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This is incorrect. They require both: highpass to protect from over-excursion below tuning and low pass where you want to transition to your mains.
It is very much correct. A passive sub only needs a low pass filter.to set the point to what frequencies it receives typically somewhere between 40 and 150 Hz. The high pass filter is associated with the mains. And it can be adjusted within a range to fully drive the mains to their sub region or something short of that. Thing is some .1 Receivers, like the Marantz NR-1200, have no high pass filter function so the mains are going to run full out.
 

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Onoo
The problem isn’t that my subwoofers will play frequencies that are too low, but rather that the subwoofers will play frequencies that are too low too loudly, is that correct? If so, does this mean I could get away without a high pass if I don’t blast them?
What it means is you just need to adjust the subwoofer gain, period. Interestingly enough, I've seen more gobbledygook on this thread that would confuse most anybody so no wonder you are confused. The high pass filter if your receiver has one controls what the lowest frequency is that is sent to the mains. Your mains might produce let's say 40 Hz at +/- 3 db, but to get that response the amp and/or speaker might be taxed into some distortion. So, if you have a high pass filter you could set it to say 50 Hz and then set the low pass to maybe 60 Hz for a good seemless blend. Now, if the sub is too loud, or dominant then the subwoofer amp's gain control can be adjusted. Thing is the sub cannot be adjusted by ear or it will always sound too loud, It needs to be adjusted by SPL, Sound Pressure Level, using an SPL meter. Typically you would listen to your mains at an average listening level of about 60db and then add the sub to the mix, adjusting its gain to match the mains gain. That's it.
 

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Huh, interesting. I was assuming going off your model on the last page, it looks like you're down 10db at 20hz compared to at 60hz. Doesn't show up here though. Maybe if you kept increasing the output level to a 110db sweep instead of 80bd it would? I dunno just guessing[/QUOTE]No I am not down 10dB at 20hz compared to 60hz. What you might be referring to is an earlier graph I posted which showed a 10dB drop at 10hz using a FMOD versus not using a FMOD.

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It is very much correct. A passive sub only needs a low pass filter.to set the point to what frequencies it receives typically somewhere between 40 and 150 Hz. The high pass filter is associated with the mains. And it can be adjusted within a range to fully drive the mains to their sub region or something short of that. Thing is some .1 Receivers, like the Marantz NR-1200, have no high pass filter function so the mains are going to run full out.
High pass filter is put in for the sub.

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High pass filter is put in for the sub.

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You are confused, the high pass filter selects the lowest frequency sent to the mains. The high pass filter does not control the subwoofer period. In my system my preamp's sub output crossover (low pass) is set to 63 Hz and my mains output crossover (high pass) is set to 50 Hz. The sub's amp is set to 0db gain and preamp's sub level is set to 0db.
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Huh, interesting. I was assuming going off your model on the last page, it looks like you're down 10db at 20hz compared to at 60hz. Doesn't show up here though. Maybe if you kept increasing the output level to a 110db sweep instead of 80bd it would? I dunno just guessing
No I am not down 10dB at 20hz compared to 60hz. What you might be referring to is an earlier graph I posted which showed a 10dB drop at 10hz using a FMOD versus not using a FMOD.

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[/QUOTE]

I was referring to your SPL graph in post #60, where you were talking about 50 volts reaching reference for your subs at 60hz. That chart shows just over 110db at 60hz as you stated, but it is down ~10db to just over 100 at 20hz.

I don't know your usual listening levels, but if you are going for reference level I'm pretty sure its 115db for the entire 20-120hz band, not just 60hz. That's where I don't see you being able to reach reference levels at 20hz, at least not without increasing the power to the drivers which in turn increases excursion. I could be wrong though.
 

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It is very much correct. A passive sub only needs a low pass filter.to set the point to what frequencies it receives typically somewhere between 40 and 150 Hz. The high pass filter is associated with the mains. And it can be adjusted within a range to fully drive the mains to their sub region or something short of that. Thing is some .1 Receivers, like the Marantz NR-1200, have no high pass filter function so the mains are going to run full out.
No, almost all ported subs will have a high pass filter to prevent them from destroying themselves under port tune. Won't be necessary if you are listening only to music that doesn't go very low or at low volume levels, but if you're turning up movie, yeah you're gonna want a high pass on your sub.
 
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You are confused, the high pass filter selects the lowest frequency sent to the mains. The high pass filter does not control the subwoofer period. In my system my preamp's sub output crossover (low pass) is set to 63 Hz and my mains output crossover (high pass) is set to 50 Hz. The sub's amp is set to 0db gain and preamp's sub level is set to 0db. View attachment 3096037
The way I understand is that when you have the subwoofer transition that has happened at a higher frequency the HPF protects the sub from driving to a level of frequency much below the tuning where driver damage can occur due to cone excursion. That's why you set it in either the minidsp or in my case if I need to do it I would have added an fmod between the receiver and amp.

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No I am not down 10dB at 20hz compared to 60hz. What you might be referring to is an earlier graph I posted which showed a 10dB drop at 10hz using a FMOD versus not using a FMOD.

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I was referring to your SPL graph in post #60, where you were talking about 50 volts reaching reference for your subs at 60hz. That chart shows just over 110db at 60hz as you stated, but it is down ~10db to just over 100 at 20hz.

I don't know your usual listening levels, but if you are going for reference level I'm pretty sure its 115db for the entire 20-120hz band, not just 60hz. That's where I don't see you being able to reach reference levels at 20hz, at least not without increasing the power to the drivers which in turn increases excursion. I could be wrong though.[/QUOTE]I am not sure which graph you are referencing to but in the one I posted I showed the dB level remaining flat until 10hz. You are comparing two different things. The point of the winisd modeling was to show what power level and at what frequency the driver shows it reaching 110dB. And per the analysis it showed a 50w input power.

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I was referring to your SPL graph in post #60, where you were talking about 50 volts reaching reference for your subs at 60hz. That chart shows just over 110db at 60hz as you stated, but it is down ~10db to just over 100 at 20hz.

I don't know your usual listening levels, but if you are going for reference level I'm pretty sure its 115db for the entire 20-120hz band, not just 60hz. That's where I don't see you being able to reach reference levels at 20hz, at least not without increasing the power to the drivers which in turn increases excursion. I could be wrong though.
I am not sure which graph you are referencing to but in the one I posted I showed the dB level remaining flat until 10hz. You are comparing two different things. The point of the winisd modeling was to show what power level and at what frequency the driver shows it reaching 110dB. And per the analysis it showed a 50w input power.

Sent from my GM1917 using Tapatalk[/QUOTE]The graph referred to in post #60 was to the winisd modeling which shows the driver can reach 110db with just 50w input power. So I am assuming based on that that as long as I keep under that the cone excursion is not exceeded.

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Interestingly enough, I've seen more gobbledygook on this thread that would confuse most anybody so no wonder you are confused
Unfortunately, you are adding to the confusion. Folks are talking about a completely separate HP filter on the subs(set in a minidsp or sub amp DSP) than the one you are talking about for the mains set in a processor/receiver.

It is not required but used as a precautionary measure to protect the driver as it unloads below tune. The variables are how hard the system is pushed and how mechanically limited the sub driver is.
 

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I am not sure which graph you are referencing to but in the one I posted I showed the dB level remaining flat until 10hz. You are comparing two different things. The point of the winisd modeling was to show what power level and at what frequency the driver shows it reaching 110dB. And per the analysis it showed a 50w input power.

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The graph referred to in post #60 was to the winisd modeling which shows the driver can reach 110db with just 50w input power. So I am assuming based on that that as long as I keep under that the cone excursion is not exceeded.

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[/QUOTE]

I am referencing post #60, on page 3 of this thread. Right, the driver reached 110db with 50v input power, but only at 60hz. Reference level is for all frequencies, not just 60hz.

You're right, your posted measurments show flat to 10hz, but that is at a fairly low SPL level of only 80db. If that's as loud as you ever listen to movies, then I agree you're fine. But you were originally talking about reference level, 115db. If you were to watch a movie at reference, and that movie had content in the 10-20hz range, as many action movies do, then I'm guessing one of two things will happen:

1) If you're limiting your power to the subs at 50V, then they will not reach reference level below 60hz, at least not unless you've got a bunch of room gain to help. A compression test up to 115db in your room could show this.
2) If you don't have a limiter, then the drivers will pull more than 50v to reach reference level below 60hz, which will increase excursion and could cause bottoming/sub damage at low frequencies.

All depends on what content you're watching and at what levels. If you're listening at closer to 80db than 115db and thus keeping your subs to 50v or less, then I'd agree you'll never have any issues without a HPF. The issue would be running a bass heavy scene like Edge of Tomorrow or War of the Worlds at reference, which for all I know you have no interest in ever doing.
 

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No, almost all ported subs will have a high pass filter to prevent them from destroying themselves under port tune. Won't be necessary if you are listening only to music that doesn't go very low or at low volume levels, but if you're turning up movie, yeah you're gonna want a high pass on your sub.
No, a common passive sub has no crossover at all, whether it is a ported model or not. The crossover (low pass filter), usually located in the preamp, controls the highest frequency the sub will receive and that might be the extent of it. Over excursion, from a sub controlled by the low pass filter, is the result of clipping, meaning not enough power t the sub to drive it at desired volume level. It is not about the sub producing lower/higher frequencies than its design parameters when the low pass filter is set within the subs operating range. Clipping a sub BTW sounds like a sledge hammer hitting a steel pylon. You will never forget it. Now, to prevent clipping it's important to have enough amp power to drive the sub. My sub requires about 600 watts to preclude clipping when I listen to music or movies at a high volume. I have been running my sub, a JBL B380 since 1986 with and without high pass filter adjustment to my mains. My mains, JBL L100t3's will produce bass down to about 35 Hz +/-3db so if the high pass filter is not applied the L100t3's may get all there is to get in bass except in the arena of felt bass. I have found however that when listening to music or movies above 70db average there is a benefit to adjusting the high pass filter to 50 Hz, it lets the mains produce volume with no sign of "tightness". In other words, the volume is without effort.
 

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Good lord. Ok, go tell everyone in the Marty sub thread, and everyone in the VBSS thread, and every other ported build thread that those guys are all wrong and should take the HPF off their subs.

Better yet, send a 10hz sine wave to your JBL and report back on how it goes.
 
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Unfortunately, you are adding to the confusion. Folks are talking about a completely separate HP filter on the subs(set in a minidsp or sub amp DSP) than the one you are talking about for the mains set in a processor/receiver.

It is not required but used as a precautionary measure to protect the driver as it unloads below tune. The variables are how hard the system is pushed and how mechanically limited the sub driver is.
I don't think he's gonna get it.
 

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Unfortunately, you are adding to the confusion. Folks are talking about a completely separate HP filter on the subs(set in a minidsp or sub amp DSP) than the one you are talking about for the mains set in a processor/receiver.

It is not required but used as a precautionary measure to protect the driver as it unloads below tune. The variables are how hard the system is pushed and how mechanically limited the sub driver is.
My early post was directed to the thread starter who said:
"Do these subs require high-pass filters or some sort of digital control? I don't want to blow them up by sending 15hz signals to them or something."
My post was germane to that thread starter. Then it appears some folks began talking about high pass filters, no matter what subset, confusing them with low pass filter function and control.
 

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Then it appears some folks began talking about high pass filters, no matter what subset, confusing them with low pass filter function and control.
The discussion has been about HP filters used to protect subs.

You're confusing that with the filtering applied by the processor between subs and mains.
 

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You are confused, the high pass filter selects the lowest frequency sent to the mains. The high pass filter does not control the subwoofer period. In my system my preamp's sub output crossover (low pass) is set to 63 Hz and my mains output crossover (high pass) is set to 50 Hz. The sub's amp is set to 0db gain and preamp's sub level is set to 0db.
No, you're confused. in this world of high output, high power, ported subs, we use:
  • a LPF (let's say at 80hz) for the subwoofer's output
  • a HPF, often automatically set to the same frequency as the LPF (80hz in this case), to the mains, to reduce the bass trying to be reproduced by them.
  • BUT ALSO, an infrasonic HPF to prevent signals of (let's say) 15hz or less be attempted by the subwoofer.

You don't have a infrasonic LPF in your system. That's what we're talking about. infrasonic. It's something you don't have in your setup.
 

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You are confused, the high pass filter selects the lowest frequency sent to the mains. The high pass filter does not control the subwoofer period. In my system my preamp's sub output crossover (low pass) is set to 63 Hz and my mains output crossover (high pass) is set to 50 Hz. The sub's amp is set to 0db gain and preamp's sub level is set to 0db. View attachment 3096037
No, a common passive sub has no crossover at all, whether it is a ported model or not. The crossover (low pass filter), usually located in the preamp, controls the highest frequency the sub will receive and that might be the extent of it. Over excursion, from a sub controlled by the low pass filter, is the result of clipping, meaning not enough power t the sub to drive it at desired volume level. It is not about the sub producing lower/higher frequencies than its design parameters when the low pass filter is set within the subs operating range. Clipping a sub BTW sounds like a sledge hammer hitting a steel pylon. You will never forget it. Now, to prevent clipping it's important to have enough amp power to drive the sub. My sub requires about 600 watts to preclude clipping when I listen to music or movies at a high volume. I have been running my sub, a JBL B380 since 1986 with and without high pass filter adjustment to my mains. My mains, JBL L100t3's will produce bass down to about 35 Hz +/-3db so if the high pass filter is not applied the L100t3's may get all there is to get in bass except in the arena of felt bass. I have found however that when listening to music or movies above 70db average there is a benefit to adjusting the high pass filter to 50 Hz, it lets the mains produce volume with no sign of "tightness". In other words, the volume is without effort.
You're in the DIY section and way off base here.

Most guys are applying a TON of boost way down low to get the in-room response they want. With no high pass to the sub, killing it with infrasonic energy in the signal chain is a real thing for most people here (couple crazy exceptions). The high pass you're talking about for the mains is done by most here in the AVR, and I'd wager probably 90%+ don't do much other than "small" or 80hz. We're not talking about that. We're talking about somewhere around 16-20hz range on some of the subs, last I fooled around with it set mine around 7hz. Send a 20hz tuned sub a 10hz signal with a couple thousand watts and you're going to have a bad time -and there are plenty here who do that. I like the vintage stuff but you're in a different world, not incorrect from your perspective but you're not fully understanding all of what's going on here.

For example, on my JBL array, I had over 20dB of boost applied below 20hz and 5kw or so to back that up, and was running a subharmonic synthesizer to make sure I exercised those cones even on top 40 pop. Now you can probably imagine needing a very low HPF to protect drivers from anything outside of the safe zone -we're pushing hardware hard. I do agree that casual listeners would almost never have an issue. These ain't casual listeners though, you're in the land of excess, bent cones and melted voice coils. Need a high pass filter and some holy water to keep these suckers from catching on fire.

Chris
 

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You're in the DIY section... you're in the land of excess, bent cones and melted voice coils. Need a high pass filter and some holy water to keep these suckers from catching on fire.
Does AVS have a "notable quotables" thread? if so, this needs to be in it. :LOL::ROFLMAO::LOL::ROFLMAO:
 
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