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Do you really have max out the crossover on the sub? - Page 2

post #31 of 57
Quote:
Originally Posted by sivadselim View Post

Right. But we're not really discussing the AVR's 'LPF of LFE', here. We're talking about the subwoofer's own variable LPF which, if invoked, will affect ALL the bass that is sent to the subwoofer, and not, as in the case of an AVR's 'LPF of LFE', only the bass that is encoded in the LFE channel.

Ahhh, mea culpa--I misread Benunc's post and thought he was referring to potentially lost information in the 80-120 range of the LFE channel only.
post #32 of 57
Quote:
Originally Posted by holt7153 View Post

Ahhh, mea culpa--I misread Benunc's post and thought he was referring to potentially lost information in the 80-120 range of the LFE channel only.

Well, in fairness, at some point in the thread someone (not going to look back and see who) did conflate (or even confuse) the 'LPF of LFE' and the subwoofer's variable low-pass filter (LPF) setting.

And I think that IS what benunc was referring to, in which case what you quoted IS relevant.

But at some point it seems the use of the term LPF became sort of obscurred. One (or more) person(s) used it to mean the subwoofer's own variable LPF and the other(s), to mean the AVR's 'LPF of LFE'.

So, just to be clear (and this is not necessarily directed at you, holt7153), we are not talking about the AVR's 'LPF of LFE'.
Edited by sivadselim - 6/7/13 at 1:47pm
post #33 of 57
Yeah, I might have created some confusion but I was really referring to both. I think in one or two posts I did mention setting it on both the sub and AVR.... but to be clear, I max or disable the sub's LPF and set the AVR's LFE LPF at 120Hz.
post #34 of 57
Quote:
Originally Posted by Bill Fitzmaurice View Post


I'm not sure what you're getting at, but if you have the AVR crossover set at 80Hz at 18dB/octave and the sub crossover also set at 80Hz at 18dB/octave the result is 80Hz at 36dB/octave. That won't affect anything below 80Hz, only above 80Hz.
With only the AVR filter in place 160Hz is down 18dB, but that makes it still very audible, due to equal loudness. Adding the sub filter as well takes 160Hz to -36dB, and even with equal loudness figured in that would be inaudible.

I'll try again, two issues:

 

1)  Cascading crossovers doubles the slope, may or may not be an issue but take it into account

 

2)  Setting the LPF on the sub lower than 120hz you could be reducing the level of content intended to be played by the subwoofer.

 

I know you understand this, guess I just wasn't clear.

post #35 of 57
Quote:
Originally Posted by primetimeguy View Post


Cascading crossovers doubles the slope.

And that's not all that cascading filters does.
post #36 of 57
Sorry to bump but this has been bugging me after hours of searching and no luck.

I understand the differences between LPF of LFE (from the avr) and the crossover setting at the back of the sub.

Most people say to put the LPF of LFE to 120hz and raise the sub xo to max or disable. On my sub though, the max xo is 100hz.

Does that mean I should put the LPF of LFE to 100hz instead of 120hz to avoid clipping?
post #37 of 57
Using the LFE input and maxing out the LPF on the sub should effectively disable/bypass the LPF.

But even if it didn't - even if the sub could only ever play frequencies up to 100Hz - having the LPF of LFE set to 120hz wouldn't cause clipping. The sub would simply ignore (not attempt to reproduce) the frequencies from 100-120Hz.
post #38 of 57
Ok thanks for clearing it up. I am in fact using the LFE input on the sub and have the dial to the max (which reads 100hz).

I will keep the LPF of LFE settting (avr menu) to 120hz then.
post #39 of 57
I could be wrong here but I was under the impression that the LPF (crossover) on the sub has nothing to do with the LFE .1 channel. I thought it only had to do with the crossover of the other speakers to the sub.
post #40 of 57
Quote:
I could be wrong here but I was under the impression that the LPF (crossover) on the sub has nothing to do with the LFE .1 channel. I thought it only had to do with the crossover of the other speakers to the sub.
If I understand your point correctly: Assuming the sub's LPF couldn't be disabled, the 100Hz max would potentially affect only speaker-channel content, while all content up to 120Hz originating in the receiver's LFE channel would be played by the sub?

Interesting. And it sounds reasonable enough. I hope someone can provide a definitive answer, one way or another.
post #41 of 57
Yes you understood what I was trying to say. Like I said I'm not sure that's just what I thought/assumed to be true.
post #42 of 57
Quote:
Originally Posted by eljaycanuck View Post

If I understand your point correctly: Assuming the sub's LPF couldn't be disabled, the 100Hz max would potentially affect only speaker-channel content, while all content up to 120Hz originating in the receiver's LFE channel would be played by the sub?

Interesting. And it sounds reasonable enough. I hope someone can provide a definitive answer, one way or another.
This is what's definitive: If you're not totally satisfied with how the system sounds with the sub low pass filter set at its highest frequency try it at lower frequencies. If it sounds better it is better. If it doesn't then don't do that.
post #43 of 57
Quote:
This is what's definitive: If you're not totally satisfied with how the system sounds with the sub low pass filter set at its highest frequency try it at lower frequencies. If it sounds better it is better. If it doesn't then don't do that.
Well, that's certainly definitive...but it doesn't answer the question. wink.gif
post #44 of 57
Quote:
I could be wrong here but I was under the impression that the LPF (crossover) on the sub has nothing to do with the LFE .1 channel. I thought it only had to do with the crossover of the other speakers to the sub.
I was sweeping up some cat litter just now and it occurred to me that, at a line level anyway, the sub has no way of knowing what channels comprise the audio stream it's being fed, so it can't possibly decide to limit any speaker content in that stream to 100Hz while allowing any LFE content above 100Hz in that stream to "play through". IOW, if the sub's LPF cannot be set above 100Hz, the entire stream is limited to 100Hz.
post #45 of 57
Quote:
Originally Posted by eljaycanuck View Post

I was sweeping up some cat litter just now and it occurred to me that, at a line level anyway, the sub has no way of knowing what channels comprise the audio stream it's being fed, so it can't possibly decide to limit any speaker content in that stream to 100Hz while allowing any LFE content above 100Hz in that stream to "play through". IOW, if the sub's LPF cannot be set above 100Hz, the entire stream is limited to 100Hz.

That's exactly what I want to confirm too.

I understand that the subwoofer receives information from two sources.

The first is the LFE content that the sound engineer puts in the .1 channel (which ranges from 80-120hz). The setting within the avr menus called LPF of LFE controls this. Most people put this at 120hz to guarantee nothing gets cut.

The other source is from the crossover setting for your speakers. Anything below your crossover settings also goes to the sub. Most people put this around 80hz.

The knob on my sub is called LPF and ranges from 50hz to 100hz. I have it connected with a cable to the LFE IN.

It's unclear if this knob serves as a cap from the content it receives below the 80hz setting, or if it serves as a cap for the content it receives from the LFE channel.

If its the former, it doesn't matter since I have it maxed to 100hz but it doesn't receive signal above 80hz anyway. If it's the latter, if my sub can only play content up to 100hz, does that mean I shoild also set my avr LPF of LFE to 100hz since anything above 100hz and up to 120hz gets cut out, and if it does get cut does i matter?

I hope I make sense, thanks guys!
post #46 of 57
Quote:
Originally Posted by pbz06 View Post

That's exactly what I want to confirm too.

I understand that the subwoofer receives information from two sources.

The first is the LFE content that the sound engineer puts in the .1 channel (which ranges from 80-120hz). The setting within the avr menus called LPF of LFE controls this. Most people put this at 120hz to guarantee nothing gets cut.

Just so you are aware the LFE (low frequency effects) channel does NOT only include freqs from 80hz to 120hz. It DOES however include frequencies as low as 3hz up to 120hz.

The LPF (low pass filter) of the LFE channel is what ranges from 80hz to 120hz. So in your AVR what ever you choose 80, 100, 120 hz you are starting the cutoff slope there.
post #47 of 57
Just saying. My bet, the poster was referencing the high of the LFE range, not the full range of the LFE channel.
post #48 of 57
Yes you may be right. I was just informing not scolding.
post #49 of 57
pbz06: IMO, you're better off leaving the LPF of LFE at 120Hz. If the sub can play it, it will; if it can't, it won't, and no harm is done.
post #50 of 57
Quote:
Originally Posted by pbz06 View Post

The knob on my sub is called LPF and ranges from 50hz to 100hz. I have it connected with a cable to the LFE IN.
It's unclear if this knob serves as a cap from the content it receives below the 80hz setting, or if it serves as a cap for the content it receives from the LFE channel.
That reminds me of why the thermos bottle is the greatest invention of all time. It keeps hot stuff hot, it keeps cold stuff cold. How does it know? rolleyes.gif

The sub doesn't know if signal going to it is sourced from the LFE channel or not, it all enters the sub via the same cable. As for the caterwallering about what you should or should not do, you do what sounds best. Isn't that the point of having all these toys? For my system that means having the AVR crossover set at 80Hz, the sub amp LP filter at 100Hz. For your system it will be whatever you find works best for you, not what someone else thinks that you should like based mainly on pure conjecture about how sound reproduction gear actually works.
post #51 of 57
Quote:
Originally Posted by Bill Fitzmaurice View Post

The sub doesn't know if signal going to it is sourced from the LFE channel or not, it all enters the sub via the same cable.

Just like a sub is never a powered sub. Even the so-called powered subs are not active subs; they are passive. Just by slapping an amp with the sub enclosure doesn't mean the sub is active.
post #52 of 57
Quote:
Originally Posted by braveheart123 View Post

Just like a sub is never a powered sub. Even the so-called powered subs are not active subs; they are passive. Just by slapping an amp with the sub enclosure doesn't mean the sub is active.
That's getting into semantics. In general the term powered is applied to any speaker with on-board amplification, active is applied to crossovers, filters and EQ, as opposed to passive crossovers, filters and EQ. The typical sub is powered and active, as the low pass filters in the on-board amps are active filters. At a higher level of sophistication they also have active EQ via on-board DSP.
post #53 of 57
Well I see no difference, whatsoever, between a passive sub powered by an external amp (with active crossover and DSP) and a sub that has an amp attached with its enclosure (with active crossover and DSP). The only difference is the amp, which is either attached to the box or put away from it.
post #54 of 57
Quote:
Originally Posted by braveheart123 View Post

Well I see no difference, whatsoever, between a passive sub powered by an external amp (with active crossover and DSP) and a sub that has an amp attached with its enclosure (with active crossover and DSP). The only difference is the amp, which is either attached to the box or put away from it.
The difference is that one is called powered, the other is called passive, and one has a much longer wire connecting the driver to the amplifier. The definitions may not be accurate but they are nonetheless accepted.
post #55 of 57
Quote:
Originally Posted by flickhtguru View Post

Yes you may be right. I was just informing not scolding.

And you did it very thoughtfully.
post #56 of 57
Quote:
Originally Posted by braveheart123 View Post

Well I see no difference, whatsoever, between a passive sub powered by an external amp (with active crossover and DSP) and a sub that has an amp attached with its enclosure (with active crossover and DSP).

WAF and aesthetics. Just saying.
post #57 of 57

Then run Audyssey again. It should compensate for the reduced harmonic output from the sub by increasing those frequencies in the L/C/R and surrounds, where they belong.

67jnKg

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