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Old 6th May 2008, 06:17 PM   #11
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Quote:
Originally posted by Klimon
...
In the application notes there's something about a certain ratio between L and C (forming the second order low-pass) which they recommend; on investigating George Short from northcreek informed me that on their commercial speakers with D28 they use that ratio e.g. Kitti Cat 11F and 0,315mH (more info on that crossover is on their website) ; Eska 7 and 0,5m. Adding: The correct choice of C and L depend on the net tweeter + L-pad resistance. For a higher net impedance, C gets smaller and L gets bigger. For a lower net impedance, C gets larger and L gets smaller. Apparently that ratio sounds best for the D28; Kitty Cat has Fx 1,65 and acoustical 3rd order highpass mated with electrical 2nd order for the midwoofer which results in 3rd order lowpass also. Ideally I'ld like to use that ratio for the tweeters X-overs but I'ld probably need to use simulation software for determining the precise value given the specific L-pad needed for matching the hds164. See here: http://www.northcreekmusic.com/Kitty..._Kat_Info.htms given I'll investigate further later on, meanwhile any input is welcome.
How much is your BSC?
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Old 6th May 2008, 07:14 PM   #12
Klimon is offline Klimon  Belgium
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I haven't implemented anything yet; for now I only have the Northcreeks and the cabs; BSC'll probably be one of the last add-ons I'll try. Why are you asking?

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Simon
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Old 6th May 2008, 08:22 PM   #13
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Default 2-Way Xover 6dB-12dB PEERLESS-NORTH 84dB~2K0

WO - 6"1/2 PEERLESS-HDS164 Nomex (BSC=5.5dB)
TW - NORTH D28-06S (fs=800Hz)

Woofer:
L1=2.7mH (DCR-0.45)
(RC damper)
R1=4.7
C1=10uF

Tweeter:
C2=12uF
L2=0.30mH (DCR-0.26)
(L-Pad)
R2=2.7 series
R3=3.9 ||
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Old 6th May 2008, 08:56 PM   #14
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Default 2-Way Xover 6dB-12dB PEERLESS-NORTH

Please, invert polarity for the tweeter (180phase).
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Old 7th May 2008, 06:46 AM   #15
Klimon is offline Klimon  Belgium
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Looks very viable, thanks!!!

What are the values for the BSC circuit? Could you make a simulation for only 3-4db BSC - it could be enough for near-wall placement and make the speakers easier to drive for my tube-amps?

Much appreciated

Cheers,

Simon
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Old 9th May 2008, 12:58 PM   #16
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Default 2-Way Xover 6dB-12dB PEERLESS-NORTH~86dB/2K2

Quote:
Originally posted by Klimon
Looks very viable, thanks!!!

What are the values for the BSC circuit? Could you make a simulation for only 3-4db BSC - it could be enough for near-wall placement and make the speakers easier to drive for my tube-amps?

Much appreciated

Cheers,

Simon
Hi Simon,

WO - 6"1/2 PEERLESS-HDS164 Nomex (BSC=4dB)
TW - NORTH D28-06S (fs=800Hz)/Tweeter with inverted polarity

Woofer:
L1=1.8mH (DCR-0.35)
(type Jantzen Cross-Coil with wood core ~30,00)
(RC damper)
R1=5.6 (n.i.)
C1=10uF

Tweeter:
C2=10uF
L2=0.27mH (DCR-0.23/air core)
(L-Pad)
R2=2.7 series (n.i.)
R3=8.2 || (n.i.)

For an 87dB~BSC=3dB use a L1=1.5mH, L2=0.24mH and R3=12 ||.
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Old 9th May 2008, 03:13 PM   #17
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Default 2-Way Xover 6dB-12dB PEERLESS-NORTH~87dB/2K0

I'm afraid is better to go with the 2K0Hz version (with BSC=3dB) because of the peak at 4KHz for the woofer, @-17dB in this xover case. More tests (adjusting) only possible after listening experience, to know if it affects anything at bandpass frequency. We can't go very low in the xover to protect for the tweeeter fs. Very tricky. The other is to have a different xover. Small is beautiful.

WO - 6"1/2 PEERLESS-HDS164 Nomex (BSC=3dB)
TW - NORTH D28-06S (fs=800Hz)/Tweeter with inverted polarity

Woofer:
L1=1.8mH (DCR-0.35/type Jantzen Cross-Coil with wood core ~30,00)
(RC damper)
R1=4R7 (n.i.)
C1=12uF

Tweeter:
C2=10uF
L2=0.30mH (DCR-0.26/air core)
(L-Pad)
R2=2R7 series (n.i.)
R3=15R || (n.i.)
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Old 9th May 2008, 04:36 PM   #18
Klimon is offline Klimon  Belgium
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Hi inductor,

I definitely agree with the less is more stance (I come from less).
Let's presume the tweeter stays at 2khz with the XO you describe. If the Peerless' breakup will prove unpleasant I presume a notch or a steeper crossover are the standard solutions.

Something that remains a question for me is the phase behaviour of the XO you modelled. Do you have an insight on the acoustical roll-offs of the drivers in the given arrangement and how those combine with regards to phase response?

Much appreciated

Cheers,

Simon
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Old 9th May 2008, 05:00 PM   #19
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Quote:
Originally posted by Klimon
Hi inductor,

I definitely agree with the less is more stance (I come from less).
Let's presume the tweeter stays at 2khz with the XO you describe. If the Peerless' breakup will prove unpleasant I presume a notch or a steeper crossover are the standard solutions.
Yes.
Quote:
Originally posted by Klimon
Something that remains a question for me is the phase behaviour of the XO you modelled. Do you have an insight on the acoustical roll-offs of the drivers in the given arrangement and how those combine with regards to phase response?
(?)
180 phase at bandpass/xover.
Attached Images
File Type: gif 2-way xover 6db-12db peerless-north phase.gif (6.4 KB, 195 views)
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Old 10th May 2008, 07:31 AM   #20
Klimon is offline Klimon  Belgium
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Thanks, I'll use your design for the new XO and let you know how it works out --- that will have to wait for couple of months after I've finished my master's paper though

Cheers,

Simon
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