible to find and I don't know that the marginal gains would be worth the hunt/additional cost. If you can fit an 8", I would recommend either the JBL 2118H or the BMS 8S215. Take it from a guy who's tried a few.


I used to run the BMS 8S215, how do those two compare, asssuming a similar 300hz filter for both. I rather liked the BMS for midrange duty, but I sold those since I can't fit a 8 where I want it and I wanted to try something different anyways. My last setup used a that BMS 8 down to 120hz and then my subs below that. They were great speakers, but I preferred their midrange sound to their midbass.


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## mikey7182

I didn't use the BMS below 250hz. To me, the Audax do best >500hz. If all you can fit is a 6.5, the Audax is the best fit and do fine down to 300. But if you can fit the BMS again, they have a better lower midrange response than the Audax.


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## thehatedguy

Yeah I'm not getting why I could spend the time and effort to horn load a bunch of 3s when a 7 or 8 direct radiator would do the same thing cheaper, easier, and faster to build.

And like I said, excursion means little when you are talking about midrange output.


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## mikey7182

thehatedguy said:


> Yeah I'm not getting why I could spend the time and effort to horn load a bunch of 3s when a 7 or 8 direct radiator would do the same thing cheaper, easier, and faster to build.
> 
> And like I said, excursion means little when you are talking about midrange output.


Even in the midbass/bass range where excursion comes into play, we've had this discussion as well. Ten 6" subs may have the same radiating surface area/displacement/efficiency as a single 15" or single 18", but the characteristic of the sound is different. I stopped running multiple small subs years ago. I'm sorry, but 25 6" subs aren't going to sound like a pair of BMS 18N862s. I don't care if they're displacing the same amount of air or not, or if they're 'as efficient.' This is a slightly different conversation than the midrange one, in terms of what defines efficiency or how arrays of multiple less efficient drivers compare to single more efficient ones, but the underlying principle is the same.


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## thehatedguy

That too.


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## fenis

mikey7182 said:


> Even in the midbass/bass range where excursion comes into play, we've had this discussion as well. Ten 6" subs may have the same radiating surface area/displacement/efficiency as a single 15" or single 18", but the characteristic of the sound is different. I stopped running multiple small subs years ago. I'm sorry, but 25 6" subs aren't going to sound like a pair of BMS 18N862s. I don't care if they're displacing the same amount of air or not, or if they're 'as efficient.'


Amen to cone area! That's why I went with the BMS18N860 instead of the JBL W15GTI (95db sensitivity vs 88) and I've never looked back!


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## T3mpest

fenis said:


> Amen to cone area! That's why I went with the BMS18N860 instead of the JBL W15GTI (95db sensitivity vs 88) and I've never looked back!


Just so everyone knows a pair of b&c21sw152 will be rounding out my subbass and some of my midbass. In a wall . Got that covered


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## mikey7182

T3mpest said:


> Just so everyone knows a pair of b&c21sw152 will be rounding out my subbass and some of my midbass. In a wall . Got that covered


Someone had to one-up me at some point! 

If you're going to run those into the midbass region, I would definitely recommend running as large of a midrange as you can (If you're doing a true 3-way/4-way setup instead of a bunch of overlap as a lot of SPL guys tend to do). If you plan on running those B&Cs up to 300hz, or even 250, I would definitely get some BMS 8S215 up front. Cone area will help it blend better. I was in the exact same boat when I swapped the Audax for the BMS. They paired with the BMS 18N862 much better. The transition was more seamless.


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## fenis

T3mpest said:


> Just so everyone knows a pair of b&c21sw152 will be rounding out my subbass and some of my midbass. In a wall . Got that covered


Holy **** that would equal 3360cm2 of cone area! Makes the 1213cm2 of my BMS18N860 seem tiny! I'll have to demo your system when I travel to the USA one day..


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## T3mpest

mikey7182 said:


> Someone had to one-up me at some point!
> 
> If you're going to run those into the midbass region, I would definitely recommend running as large of a midrange as you can (If you're doing a true 3-way/4-way setup instead of a bunch of overlap as a lot of SPL guys tend to do). If you plan on running those B&Cs up to 300hz, or even 250, I would definitely get some BMS 8S215 up front. Cone area will help it blend better. I was in the exact same boat when I swapped the Audax for the BMS. They paired with the BMS 18N862 much better. The transition was more seamless.


Blah not what I wanted to hear. Sounds like I need to look harder into fitting an 8 lol. Just got those BMS into my friends car, he likes them quite a bit.


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## mikey7182

T3mpest said:


> Blah not what I wanted to hear. Sounds like I need to look harder into fitting an 8 lol. Just got those BMS into my friends car, he likes them quite a bit.


I know the feeling  Just picture it the same as most people trying to pair some 6.5" 2 ways with two 15" ported subs with 3kw. Doesn't sound very balanced. This is obviously taking some more thought than that, but the principle is the same. Good luck making them fit! Is it depth or diameter that's giving you an issue? Pyle and Cadence both made some pretty shallow 8" high efficiency mids that you may want to look into if depth is your issue. If it's diameter, the Audax really isn't THAT much smaller than an 8.


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## Patrick Bateman

thehatedguy said:


> Yeah I'm not getting why I could spend the time and effort to horn load a bunch of 3s when a 7 or 8 direct radiator would do the same thing cheaper, easier, and faster to build.
> 
> And like I said, excursion means little when you are talking about midrange output.


Price, packaging.

Here at my desk I have a horn loaded Dayton ND91 in a 0.4cf box that has an efficiency of about 94dB. Cost is about $50. *Horn loading raises the efficiency from anemic (84dB) to prosound level (94dB)*

I could get similar results with a B&C 8NDL51 in a sealed box, but the cost is triple. The size is about the same.

The 8NDL51 will get a little bit louder, maybe 3dB, due to higher power handling.











Remember, *all of this boils down to Hoffman's Iron Law.* The whole reason that companies like Bose use 5" subwoofers in boxes that are big enough to house a twelve is simply money and packaging. Bose could get the same results with a sealed 12", but the cost would be higher and you can make horns and transmission lines in shapes that you can't use for a sealed 12".

Here's an example of what I mean:

My horn loaded 3" worked out really well. It's 6" tall, and I'd like to make something similar that will fit under my couch. My couch can accomodate a box that's 4" tall.

That gives me a couple of options:

1) the easy option : buy a shallow subwoofer, put it in a sealed box. If I do that, it will cost me about $600 for four boxes.

2) the hard option : horn load a 3.5" woofer. The space and output is about the same, but the cost for four boxes is about $100, or 17% of the "easy" option


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## T3mpest

mikey7182 said:


> I know the feeling  Just picture it the same as most people trying to pair some 6.5" 2 ways with two 15" ported subs with 3kw. Doesn't sound very balanced. This is obviously taking some more thought than that, but the principle is the same. Good luck making them fit! Is it depth or diameter that's giving you an issue? Pyle and Cadence both made some pretty shallow 8" high efficiency mids that you may want to look into if depth is your issue. If it's diameter, the Audax really isn't THAT much smaller than an 8.


Diameter. I'll work on it and possibly do a build log once this gets going.. really wish I could pony up for h800, butthink I'll have to start with my ms8 I already own and if it's a complete failure do a h701. I've gotten decent at making my ms8 do a good job. Ms8 with horns has been mixed results but I've gotten good midbass out of it at least now.


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## Jesus Christ

Patrick Bateman said:


> output trumps efficiency.





Patrick Bateman said:


> The 8NDL51 will get a little bit louder


Sounds like you should have gotten the B&C then.


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## Patrick Bateman

Jesus Christ said:


> Sounds like you should have gotten the B&C then.


For six times the price?

No thanks, I have better things to spend my money on.


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## thehatedguy

But my time is worth money too.

You have time to find speakers, to sim the speakers in hornresp, build patterns to make the horn, etc....

And from the amount of time I saved doing the B&C might would make up for the differences in driver cost.

But checking PE, the B&C is $120 each and the ND91s are in special for $26 each...and you would need at least 4 per side. So I don't see the cost savings being important.


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## T3mpest

thehatedguy said:


> But my time is worth money too.
> 
> You have time to find speakers, to sim the speakers in hornresp, build patterns to make the horn, etc....
> 
> And from the amount of time I saved doing the B&C might would make up for the differences in driver cost.
> 
> But checking PE, the B&C is $120 each and the ND91s are in special for $26 each...and you would need at least 4 per side. So I don't see the cost savings being important.


And the added complexity of the enlclosure. Sure you can get similar results using some super exotic build, but is spending time modelling, 3x the construction time, extra time measuring to make sure things came out like you wanted it really worth saving a bit of money.. KISS comes in at some point, especially in a car since your not only having to build exotic enclosures, you have to fit them into the countours of the vehicle without making it look like a hack job.


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## Patrick Bateman

thehatedguy said:


> But my time is worth money too.
> 
> You have time to find speakers, to sim the speakers in hornresp, build patterns to make the horn, etc....
> 
> And from the amount of time I saved doing the B&C might would make up for the differences in driver cost.
> 
> But checking PE, the B&C is $120 each and the ND91s are in special for $26 each...and you would need at least 4 per side. So I don't see the cost savings being important.












Does this LOOK difficult to build?!

It's a rectangular box with a divider down the middle. I built it in less than an hour.









As for the hornresp sims, *I work at a company where we spend literally half our day on conference calls.* While someone is yammering on about mission statements, I'm doing one of three things:

1) hitting 'refresh' on Reddit
2) coming up with bizarre horns
3) checking audio sites




(in all seriousness, I really DO write finance software for a living, and YES, it's exactly like Office Space.)


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## SQram

This:



Looks more complicated and time consuming than this:



Am I missing something?


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## Patrick Bateman

SQram said:


> This:
> 
> 
> 
> Looks more complicated and time consuming than this:
> 
> 
> 
> Am I missing something?


Well that brings up an entirely seperate topic, which is that speakers in a car door should be in a sealed enclosure or a vented enclosure.

100hz is over three meters long; when you put a loudspeaker in a car door it's hardly an infinite baffle. The idea that you can treat a car door as an infinite baffle is false, it's truly a very lossy sealed box. *If you have *anything* that leaks in that door, the backwave is going to escape, and it's going to reduce the output coming off of the front of the cone.* My car doors have easily a dozen holes in them, and some of them are large. *And even if you dynamat the entire door, air will escape out of the top where the window is.* You just can't treat it as an IB, unless your F3 is 200hz. 100hz is just too long; the sound WILL get out if there's any hole in the door. It's way more effective to just stick the woofer in a proper enclosure. The reason that people have good results with eights and tens is that eights and tens have so much displacement *you're basically combating the rear wave using brute force*, exactly as Linkwitz does in his dipole subwoofers.


















That's the reason my "conventional" midbass enclosures look like this










not this


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## thehatedguy

But you need that ring to make kickpanels...I think that is what he was getting at.


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## thehatedguy

Plus I can't find anywhere with enough floor space to but a 12" deep square box in my car. If I had that kind of space, I would just put a much larger speaker in there to begin with.


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## SQram

Oh I don't dispute the sonic benefits of an enclosure rather than having a driver mounted in a door. My post was only in response to:



Patrick Bateman said:


> Does this LOOK difficult to build?!



without ending up with something that looks like this:


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## Eric Stevens

Patrick Bateman said:


> Well that brings up an entirely seperate topic, which is that speakers in a car door should be in a sealed enclosure or a vented enclosure.
> 
> 100hz is over three meters long; when you put a loudspeaker in a car door it's hardly an infinite baffle. The idea that you can treat a car door as an infinite baffle is false, it's truly a very lossy sealed box. *If you have *anything* that leaks in that door, the backwave is going to escape, and it's going to reduce the output coming off of the front of the cone.* My car doors have easily a dozen holes in them, and some of them are large. *And even if you dynamat the entire door, air will escape out of the top where the window is.* You just can't treat it as an IB, unless your F3 is 200hz. 100hz is just too long; the sound WILL get out if there's any hole in the door. It's way more effective to just stick the woofer in a proper enclosure. The reason that people have good results with eights and tens is that eights and tens have so much displacement *you're basically combating the rear wave using brute force*, exactly as Linkwitz does in his dipole subwoofers.


So if I understand you correctly, what you are saying is:

If the enclosure is leaky and lossy the rear sound waves will escape the doors cavity and this will result in a loss of the sound waves coming off the front of the speaker creating a reduction in volume level or amplitude????

WOW?????


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## Eric Stevens

Patrick Bateman said:


> Well that brings up an entirely seperate topic, which is that speakers in a car door should be in a sealed enclosure or a vented enclosure.
> 
> 100hz is over three meters long; when you put a loudspeaker in a car door it's hardly an infinite baffle. The idea that you can treat a car door as an infinite baffle is false, it's truly a very lossy sealed box. *If you have *anything* that leaks in that door, the backwave is going to escape, and it's going to reduce the output coming off of the front of the cone.* My car doors have easily a dozen holes in them, and some of them are large. *And even if you dynamat the entire door, air will escape out of the top where the window is.* You just can't treat it as an IB, unless your F3 is 200hz. 100hz is just too long; the sound WILL get out if there's any hole in the door. It's way more effective to just stick the woofer in a proper enclosure. The reason that people have good results with eights and tens is that eights and tens have so much displacement *you're basically combating the rear wave using brute force*, exactly as Linkwitz does in his dipole subwoofers.


An enclosure with a lossy rear chamber (our vehicles door) will alter the response curve by shifting and changing the resonance of the system. It WILL NOT reduce the output level or sensitivity of the system other than changing the Q of the roll off on the bottom end.

Only way the rear wave leaking will reduce output is if it leaks out the front side and creates a destructive cancellation.


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## Patrick Bateman

Eric Stevens said:


> An enclosure with a lossy rear chamber (our vehicles door) will alter the response curve by shifting and changing the resonance of the system. It WILL NOT reduce the output level or sensitivity of the system other than changing the Q of the roll off on the bottom end.
> 
> Only way the rear wave leaking will reduce output is if it leaks out the front side and creates a destructive cancellation.


Yes, if the rear wave of the speaker leaks to the front, it creates destructive cancellation.









The frequency at which this happens will depend on the distance from the front to the back of the cone. For instance, in this door, the distance from front to back is about 30cm.

So we're going to get destructive cancellation at 283hz:
(speed of sound / distance / 4) =
(34000cm / 30cm / 4)
= 283hz

As noted in the thread "bass how low can you go?", the octave from 100hz to 200hz is possibly the most difficult to reproduce.

So in this scenario, *we have destructive interference at the worst possible frequency*; right where we need the output we're destroying it, due to that hole in the door.


Your statement that _"An enclosure with a lossy rear chamber (our vehicles door) will alter the response curve by shifting and changing the resonance of the system. It WILL NOT reduce the output level or sensitivity of the system other than changing the Q of the roll off on the bottom end._" is only true if the leaks are very small.









For instance, in an enclosure with a Scanspeak variovent we have a hole in the box. But the reason that you can get away with this is that the hole is not large, and most importantly *the rear wave is attenuated by a **** ton of fiberglass.* In a car door, we don't have that luxury; the rear wave of the woofer is not attenuated.

Fiberglass can REALLY nuke that rear wave; I've seen as much as 10dB of attenuation from a couple of inches of fiberglass.


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## Eric Stevens

Patrick Bateman said:


> Yes, if the rear wave of the speaker leaks to the front, it creates destructive cancellation.
> 
> Your statement that _"An enclosure with a lossy rear chamber (our vehicles door) will alter the response curve by shifting and changing the resonance of the system. It WILL NOT reduce the output level or sensitivity of the system other than changing the Q of the roll off on the bottom end._" is only true if the leaks are very small.


Only possible leak back into the listening environment is the inner window seal. When the window is in the up position it is well sealed. At least in all of the cars I have owned or worked on. Any other leaks will be outside the listening environment.

I don't care how big the leaks are my statement ""An enclosure with a lossy rear chamber (our vehicles door) will alter the response curve by shifting and changing the resonance of the system. It WILL NOT reduce the output level or sensitivity of the system other than changing the Q of the roll off on the bottom end"" holds true because the leaks are outside the listening environment. This was my point from the very beginning.


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## mikey7182

Patrick Bateman said:


> Yes, if the rear wave of the speaker leaks to the front, it creates destructive cancellation.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The frequency at which this happens will depend on the distance from the front to the back of the cone. For instance, in this door, the distance from front to back is about 30cm.
> 
> So we're going to get destructive cancellation at 283hz:
> (speed of sound / distance / 4) =
> (34000cm / 30cm / 4)
> = 283hz
> 
> As noted in the thread "bass how low can you go?", the octave from 100hz to 200hz is possibly the most difficult to reproduce.
> 
> So in this scenario, *we have destructive interference at the worst possible frequency*; right where we need the output we're destroying it, due to that hole in the door.
> 
> 
> Your statement that _"An enclosure with a lossy rear chamber (our vehicles door) will alter the response curve by shifting and changing the resonance of the system. It WILL NOT reduce the output level or sensitivity of the system other than changing the Q of the roll off on the bottom end._" is only true if the leaks are very small.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> For instance, in an enclosure with a Scanspeak variovent we have a hole in the box. But the reason that you can get away with this is that the hole is not large, and most importantly *the rear wave is attenuated by a **** ton of fiberglass.* In a car door, we don't have that luxury; the rear wave of the woofer is not attenuated.
> 
> Fiberglass can REALLY nuke that rear wave; I've seen as much as 10dB of attenuation from a couple of inches of fiberglass.


Why wouldn't that be possible in a car door? As long as electronics and window mechanisms are avoided, people rear insulate their drivers all the time. I had both polyfill and egg carton foam behind the drivers when I had door mounted midbass. 

I also still don't see what you're trying to accomplish, other than an alternative way of arriving at efficiency. Your end goal is output, but they're the same thing. You keep talking about output trumping efficiency, but you can't stop using the word 'efficiency' when talking about the effects your enclosures/horns have on less efficient drivers in order to increase their output. If your goal is to think outside the box or attempt to save money, I can appreciate that. But I think you're trying to make a distinction between output and efficiency when one need not be made. Output is essentially efficiency. Saying a bunch of horn loaded inefficient drivers have more overall output capability than a more efficient single driver is essentially saying this new speaker you've created is simply more efficient. Horn load the more efficient one in similar quantities and it'll destroy the first one you built. Sure it'll be much larger, so your point seems to really be that you can extract more efficiency out of the same physical space by using arrays/horns. I think it's a good pursuit but I don't see much of it in the car audio realm. You're talking about putting small boxes somewhere; I would argue that a ported fiberglass enclosure of similar dimensions with a high efficiency midbass would be the better option in most cases.


----------



## Patrick Bateman

Eric Stevens said:


> Only possible leak back into the listening environment is the inner window seal. When the window is in the up position it is well sealed. At least in all of the cars I have owned or worked on. Any other leaks will be outside the listening environment.
> 
> I don't care how big the leaks are my statement ""An enclosure with a lossy rear chamber (our vehicles door) will alter the response curve by shifting and changing the resonance of the system. It WILL NOT reduce the output level or sensitivity of the system other than changing the Q of the roll off on the bottom end"" holds true because the leaks are outside the listening environment. This was my point from the very beginning.


That's simply a bizarre statement. The sound radiates into the door, and out of the gap along the top of the door.









*It doesn't take a lot of radiation to nuke the front wave.* For instance, in a vented box a hole that's a fraction of the cone's size is enough to nuke the front wave.


Of course, some will say "what are you talking about Bateman, vented boxes are louder than sealed boxes." And that's true; they ARE louder, ABOVE the tuning frequency. But BELOW the tuning frequency, *the box unloads; the rear wave is destroying the front wave.*









A similar phenomenon happens in a car door.

We have a few octaves where the front is isolated from the back.
We have one frequency where the front and the back are in-phase, and that's going to create a big fat peak.

And then it unloads.



I thought all of this was common knowledge? I can't be the only person who's put midbasses in sealed enclosures and found that they were way WAY louder than a car door.

It's the whole reason people use eights and tens and twelves in a car door; you're battling that rear wave, you're fighting it with brute force. It doesn't take a big hole to interfere with the front, even a few square inches will do the trick.


----------



## thehatedguy

I haven't had much if any problems with the backwave leaking past the interior window seals in any car that I've owned or worked on...not with the windows up.

And as a window tinter, those gaskets on the interior usually stick pretty close to the glass. Close enough that if the glue on the tint isn't cured it will/can peel the film off of the window.


----------



## Eric Stevens

This is a simple mechanical issue not even one of acoustics. 

If the window seal in your car doors leak enough to cause a destructive cancellation your car needs repair. When the window is has been rolled down it is possible for it to leak where the gap is created. I can model the leak area of the window seal as if its not there in LEAP and guarantee that what you describe below will not happen.

If you have mounted drivers into a factory location and thrown away the plastic door liner and didnt replace/reseal it with metal and dynamat then I could understand the loss of output. But that is not a lossy enclosure problem that is poor and improper installation.



Patrick Bateman said:


> That's simply a bizarre statement. The sound radiates into the door, and out of the gap along the top of the door.
> 
> We have a few octaves where the front is isolated from the back.
> We have one frequency where the front and the back are in-phase, and that's going to create a big fat peak.
> 
> And then it unloads.
> 
> I thought all of this was common knowledge? I can't be the only person who's put midbasses in sealed enclosures and found that they were way WAY louder than a car door.
> 
> It's the whole reason people use eights and tens and twelves in a car door; you're battling that rear wave, you're fighting it with brute force. It doesn't take a big hole to interfere with the front, even a few square inches will do the trick.


----------



## Patrick Bateman

thehatedguy said:


> I haven't had much if any problems with the backwave leaking past the interior window seals in any car that I've owned or worked on...not with the windows up.
> 
> And as a window tinter, those gaskets on the interior usually stick pretty close to the glass. Close enough that if the glue on the tint isn't cured it will/can peel the film off of the window.


Show me the data.









Here's an 8NDL51 in a sealed box that's so small it's JUST big enough to contain the basket. In the car we have an F3 around 70hz, *but the response mostly varies depending on where you put it.* The blue curve is in the kicks, the orange curve is in the rear quarter panel. Rear quarter panel exhibits a notch due to the reflection off of the boundaries of the cabin.

This is a TINY enclosure; if I was gunning for an F3 of 80hz I could probably get it with a 6" woofer in a box small enough to hold in your hand.



Seriously, you don't need a big box; just ignore everything that the sims tell you, *because cabin gain changes everything.* It changes the Q, it changes the rolloff, it changes the phase, it changes the impedance, it changes the impulse response, it changes the group delay.

BTW, the predicted F3 was something like 200hz, nearly an octave and a half higher than the measured response in car.


So... Who's going to show me a woofer in a door that has an F3 of 70hz or less with an efficiency of 98dB or higher? I'm willing to bet it can't be done without an enclosure. You gotta contain that back wave, or use a really REALLY big woofer, like a ten or even a twelve. (The 8NDL51 has an efficiency of 93dB at 1khz, and the predicted output at 80hz was about 78dB.)


----------



## thehatedguy

Hoffman's Iron Law says you can't do what you want to do with anything smaller than a 10.


----------



## Patrick Bateman

thehatedguy said:


> Hoffman's Iron Law says you can't do what you want to do with anything smaller than a 10.











See how the orange trace has a dip at 180hz, but about 6dB more output at 90hz?

What's happening here is that the interior of the car itself is acting as a quarter wave resonator. At 90hz we're getting about 6dB of boost, and at 180hz we're getting a null.

So that's part of the puzzle: it's generally accepted that cabin gain starts at 80hz. IMHO, cabin gain can start higher in frequency but you have to get the drivers closer to the center of the car.

Check out some of the SPL cars, you'll see them getting crazy levels when the sub is placed in the center of the car, I think this is what we're seeing here.

There's no free lunch; you incur a dip higher in frequency.

But if you can live with that, *you can get as much as six decibels more output by moving the midbass around.* Yes, Hoffman's Iron Law still applies, but now we're optimizing the cabin itself as part of the enclosure.

And that's like going from a 6" woofer to a 10" woofer.



*TLDR: you can get mighty bass out of small drivers. The location in the car has a huge impact. And small drivers are easier to place; it's easy to hide a small sealed box.*


----------



## Orion525iT

So...you guys never have your windows rolled down? I do quite often when the weather is nice and when rolling across town at night.



mikey7182 said:


> Even in the midbass/bass range where excursion comes into play, we've had this discussion as well. Ten 6" subs may have the same radiating surface area/displacement/efficiency as a single 15" or single 18", but the characteristic of the sound is different. I stopped running multiple small subs years ago. I'm sorry, but 25 6" subs aren't going to sound like a pair of BMS 18N862s. I don't care if they're displacing the same amount of air or not, or if they're 'as efficient.'


Not to derail things. But the above statement has been driving me nuts. It makes no sense to me, but I have read it over and over. What is the science behind this? Where are the measurements that prove this? There must be something quantifiable that can explain this view, but nothing I have ever read points to any data that actually supports this hypothesis.


----------



## Jesus Christ

So first output was all that was important, then as you pointed out the efficient driver still had more output than the inefficient driver in a horn so the argument then became output is only important as long as it doesn't cost too much. Now the argument is that enclosure doesn't matter and placement within the car is what's important. Am I the only one having a hard time figuring out what exactly your argument is other than it seems you like to argue?


----------



## thehatedguy

I have no data to support it other than years of installing hundreds and hundreds of subs of varying numbers and sizes.

A wall of 24 10s while drilled up high in the bass never had the same guttural feeling of 8 18s down low.

Same with midbasses 4 6.5s never had the same tactile feeling of a pair of 10s though having roughly the same Sd.

They all (to me) sounded like a lot of smaller speakers...not larger. Just louder versions of what you started with. 



Orion525iT said:


> So...you guys never have your windows rolled down? I do quite often when the weather is nice and when rolling across town at night.
> 
> 
> 
> Not to derail things. But the above statement has been driving me nuts. It makes no sense to me, but I have read it over and over. What is the science behind this? Where are the measurements that prove this? There must be something quantifiable that can explain this view, but nothing I have ever read points to any data that actually supports this hypothesis.


----------



## Orion525iT

thehatedguy said:


> I have no data to support it other than years of installing hundreds and hundreds of subs of varying numbers and sizes.
> 
> A wall of 24 10s while drilled up high in the bass never had the same guttural feeling of 8 18s down low.
> 
> Same with midbasses 4 6.5s never had the same tactile feeling of a pair of 10s though having roughly the same Sd.
> 
> They all (to me) sounded like a lot of smaller speakers...not larger. Just louder versions of what you started with.


I know, I do believe the testimony. I just want some real data to back it up, to rule out other variables. I guess I don't believe that multiples _can't_ sound like larger drivers. I wonder if this is an issue of proper implementation.


----------



## Patrick Bateman

Jesus Christ said:


> So first output was all that was important, then as you pointed out the efficient driver still had more output than the inefficient driver in a horn so the argument then became output is only important as long as it doesn't cost too much. Now the argument is that enclosure doesn't matter and placement within the car is what's important. Am I the only one having a hard time figuring out what exactly your argument is other than it seems you like to argue?


I consistently get in religious arguments on the HLCD forum because I don't think that efficiency is an important parameter:
*I personally believe that output trumps efficiency.*

But this is counter to what 90% of the people on the forum believe, so I generally come off as a kook.

I do agree with Jason and Eric a lot, in particular that it is simpler (but more expensive) to use a prosound driver in a conventional box. Having said that, you can get comparable results with smaller drivers in horns, but then you have to know how to design and build a horn. But I can do that in my sleep, been building horns for two decades now.

On top of all this, trying to follow my posts is a lot like trying to decipher the ramblings of that homeless guy who spends all day at the bus stop.


----------



## Jesus Christ

Patrick Bateman said:


> I don't think that efficiency is an important parameter:
> *I personally believe that output trumps efficiency.*


If efficiency isn't important then why use a horn? The purpose of the horn is to raise efficiency right? So, without using a horn because efficiency isn't important explain to me how a driver with a sensitivity in the mid 80's with a power handling of 30w is going to have more output than a driver with a sensitivity in the mid 90's and a power handling of 200w.


----------



## mikey7182

Jesus Christ said:


> If efficiency isn't important then why use a horn? The purpose of the horn is to raise efficiency right? So, without using a horn because efficiency isn't important explain to me how a driver with a sensitivity in the mid 80's with a power handling of 30w is going to have more output than a driver with a sensitivity in the mid 90's and a power handling of 200w.


I've said this 8 different ways in this thread and brought it up in others and all I get quoted saying is how small arrays don't sound like single bigger drivers. These usually turn into an Eric vs Patrick thread. It would be nice to have my (and your) points addressed...


----------



## Patrick Bateman

mikey7182 said:


> I've said this 8 different ways in this thread and brought it up in others and all I get quoted saying is how small arrays don't sound like single bigger drivers. These usually turn into an Eric vs Patrick thread. It would be nice to have my (and your) points addressed...


Nah it's not an Eric vs Patrick thing at all, I have mad respect for Eric and Jason.

The thing you have to remember is that I'm basically a dude who writes software that has way too much time on my hands, while they're actually making things in the real world.

So my solutions tend to be really byzantine; they're intentionally obtuse.

It's like a couple of car guys arguing about a Ford 5.0L V8 versus a turbocharged Honda 2.0L. Both solutions have the exact same horsepower, one is just hideously complex. In the real world, the 5.0L V8 will probably work more reliably and predictably, but it's also fun to coax as much power as humanly possible out of a small engine. Or a small woofer.


----------



## Patrick Bateman

Jesus Christ said:


> If efficiency isn't important then why use a horn?


Hoffman's Iron Law rules over all. A 28 liter horn and a 28 liter sealed box will have similar output levels. Output will depend on F3 and displacement, but if they're similar for both enclosures, then output will be similar also.

Basically you can use a horn to bump up the output of an inefficient woofer. I hardly invented this idea; it's the entire basis of Danley's Labhorn:

_"Well the main reason is that at the low end there is Hoffman's iron law which governs the efficiency. When you pick a box volume and low corner F, then you have defined the highest efficiency possible with the perfect driver. 
Low bass is the problem here because if one lowers the low corner frequency an octave, and leave the box volume the same, then you have also lowered the efficiency by 9dB."_ (Tom Danley, Audio Asylum)



Jesus Christ said:


> The purpose of the horn is to raise efficiency right? So, without using a horn because efficiency isn't important explain to me how a driver with a sensitivity in the mid 80's with a power handling of 30w is going to have more output than a driver with a sensitivity in the mid 90's and a power handling of 200w.


Basically you just have to decide how much output you want. Horn loading a woofer will get you about 5-10dB more efficiency. So that 3" 84dB woofer goes up to about 89-94dB when you horn load it. Add another woofer and you're up to 92-97dB or so.

Just keep adding woofers until you reach the output level you want; keep in mind that Hoffman's Iron Law rules, and it doesn't matter if your woofer is a $120 B&C or a $24 Dayton, Hoffman wins.

You can go the other way too. Do you want to get 20hz out of a 1cf box? It's possible, as long as you can live with an enclosure that has an efficiency in the 70s.


----------



## Jesus Christ

Patrick Bateman said:


> Basically you just have to decide how much output you want. Horn loading a woofer will get you about 5-10dB more efficiency. So that 3" 84dB woofer goes up to about 89-94dB when you horn load it. Add another woofer and you're up to 92-97dB or so.


Either efficiency isn't important and horns and multiple drivers are a waste or efficiency is important and that's why you advocate horns and multiple drivers. So which is it? It doesn't matter if the efficiency comes from a single efficient driver or either horn loading or using multiple less efficient drivers, the key to output is still efficiency no matter how you look at it.


----------



## Patrick Bateman

Jesus Christ said:


> Either efficiency isn't important and horns and multiple drivers are a waste or efficiency is important and that's why you advocate horns and multiple drivers. So which is it? It doesn't matter if the efficiency comes from a single efficient driver or either horn loading or using multiple less efficient drivers, the key to output is still efficiency no matter how you look at it.


Output is dictated by displacement.
Efficiency isn't even in the equation.

You *do* understand that right?

Here's the equation, if anyone feels like throwing it into a spreadsheet:

SPL= 20 * log(10) (1.18 / 0.00002 * Sd * Xmax / SQRT(2) * 2 * PI * F^2)


Some things you'll notice:

1) increasing cone area increases SPL
2) increasing xmax increases SPL

*Efficiency isn't in the equation.* 


For instance, let's say you have two woofers. One woofer is 3" in diameter and has an efficiency of 80dB. It has a displacement of 0.1 liter.

The other woofer is 6" in diameter and has an efficiency of 100dB. It has a displacement of 0.1 liter.

*Which woofer will play louder?*


----------



## Jesus Christ

Patrick Bateman said:


> For instance, let's say you have two woofers. One woofer is 3" in diameter and has an efficiency of 80dB. It has a displacement of 0.1 liter.
> 
> The other woofer is 6" in diameter and has an efficiency of 100dB. It has a displacement of 0.1 liter.
> 
> *Which woofer will play louder?*


The 6" because the 3" doesn't have the power handling to reach that 0.1 liter of displacement. The 3" would take 100w to reach the same output of the 100db 6" at 1w and that's not even considering power compression which can be a real cocksucker. Show me a 80db 3" driver that can match the output of a 100db 6" driver. Displacement means nothing if a driver doesn't have the sensitivity/power handling to reach that displacement.


----------



## fenis

Patrick Bateman said:


> SPL= 20 * log(10) (1.18 / 0.00002 * Sd * Xmax / SQRT(2) * 2 * PI * F^2)
> 
> Some things you'll notice:
> 
> 1) increasing cone area increases SPL
> 2) increasing xmax increases SPL
> 
> *Efficiency isn't in the equation.*
> 
> For instance, let's say you have two woofers. One woofer is 3" in diameter and has an efficiency of 80dB. It has a displacement of 0.1 liter.
> 
> The other woofer is 6" in diameter and has an efficiency of 100dB. It has a displacement of 0.1 liter.
> 
> *Which woofer will play louder?*


Patrick, I don't understand why you always totally ignore the issue of power compression. Of course the 6" driver in your theoretical example above will play louder. I explained power compression pretty well in another thread but here it is again:



fenis said:


> I disagree that you can arrive at the same output as long as the lower efficiency speaker has the power handling to get there. Eg. Beyma provides the power compression figures for the 10G40 (a very high regarded pro sound driver with 95dB 1w/1m sensitivity) and after 5 minutes of AES power (400w) using pink noise there is 4.5dB of power compression! 18sound drivers are slightly better with compression figures in the 2.8 to 3.5dB range. So at realistic volumes your horns are cruising along barely receiving 5w, meanwhile your midbass is heating up and falling behind by 3-4dB!


----------



## Patrick Bateman

Jesus Christ said:


> The 6" because the 3" doesn't have the power handling to reach that 0.1 liter of displacement. The 3" would take 100w to reach the same output of the 100db 6" at 1w and that's not even considering power compression which can be a real cocksucker. Show me a 80db 3" driver that can match the output of a 100db 6" driver. Displacement means nothing if a driver doesn't have the sensitivity/power handling to reach that displacement.


Ever seen me use a single small woofer?

Nope.

Not dumb, I know you need to array them. My last project used five per side, and the only reason I didn't use more was because I only bought ten!










Here's DB Keele, who practically wrote the book on modern CD horns.








And that's my main point: A single modern woofer will get you the same SPL as some of these 1970s throwbacks you guys are using. Do you need more SPL? Then use more of them. Or horn load them. Or both.

Tweeter line arrays are still stupid. But for midbass and bass it's just a no-brainer.


----------



## Patrick Bateman

fenis said:


> I disagree that you can arrive at the same output as long as the lower efficiency speaker has the power handling to get there. Eg. Beyma provides the power compression figures for the 10G40 (a very high regarded pro sound driver with 95dB 1w/1m sensitivity) and after 5 minutes of AES power (400w) using pink noise there is 4.5dB of power compression! 18sound drivers are slightly better with compression figures in the 2.8 to 3.5dB range. So at realistic volumes your horns are cruising along barely receiving 5w, meanwhile your midbass is heating up and falling behind by 3-4dB!


400 watts into a pair of 95dB Beyma 10G40 would yield 114dB.

I don't *need* this much SPL at 1khz.

As noted in the "Bass How Low Can You Go" thread, I mostly listen to EDM, so I need output from 30hz to 120hz. The basslines tend to be about 20-30dB above the mix, so if my sub is capable of 120dB, *all I need at 1khz is about 95-105dB.*


I personally tend to use shallower xover slopes, and that plays a role here too. For instance, the rolloff of my sub is about 12dB per octave, so if I xover at 100hz the sub is still making a significant contribution to the SPL at 200hz. For instance, if I'm doing 120dB at 100hz the sub is generating 108dB at 200hz.



TLDR : 400 watts into a pair of Beymas will get you to about 114dB. Due to the type of music I listen to, the bass tends to be about 20-30dB above the midrange. 120dB is about as loud as I go on the bass. Therefore, I need a midrange capable of about 95-105dB, and a midbass capable of about 110-115dB. Due to my shallow slopes, my subs are generating a significant fraction of my midbass.


----------



## T3mpest

Patrick Bateman said:


> Output is dictated by displacement.
> Efficiency isn't even in the equation.
> 
> You *do* understand that right?
> 
> Here's the equation, if anyone feels like throwing it into a spreadsheet:
> 
> SPL= 20 * log(10) (1.18 / 0.00002 * Sd * Xmax / SQRT(2) * 2 * PI * F^2)
> 
> 
> Some things you'll notice:
> 
> 1) increasing cone area increases SPL
> 2) increasing xmax increases SPL
> 
> *Efficiency isn't in the equation.*
> 
> 
> For instance, let's say you have two woofers. One woofer is 3" in diameter and has an efficiency of 80dB. It has a displacement of 0.1 liter.
> 
> The other woofer is 6" in diameter and has an efficiency of 100dB. It has a displacement of 0.1 liter.
> 
> *Which woofer will play louder?*


Your still missing part of the equation patrick. Excursion requirements are heavily based on frequency in question. Every time you drop an octave you increase needed excursion to maintain SPL by a factor of 4. If we are talking about a 1khz tone, xmax becomes a moot point. a 80db/1w/1m speaker can have 45mm xmax for all the good it will do it. You'd need 500,000 watts to even come close to pushing it to xmax at 1000hz. Since speakers at high frequencies are power limited, they are effeciency and power handling limited. You can have the given SD and xmax to reach a SPL level, but how much xmax your actually using for 1watt of input then becomes the limit back in the real worlds, since we need to put power through the coil to make it happen. Powerhanlding in and of itself is great, but since speakers are so ungodly ineffecient, power compression bites you in the ass in the long run.

As you drop into bass frequencies, xmax and total displacement matter a lot more. Especially with things like tapped horns where we can push the 1w/1m effeciency high enough that displacement limits can be reached, that's one thing you gain when you start using really large enclosures.

To answer your question, if we are talking displacement as in total air swept, they will be the same.. ASSUMING, they are both playing the same frequency  However, we also have to deal with the REALITY that the 3inch driver may need much more power to get it there and is likely closer to it's xmax since per given amount of vd it's moving further since the cone is smaller. Now if the frequency is low enogh the smaller driver may be more effeicneint down low, since it's lower effeciency up top, however now xmax matters that much more since lower frequencies use more of it for the same SPL.

In summation total output is always dicated by radiating area and excursion. However, excursion is dictated by the frequency your playing and how far the cone can move with a given amount of power input at that frequency.


----------



## Patrick Bateman

T3mpest said:


> Your still missing part of the equation patrick. Excursion requirements are heavily based on frequency in question. Every time you drop an octave you increase needed excursion to maintain SPL by a factor of 4. If we are talking about a 1khz tone, xmax becomes a moot point. a 80db/1w/1m speaker can have 45mm xmax for all the good it will do it. You'd need 500,000 watts to even come close to pushing it to xmax at 1000hz. Since speakers at high frequencies are power limited, they are effeciency and power handling limited. You can have the given SD and xmax to reach a SPL level, but how much xmax your actually using for 1watt of input then becomes the limit back in the real worlds, since we need to put power through the coil to make it happen. Powerhanlding in and of itself is great, but since speakers are so ungodly ineffecient, power compression bites you in the ass in the long run.
> 
> As you drop into bass frequencies, xmax and total displacement matter a lot more. Especially with things like tapped horns where we can push the 1w/1m effeciency high enough that displacement limits can be reached, that's one thing you gain when you start using really large enclosures.
> 
> To answer your question, if we are talking displacement as in total air swept, they will be the same.. ASSUMING, they are both playing the same frequency  However, we also have to deal with the REALITY that the 3inch driver may need much more power to get it there and is likely closer to it's xmax since per given amount of vd it's moving further since the cone is smaller. Now if the frequency is low enogh the smaller driver may be more effeicneint down low, since it's lower effeciency up top, however now xmax matters that much more since lower frequencies use more of it for the same SPL.
> 
> In summation total output is always dicated by radiating area and excursion. However, excursion is dictated by the frequency your playing and how far the cone can move with a given amount of power input at that frequency.


I know all of this.

On the HLCD forum there's been a history of people picking midbasses on their efficiency spec. The Audax PR170 is a good example of this; it has an efficiency of 100dB and an xmax of half a millimeter.

A single Dayton ND91 will clobber the Audax at 100hz; the Audax is limited by it's ****ty xmax spec.

What I'm trying to express here (and no one agrees with) is that *with an array you can dial in whatever output level and efficiency you would like.*

I'm not saying that a single Dayton ND91 is a reasonable substitute for an Audax PR170. *I'm saying that you shouldn't ignore low efficiency drivers simply based on their efficiency spec.* You can raise that efficiency in a number of ways, and turn a low efficiency driver into a giant-killer.

Array it, horn load it, etc.


The prosound guys figured this out twenty years ago; even JBL uses 2" and 3" midranges in their Vertec speakers.









Here's Audio God DB Keele with a Vertec Array. (Same dude who made the CBT array, wrote the book on CD horns, etc.) *Look at the size of this thing!* There are seven drivers in that cabinet, and it's so small, you could nearly fit it under the dash of a car. Output capability is comparable to that Beyma, *but the Vertec is full range.* The Vertec uses four 3" midranges.

The Vertec that Keel is holding is capable of 136dB(!) It's 23" wide and 8" tall. Yes, that's bigger than an Eric Stevens HLCD, but if you reduced output by 10dB or so you could reduce the footprint of the Vertec by easily 75%. The Vertec approach is similar to what I do with a lot of my projects : cram as many drivers as humanly possible into a small space.

Imagine a point source loudspeaker, capable of playing from 100hz to 20khz at 126dB, that's 20" wide, 4" tall, and fits under your dash. *We can do this right now, but it won't use a 10" midbass.*


Or don't do this. Either solution is valid; I'm just suggesting an alternative to the ubiquity of single-midbass solutions.

Vertec specs : http://www.jblpro.com/ProductAttachments/JBL_VT4886_v3.pdf


----------



## thehatedguy

But the Audax is a proper midrange. It as a Fs in the 115-120 range...it can't physically play to 100 hertz, but it is a beast from 300 and up. The home guys used them in pairs OB from 450-500 and up.

It's not a fair comparison.

But I would be willing to bet the Audax would clobber the Dayton when both as used as the Audax is intended- as a midrange from 3-400 and up.


----------



## Patrick Bateman

thehatedguy said:


> But the Audax is a proper midrange. It as a Fs in the 115-120 range...it can't physically play to 100 hertz, but it is a beast from 300 and up. The home guys used them in pairs OB from 450-500 and up.
> 
> It's not a fair comparison.
> 
> But I would be willing to bet the Audax would clobber the Dayton when both as used as the Audax is intended- as a midrange from 3-400 and up.












That's why I do as Danley and Keele do: I use a combination of low efficiency and horn loading.

For instance, you only need a horn that's 8.4" deep to get horn loading down to 400hz.

That's what's going on in that Vertec box; that horn in the center of the cabinet probably looks fairly pointless, *but it's not.* It's horn loading the midranges and the compression driver. To be specific, the midrange in the Vertec covers two octaves, from 400hz to 1.6khz.

I wouldn't be surprised if the midranges in the Vertec have an efficiency in the 80s. The efficiency on the midbasses is probably significantly higher, but that's needed because the midbasses aren't horn loaded whatsoever.


In the car we can use the car itself to do our horn loading, which is a big part of the reason that I can get away with 2" and 3" drivers.


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## thehatedguy

But a 9" deep horn is a bit impractical in most cars...considering the size of the mouth you would also need.


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## Patrick Bateman

thehatedguy said:


> But a 9" deep horn is a bit impractical in most cars...considering the size of the mouth you would also need.


Check this out:

http://www.diymobileaudio.com/forum...r-audio-discussion/166341-jbl-vertec-car.html

And see how much output you can get from four 2.5" midranges on a waveguide small enough to hold in your hand

(Still doing the sims, data will be up by 1pm pst)


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