High Sensitivity midbass drivers

[JonJT 10+ year member]

Out of sheer boredom, I decided to lurk these forums in search of answers to an old question. Some time ago I researched the possibility of putting horns in my car and dug up a load of information, as well as one burning problem:

High sensitivity midbass drivers

I have a pair of Koda 8's I bought on impulse which would have worked well with a normal unloaded front stage, but I feel they lack the sensitivity to really keep up with the dynamics of the horns and the highly sensitive midrange I plan on using. When I dropped the project, I left without finding a midbass driver that had both the displacement to match a heavy subbass stage and the sensitivity to keep up with the rest of the front stage. After lurking a little, I see this problem still exists.

The B&C 8NDL51 is the best thing Ive seen so far, but I fear it lacks the displacement capabilities to reach down to my desired X-over point. I haven't done too much searching for high sensitivity woofers that would work, but I did come across a nice 10 inch woofer made by the same company. The B&C 10NW64.

This woofer trumps the Koda 8's I have in displacement and is much more sensitive at 96db. My only real worry is the woofers behavior in an IB environment. My knowledge of first order setups is quite rusty, as I've been cramming engineering principals into my brain for the last 4 months. So, the purpose of this post is to get your input as far as this woofers pracitcality in an IB alignment as well as the feasibility of making such an alignment within the average car door.

In the mean time, I'm going to go brush up on speaker design theory so I can make some decisions myself.

Good to be back.

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[helotaxi 5,000+ posts]

I'm thinking that the average car door isn't going to have the air volume required to get true IB performance out of those drivers. An install behind a heavily modded kickpanel that used either the fender or the great outdoors to get an IB setup would be the option there. If you wanted a more controlled environment, sealing the fender and filling it with expanding foam and then carving out the volume desired would probably be the way to go.

Couple of questions, why a 3-way front stage with horns? Most every car horn I've seen was capable of playing low enough to couple nicely with just a midbass. Second, why not just find a good midbass and power the crap out of it rather than trying to find one that is really sensitive? The combination of sensitivity and low extension needed to get it to blend nicely with a powerful substage are going to dictate an enclosure that will mke it pretty much impossible to practically integrate into a car without serious creativity and modification. Forgo sensitivity to get a small enclosure requirement and take advantage of the readily available cheap amplification out there.

Just my thoughts...

 

[JonJT 10+ year member]

I'm thinking that the average car door isn't going to have the air volume required to get true IB performance out of those drivers. An install behind a heavily modded kickpanel that used either the fender or the great outdoors to get an IB setup would be the option there. If you wanted a more controlled environment, sealing the fender and filling it with expanding foam and then carving out the volume desired would probably be the way to go.
Couple of questions, why a 3-way front stage with horns? Most every car horn I've seen was capable of playing low enough to couple nicely with just a midbass. Second, why not just find a good midbass and power the crap out of it rather than trying to find one that is really sensitive? The combination of sensitivity and low extension needed to get it to blend nicely with a powerful substage are going to dictate an enclosure that will mke it pretty much impossible to practically integrate into a car without serious creativity and modification. Forgo sensitivity to get a small enclosure requirement and take advantage of the readily available cheap amplification out there.

Just my thoughts...

I'm going 3 way front stage because its even harder to find a woofer that can cover the midrange and the midbass while blending property with the horns I want to use. I am looking at the CDes for a number of reasons. Price, and size are the foremost important. They don't extend that far and for aformentioned reasons, it would be much easier to find the right combination of woofers to make a 3 way front stage than a two way.

Now, over powering an inefficient, low sensativity woofer is an option, but it still won't produce the dynamics and play with the same "ease" as an efficient, sensitive woofer would. Its been done before and I've been warned with much vigor by more experienced horn owners not to mix and match a midbass with, for examble, 88db 1W/1M sensitivity with a horn at 97db 1W/1M or greater.

 

[JonJT 10+ year member]

I ran the woofer through WinISD quickly and responce down to about 80hz was pretty good in a 6 liter sealed enclosure. With some work and some Eqing, I bet they would do pretty well mounted in door.

mhmmmmmmm

 

[req 5,000+ posts]

hows about this?

http://www.criticalmassaudio.com/catalog/index.php?act=viewProd&productId=5

 

[JonJT 10+ year member]

hows about this?
http://www.criticalmassaudio.com/catalog/index.php?act=viewProd&productId=5

That woofer is actually very insensitive. Its rated at 2.83 volts into 2 ohms, which works out to 4 watts. You have to subtract 6 db from the sensitivity rating to compair it properly to the B&C woofer I mentioned. Its actual sensitivity is then 87db 1W/1M. I think my Koda 8s are more sensitive and probably displace more as well. Although, I will never actually know about the displacement unless that company releases some more detailed T/S and electro-mechanical data.

 

[req 5,000+ posts]

well dont forget.

these are 2ohms. so in my opinion - that makes up for a lower sensitivity does it not?

and as far as kodas are concerned. they are nigh on 5" deep. not like you can install those in a car door without a lot of modification. they also have a very low bandwidth, more suitable as a subwoofer than as a dedicated midbass. IIRC, they don't go above 800hz without severe breakup. these suckers can play up to 1khz easy to mate with horns, they have a good amount of cone area and significant displacement over a 6.5. and these are 2ohm which imo - is an awesome benefit for a midbass speaker.

//content.invisioncic.com/y282845/emoticons/naughty.gif.94359f346c0f1259df8038d60b41863e.gif

 

[JonJT 10+ year member]

well dont forget.
these are 2ohms. so in my opinion - that makes up for a lower sensitivity does it not?

and as far as kodas are concerned. they are nigh on 5" deep. not like you can install those in a car door without a lot of modification. they also have a very low bandwidth, more suitable as a subwoofer than as a dedicated midbass. IIRC, they don't go above 800hz without severe breakup. these suckers can play up to 1khz easy to mate with horns, they have a good amount of cone area and significant displacement over a 6.5. and these are 2ohm which imo - is an awesome benefit for a midbass speaker.

//content.invisioncic.com/y282845/emoticons/naughty.gif.94359f346c0f1259df8038d60b41863e.gif

The fact that isn't 2 ohmns doesn't actually make up for the lack of sensitivity. The 2 ohmn rating only means that you will be able to push more current through the voice coils for a givin voltage. If you look at the B&C woofer I cited, you will see that though it is an 8 ohmn transducer. It also has a much high sensitivity rating. Since it is 8 ohmns and the critical mass audio woofer is 2, you will be able to push about 3 times teh wattage through the critical mass audio woofer, but the B&C has the ability to play louder at maximum because it is over 3 times more sensitive.

This higher sensitivity also means the woofer will respond to changes in input power faster and have better dynamics.

All this means higher volumes, better transient responce and cooler amps.

 

[JonJT 10+ year member]

Also, the Critical mass audio woofers are rated to play up to 1khz, but I was wondering what placing the motor right int he middle of the cone does for breakup of high frequencies. It can't be good. I'd love to see concrete testing of that woofer at 800+hz. In anycase, its not the best woofer for use with horns anyway you look at it. It would deffineatly be the weak link in a 2 way system with nice horns and a large, powerful sub stage. Ideally, I'd need more displacement (only guessing here, but the surround doesn't look like it could take any more than 7mm +/- of cone movement) and more sensitivity.

And yes the Kodas are big Mofos but I'm prepaired to modify my doors when the time comes. I never intended to try to stick the midbasses in the stock location without any door modification.

 

[req 5,000+ posts]

that is true //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

but i seriously dont have anywhere near 150w@8ohm to give this sucker to keep up with my CD2 HLCD's and pair of IDQ15's.

and on top of that, are they suitible for infinite baffle? i see they want .5 cubes for an enclosure and thats way more than im even willing to give any midbass. im not modifying my doors or building fiberglass pods. i did that in my saturn with great results - but im not willing to hack up my next car that im paying 15k on if you get my drift.

i want an IB speaker that will play from 50hz to 1.2khz.

i dont deny that that transducer would be optimal, but i am wary about the 8ohm voicecoils...

 

[JonJT 10+ year member]

that is true //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
but i seriously dont have anywhere near 150w@8ohm to give this sucker to keep up with my CD2 HLCD's and pair of IDQ15's.

and on top of that, are they suitible for infinite baffle? i see they want .5 cubes for an enclosure and thats way more than im even willing to give any midbass. im not modifying my doors or building fiberglass pods. i did that in my saturn with great results - but im not willing to hack up my next car that im paying 15k on if you get my drift.

i want an IB speaker that will play from 50hz to 1.2khz.

i dont deny that that transducer would be optimal, but i am wary about the 8ohm voicecoils...

Well to each there own. For me, power is cheep. Its not TOO hard to find a 2 channel amp tht can push 150+ watts into 8 ohmns, you will just have to pay big bucks for it.

As an aside, B&C does mention that other impedances are avaliable for this woofer, but you need to ask for them. I donno what a 4 ohmn version would do for the other T/S parameters, but it couldn't be very different.

And I am willing to hack up my doors or try something different with an IB venting to the outside. Or maybe even an aperiodic. As I glance over the specs of this woofer again, it looks even more sutiable for a 2 way system with horns cause it looks to have the extension to match a pair of minihorns AND has the displacement I need down low. If I could find some way to IB/aperiodic this sucker either in doors or in pods I bet it woudl rock!

 

[Thnking 10+ year member]

I doubt you're going to find high sensitivity mid-bass driver, as sensitivity is increasing bass output decreases.

The damping of the woofer (system, once it's installed in a box) describes the transient response, the sensitivity describes the amplitude.

Really what you're looking for is a linear(for transient response), higher displacement(for an IB application), higher power handling (to minimize EQ'ing) mid-bass.

 

[JonJT 10+ year member]

I doubt you're going to find high sensitivity mid-bass driver, as sensitivity is increasing bass output decreases.
The damping of the woofer (system, once it's installed in a box) describes the transient response, the sensitivity describes the amplitude.

Really what you're looking for is a linear(for transient response), higher displacement(for an IB application), higher power handling (to minimize EQ'ing) mid-bass.

The QTC your saying? I wish that critical mass audio woofer had published T/S data.

Another question. If qtc alone describes trancient responce, then why are some of the older guys saying that one should only use high sensitivity woofers with horns? I was warned severly against using typical woofers with even a mini horn.

 

[T3mpest 10+ year member]

I'm also working on a similar install to yours and have had similar issues. The B&C's seemed like the a good choice to me. Other good midbasses for horns are hard to find. Here's a couple ones though. One driver that might be a decent choice, again it's discontinued is the peerless xls. It's 90db effecient, which isn't terrible, but is a good sized 8 and handles alot of power. I think it might have the dynamics needed for a horn system. What midrange are you planning on using, audax?

IDQ 8

JL IB8

JBL2 118

Audax and PHL both have high sensativity midbass, I've been told PHL mids are REALLY nice, by quite a few sources. Not sure how they'd work in a car environment though, it'd take some work, that's for sure.

 

[Thnking 10+ year member]

The QTC your saying? I wish that critical mass audio woofer had published T/S data.
Another question. If qtc alone describes trancient responce, then why are some of the older guys saying that one should only use high sensitivity woofers with horns? I was warned severly against using typical woofers with even a mini horn.

Yes, primarily QTC is the controller of the transient. The actual transient is a function of the acoustical model of the speaker as current/voltage is applied to the voice coil over a period of time. Sensitivity is more or less efficiency (amplitude in the output function). But sensitivity can be an indicator of damping. Unfortunately, increases in damping decreases bass output. So a highly sensitive speaker will generally have low amplitude bass output.

People will tell you to match sensitivity because of the large difference between a horn and standard woofer...over 10db in some cases. What a horn does is takes a transducer and helps to match air loaded impedance. So it increases efficiency. It also reduces distortion due to lower power needed to meet the same DB level, and lower air impedance distortion.

IMO, it's better to have a linear woofer, which can handle a lot of power to match the output of the horn, than to have a highly efficient woofer and EQ the low end sometimes 6-10db.