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Multi-Way Conventional loudspeakers with crossovers

Protecting Yamaha NS-1000M woofer with active high-pass filter?
Protecting Yamaha NS-1000M woofer with active high-pass filter?
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Old 5th October 2018, 07:38 AM   #1
XScorpius is offline XScorpius  Finland
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Default Protecting Yamaha NS-1000M woofer with active high-pass filter?

I have Yamaha NS-1000M speakers in my stereo setup along with 2x Arendal 2.5 Subwoofers which go to ~18Hz. Yammies have modified crossovers; Class A SET-tube amp is driving berylliums and Luxman poweramp is driving woofers. minidsp handles the active crossovering. dSpeaker antimode 2.0 handles frequency response up to 200Hz.



I was twiddling with signal generator yesterday and noticed that those 12dB/octave sloping woofers eat up 20Hz but obviously, producing little sound (but lots of heat I guess!). Since I do not want to damage my cones, what type of highpass filter should I program to minidsp to prevent woofer from possible damage but still preserving PRaT?


Afaik -3 point of 1000m woofer is ~50Hz and it slopes down 12dB/oct due to its closed box design.
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Old 5th October 2018, 07:51 AM   #2
Dave Bullet is offline Dave Bullet  New Zealand
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You could try a passive line level filter, ie between source and preamp and see if you can hear the PRaT difference?
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Old 5th October 2018, 09:01 AM   #3
richie00boy is offline richie00boy  United Kingdom
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Protecting Yamaha NS-1000M woofer with active high-pass filter?
Try 20Hz Butterworth 2nd order. At less than half your -3db point it should have only very small audible impact. Maybe nudge it up to 25Hz if it's not obtrusive.
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Old 5th October 2018, 09:03 AM   #4
chris661 is offline chris661  United Kingdom
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Quote:
Originally Posted by Dave Bullet View Post
You could try a passive line level filter, ie between source and preamp and see if you can hear the PRaT difference?
If anything noticeably messes up "PRaT", it's broken.


To the OP, if you add a Butterworth 12dB/octave filter at 50Hz, you'll have an LR4 acoustic curve with a -6dB point of 50Hz. Should be nice and easy to integrate the subs to.

Chris
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Old 5th October 2018, 09:28 AM   #5
XScorpius is offline XScorpius  Finland
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Quote:
Originally Posted by richie00boy View Post
Try 20Hz Butterworth 2nd order. At less than half your -3db point it should have only very small audible impact. Maybe nudge it up to 25Hz if it's not obtrusive.

Will try!


Quote:
Originally Posted by chris661 View Post
To the OP, if you add a Butterworth 12dB/octave filter at 50Hz, you'll have an LR4 acoustic curve with a -6dB point of 50Hz. Should be nice and easy to integrate the subs to.

Chris

Hmm, you sure about this? I read a review where it was emphasised that closed enclosure of 1000m produces accurate bass because of its 12dB/oct slope and thus lowQ (0.5). Would LR4 mess up this?


Subs are being integrated beautifully already with dSpeaker antimode
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Old 5th October 2018, 09:37 AM   #6
fatmarley is offline fatmarley  England
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A port tuned to 20hz.
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Old 5th October 2018, 10:28 AM   #7
XScorpius is offline XScorpius  Finland
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Quote:
Originally Posted by fatmarley View Post
A port tuned to 20hz.
nope

Last edited by XScorpius; 5th October 2018 at 10:31 AM.
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Old 5th October 2018, 12:05 PM   #8
marco_gea is offline marco_gea  Italy
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Quote:
Originally Posted by XScorpius View Post
nope
I understand the gut reaction ("I don't want to screw the beautiful, tight bass I have"), but it wasn't a bad suggestion at all.

I modeled it for you - look at the frequency response, group delay and cone excursion (with 50W input) below.

Porting the cabinet that low (20Hz) does not significantly alter the response anywhere audible (>40Hz), while it does provide additional protection from over-excursion between 15 and 40Hz.

Below 15Hz there won't be any input to excite the woofer anyway, so it shouldn't matter (except if you use vinyl, then you should really have a subsonic filter in place...)

Marco
Attached Images
File Type: png FR closed vs ported.PNG (11.0 KB, 151 views)
File Type: png GD closed vs ported.PNG (30.7 KB, 155 views)
File Type: png Excursion closed vs ported.PNG (32.3 KB, 156 views)
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Old 5th October 2018, 12:12 PM   #9
fatmarley is offline fatmarley  England
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Yep, i've done it with my own diy speakers based on the Vifa M21WG-09-08. They started life in a sealed box but now ported at 18hz and the bass sounds the same but with a touch more depth. They will also go louder without distortion.
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Old 5th October 2018, 02:50 PM   #10
XScorpius is offline XScorpius  Finland
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Quote:
Originally Posted by fatmarley View Post
Yep, i've done it with my own diy speakers based on the Vifa M21WG-09-08. They started life in a sealed box but now ported at 18hz and the bass sounds the same but with a touch more depth. They will also go louder without distortion.

Please read my original post. Adding port to my speaker, (especially to NS-1000M) is suboptimal solution at best. NS-1000M is designed to be overdamped closed box and have accurate bass. Its distortion is very low already. I could understand protecting woofer with port only if one cannot use active crossovers. But with active crossovers you don't even need to unnecessarily feed your amplifier with a signal that is not audible anyway.



What I was asking was ACTIVE way to protect woofer since I alreade have minidsp in signal line.
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