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Multi-Way Conventional loudspeakers with crossovers

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Old 13th June 2013, 03:43 PM   #1
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Question Feedback on drivers for 3-way bookshelf

I am considering a 3-way bookshelf (maybe better called a mini-tower as it will be about a 24" high front ported design) to be used as mains in a 5.2 system (for both HT and m-ch music).

The speakers will be crossed to sub(s) at 80Hz, so I'm thinking an f3 of about 60Hz should be OK.

Current driver thoughts are:

- woofers, a pair of Seas L16 (crossed to mid at 400 - 600Hz)

- midrange, Audax HM100Z0 (crossed to tweeter at 2.5 - 4 kHz)

- tweeter, Hyquphon OW4

These will be placed within 6" of the back wall, so this will be considered in BSC calculations.

Any thoughts, concerns, reactions from those with experience to this concept (driver selection, crossover ranges, etc)?

Thanks (a humble rookie)

PS. What impact would replacing the Seas L16 with Audax HM170C0 have? Higher sensitivity and lower power handling - anything else?

Last edited by rick240; 13th June 2013 at 03:57 PM.
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Old 13th June 2013, 05:03 PM   #2
AllenB is offline AllenB  Australia
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Quote:
Originally Posted by rick240 View Post
These will be placed within 6" of the back wall, so this will be considered in BSC calculations.
How do you figure?
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Old 13th June 2013, 05:12 PM   #3
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Originally Posted by AllenB View Post
How do you figure?
Correct me if I'm wrong, but when doing BSC calculations, if you know the speakers are being placed against the wall then you know that the in-room response will have reinforcement at lower frequencies so the amount of compensation will be different than if you were designing for flat frequency response in open space.
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Old 13th June 2013, 05:17 PM   #4
Jay1111 is offline Jay1111  United States
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The mid will have to be padded down heavily. I take caution and parallel resistors to make sure they wont see to much power when padding the mid of a 3 way.

The CTC distance of your mid/tweet will limit how high you can cross. A neo tweeter tends to make more sense with a small mid because of this.
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Old 13th June 2013, 05:30 PM   #5
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Originally Posted by Jay1111 View Post
The mid will have to be padded down heavily. I take caution and parallel resistors to make sure they wont see to much power when padding the mid of a 3 way.
Would most of the padding be due to lower sensitivity of woofers (but doesn't having two of them help here a lot), or the tweeter?

Quote:
The CTC distance of your mid/tweet will limit how high you can cross. A neo tweeter tends to make more sense with a small mid because of this.
If the flangeless OW tweeter is used then the CTC would be under 4". Also, isn't CTC more of an issue in horizontal designs?

PS. Thanks for educating a newbie.
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Old 13th June 2013, 05:52 PM   #6
Jay1111 is offline Jay1111  United States
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Quote:
Originally Posted by rick240 View Post
Would most of the padding be due to lower sensitivity of woofers (but doesn't having two of them help here a lot), or the tweeter?



If the flangeless OW tweeter is used then the CTC would be under 4". Also, isn't CTC more of an issue in horizontal designs?

PS. Thanks for educating a newbie.

I missed where you said a pair of woofers, still even with minimal BSC you're looking at around 88db from the Seas (and a low impedance). The mid is in the low 90's, plus there's band pass gain for the mid in a 3 way. A pair of those Audax woofers would get you better match.

Drivers should be within a minimum of 1 wavelength at the crossover point.

Sorry didnt know there's a flange less OW4, all I've seen is this.

Click the image to open in full size.

How are you designing the crossover?
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Old 13th June 2013, 05:55 PM   #7
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How are you designing the crossover?
I actually don't have DIY skills, but do enjoy doing the research to come up with the high level design for the speakers.

Ultimately this will end up being a commission to Salk Sound (he builds gorgeous speakers and is open to custom projects), so the crossover would get designed by Dennis Murphy (he designs great crossovers).
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Old 13th June 2013, 06:03 PM   #8
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Quote:
Originally Posted by Jay1111 View Post
I missed where you said a pair of woofers, still even with minimal BSC you're looking at around 88db from the Seas (and a low impedance). The mid is in the low 90's, plus there's band pass gain for the mid in a 3 way. A pair of those Audax woofers would get you better match.
Could you clarify my minimal understanding of band pass gain?

I'm starting to think the Audax woofers may be a better match.

Quote:
Drivers should be within a minimum of 1 wavelength at the crossover point.
So if my math is right, 3kHz max distance is 4.5" and 3.4kHz max is 4.0"

Quote:
Sorry didnt know there's a flange less OW4
It's an option with all OWs.

Is the efficiency of the tweeter apt to be an issue here?
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Old 13th June 2013, 06:18 PM   #9
Jay1111 is offline Jay1111  United States
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Originally Posted by rick240 View Post
Could you clarify my minimal understanding of band pass gain?

I'm starting to think the Audax woofers may be a better match.



So if my math is right, 3kHz max distance is 4.5" and 3.4kHz max is 4.0"



It's an option with all OWs.

Is the efficiency of the tweeter apt to be an issue here?

Bandpass gain is basically where the summing of the overlapping outputs of the woofer/mid/tweeter are greater then the output of the mid alone.

Your CTC numbers are good.

The tweeter sensitivity could limit you, depending on the amount of BSC with those Audax woofers. I would consider the SB29RDNC personally.
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Old 13th June 2013, 06:22 PM   #10
AllenB is offline AllenB  Australia
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Originally Posted by rick240 View Post
...the in-room response will have reinforcement at lower frequencies so the amount of compensation will be different than if you were designing for flat frequency response in open space.
The wall will only be exposed to sound that the baffle has already sent in that direction so the baffle is already out of the picture, at least until some low frequency where the gap disappears. The spacing will cause a series of related peaks and dips as they come back.

The wall should therefore give a boost at some point which might, for example, happen just below the baffle frequency giving the illusion of it being extended. Above and below this there may be a cancellation.

If I had a point it would be that to some degree the wall is a separate issue, and you might at some later point want to make some adjustment with it.
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