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Discussion Starter · #1 ·
Originally I planned to try an array of midbass arrays with each group mounted in dual opposing manifolds. 4 drivers in each manifold with 2 per long side in a 11" x 4.5" rectangle with a depth of 5.5", diver width. One group in the door and the other group under the seat. When that was my primary plan I wasn't so concerned with how high i could run them since the door midbass should anchor the underseat set from what I've read.

Have read that distortion and vibrations tend to pull the sound under the seats when that location is used. Since the drivers I have are fairly low distortion in the upper midbass/lower midrange and I will be reducing enclosure vibrations as much as possible maybe I can shove them all under the seats. Seams like this could be doable at normal listening levels, not so concerned about louder level listening.

The drivers are 8 per side of the Dayton ND140-8 which will be vented to the atmosphere. If the ND140-8 measures close to the ND140-4 that Hanatsu measured here then this may play out well.

So I'd have 692.8 sq cm of midbass under each seat with a sensitivity of 93.5db at 1 watt and 480rms of power handling. If bandpassed these 70/80-280/320hz should be able to get loud enough for typical listening levels with very little power input or excursion.

Hanatsu's test was done at 90db/1 meter equivalent on the ND140-4 which is rated at 88.4dB 2.83V/1m so roughly 3 watts.

The ND140-8 is rated at 84.5dB 2.83V/1m and I have 8 so that's a 9db increase, puts the array at 93.5db/1m plus the 3 watts per driver so that's roughly 107db for 1 side under similar conditions.

Hanatsu's test shows distortion levels of 0.5% at 300hz rising to 0.8% at 600hz an octave above my intended LPF. So if I could achieve similarly low levels at 107db stereo or 113db mono would this blend/disappear? Assuming vibrations from the enclosures themselves are kept in check does this seam like it could work?

@GotFrogs believe you've won a competition with the MS-8 and a pair of 8" woofers under the seats with a LPF at 200hz. What exactly limited you to 200hz? How low did you run them?

@I800C0LLECT you ran the GB60's in sealed enclosures and said they were good up to 300hz until you reached loud levels. What is your definition of loud? Also if I remember correctly I think you said you only ran them down to 70hz because any lower there was too much tactile feedback. Are you referring to feeling vibrations in the floor boards, seats, etc?

@dumdum I know your all about under seat or maybe in front of the seat midbass. You don't run them very high though but I believe you said you've gotten a good response up to 400hz. Why do you cross so low, I think it was somewhere around 150hz with you Satori's? I know you compete at a fairly high level, guessing volume levels are relatively low during use.

@Hanatsu if you see this thanks for the measurements.

Additional information I have 8 channels of application to use and 16 drivers so each channel will run 2 in parallel for a 4 ohm load. Each manifold will will be given a DSP channel 4 total so I can set slight delays.

How I ended up with 16 ND140-8. I originally ordered 6 do to depth and how well they model for IB applications. Planned 1 in each door with a corresponding pair under each seat... Then decided I wanted to do manifolds, have higher sensitivity/power handling/displacement so I ordered another 6.. changed my amp situation a bit so I had 2 spare channels so I ordered another 4.

Thanks to anyone who takes time to read this and give input.
 

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My box was too small for the GB60s. But what I mean by tactile feedback is vibrations. The vibrations ruined the illusion. I found my best tune with them set to 80Hz with 24 decibel slopes.

I couldnt go much higher than 300Hz with 24dB slopes because it would localize mid-range when I got loud... Meaning mid-130 decibels C weighted on my RadioShack meter. I couldn't believe the frogs could push all that. Of course... RadioShack meter though. No telling how accurate. But everybody agreed that it could boogy.

As far as I'm concerned if you have a 3 way setup and ample processing and channels... Under seat is the only way to go
 

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Discussion Starter · #3 ·
Thanks for the reply. Don't think I typically get close to those levels. Based on ErinH's measurements I think I'll be good as far as distortion goes. Hopefully manifold mounting and low levels of excursion will minimize vibrations, obviously I can't do anything about acoustic pressure.
 

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Originally I planned to try an array of midbass arrays with each group mounted in dual opposing manifolds. 4 drivers in each manifold with 2 per long side in a 11" x 4.5" rectangle with a depth of 5.5", diver width. One group in the door and the other group under the seat. When that was my primary plan I wasn't so concerned with how high i could run them since the door midbass should anchor the underseat set from what I've read.

Have read that distortion and vibrations tend to pull the sound under the seats when that location is used. Since the drivers I have are fairly low distortion in the upper midbass/lower midrange and I will be reducing enclosure vibrations as much as possible maybe I can shove them all under the seats. Seams like this could be doable at normal listening levels, not so concerned about louder level listening.

The drivers are 8 per side of the Dayton ND140-8 which will be vented to the atmosphere. If the ND140-8 measures close to the ND140-4 that Hanatsu measured here then this may play out well.

So I'd have 692.8 sq cm of midbass under each seat with a sensitivity of 93.5db at 1 watt and 480rms of power handling. If bandpassed these 70/80-280/320hz should be able to get loud enough for typical listening levels with very little power input or excursion.

Hanatsu's test was done at 90db/1 meter equivalent on the ND140-4 which is rated at 88.4dB 2.83V/1m so roughly 3 watts.

The ND140-8 is rated at 84.5dB 2.83V/1m and I have 8 so that's a 9db increase, puts the array at 93.5db/1m plus the 3 watts per driver so that's roughly 107db for 1 side under similar conditions.

Hanatsu's test shows distortion levels of 0.5% at 300hz rising to 0.8% at 600hz an octave above my intended LPF. So if I could achieve similarly low levels at 107db stereo or 113db mono would this blend/disappear? Assuming vibrations from the enclosures themselves are kept in check does this seam like it could work?

@GotFrogs believe you've won a competition with the MS-8 and a pair of 8" woofers under the seats with a LPF at 200hz. What exactly limited you to 200hz? How low did you run them?

@I800C0LLECT you ran the GB60's in sealed enclosures and said they were good up to 300hz until you reached loud levels. What is your definition of loud? Also if I remember correctly I think you said you only ran them down to 70hz because any lower there was too much tactile feedback. Are you referring to feeling vibrations in the floor boards, seats, etc?

@dumdum I know your all about under seat or maybe in front of the seat midbass. You don't run them very high though but I believe you said you've gotten a good response up to 400hz. Why do you cross so low, I think it was somewhere around 150hz with you Satori's? I know you compete at a fairly high level, guessing volume levels are relatively low during use.

@Hanatsu if you see this thanks for the measurements.

Additional information I have 8 channels of application to use and 16 drivers so each channel will run 2 in parallel for a 4 ohm load. Each manifold will will be given a DSP channel 4 total so I can set slight delays.

How I ended up with 16 ND140-8. I originally ordered 6 do to depth and how well they model for IB applications. Planned 1 in each door with a corresponding pair under each seat... Then decided I wanted to do manifolds, have higher sensitivity/power handling/displacement so I ordered another 6.. changed my amp situation a bit so I had 2 spare channels so I ordered another 4.

Thanks to anyone who takes time to read this and give input.
We used the factory BMW underseat woofers. We chose 200Hz because that was as low as the 4" door speakers could play loudly and it's best to keep a speaker's bandwidth when using crossovers to at least an octave. They played 80-200. The sub was 60 and down, or thereabouts. I'm kind of guessing at that because MS-8 includes EQ that changes the effective crossover point (as does all EQ).
 

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Discussion Starter · #5 ·
Awesome Andy thank you. I have a 4.75" ish speaker for the mids but I'm trying to keep IMD low so whatever load I can unbear is nice. Can always do a fun tune and a responsible listening tune and run it lower.
 

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We used the factory BMW underseat woofers. We chose 200Hz because that was as low as the 4" door speakers could play loudly and it's best to keep a speaker's bandwidth when using crossovers to at least an octave. They played 80-200. The sub was 60 and down, or thereabouts. I'm kind of guessing at that because MS-8 includes EQ that changes the effective crossover point (as does all EQ).
Pretty much this ^^^ I get a phase issue due to a standing wave in the midbass at 210ish, and have similar in the midrange at 130, so crossing between the two points makes an excellent job of the crossover, and while they do play around 85-90db for competition they get lots louder when I up the wick and stay composed 😈 I like it loud when required! The bottom end of the subs is at 125ish I’d guess at full pelt and the midbass blend very well at that 😎
 

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Discussion Starter · #7 ·
it's best to keep a speaker's bandwidth when using crossovers to at least an octave.
For this part are you referring to the bandwidth within a speakers crossovers ie bandpass, or a LPF/HPF with the driver playing to it's natural roll off? Guessing this is what you're saying.

I've heard too little bandwidth can cause phase issues do to the crossovers effect on phase and then being so close together. Is this more pronounced at lower frequencies? Saw a midbass only playing 80-160hz vs a mid/horn playing 800-1600hz. A difference of 80 cycles in the first example but the second has a difference of 800.

Or do you mean say the a driver has an effective response down to 100hz so you set a HPF an octave above at 200hz?
 

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For this part are you referring to the bandwidth within a speakers crossovers ie bandpass, or a LPF/HPF with the driver playing to it's natural roll off? Guessing this is what you're saying.

I've heard too little bandwidth can cause phase issues do to the crossovers effect on phase and then being so close together. Is this more pronounced at lower frequencies? Saw a midbass only playing 80-160hz vs a mid/horn playing 800-1600hz. A difference of 80 cycles in the first example but the second has a difference of 800.

Or do you mean say the a driver has an effective response down to 100hz so you set a HPF an octave above at 200hz?
I’m presuming he means 1khz to 500 or 300-150 or 160-80, so each crossover point is an octave apart at least…
 

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Discussion Starter · #9 ·
That's what I figured. I'm just always wondering if I'm misinterpreting someone. I'm probably autistic because I've always been like that.. even when I'm fairly sure what someone means I still try to make them clarify.
 
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