Hello Folks,
at the beginning of this year I purchased a PA Sub, the Behringer B1800D-PRO.
It is a 18" drive based bass-reflex unit.
It is equipped with a Class-D 1400W amplifier with an integrated X-over.
My objective when I purchased is was to conver the 10 to 50Hz frequency range.
For the purpuse I am also using a DSP to correct the native response of the B1800.
Measuring its "native" response, I detected two things:
1) The integrated Class-D ampli looks to be filtered with an HP at 20Hz with a 6 or 12dB/oct roll-off factor.
2) The Sub is PA "tuned" and its response quickly drop below 35Hz.
Any suggestion on how to modify the bass-reflex / enclosure to lower the "native" frequency response of this unit?
Anybody before me tried to modify the embedded Class-D ampli to get-rid of the 20Hz HP filter?
Many thanks in advance and kind regards,
Andrea
at the beginning of this year I purchased a PA Sub, the Behringer B1800D-PRO.
It is a 18" drive based bass-reflex unit.
It is equipped with a Class-D 1400W amplifier with an integrated X-over.
My objective when I purchased is was to conver the 10 to 50Hz frequency range.
For the purpuse I am also using a DSP to correct the native response of the B1800.
Measuring its "native" response, I detected two things:
1) The integrated Class-D ampli looks to be filtered with an HP at 20Hz with a 6 or 12dB/oct roll-off factor.
2) The Sub is PA "tuned" and its response quickly drop below 35Hz.
Any suggestion on how to modify the bass-reflex / enclosure to lower the "native" frequency response of this unit?
Anybody before me tried to modify the embedded Class-D ampli to get-rid of the 20Hz HP filter?
Many thanks in advance and kind regards,
Andrea
Hi AndreaT,
I'm with epa on this one. Additionally, you could measure the T/S parameters of the driver, and use a simulation program (e.g.: Hornresp) to evaluate what you could do with this driver. Then you can evaluate if there is any way to modify the enclosure to arrive at your desired response. By the way, 10Hz does not sound very realistic?
Regards,
I'm with epa on this one. Additionally, you could measure the T/S parameters of the driver, and use a simulation program (e.g.: Hornresp) to evaluate what you could do with this driver. Then you can evaluate if there is any way to modify the enclosure to arrive at your desired response. By the way, 10Hz does not sound very realistic?
Regards,
Dear Friends,
thanks for your first replies.
Let me try to reply to you all here with these further details:
a) I already have the Sub working flat from 10Hz and then rolling down as expected (I actualy filtered it with a 42 dB/oct 35Hz LPF).
b) To get this "good & wanted" response I am "deeply" using the EQ capability of my DSP, the Thunea Frequency Allocator and Phase Arbitrator.
c) However, as my original post should figure-out, I am now really heavily adjusting (even up to 35 dB peak correction) a "native" response that is quite far-away the desired.
d) I can confirm that the flatness at 10Hz are not the "killing detail" making your system good or bad, but it mattersa a lot in the final sound stage inpact and in the realism of the entire "sound pressure".
So, based on your replyes, I will move-on with TB46 suggestion.
Let me know if you have more tips!
Many thanks and kind regards,
Andrea
thanks for your first replies.
Let me try to reply to you all here with these further details:
a) I already have the Sub working flat from 10Hz and then rolling down as expected (I actualy filtered it with a 42 dB/oct 35Hz LPF).
b) To get this "good & wanted" response I am "deeply" using the EQ capability of my DSP, the Thunea Frequency Allocator and Phase Arbitrator.
c) However, as my original post should figure-out, I am now really heavily adjusting (even up to 35 dB peak correction) a "native" response that is quite far-away the desired.
d) I can confirm that the flatness at 10Hz are not the "killing detail" making your system good or bad, but it mattersa a lot in the final sound stage inpact and in the realism of the entire "sound pressure".
So, based on your replyes, I will move-on with TB46 suggestion.
Let me know if you have more tips!
Many thanks and kind regards,
Andrea
Hi Turbodawg, yes doing that 10Hz EQ, I got group delay issues, but no port noise (so far).
I corrected the group delay by Thunea Phase Arbitrator delay adjustment.
I didn't hear any port noise, probably because I am using no more than the 20% of this PA Sub power.
It is a long excursion 1400W sub, I am not using more than 200W.
//Andrea
I corrected the group delay by Thunea Phase Arbitrator delay adjustment.
I didn't hear any port noise, probably because I am using no more than the 20% of this PA Sub power.
It is a long excursion 1400W sub, I am not using more than 200W.
//Andrea
Given what you say, I would see about lengthening the port quite a bit. Or consider removing the port entirely and sealing up the box, plus EQ and filter.
Pack the port with socks, clothes or whatever
This will give it a simulated sealed box response, EQ it and listen. If you like it and the woofer does not make bad noises--it might work for you as a sealed box. It won't be as loud as the ported box but it is a PA woofer....those drivers tend not to have a ton of Xmax.
I built a subwoofer tuned to 22 Hz with two PA 15" woofers (Fs = 32Hz) loaded them push-pull isobaric in the stock PA box to cut the Vas in half and double the power handling. Since I had no T/S specs, I went with an 18" passive radiator and tuned it in place in the corner. My SPL meter was used to get the final tuning down which was around 22Hz.
If I move the sub, I can easily retune the passive radiator to wherever it ends up for the next location. No problems with peaks of 300 watts hitting the woofers (150W each) and I love the sound quality. Good luck!
This will give it a simulated sealed box response, EQ it and listen. If you like it and the woofer does not make bad noises--it might work for you as a sealed box. It won't be as loud as the ported box but it is a PA woofer....those drivers tend not to have a ton of Xmax.
I built a subwoofer tuned to 22 Hz with two PA 15" woofers (Fs = 32Hz) loaded them push-pull isobaric in the stock PA box to cut the Vas in half and double the power handling. Since I had no T/S specs, I went with an 18" passive radiator and tuned it in place in the corner. My SPL meter was used to get the final tuning down which was around 22Hz.
If I move the sub, I can easily retune the passive radiator to wherever it ends up for the next location. No problems with peaks of 300 watts hitting the woofers (150W each) and I love the sound quality. Good luck!
A sealed cabinet would provide excursion damping all the way to DC, by keeping half of the driver's output inside the cabinet - I think that's what he's referring to. Problem with ported cabinets is that using them below port tuning is a bad idea - they have next to no power handling as excursion (and therefore distortion) increases rapidly as frequency decreases.
Andrea, could you provide a link to some of these studies? I'm rather curious about their testing methods.
Andrea, could you provide a link to some of these studies? I'm rather curious about their testing methods.
I would forget about 10Hz--it is only sound
Infrasound is 15Hz and below--some people are sensitive to 12Hz for example, it makes you sick.
I'd stuff it, get it to work without noise at 20 to 25Hz and if I want lower, go with an infrasonic subwoofer crossing at 20Hz and down.
Here is an interesting read about playing around with infrasound.
http://customers.hbci.com/~wenonah/history/gavreau.htm
Infrasound is 15Hz and below--some people are sensitive to 12Hz for example, it makes you sick.
I'd stuff it, get it to work without noise at 20 to 25Hz and if I want lower, go with an infrasonic subwoofer crossing at 20Hz and down.
Here is an interesting read about playing around with infrasound.
http://customers.hbci.com/~wenonah/history/gavreau.htm
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Hi, Simply not true at all regarding pyschoacoustics, rgds, sreten.
20Hz to 20KHz is commonly quoted, but 32Hz to 16KHz is more realistic.
You can add octaves top and bottom for 16Hz to 32KHz but they are
both only possibly audible at high SPL's, very high for domestic audio.
Hello Friends,
here are my replies for you all:
- for Chris661, you don't need to look far away, just buy or rent Audio Engineering Handbook Amazon.com: Audio Engineering Handbook (9780070047778): K. Blair Benson: Books
This is my favourite starting point and it is a common students' book in US. On it you will find confirmed all I stated (read the first pages on fundamentals of sounds and music).
- I agree that 10Hz flatness matters more when music is played loud... that's why I have about 5 kW total audio amplifying power driving my loudspeaker-system.
The sound level I have in my listening room is mostly the same of a live stage event.
- Horgan music, even playing notes at 16Hz for several seconds and up to minutes, never killed or made sick anybody.
I am not speaking about generating 10Hz at 120 dB-SPL for 1 hour or so, I am speaking about giving more realism to drums, bass guitar and to "timpani" (of the big classic phylarmonic orchestra). So, I am speaking about 10Hz-band components playing loud for very small fractions of seconds only.
- About frequency extensions.... my daughet of 7 years can perfectly hear 19kHz pure sinusoidal tone at low volume. My wife 47 can hear 17 kHz. I cannot both of them as singole tones, but if I cut my highs at 17 kHz I can really "listen" worse than when I have flat response up to 20kHz.
Moreover, I am sure that most of you can hear the different sound could be played by loudspeakers having a flat response up to 35kHz.
Mostly of that is due to the "transient speed and clarity" that such a kind of wide-band loudspeakers can reproduce.
Regards
Andrea
here are my replies for you all:
- for Chris661, you don't need to look far away, just buy or rent Audio Engineering Handbook Amazon.com: Audio Engineering Handbook (9780070047778): K. Blair Benson: Books
This is my favourite starting point and it is a common students' book in US. On it you will find confirmed all I stated (read the first pages on fundamentals of sounds and music).
- I agree that 10Hz flatness matters more when music is played loud... that's why I have about 5 kW total audio amplifying power driving my loudspeaker-system.
The sound level I have in my listening room is mostly the same of a live stage event.
- Horgan music, even playing notes at 16Hz for several seconds and up to minutes, never killed or made sick anybody.
I am not speaking about generating 10Hz at 120 dB-SPL for 1 hour or so, I am speaking about giving more realism to drums, bass guitar and to "timpani" (of the big classic phylarmonic orchestra). So, I am speaking about 10Hz-band components playing loud for very small fractions of seconds only.
- About frequency extensions.... my daughet of 7 years can perfectly hear 19kHz pure sinusoidal tone at low volume. My wife 47 can hear 17 kHz. I cannot both of them as singole tones, but if I cut my highs at 17 kHz I can really "listen" worse than when I have flat response up to 20kHz.
Moreover, I am sure that most of you can hear the different sound could be played by loudspeakers having a flat response up to 35kHz.
Mostly of that is due to the "transient speed and clarity" that such a kind of wide-band loudspeakers can reproduce.
Regards
Andrea
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5kw of system and you are trying to do infrasound with a cheap low end sub designed for beginner DJ's needing 50-120hz thump?
Design and build a sub for the frequencies you want but remember most recordings have nothing under 25hz.
Use a spectograph on your soundcard/amp when running test tones to see if any harmonics are getting through, most systems can't reproduce a "pure" tone at ultra high frequencies.
Design and build a sub for the frequencies you want but remember most recordings have nothing under 25hz.
Use a spectograph on your soundcard/amp when running test tones to see if any harmonics are getting through, most systems can't reproduce a "pure" tone at ultra high frequencies.
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