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"speakers angled facing" theories

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_Natty_ View Drop Down
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    Posted: 07 September 2017 at 1:04pm

can anyone try to explain to me what is the principles for having 2 speakers like in this mid cab,
is not based on "push pull" principles or I wrong?




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Conanski View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 07 September 2017 at 3:05pm
In this case it's all about packaging.. more drivers equals more output simple as that. At the frequencies those woofers operate at the angled baffle has no acoustic effect.. positive or negative.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DMorison Quote  Post ReplyReply Direct Link To This Post Posted: 07 September 2017 at 3:08pm
Sorry if this seems rude (especially if you're typing in a second language), but what you've written doesn't really make it clear what you want to know.
You ask about 2 drivers, but there's 6 in the cab.
So, I'll answer based on my best guess what you meant ;-)
The cab as shown does not use push pull; all 4 low-mid drivers are facing the same way and being fed signal with the same polarity.
Theoretically mounting one side's drivers reversed and flipping polarity on their connections would give some reduction in distortion, but it would introduce one or two other complications, which is presumably why Mackie didn't.
First, it looks like there's not a lot of space for the backside of the HF driver as-is - it would never fit if the backside of one of the 12's was sticking out rather than in, so they'd need to redesign the cab or make it even bigger to get around that. Similarly, I don't think there's enough space to do the flip on both of the bottom 12's, as their magnets would foul each other.
Secondly, (depending on how high the crossover to the high-mid is), reversing mid drivers could result in sound quality and or dispersion problems if sound waves reflected badly off the outward facing magnet. (Probably not that big a deal in this case, as they'd also interact in the same way with the rear surface of the HF horn, but it's a principle to be aware of.)
Thirdly, Mackie are very sensitive to customer expectations and like to try and present their manuals etc in an accessible manner. Deploying drivers in a less common layout would give them more work to to do explain themselves and avoid having people think there was something "wrong" with the speakers as a result.

HTH,
David.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Crashpc Quote  Post ReplyReply Direct Link To This Post Posted: 08 September 2017 at 8:00pm
Right now I'm in the decision mode for new tops, and I wonder if this alignment (V shaped mids and horn in the middle is doable for two 8"s setup with 1" or 1,4" crossed at 1500Hz.... That would be good compromise between conventional designs and coaxial drivers in 10" size....
Nikon and Canon people should not be married to each other. Why did you let this happen?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dlyxover Quote  Post ReplyReply Direct Link To This Post Posted: 08 September 2017 at 9:02pm
Just coming to completion on a 12v cab.

Rather happy with the outcome



Edited by dlyxover - 09 September 2017 at 9:11pm
In the Truth there is no news, and in the News there is no truth
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2017 at 1:27am
even though the baffle is angled I think it will behave as a manifold to some extent giving up to 3dB extra sensitivity at the low end.

http://fulcrum-acoustic.com/assets/pdf/whitepapers/loudspeaker-manifolds-high-level-concert-sound-reinforcement-1986.pdf
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Post Options Post Options   Thanks (0) Thanks(0)   Quote matty w Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2017 at 3:00am
Which Mackie cab is this ?
Black to black , red to red , blue to bits ....

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Post Options Post Options   Thanks (0) Thanks(0)   Quote BJtheDJ Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2017 at 7:40am
Originally posted by matty w matty w wrote:

Which Mackie cab is this ?


Mackie Fussion 3000

https://forum.speakerplans.com/mackie-fussion-3000_topic18521.html



if the above d
oesn't work then try https://www.youtube.com/watch?v=8ehORyArkKw


Edited by BJtheDJ - 09 September 2017 at 7:42am
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_Natty_ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _Natty_ Quote  Post ReplyReply Direct Link To This Post Posted: 13 September 2017 at 1:52pm
Hi to all,
and thanks for all the replies... sorry for the late reply but I was away for a little time!

I try to put some order...
Originally posted by Conanski Conanski wrote:

In this case it's all about packaging.. more drivers equals more output simple as that. At the frequencies those woofers operate at the angled baffle has no acoustic effect.. positive or negative.
Wich are this frequencies where this cab working?

Quote
Sorry if this seems rude (especially if you're typing in a second language), but what you've written doesn't really make it clear what you want to know. You ask about 2 drivers, but there's 6 in the cab. So, I'll answer based on my best guess what you meant ;-) The cab as shown does not use push pull; all 4 low-mid drivers are facing the same way and being fed signal with the same polarity. Theoretically mounting one side's drivers reversed and flipping polarity on their connections would give some reduction in distortion, but it would introduce one or two other complications, which is presumably why Mackie didn't. First, it looks like there's not a lot of space for the backside of the HF driver as-is - it would never fit if the backside of one of the 12's was sticking out rather than in, so they'd need to redesign the cab or make it even bigger to get around that. Similarly, I don't think there's enough space to do the flip on both of the bottom 12's, as their magnets would foul each other. Secondly, (depending on how high the crossover to the high-mid is), reversing mid drivers could result in sound quality and or dispersion problems if sound waves reflected badly off the outward facing magnet. (Probably not that big a deal in this case, as they'd also interact in the same way with the rear surface of the HF horn, but it's a principle to be aware of.) Thirdly, Mackie are very sensitive to customer expectations and like to try and present their manuals etc in an accessible manner. Deploying drivers in a less common layout would give them more work to to do explain themselves and avoid having people think there was something "wrong" with the speakers as a result.  HTH, David.
yes david, apologize for my poor eng!
and yes thanks u guess right... honestly i didnt see the other 2 drivers up (ive seen just 2) and I choose this pic just because i'd like to understand what type of loading is that one and looking in what are based and for what... at least the name of the loading type!
If I well understud we talks about a normal sealed or reflex (i cant see in deep the box if its open in the middle of the angle) for optimize spacing and number of driver/speakers!
it seems that u know well this cab... so how its sound in the mid-woofer part?
Im looking for a solution from 200 to 800-1000hz...

Quote
Right now I'm in the decision mode for new tops, and I wonder if this alignment (V shaped mids and horn in the middle is doable for two 8"s setup with 1" or 1,4" crossed at 1500Hz.... That would be good compromise between conventional designs and coaxial drivers in 10" size....

this is exactly my goal too! but about 12" and 2" !

Quote
Just coming to completion on a 12v cab.
Rather happy with the outcome 

Are sealed or open in the middle? nice design!

Quote

even though the baffle is angled I think it will behave as a manifold to some extent giving up to 3dB extra sensitivity at the low end.

http://fulcrum-acoustic.com/assets/pdf/whitepapers/loudspeaker-manifolds-high-level-concert-sound-reinforcement-1986.pdf

thanks a lot for the link! ill check it carefully!

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markie View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote markie Quote  Post ReplyReply Direct Link To This Post Posted: 13 September 2017 at 3:30pm
One of my many unstarted projects is for 4 x VOLT 10" studio bass drivers (B250.2s). I was thinking of making 2,  2x10 cabs and was planning to use a V baffle as above. My reasoning was simply to make the cabinets deeper, thus more stable for pole mounting some 8" tops.

But I would also like to know if there is any acoustic benefit for doing this?
If it's got wheels or tits it's gonna cost a fortune
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Conanski View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 13 September 2017 at 4:02pm
Originally posted by _Natty_ _Natty_ wrote:

Originally posted by Conanski Conanski wrote:

In this case it's all about packaging.. more drivers equals more output simple as that. At the frequencies those woofers operate at the angled baffle has no acoustic effect.. positive or negative.
Wich are this frequencies where this cab working?
In this case it's going to be something like 100-150hz to maybe 500-800hz given the large 2" exit mid horn/driver.



Originally posted by _Natty_ _Natty_ wrote:

Right now I'm in the decision mode for new tops, and I wonder if this alignment (V shaped mids and horn in the middle is doable for two 8"s setup with 1" or 1,4" crossed at 1500Hz.... That would be good compromise between conventional designs and coaxial drivers in 10" size....

Any time there is more than 1 driver in a pass band you get mutual coupling at frequencies below where the the wavelength is equal to the driver diameter, for an 8" driver that is about 1.5khz so as long as your crossover is there or below you are good. That means a 1.4" driver crossed a bit lower would work better especially of this is a high output application.







Edited by Conanski - 13 September 2017 at 4:05pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FrederikMA Quote  Post ReplyReply Direct Link To This Post Posted: 13 September 2017 at 4:49pm
+1 Conanski
You can, with a bit of simple geometry and some trial and error if needed, benefit from the destructive interference to match directivity through crossover passband between the comp horn and the lowmid section .
Best regards, Fred
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