What are my options: dedicated 2 ohm midbass to fill 8" hole

There is no way a 2 ohm 83db sensitivity on 100w is going to get up to 94db sensitive with 50w, if all else is equal. I would also be leary about a 94db sensitive midbass....that is really high sensitivity and I would personally want to investigate how that number was determined. Similar with the 83db sensitivity, how was that determined? The only way that I have seen that is semi-accurate for this is using something like the klippel to measure the speaker and then actually see the response and look at what spl it is at. Otherwise it seems the numbers are usually off by quite a bit.

If the 4ohm was rated at 1000hz, it might be only 80db sensitive in the sub frequencies. Also is it 2.83v/m or 1w/m ratings. In other words, too many variables to actually be able to figure this out. Do you have Frequency response charts of both speakers? That would be better help than just a sensitivity number.

If all things are equal though, you can see below the power to achieve certain SPL's assuming no compression.

2 0hm 83db sensitive

1w @83db
2w @86db
4w @89db
8w @92db
16w @ 95db
32w @ 98db
64w @ 101db
100w @ ~102db
128w @ 104db



4 0hm 94db sensitive

1w @ 94db
2w @ 97db
4w @ 100db
8w @ 103db
16w @ 106db
32w @ 109db
50w @~110db
64w @ 112db

Here is the only info I can find... I'm comparing 2 different 8" speakers from same brand . A sub @ claimed 83dB OR a midbass @ claimed 94dB, both using the stock Bose door amps. I believe the midbass would be easier to push, but doesn't have the lows of the sub. My concern is the amp not having enough power to move the sub. Now trying to get a thumper, but best sound and fitment. I've built extreme systems and simply do not want to go that route. I also road race this car, so wanting to keep simple, light weight and mounted in door with a baffle. Also concerned that the sub dedicated amps may be crossed over to low for the Midbass to operate. Sorry for confusion as I'm no expert. Would like to learn and buy correct speaker instead of just throwing one in there. Thanks!

8" SUB: Dual 4 ohm voice coil. RMS power : 150 watts, max power : 300 watts,

• 2" BASV High Temperature Copper Voice Coil
• Motor Weight: 30 oz
• Frequency Response: 30 - 350 Hz
• Sensitivity: 83.2 dB
• Fs: 48.3 Hz
• Re: Dual 2 Ω
• Qms: 5.09
• Qes: 0.76
• Qts: 0.66
• Rms: 4.2 Kg/s
• Cms: 0.15 mm/N
• Bl: 10.6 n/a
• Vas: 8.7 L
• Xmax: 7 mm

8" MIDBASS: Single 4-ohm voice coil configuration. Rated at 350 watts Max power, and 175 watts RMS.

• Voice Coil Configuration: Single 4 Ω
• 1.5" Copper Voice Coil
• High Quality Paper Cone
• 25 oz Ferrite Magnet
• Pressed Steel Basket
• Solid Composition Paper Dust Cap

• RMS Power Handling	175 Watts
  Peak Power Handling	350 Watts
  Frequency Response	80 - 6,000 Hz
  Sensitivity	94.5 dB

Honestly there isn't enough to say either way then.

Even then, the "sub" only has a claimed 6mm xmax, and it is probably less than that too. So neither are going to be all that great for lower frequencies.

I'm thinking throw the lighter weight midbass in there, then add a true external amp powered sub in rear later if needed. Thanks for all the help everyone! Cheers

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Originally Posted by Dueydog

I'm thinking throw the lighter weight midbass in there, then add a true external amp powered sub in rear later if needed. Thanks for all the help everyone! Cheers

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Are those facrtory subs in the doors actual subs or more midbass drivers? Are they low passed or high passed at some frequency? If they are actually subs, those lighter ones show 80hz as their low point. As in, they will probably suck at anything below that.

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Originally Posted by JaySea20

Have you looked at the Audio Development w800neo? They are a little pricey. But, are one of the best shallow mount on the market. I think Geo had a set in his Porsche for a bit. You could ask him about the results.

-Jay

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Yes I did have a set. I wish I had kept them for future use. They are a very nice 8" shallow mount driver. They are also really light weight.

I had them crossed at 70Hz 24dB/octave and they didn't break a sweat. I dropped them down to 65Hz but never really tested their limits at that freq.

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Originally Posted by Jdunk54nl

Are those facrtory subs in the doors actual subs or more midbass drivers? Are they low passed or high passed at some frequency? If they are actually subs, those lighter ones show 80hz as their low point. As in, they will probably suck at anything below that.

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I had the Bose system with 8" front door midbass divers in my Macan. Bose rolls them off at about 400Hz on the top end. They do not apply a high pass filter on the low end. They just let the drivers roll off naturally. Mine played down to about 45hz even though they should not have. The speakers made pretty bad farting noises when driven hard :)

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Originally Posted by Jdunk54nl

Are those facrtory subs in the doors actual subs or more midbass drivers? Are they low passed at some frequency? If they are actually subs, those lighter ones show 80hz as their low point. As in, they will probably suck at anything below that.

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Not much info on BOSE system, but they are called actual subs with dedicated 2 ohm 100w amps each. I do not know frequency and that's one of my questions. Will the mid bass work at half power or should I go with an actual sub at normal power? There is no box, so they will be in baffles and doubt I could get much lows anyway. Why I here trying to get some advice. Here is a nice post with 8' kicker subs installed down to 2 ohms, but he's using an aftermarket amp to power.

https://www.corvetteforum.com/forums...s-in-door.html

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Originally Posted by Ge0

Yes I did have a set. I wish I had kept them for future use. They are a very nice 8" shallow mount driver. They are also really light weight.

I had them crossed at 70Hz 24dB/octave and they didn't break a sweat. I dropped them down to 65Hz but never really tested their limits at that freq.

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I have a set too, and in my large truck doors, they start hitting xmax @ 60 hz. I was hoping you would have a better comparison for the smaller doors.

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OP, While I am certainly no expert, I do have a fair bit of experience with the Skar IX-8, and with an 8" pro mid/midbass driver (the Rockford Fosgate PPS4-8 https://rockfordfosgate.com/products/details/pps4-8/ ) that I suspect, in terms of midbass output, would perform very much like the FSX8.

Here is a WinISD SPL plot showing both drivers (IX-8 red; FSX8 blue), each in 4.0 ft^3 (to simulate IB/door) at 100 watts:

https://images2.imgbox.com/20/62/pP2iQ2nU_o.png

Based on ^this^ and on my experience with these two drivers, if it is midbass that you're looking for (and not something that might pretend to blend well with a tweeter), between the IX-8 and the FSX8, I think your best bet would be the IX-8.

Also, at 100 watts there should be no overexcursion issues with the IX-8, given the addition of a high-pass filter to cut/reduce the very low end (set at 25 to 30 Hz, for example).