39 replies to this topic

[Domza]

I am currently in the process of finalizing my 3 way front stage (active), so my question is:

Which Midbass would you use out of either the Alpine SPX-17PRO (midbass only) from their Type X series or the Focal 165V30 (midbass only) from their Polyglass series? I have provided some information below on both the SPX-17PRO and the 165V30's.

Alpine:
http://www.alpine.co....php?item_id=83

Focal:
http://www.focalaust...5v30_driver.pdf

The rest of my frontstage/subwoofer comprises of the following;

Midbass: Alpine or Focal (Undecided)
Midrange: Morel CDM88
Highs: Vifa XT25TG30-04
Subwoofer: Boston Acoustics (12") G2-1244

The power I have for the midbass drivers will be adequate enough to drive either the Alpine or the Focal midbass. I am using an Eclipse DA6213 (2 channel) rated at a healthy 250watts RMS X 2. The main factor for me is I'm looking for something that will integrate well with my sub and midrange. Musical midbass performance and detail/resolution around the 70hz to 120hz area is predominantly what I'm looking for. I will most probably have the CDM88 (midranges) HP around 450hz which means either the Alpine or the Focal will be BP at 71hz to 450hz (approx). I know that the resonant frequency of the Focal's is stated at 72hz but not sure about the Alpine..

Oh and midbass location will be in the lower of the door (factory) using the door cavity as the enclosure, doors will be sound deadend throughout.

If anyone has had any experience with either or both your feedback would be much appreciated or anyone else with their thoughs, thanks in advance.

Regards,
Domza.

[Gizzards12]

Domza,
I have a set of focal utopia 6W2 6.5" mid drivers just run in and punchy as hell. Rated at 100rms @ 4ohms. I used in an active set up for a short time but have since changed to a DLS passive iridium tweets and UP6I 6.5" set up for my front stage. I was putting 300rms a side into these Utopias and they were singing. If your interested pm me I'm not using them so you can grab a bargain. Boxed safely for shipping if your not in Sa.
Cheers
Aaron
Ps
Am running the morel ultimo 12" 1000rms @ 2ohms active from a pdx m12 and it's by far the best sub I've used/heard

Edited by Gizzards12, 28 January 2012 - 10:39 PM.

[Damo95]

Dom..

Those focals.. That's from the 30th anniversary set you've got yes? I'd give those a shot..

I've heard a pair of type x pro's (active off pdx f6) and not punchy enough.. My old focal midbass however... Different animal.. People usually fault the focal tweeters, yet the midbass has been good..

Try what you've got first, then decide if you need to change..

(null)

[muzzy66]

The Focal is one of the better <7" midbasses out there for typical autosound applications. It would be my choice out of those two, and (for that matter) above most car audio specific woofers.

[Domza]

Thanks very much, I will try the Focal's first, I just thought that the Alpine might have better midbass! In my previous set up I had the Focal's running passive and was quiet happy with them, do you think that they will sound better running active vs passive?

On paper the Focal's seem better then the Alpine but the Fs is lower on the Alpine which led me to believe that the crossover point could be lower on the Alpine. With my 165V30's I had them HP @ 80Hz with a 12dB slope and my sub was LP @ 71hz with a 24dB slope, my initial thoughts were that they sounded good but with a little EQ they sounded even better. Do you think that the passive crossover (165V30) attributes to this?

Regards,
Domza.

Ps: Those Utopia's sound tempting...

[268669♫]

Scanspeak W18's

Ant

Scanspeak 18W/8535's

Ant

[Big_Valven]

I'd use the focals out of that two.

[muzzy66]

Domza, on 29 January 2012 - 09:28 AM, said:

Thanks very much, I will try the Focal's first, I just thought that the Alpine might have better midbass! In my previous set up I had the Focal's running passive and was quiet happy with them, do you think that they will sound better running active vs passive?

On paper the Focal's seem better then the Alpine but the Fs is lower on the Alpine which led me to believe that the crossover point could be lower on the Alpine. With my 165V30's I had them HP @ 80Hz with a 12dB slope and my sub was LP @ 71hz with a 24dB slope, my initial thoughts were that they sounded good but with a little EQ they sounded even better. Do you think that the passive crossover (165V30) attributes to this?

How much lower is the FS?

For a decent indication of midbass capabilities I will typically look at:
* FS - indicates at how low a driver will play in general. Lower is better. For a pure midbass I probably wouldn't bother with an FS any higher then 75hz.
* Qtc - indicates how well dampened (i.e. how linear and controlled) a driver will be in a given enclosure. For a car door higher is better, with a Qts of about 0.5 being decent and 0.7 or higher being optimal.
* Xmax - indicated how much a driver can move from the rest position before it reaches the limits of it's suspension. Higher xmax means a driver can take more power at low frequencies before it bottoms out.
* Cone area (sd) - The total surface area taken up by the cone of a driver. Combined with xmax, gives you the total displacement of the driver. The greater the cone area, the less xmax you need to achieve the same displacement.

As a secondary option I also look at:
* Sensitivity (1w/1m) - how much input power a driver needs to reach a given output level. For each 3dB increase in sensitivity, you need half the power to achieve XdB of output. If a driver has lower power handling, then you want high sensitivity.
* Power handling - typically represents the maximum recommended input power before a driver's voice coil reaches thermal limits. Note that this is a guide for how much power the driver can handle, not how much your amp is rated to output.

Typically the first things I'll do to give myself a rough indication of how a driver will perform in a car door is:
1. Calculate the FS/QTS value - For a car door you want low FS and high QTS, so a lower value will generally mean better ballance between control and extension in a car door. For a midbass I wouldn't bother with values over about 100
2. Calculate Xmax * SD - This approximates the potential displacement of the driver, and indicates how power it can take at low frequencies before it bottoms out. I'd aim for values > 600.

I'm sure this guide isn'r perfect, but it should help to give a pretty decent idea of what different midbass drivers are capable of in this context. What it doesn't tell you is how defined your midbass will sound, as there is no way to get distortion information purely from TS specs. For most people though this is not high on the priority list.

As Ant suggested the Scanspeak 8535 is definately one of the top pure mid-bass drivers out there up to 7 inches, but since you were only tossing up between the Alpine and Focal I didn't bring this up.

Edited by muzzy66, 29 January 2012 - 02:31 PM.

[Domza]

muzzy66, on 29 January 2012 - 01:50 PM, said:

How much lower is the FS?

For a decent indication of midbass capabilities I will typically look at:
* FS - indicates at how low a driver will play in general. Lower is better. For a pure midbass I probably wouldn't bother with an FS any higher then 75hz.
* Qtc - indicates how well dampened (i.e. how linear and controlled) a driver will be in a given enclosure. For a car door higher is better, with a Qts of about 0.5 being decent and 0.7 or higher being optimal.
* Xmax - indicated how much a driver can move from the rest position before it reaches the limits of it's suspension. Higher xmax means a driver can take more power at low frequencies before it bottoms out.
* Cone area (sd) - The total surface area taken up by the cone of a driver. Combined with xmax, gives you the total displacement of the driver. The greater the cone area, the less xmax you need to achieve the same displacement.

As a secondary option I also look at:
* Sensitivity (1w/1m) - how much input power a driver needs to reach a given output level. For each 3dB increase in sensitivity, you need half the power to achieve XdB of output. If a driver has lower power handling, then you want high sensitivity.
* Power handling - typically represents the maximum recommended input power before a driver's voice coil reaches thermal limits. Note that this is a guide for how much power the driver can handle, not how much your amp is rated to output.

Typically the first things I'll do to give myself a rough indication of how a driver will perform in a car door is:
1. Calculate the FS/QTS value - For a car door you want low FS and high QTS, so a lower value will generally mean better ballance between control and extension in a car door. For a midbass I wouldn't bother with values over about 100
2. Calculate Xmax * SD - This approximates the potential displacement of the driver, and indicates how power it can take at low frequencies before it bottoms out. I'd aim for values > 600.

I'm sure this guide isn'r perfect, but it should help to give a pretty decent idea of what different midbass drivers are capable of in this context. What it doesn't tell you is how defined your midbass will sound, as there is no way to get distortion information purely from TS specs. For most people though this is not high on the priority list.

As Ant suggested the Scanspeak 8535 is definately one of the top pure mid-bass drivers out there up to 7 inches, but since you were only tossing up between the Alpine and Focal I didn't bring this up.

Wow thanks for that valuable information Muzzy66, that's greatly appreciated, your wealth for knowledge is amazing. I think as most people here have suggested I will go with Focal's, upon my recent research (Internet) on the SPX-17PRO the majority have concluded that the Alpine's midbass is good but not great where on the other hand the Focal's have been consistently praised for their midbass performance. My reasons for choice on the Alpine's were because I can get a set at a really good price but if it's like most have indicated in the way of "not so great" midbass performance then I guess it a no brainier.

I have provided a comparison chart between the Alpine & the Focal so you can give some insight as to what I'm looking at, I have basic knowledge in this area so if anyone could shed some light it would be much appreciated.

Alpine SPX-16PRO:

Rms: 100 watts
Fs: 45Hz
Xmax: 6.3mm
Vas: 24.1 L
Qts: 0.51
Qms: 5.24
Re: 2.8 Ohm
Sd: 133cm2
SPL: 88dB

Focal 165V30:

Rms: 80 watts
Fs: 72.23Hz
Xmax: 5mm
Vas: 8.46 L
Qts: 0.76
Qms: 12.10
Re: 3.13 Ohms
Sd: 132.73cm2
SPL: 87.79dB

Regards,
Domza.

[muzzy66]

I have to say the Alpine specs do look pretty capable! If you like I'd be happy to model both drivers and post up the graphs/results for you. If so just drop me a PM - the little PM popup will help my disfunctional self from forgetting

Looking at the specs alone my estimate is that the Alpine should play lower outright and also handle power a little better down low thanks to the lower FS and greater Xmax, but the higher Q on the Focal should give a smoother and more even midbass response once they are in a car door.

Not sure how significantly the Alpines will be affected by the lower Q - I'll have to model it out and see if you get the same 'droop' around 60hz-120hz that you typically get on drivers with a low FS and low Q in a car door. Drivers with a Q up around 0.6 (such as the Rainbow Power) don't seem to be affected too badly, but I have a feeling the issue may be more pronounced once you get down to 0.5 and below.

How low do you intend on crossing the midbass?

If past modelilng is anything to go by the Focals (with their nice high Q) should give excellent output from about 100hz upwards, so they will probably be tough to beat if you're planning on crossing up around 80hz - 100hz (typically recommended for power handling on a ~6" driver). Their weakness is that due to the fairly modest FS they simply don't play that low, so if you want to cross lower then 80hz (or if your sub doesn't handle higher frequencies very well) then they might not be the best solution.

On the plus side you might be able apply a slightly shallower slope on the midbass (e.g. 60hz @ 24dB/oct on the sub and 60hz @ 18dB on the midbass) to take advantage of the natrual acoustic rolloff of the driver. On most drivers this isn't easy to do because the high Q gives you a droop at 60hz-120hz and then a peak below that - running a shallow slope causes some 'all over the shop' effects. With the Focal though the smooth natural rolloff (due to the hgiher Q) might make this pretty easy to achieve My only concern with this approach would be power handling of the midwoofer, as the shallower slope would force the woofer to produce more low frequency information.

Anyways I will model them out either way and see how it comes out!

[Big_Valven]

Despite what the numbers may suggest, I consider the Focal to be a far better midbass performer.

[Domza]

muzzy66, on 30 January 2012 - 05:50 AM, said:

I have to say the Alpine specs do look pretty capable! If you like I'd be happy to model both drivers and post up the graphs/results for you. If so just drop me a PM - the little PM popup will help my disfunctional self from forgetting

Looking at the specs alone my estimate is that the Alpine should play lower outright and also handle power a little better down low thanks to the lower FS and greater Xmax, but the higher Q on the Focal should give a smoother and more even midbass response once they are in a car door.

Not sure how significantly the Alpines will be affected by the lower Q - I'll have to model it out and see if you get the same 'droop' around 60hz-120hz that you typically get on drivers with a low FS and low Q in a car door. Drivers with a Q up around 0.6 (such as the Rainbow Power) don't seem to be affected too badly, but I have a feeling the issue may be more pronounced once you get down to 0.5 and below.

How low do you intend on crossing the midbass?

If past modelilng is anything to go by the Focals (with their nice high Q) should give excellent output from about 100hz upwards, so they will probably be tough to beat if you're planning on crossing up around 80hz - 100hz (typically recommended for power handling on a ~6" driver). Their weakness is that due to the fairly modest FS they simply don't play that low, so if you want to cross lower then 80hz (or if your sub doesn't handle higher frequencies very well) then they might not be the best solution.

On the plus side you might be able apply a slightly shallower slope on the midbass (e.g. 60hz @ 24dB/oct on the sub and 60hz @ 18dB on the midbass) to take advantage of the natrual acoustic rolloff of the driver. On most drivers this isn't easy to do because the high Q gives you a droop at 60hz-120hz and then a peak below that - running a shallow slope causes some 'all over the shop' effects. With the Focal though the smooth natural rolloff (due to the hgiher Q) might make this pretty easy to achieve My only concern with this approach would be power handling of the midwoofer, as the shallower slope would force the woofer to produce more low frequency information.

Anyways I will model them out either way and see how it comes out!

That would be great if you could compile that information and graph it out for me. As far as the crossover setting goes, I would ideally like to cross the at around 71Hz @ 12dB or even possibly 80Hz @ 6/12dB, what would you recommend. The subwoofer I have is the Boston Acoustics G2 1244 which I would like to crossover at 63-71Hz @ 18/24dB slope. By the sounds of it, it sounds like the Focals are more suited to my application for musical capabilities (detail & resolution) but I'll wait for your findings, thanks again Muzzy66 much appreciated mate.

Regards,
Domza.

Edited by Domza, 30 January 2012 - 10:07 AM.

[muzzy66]

Ok, the results are in!!!

First thing I'd like to do is apologise in advance for the length of this post - since you wanted the information, I wanted to ensure it's as complete and useful as I could possibly make it. Next thing I would like to make clear is that these are modelled results, and as with any model they are merely an approximation of how the drivers would perform in a car door-like application. It does not allow for things like reflections, resonaces, etc. I've used 200L sealed to approximate a car door - 1,000L is considered a fair estimate for Infinite Baffle, but since a car door isn't truly IB I've used 200L instead. This is large enough to represent the high volume/Q of a car door, yet small enough to represent an enclosure that is still finite. I've also used a plug in effect to represent the potential impact of cabin gain - I've found this 'modifier' to be fairly accurate in the past. Since you said you plan to cross at 71hz, I've used this as the reference point for you.

Now, to the results!

1. Frequency Response - Focal 165 V30:




2. Frequency Response - Alpine SPX-16 Pro:




3. Frequency Response - Both drivers overlapped




Conclusion:
Looking at these two results individually you will see that at 71hz there is really minimal difference in output between the two drivers - less the 0.5dB advantage to the Alpine. You'll see that the Alpine also has significantly more output below 70hz then the Focal.

Looking at the 'overlapped' graph though, you will see what I mean by the "low Q" effect. Note how the Alpine FR dips down around that 70hz mark (about 3dB down) and then rises again to about 40hz before rolling off naturally. This is a common effect I've found with just about all drivers that have a low FS and a reasonably high Q. It can make the driver quite challenging to blend smoothly with a sub, because the only way you can get a smooth response is to cross it at around 40hz and then EQ out the dip...but then because of the shape of that dip, it's almost impossible to actually EQ it out to a smooth curve. If you leave it as is, then crossing at 70hz will be challenging because you are crossing over right in the middle of that dip. To blend it with the sub by ear you will end up pushing that midbass up by 3dB so it's level at the crossover point, but then there's going to be 3dB peaks at 40hz and 120hz which will give you a nasty boomy midbass. Alternatively you will set it so that the overall midbass level is even with the sub, but then it will sound hollow in the midbass around that 70hz region. I've noticed this issue in the real world from my own personal experience, and it truly is a royal pain in the butt.

Alternatively if you look at the Focal you'll see it has less output down low, however it has a near 6db / oct naturall rolloff starting from 110hz downwards (0dB @ 110hz, -3dB @ 70hz, -6dB @ 40hz). It's not quite a perfect 6dB slope, but it's fairly close. You could simply cross this driver on a 6dB shallower slope then your sub, and you should get a realtively nice and smooth blend. No EQ and pain required. This is the big benefit of high Q in a an enclosure with a large air mass (such as a car door) - the stiffness of the suspension allows the driver to better deal with all that extra air and maintain better control over the driver cone.

Next, lets take a look at cone displacement (i.e. excursion) at 71hz and see how much each driver can take before reaching their xmax limit:


1. Displacement at 71Hz - Focal 165 V30:




2. Displacement at 71Hz - Alpine SPX-16 Pro:




3. Displacement at 71Hz - Both drivers overlapped:




Conclusion:
Ok, so looking at the overlapped results we can see that both drivers will have roughly the same cone displacement from 71Hz upwards given the same input power, so if all else was even we'd have a tie. However, all else isn't equal - the Alpine does have 1.3mm greater xmax, and this is where the Alpine gains the advantage. Both drivers reach about 5mm of xmax with about 48W of input power when inside our little 'car door' - by this point the Focal has reached it's xmax, so it's essentially reached it's limits...but the Alpine hasn't. It takes roughly an additional 30W (76W total) before the Alpine reaches it's xmax limit of 6.3mm, and so at first glance the Alpine can take a good 60% more power at 71Hz before it reaches it's xmax limits.

However, there is a problem with this theory - a crossover is not a pure cut off, but a graduall roll-off. This means that even with a 71Hz @ 24dB crossover, your driver will still be producing a good amount of output below 71Hz. Check the 'overlap' graph and this is where the lower Q on the Alpine once again brings a potential issue. Because the driver is underdamped it's not able to maintain proper control of cone motion in such a large 'enclosure' with so much air behind it, and so once you get below 70hz the cone displacement increases dramatically - much like what happens below the tuning frequency in a ported enclosure. At 50hz you're already at 10mm displacement (60% above rated xmax), and by 40hz you're at 12mm excursion, which is likely pretty close to the mechanical limit of the suspension. The Focal on the other hand (with it's high Q) doesn't need to move any more at 10hz then it does at 30hz. That said, I still wouldn't the Focal much below 80hz, as excursion does increase from 80hz down to about 30hz and power handling will quickly drop as the frequency does.

So with all that information on the table, I will leave it entirely up to you to decide which of those drivers you think will be more suitable for your application. The Alpine on paper looks like a more capable midbass driver as it can play lower and take more power, but once the Q comes into the equation it can also become potentially much more complicated to get right. The Focal probably doesn't have as much outright potential in a perfect world, but getting good results out of it should be as easy as simply by chucking it in and playing around with the crossovers a little bit.

If it were myself personally I'd probably go with the Focal, then cross fairly high (around 80hz-100hz) where I could take advantage of the nice and smooth upper midbass response to give myself a nice smooth blend with my sub. That said I use a Peerless XXLS which is a very wide bandwidth sub (flat response out to about 500hz) and so I can take advantage of that nice smooth transition. Plus you already have the Focal, so I'd be hessitant myself to fork out extra money on something that may not be any better for you. That said, very few subs play as flat and high as an XXLS so who knows - if your sub has a natrual peak around 70hz or 80hz then it might even benefit from the dip the Alpine has around that range. Mmm...gotta love the complexities of audio!!

Once again I stress that this is all based on simulations and not real world data - I've been happy with the accuracy of these simulations in the past, but I'll leave it up to you to decide how much weight you put on these results. I never expect people to look at my results or predictions and take them as reality - I always urge people to look at whatever data is available with an open mind, and make a decision based on what they think is right.

[Domza]

Wow talk about comprehensive!!! That analysis is quiet technical but at the same time easy to understand, I have a fair idea of direction now. Obviously these comparisons as you suggested are a guide and as the figures suggest each driver (Alpine & Focal) have there good & bad points.

The Alpine is quiet capable when it comes to power due to it's higher Xmax but like you said it would be a fair task to get it to blend well with the subwoofer due to the dip in it's response in the critical location (near the crossover point). The great benifet I would think of this particular driver based on you FR chart would be it's ability to play flat up high which means a very nice response to blend with a tweeter in a 2 way application (compared to the Focal) which doesn't really help me in my case.

The Focal is probably more the direction I'm heading based on the reasonably flat curve around where I want the crossover point to be. The Fs would be my only concern also being next to my ideal crossover point, I suppose I could experiment with the crossover and see what works. In my experiance I've found that a crossover point (HP) of 90-100Hz or higher compromises the midbass performance, to me it sounds like it's less 'Fluid' then say around the 70Hz area (if that makes sense), I just find it to have less of an impact then the former, I'm not sure what your thoughts are on this, but it didn't really work for me.

I guess what it all comes down to is " The Sound" in which I think the edge will go towards the Focal having listened to the Alpine last night, I found them (Alpine) to be a great 2 way system which if I had them in this passive configuration would sound quiet nice given the complexity and flexibility of it's crossover and very linear tweeter design (dual concentric), but personally for me already having the Morel's and the Vifa would make it a null point if I only need a midbass driver that only plays up to 400-450Hz or so! The Alpine in my personal opinion does have good midbass performance, but when compared to the Focal's they are not as musical to listen to. The Focal's on the otherhand do have a certain quality that is more natural and more liquid especially in the upper midbass department.

Thanks to all who responded to this post and especially to Muzzy66 for this comprehensive report, I can't thank you enough for taking the time to compile this information and translating it in to an easy to understand graph, thanks again.

Regards,
Domza.

[muzzy66]

No problems at all, happy to help!

Just for the record I wouildn't worry too much about the top end response. This application is more useful for simulating the effect of different enclosures, so I wouldn't pay too much attention to the response above about 400hz.

Focal's are nice sounding mids for sure, and even in a two-way application I've found then nicer then a lot of other mids out there. Last time I heard the Alpine Type X set (not sure if that uses the same woofer) I wasn't really that impressed with how it sounded overall tbh, but I can't remember what I thought of the midbass performance - I just remember the midrange/highs didn't really impress me.

Crossing over higher is a bit more of a challenge. You will naturally have more information coming from the sub (in the rear) and less from the midbass (in the front) so it can potentially take more work to get the drivers to blend smoothly Higher crossover also means more upper midbass information is coming through, so it can get pretty important to ensure that timing is correct between midbass/sub, etc. When you do get it right through, I've found it can really work great.

Whichever way you go, I'm sure it will work well for you