6th order bandpass question

tinitus · 1st March 2009, 09:40 PM

Hi

I am wondering why low end rolloff on a 6th order bandpass is always rated as equal to driver Fs, or close to, which would make it very attractive with use of pro woofers

Is that fore real ?

To me it doesnt look much different from ordinary BR, but it obviously is

Does anyone have any explanation to this ?

GM · 1st March 2009, 11:10 PM

Oh really?! News to me.

GM

tinitus · 2nd March 2009, 12:56 AM

Thanks GM, I was hoping you would turn up

As I expected, its an error with that low rolloff

May be that its the frequency where its 12db down, or something like that
I dont know the standards fore bandpass, apart from having steep rolloff

Nope, it says 3db down at 32hz
driver Fs of 30hz, 0.25Qts, Vas 300 (imaginary woofer)

Rear chamber 174liter, two ports tuned to 30hz, each with ø100mm x 260mm long

Front chamber 60liter, one port tuned to 60hz, ø100mm x 170mm long

tinitus · 2nd March 2009, 02:03 AM

Quote:

Originally posted by GM
Oh really?! News to me.

GM

Ahh, yes I see now...its just the tuning...stupid me

tinitus · 2nd March 2009, 01:57 PM

I may be naughty, but in my files I call this a "Tapped Ported Bandpass"

Question is whether there could be phasing issues between the ports ?

GM · 2nd March 2009, 02:28 PM

Agreed.

There will be if not properly tuned, same as a TP, TH.

GM

tinitus · 2nd March 2009, 02:48 PM

Ok, thanks

1. Will it be better this way ?

2. Or maybe bottom port should face downwards ?

3. Or will port phasing always be a risk/issue ?

4. Any suggestions what to do best ?

GM · 2nd March 2009, 03:19 PM

Don't know, they all seem same-same to me, so better to use an 8th order Karlson IMO if not a TP or TH or even a B@$3 WC if a vented rear chamber is used, with bulk Vs output for a given BW being the final arbiter.

GM

tinitus · 2nd March 2009, 03:33 PM

I know what a TH means

But the other WC, TP, BW or 8th order Carlson...sorry, dont know what that means

GM · 2nd March 2009, 03:45 PM

Bose Wave Cannon, tapped pipe, band-width, Karlson K-15 box alignment, an 8th order band-pass (four tuned resonant cavities).

GM

1st March 2009, 09:40 PM	#1
tinitus diyAudio Moderator Join Date: Nov 2005	6th order bandpass question Hi I am wondering why low end rolloff on a 6th order bandpass is always rated as equal to driver Fs, or close to, which would make it very attractive with use of pro woofers Is that fore real ? To me it doesnt look much different from ordinary BR, but it obviously is Does anyone have any explanation to this ?

1st March 2009, 11:10 PM	#2
GM diyAudio Member Join Date: Jun 2003 Location: Chamblee, Ga.	Oh really?! News to me. GM __________________ Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

2nd March 2009, 02:28 PM	#6
GM diyAudio Member Join Date: Jun 2003 Location: Chamblee, Ga.	Agreed. There will be if not properly tuned, same as a TP, TH. GM __________________ Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

2nd March 2009, 03:19 PM	#8
GM diyAudio Member Join Date: Jun 2003 Location: Chamblee, Ga.	Don't know, they all seem same-same to me, so better to use an 8th order Karlson IMO if not a TP or TH or even a B@$3 WC if a vented rear chamber is used, with bulk Vs output for a given BW being the final arbiter. GM __________________ Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

2nd March 2009, 03:45 PM	#10
GM diyAudio Member Join Date: Jun 2003 Location: Chamblee, Ga.	Bose Wave Cannon, tapped pipe, band-width, Karlson K-15 box alignment, an 8th order band-pass (four tuned resonant cavities). GM __________________ Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.


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2nd March 2009, 12:56 AM	#3
tinitus diyAudio Moderator Join Date: Nov 2005	Thanks GM, I was hoping you would turn up As I expected, its an error with that low rolloff May be that its the frequency where its 12db down, or something like that I dont know the standards fore bandpass, apart from having steep rolloff Nope, it says 3db down at 32hz driver Fs of 30hz, 0.25Qts, Vas 300 (imaginary woofer) Rear chamber 174liter, two ports tuned to 30hz, each with ø100mm x 260mm long Front chamber 60liter, one port tuned to 60hz, ø100mm x 170mm long

2nd March 2009, 03:33 PM	#9
tinitus diyAudio Moderator Join Date: Nov 2005	I know what a TH means But the other WC, TP, BW or 8th order Carlson...sorry, dont know what that means

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