Why crossover so high @ 80hz? Should I go lower? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 57 Old 09-15-2019, 01:06 PM - Thread Starter
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Why crossover so high @ 80hz? Should I go lower?

I have great Klipsch RP280FA speakers I am going to be setting up with a single SVS SB-2000 (WAF, Budget, Neighbors).

These speakers extend down to 32hz and apparently do a good job, lots of bass output and dual 8” woofers on both.

Clearly the SB-2000 is larger and more powerful but I am wondering if there is any thoughts on crossing over my Klipsch RPs lower (like 40-60hz) in order to maintain use of the four 8” woofers that will otherwise basically just get “turned off” below 80hz?

Wouldn’t this help delocalize, and even-out, bass output from two sources in the 40-80hz (or 60-80hz) range since the towers seem so good? And them, just leave the sub for either 20-40hz or 20-60hz output?

Perhaps this would make no sense at all... but please help me understand *WHY* I should cross over “so high” at 80hz when using such good tower speakers (and when not running dual subs)? It seems, in my limited understanding, that four 8” woofers in two locations would be superior to one 12” woofer in one location, for the frequencies of 60-80hz (or maybe even 40-80hz)?

Thanks for the insights!
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post #2 of 57 Old 09-15-2019, 01:09 PM
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The woofers don’t “turn off” below the crossover.

If you set a 80hz crossover, woofers are still working well below 80hz, sometimes only down 12dB at 20hz.

It also doesn’t really help with delocalization because at 80hz the wavelengths are so long that they are essentially omniradiant.

Leave it at 8 ohms and call it a day :)
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post #3 of 57 Old 09-15-2019, 01:25 PM
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Quote:
Originally Posted by filmguy123 View Post
Perhaps this would make no sense at all... but please help me understand *WHY* I should cross over “so high” at 80hz when using such good tower speakers (and when not running dual subs)? It seems, in my limited understanding, that four 8” woofers in two locations would be superior to one 12” woofer in one location, for the frequencies of 60-80hz (or maybe even 40-80hz)?
Mostly, it's to ease some of the workload off from the speaker, and allowing the sub to do the grunt work. AFAIK, it also makes it easier to drive the speakers since they're not having to work as hard because the sub is handling the lower frequencies, and it'll produce cleaner/clearer bass.

You can go lower if you want - usually 20Hz above the speaker's lowest Frequency Response spec is fine as I have been told in other AV forums. If your towers go down to the 30Hz range, try setting 60Hz as your crossover. If that sounds better to you, and you're not able to localize the sub then leave it there.
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post #4 of 57 Old 09-15-2019, 01:46 PM - Thread Starter
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Ryan -- Aha - that's interesting about the 60hz potential - with a Denon X4500H and 125w/channel on a 5.1.2 setup on those efficient Klipsch speakers, I think dropping the crossover to 60hz might be a good fit. Now, obviously this will come down to sound and I *must* test that (but I can't for a few weeks!). But out of intellectual curiosity, in theory, is there any reason why this would be better/worse? Was my speculation on-point regarding such?

Russ -- Ahhh this may invalidate my above question to Ryan. I did not know that, someone somewhere gave me misinformation. I was told the cross over was a hard stop for the speakers, not the point where it gradually fades off (which makes a lot more sense to me). So, what you are saying is below 80hz, the towers taper off and the sub tapers in? If that's the case, it would seem to make zero sense to set my crossover lower at 60hz? Or is there any reason at all to do that?

(also, how does the AV receiver calculate how much and at what curve the crossover taper takes place?)

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post #5 of 57 Old 09-15-2019, 01:54 PM
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Quote:
Originally Posted by filmguy123 View Post
Ryan -- Aha - that's interesting about the 60hz potential - with a Denon X4500H and 125w/channel on a 5.1.2 setup on those efficient Klipsch speakers, I think dropping the crossover to 60hz might be a good fit. Now, obviously this will come down to sound and I *must* test that (but I can't for a few weeks!). But out of intellectual curiosity, in theory, is there any reason why this would be better/worse? Was my speculation on-point regarding such?



Russ -- Ahhh this may invalidate my above question to Ryan. I did not know that, someone somewhere gave me misinformation. I was told the cross over was a hard stop for the speakers, not the point where it gradually fades off (which makes a lot more sense to me). So, what you are saying is below 80hz, the towers taper off and the sub tapers in? If that's the case, it would seem to make zero sense to set my crossover lower at 60hz? Or is there any reason at all to do that?



(also, how does the AV receiver calculate how much and at what curve the crossover taper takes place?)

Crossovers are generally set in multiples of 6dB per octave. Standard is 12dB an octave.

Octave: Doubling the Hz, so 80-160hz is an octave and so is 40-80hz.

The type of filter/crossover also depends, but generally Linkwitz-Riley (Also known as L/R) crossover slopes are standard (I think?) and you can look up an example of that. But if you look up “Second Order (Order refers to dB/octave, 2nd Order means 12dB an Octave, 2 x 6dB like I said earlier) Linkwitz-Riley Crossover Slope” you can see the filter.

It doesn’t really matter where you set it at, watch the same movie with the different crossovers and determine whichever setup you liked better.

Sorry if my explanation above was crude, I’m not exactly a pro.
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Leave it at 8 ohms and call it a day :)
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post #6 of 57 Old 09-15-2019, 02:01 PM
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Originally Posted by Ryan Statz View Post
If that sounds better to you, and you're not able to localize the sub then leave it there.
This is what it all boils down to. Try different crossovers with the same source material and use whichever sounds best to you.

Quote:
Originally Posted by filmguy123
(also, how does the AV receiver calculate how much and at what curve the crossover taper takes place?)
In most consumer AVRs the crossover slope is fixed (I believe most use 2nd order, or 12dB/octave, but I can't verify that). Some higher end AVRs allow the user to adjust the slope.


ETA: I see Russ beat me to it.

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post #7 of 57 Old 09-15-2019, 02:11 PM
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Originally Posted by filmguy123 View Post
Ryan -- Aha - that's interesting about the 60hz potential - with a Denon X4500H and 125w/channel on a 5.1.2 setup on those efficient Klipsch speakers, I think dropping the crossover to 60hz might be a good fit. Now, obviously this will come down to sound and I *must* test that (but I can't for a few weeks!). But out of intellectual curiosity, in theory, is there any reason why this would be better/worse? Was my speculation on-point regarding such?

Russ -- Ahhh this may invalidate my above question to Ryan. I did not know that, someone somewhere gave me misinformation. I was told the cross over was a hard stop for the speakers, not the point where it gradually fades off (which makes a lot more sense to me). So, what you are saying is below 80hz, the towers taper off and the sub tapers in? If that's the case, it would seem to make zero sense to set my crossover lower at 60hz? Or is there any reason at all to do that?

(also, how does the AV receiver calculate how much and at what curve the crossover taper takes place?)
I'm not sure whether it would be better or worse. AFAIK it's done to achieve a more seamless blend in the frequencies produced by both the speakers and sub to eliminate one's ability to localize the subwoofer. I also suspect it has a lot to do with achieving a flatter response time. However, I think placement of your subwoofer might also play a part in how flat the response time is as well? You wouldn't really be able to tell any of that without taking proper measurements with a calibrated mic and REW software. I think if you take those measurements, and you see a dip in where the crossover points take place, then adjusting the crossover of the speakers or adjusting the placement of your subwoofer could possibly result in an overall flatter response time? That's just what the logic in my brain tells me, I think someone with greater experience will be able to steer you in the right direction (and I invite anyone to correct anything I've said).

Yeah, it's a gradual tapering off/tapering in, not so much a hard stop.

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We see the 80 hz cross over setting question all the time. Here are my two thoughts:

1) It all depends on your system, room, and listening preference. Do what sounds best to you. Run some test tone sweeps and also replay some of your favorite songs or movie scenes under the different settings to see what you like.

2) There's no home theater police who'll drag you to jail for having some taboo cross over.
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post #9 of 57 Old 09-15-2019, 03:59 PM - Thread Starter
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Y'all are awesome. Thanks for the help and insights! (also, sorry to ask a question you see all the time!)

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post #10 of 57 Old 09-15-2019, 05:14 PM
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Quote:
Originally Posted by filmguy123 View Post
I have great Klipsch RP280FA speakers I am going to be setting up with a single SVS SB-2000 (WAF, Budget, Neighbors).

These speakers extend down to 32hz and apparently do a good job, lots of bass output and dual 8” woofers on both.

Clearly the SB-2000 is larger and more powerful but I am wondering if there is any thoughts on crossing over my Klipsch RPs lower (like 40-60hz) in order to maintain use of the four 8” woofers that will otherwise basically just get “turned off” below 80hz?

Wouldn’t this help delocalize, and even-out, bass output from two sources in the 40-80hz (or 60-80hz) range since the towers seem so good? And them, just leave the sub for either 20-40hz or 20-60hz output?

Perhaps this would make no sense at all... but please help me understand *WHY* I should cross over “so high” at 80hz when using such good tower speakers (and when not running dual subs)? It seems, in my limited understanding, that four 8” woofers in two locations would be superior to one 12” woofer in one location, for the frequencies of 60-80hz (or maybe even 40-80hz)?

Thanks for the insights!
You have 2x8" sealed woofers in each tower. The subwoofer you have in mind is 12" sealed sub.
I assume that the woofers have Xmax=7 and Vd=150cm3, and subwoofer has Xmax=14mm, Vd=725cm3.

When you look at the displacement capabilities of the 4x8" (two tower speakers) vs 1x12" (single subwoofer) their displacement is almost identical. That is if you equalize both setups to 20Hz the 4x8in woofers SPL will be only 1.6dB below the 1x12" sealed subwoofer SPL. There is no point of adding 1x12" sealed sub.

If you want to xover at 40Hz and have subs output at 20Hz match the 4x8" output at 40Hz (flat FR, not counting room gain) you should get 4x12" sealed subs.

I hope that helps.

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post #11 of 57 Old 09-15-2019, 08:48 PM - Thread Starter
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When you look at the displacement capabilities of the 4x8" (two tower speakers) vs 1x12" (single subwoofer) their displacement is almost identical. That is if you equalize both setups to 20Hz the 4x8in woofers SPL will be only 1.6dB below the 1x12" sealed subwoofer SPL. There is no point of adding 1x12" sealed sub.

If you want to xover at 40Hz and have subs output at 20Hz match the 4x8" output at 40Hz (flat FR, not counting room gain) you should get 4x12" sealed subs.
I'm confused... you're saying having the SVS SB-2000 with my RP-280FA speakers is pointless? My understanding was the following:

1. the SB-2000 digs deeper and lower down 19hz
2. offloading low frequencies to sub allows less distortion and lessens strain on my receiver
3. the sub would be better at handling low frequencies even so due to specific tuning

But it sounds like you're saying I shouldn't even bother with the sub, or, I would need 4 of those SVS subs to do the same job?

I'd love to hear more on this...
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post #12 of 57 Old 09-15-2019, 09:01 PM
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Originally Posted by filmguy123 View Post
I'm confused... you're saying having the SVS SB-2000 with my RP-280FA speakers is pointless? My understanding was the following:

1. the SB-2000 digs deeper and lower down 19hz
2. offloading low frequencies to sub allows less distortion and lessens strain on my receiver
3. the sub would be better at handling low frequencies even so due to specific tuning

But it sounds like you're saying I shouldn't even bother with the sub, or, I would need 4 of those SVS subs to do the same job?

I'd love to hear more on this...
I wouldn't worry about any of that. The moment someone starts bringing math equations into the discussion is the moment when it gets needlessly complicated.

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post #13 of 57 Old 09-15-2019, 09:08 PM
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But it sounds like you're saying I shouldn't even bother with the sub...
No, forget that. Keep the sub for the reasons already mentioned. Ideally, you would want to measure the 60 Hz and 80 Hz configurations and see which is smoother. If you don't want to/can't measure then try both. If you want to keep it even more simple, put it at 80 and call it a day.

Two or more subs will give you better potential to smooth out the response, give you an efficiency gain, and lower distortion, but one sub is better than none.
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post #14 of 57 Old 09-15-2019, 09:45 PM
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Originally Posted by filmguy123 View Post
I'm confused... you're saying having the SVS SB-2000 with my RP-280FA speakers is pointless? My understanding was the following:

1. the SB-2000 digs deeper and lower down 19hz
That's correct as long as the towers are not EQd. Their Fb will be around 45Hz (my guess). In sealed boxes Fb will depend on the driver (subwoofer has lower Fs). Below Fb if not EQd there the SPL will attenuate 12dB/oct.

If you EQ your tower speakers to be flat until Fb of the subwoofer (let say 34Hz) from 34Hz below the subwoofer and the tower speakers SPL would be identical. It will get weaker by 12dB/oct.
Remember that in both cases we have acoustic suspension drivers (sealed boxes). It's all about displacement. Different size boxes and different drivers (TS parameters) will get different Fb for each box.
If the box is sufficiently large the driver will get to Xmax before reaching Pmax. Both 4x8" and 1x12" will get similar SPL when playing at Xmax.
The power they will require to get there will be different for each box though.


Quote:
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2. offloading low frequencies to sub allows less distortion and lessens strain on my receiver
True. The less a driver moves the less distortion it produces due to non-linenarities in the driver motor design, power compression and "dopler distortion" to name a few.


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3. the sub would be better at handling low frequencies even so due to specific tuning
Sealed subwoofer handles low frequencies by it's displacement. The ported subs are more complex and rely on tuning as well. Ported subs get to lower port resonance freq but the drop out below that is really steep (24dB/oct). For the same displacement the ported sub would have 12dB more SPL at port frequency for the same driver displacement but it's output would almost disappear below resonance freq while the sealed sub would continue playing at lower frequencies. All that is a really simplified look at the different designs though.

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But it sounds like you're saying I shouldn't even bother with the sub, or, I would need 4 of those SVS subs to do the same job?
1. If you are after LF SPL only then you would not get any more SPL if you crossover to 1x12" sealed sub
2. If you just want to delegate the low frequency large excursion duties and reduce the distortion from the woofers this way - yes, 1x12" sub would work great.

1x12" sealed subs would deliver the same SPL down to 20Hz as the 4x8" woofers at 20Hz. (97dB)

4x12" sealed subs would continue to deliver the same SPL down to 20Hz as the 4x8" woofers at 40Hz where they would delegate to the subs. (109dB)

4x8in woofers would get 97dB at 20Hz alone, the same for 1x12" sub at 20Hz.
4x8in woofers would get 109dB at 40 Hz and xover to 4x12" subs will get 109dB at 20Hz.

I hope this helps. :-)

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post #15 of 57 Old 09-15-2019, 10:47 PM - Thread Starter
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Hmmm yes this does sound a bit complicated. I just want the cleanest, most accurate, nuanced bass possible in the largest spectrum of frequencies.

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post #16 of 57 Old 09-15-2019, 11:15 PM
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Hmmm yes this does sound a bit complicated. I just want the cleanest, most accurate, nuanced bass possible in the largest spectrum of frequencies.
That calls for a sealed sub. You already have sealed woofers in the tower which is great. At 80Hz xover the tower woofers would move only 1/10 of current excursion and distortion associated with that would drop significantly.

As far as the size and number of subs - I would go with 2x10" instead of 1x12" as minimum size and number of subs if I had the option.
10" sealed sub has better cone control than 12" in sealed sub everything else being equal.
Keep in mind that 12" sub is still pretty good too (you are looking for "cleanest, most accurate, nuanced bass"..).
2x10" would give you 4.4dB more at 20Hz than you would get with EQ of the tower speakers. 1x12" would give you only 1.6dB more at 20Hz.

Again, if 1x12" is the only option - go for it.
Xover at 80Hz for the lowest distortion from the woofers.


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post #17 of 57 Old 09-16-2019, 02:06 AM
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Hmmm yes this does sound a bit complicated. I just want the cleanest, most accurate, nuanced bass possible in the largest spectrum of frequencies.
It doesn't need to be complicated. The Klipsch speakers and SVS sub will make for a very nice system. The most complicated part will be integrating them. It's fun though and this will help:

https://www.avsforum.com/forum/113-s...eferences.html

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10" sealed sub has better cone control than 12" in sealed sub everything else being equal
Can you explain what you mean by that?

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post #18 of 57 Old 09-16-2019, 07:11 AM
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Hmmm yes this does sound a bit complicated. I just want the cleanest, most accurate, nuanced bass possible in the largest spectrum of frequencies.
Bingo, that's exactly what you should want to achieve. There is lots of good info' in this thread that are certainly "Factors" ...but your realities and limiting factors are getting the best from the equipment you have in the room you are working with. This may be redundant but I would recommend relooking your LRC placement (distance from walls, tow-in, HF driver height) if you haven't already done so, then do a sub crawl if you have not already done so in order to find the best possible location in your room. Both of these steps can lead to simple adjustments that can make huge sonic improvements. Once you've optimized speaker locations you can simply start playing with your LF cutoff and sub gain until you find the the "Blend" that is most pleasing to you. As previously mentioned, a good rule of thumb is to crossover at the lowest frequency you can that gives you the smoothest most pleasing result from the equipment you have.

I'll end by saying that IMHO adding a second or more subs to any "1 sub system" is perhaps the most beneficial and underrated sonic improvement anyone can make to their system. Adding subs reduces LF room nulls, provides smoother low end frequency response throughout much more of the room, increases LF room gain meaning you will get more low end presence along with smoother response from less sub "volume". I think getting 20-90hz right is foundational to a good sounding system. Good luck
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post #19 of 57 Old 09-16-2019, 07:32 AM
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Originally Posted by Vergiliusm View Post
"..10" sealed sub has better cone control than 12" in sealed sub everything else being equal..."

Can you explain what you mean by that?
Every time the subwoofer size is increased or the driver motor design is modified to provide "High Output" that reduces the cone control. That reduces the "musicality" of the subwoofer, it's ability to blend in with the speakers.

You can see that in the subwoofer driver Impedance and Phase graphs around Fs. The subwoofer drivers are the only type of driver used within it's own resonant frequency due to the lack of other alternatives.

The harder it is for the driver motor to control the cone the more uneven the graphs appear.

Below are the Impedance/ Phase graphs for some Dayton Audio Reference 10in, 10in HO, 15in, 15in HO and 18in HO subwoofer drivers.

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Klipsch RP-280FA are actually bass reflex loudspeakers. They have a claimed -3 dB point of 32 Hz. Brent Butterworth of hometheaterreview.com measured them and found -3dB at 37 Hz using the ground plane technique. The measurements suggest the port tuning frequency is around 40 Hz. Below that, they will roll off at the usual 24/dB per octave. His measurements show them 23-23 dB down at 20 Hz, which is right where you would expect.


https://hometheaterreview.com/klipsc...viewed/?page=2


I don't think you can equalize them flat to replace the SVS SB-2000. Even if they were sealed with the same specs and needed only half the EQ boost, +12 dB at 20 Hz is still a lot to ask for. Most likely you'd just suck up a lot of amplifier power to produce a lot of distortion. There's a reason why sub are practically required for home theater.


To OP, I would try 60 Hz crossover but no lower. If it sounds better than 80 Hz, great.
Regarding potential improvements, my vote would be to measure the room first, to get a handle on what the problem areas are in the bass. But without data, my guess is that you would be best off adding a second matching subwoofer and placing the two subs in locations where they can cancel room modes. Then add bass trapping.
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post #21 of 57 Old 09-16-2019, 10:33 AM
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Hmmm yes this does sound a bit complicated. I just want the cleanest, most accurate, nuanced bass possible in the largest spectrum of frequencies.
If ideal bass is your goal, the next move you need is to get another sub just like the one you have. I realize your space might not allow it, but that is the single greatest thing you can do for your system.

Otherwise, my longtime (unprofessional) experience has been that 80 Hz is a great setting to really let your subs be what they are. Your towers will still play below that, but not to the point where they are fighting with the subs over low-end frequencies. Setting the crossovers too low sounds awkward to me with a sub involved.
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post #22 of 57 Old 09-16-2019, 12:13 PM
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Ryan -- Aha - that's interesting about the 60hz potential - with a Denon X4500H and 125w/channel on a 5.1.2 setup on those efficient Klipsch speakers, I think dropping the crossover to 60hz might be a good fit. Now, obviously this will come down to sound and I *must* test that (but I can't for a few weeks!). But out of intellectual curiosity, in theory, is there any reason why this would be better/worse? Was my speculation on-point regarding such?

Russ -- Ahhh this may invalidate my above question to Ryan. I did not know that, someone somewhere gave me misinformation. I was told the cross over was a hard stop for the speakers, not the point where it gradually fades off (which makes a lot more sense to me). So, what you are saying is below 80hz, the towers taper off and the sub tapers in? If that's the case, it would seem to make zero sense to set my crossover lower at 60hz? Or is there any reason at all to do that?

(also, how does the AV receiver calculate how much and at what curve the crossover taper takes place?)
don't forget that the 125w is for 2 channels only, when you are really only sending ~70watts to each speaker with all 7 going. Though probably negligible as that's less than a 3db change.

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post #23 of 57 Old 09-16-2019, 12:40 PM
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Hmmm yes this does sound a bit complicated. I just want the cleanest, most accurate, nuanced bass possible in the largest spectrum of frequencies.
As mentioned, your towers' woofers are not sealed and have solid extension down to about 40hz while the SB2000 has essentially flat response up to 100hz and a -3db point of 19hz.

The more work the sub does in your scenario the better for the reasons mentioned below.

I have towers of similar extension and I've played with 60hz and 80hz and noticed little difference.

"Win 1. Since you are now not putting in 20 Hertz 80 Hertz into the mains you are not using up the available low frequency cone movement with bass, so the low frequency cone in your main speaker is able to play its higher frequencies (up to it’s crossover point) much more cleanly. You get an apparent 6dB or more dynamic range. You can play your system louder, and also with less compression distortion in the low frequency driver...

Win 2. Since you are not putting bass into that same driver...This means cleaner mids. By far.

Win 3. You are not sucking current out of your main power amp at low frequencies, so there is more current reserve to play those highs louder.

Win 4. Since the cones are not moving as far at the low frequencies...there is far less current draw by the speakers. "

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post #24 of 57 Old 09-16-2019, 01:02 PM
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To the OP,

If your receiver has bass mangement set LFE to 80hz

Set your speakers to small and cross at 80hz

On the SVS SB-2000 set the physical crossover to 80hz

Enjoy
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post #25 of 57 Old 09-16-2019, 01:07 PM
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Can you explain what you mean by that?
It's a false claim based on an old audio myth. He's repeated it a few times lately, and is always refuted with evidence. He then slinks away to repeat the falsehood when opportunity arises again

edit: Great rebuttal of his misinformation here: https://www.avsforum.com/forum/113-s...l#post58454024
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post #26 of 57 Old 09-16-2019, 01:13 PM
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To the OP,

If your receiver has bass mangement set LFE to 80hz

Set your speakers to small and cross at 80hz

On the SVS SB-2000 set the physical crossover to 80hz

Enjoy
Actually the recommendation is LFE at 120hz though some use 80hz successfully, but for sure the physical crossover on the sub should be set to it maximum, (on the SVS that is labeled LFE).

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post #27 of 57 Old 09-16-2019, 01:35 PM
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Actually the recommendation is LFE at 120hz though some use 80hz successfully, but for sure the physical crossover on the sub should be set to it maximum, (on the SVS that is labeled LFE).
Correct the LFE of 120hz is the THX recommanded setting, but it has also been noted by many professionals that 100hz and 80hz works just well since 90% of the LFE channel is below the 80hz crossover. I have both SVS PB-2000 and dual PB-3000 and I have always used 100hz for the LFE until I got the 3000's and started using cascading crossovers of 80hz.

With the PB-3000's you can actually tell the difference between max and 80hz with 80hz being more controlled and tighter sounding below 80hz.

Currently I have LFE off by default and control all bass management through the SVS app on the 3000's

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post #28 of 57 Old 09-16-2019, 01:55 PM
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Correct the LFE of 120hz is the THX recommanded setting, but it has also been noted by many professionals that 100hz and 80hz works just well since 90% of the LFE channel is below the 80hz crossover. I have both SVS PB-2000 and dual PB-3000 and I have always used 100hz for the LFE until I got the 3000's and started using cascading crossovers of 80hz.

With the PB-3000's you can actually tell the difference between max and 80hz with 80hz being more controlled and tighter sounding below 80hz.

Currently I have LFE off by default and control all bass management through the SVS app on the 3000's
Sure, why not throw out up to 10% of the sounds on the LFE channel? They must not have been important if they were over 80 Hz

You're saying your sub sounds different within the same under-80 Hz frequency range when you lower the onboard crossover?? That's improbable at best. Have any measurements, or just a hunch?
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post #29 of 57 Old 09-16-2019, 02:05 PM
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Originally Posted by filmguy123 View Post
Hmmm yes this does sound a bit complicated. I just want the cleanest, most accurate, nuanced bass possible in the largest spectrum of frequencies.
You can also try running your towers as "full range" or whatever Denon labels it. I run my towers full range most of the time because it sounds a little better a lower volumes like when watching TV or casual music listening.

I typically use 100 or 120hz crossover when watching bass heavy movies.

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post #30 of 57 Old 09-16-2019, 02:16 PM
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Originally Posted by filmguy123 View Post
Ryan -- Aha - that's interesting about the 60hz potential - with a Denon X4500H and 125w/channel on a 5.1.2 setup on those efficient Klipsch speakers, I think dropping the crossover to 60hz might be a good fit. Now, obviously this will come down to sound and I *must* test that (but I can't for a few weeks!). But out of intellectual curiosity, in theory, is there any reason why this would be better/worse? Was my speculation on-point regarding such?

Russ -- Ahhh this may invalidate my above question to Ryan. I did not know that, someone somewhere gave me misinformation. I was told the cross over was a hard stop for the speakers, not the point where it gradually fades off (which makes a lot more sense to me). So, what you are saying is below 80hz, the towers taper off and the sub tapers in? If that's the case, it would seem to make zero sense to set my crossover lower at 60hz? Or is there any reason at all to do that?

(also, how does the AV receiver calculate how much and at what curve the crossover taper takes place?)

You're getting a lot of good input here in this thread. There's one point I do want to make, that "it goes both ways" about crossovers, but first, just at a high level (and to repeat some of the points that have already been made):


You definitely don't want to cross over at *higher than* 80 Hz if you can help it. The only reason you "couldn't help it" is if your speakers aren't capable of playing down to and through 80 Hz without much roll-off. It sounds like this is not your situation (which is good). From about 80 Hz on down, sound is pretty much "omni-directional", so sending those frequencies over to be output at the sub doesn't tend to shmear or otherwise mess up your stereo imaging / directivity.

But otherwise, there's a trade-off to be had, as-follows:
1) On the one hand, crossing over higher up (80 Hz rather than 60 Hz or 40 Hz) tends to "off-load" the work-load from my 250 watt (125-watts-per-channel, into 2-channel, @ 8 ohms) Denon AVR, and let the 800 watt amp in my Rythmik "eat".

But, the one thing to keep in mind, is that a "cross-over" is not a hard, abrupt, changepoint. It is not as if an 80 Hz crossover means that 82 Hz tones, 81 Hz tones, 80.1 Hz, plays *entirely and only* from the speakers, and 79.9 Hz, 79 Hz, 78 Hz, etc. plays *entirely and only* from the sub. That's not how it works. They "cross over" into each other gently. It's not a hard, discrete, switch. With an 80 Hz cross-over, you're speakers are still playing some at 70 Hz, 60 Hz, etc, and your sub is still playing some at 90 Hz, 100 Hz, 120 Hz, etc. I think what what kind of software you're using to control those cross-overs generally dictates how sharp-or-gradual that handoff is? It's my understanding that I think Audyssey uses 12 db/octave as it's default setting, at least for how quickly the sub rolls off above the cross-over point. If I'm right about that (which, fair warning, I might not be), that means that the subwoofer is still playing, all-be-it 12 dB lower, at 160 Hz, with an 80 Hz cross-over...

2) SO, the "pro" to reducing your cross-over below 80 Hz is it helps get your subwoofer "out of the way" for frequencies that are directional and can shmear your stereo imaging...


I like to keep the 80 Hz crossover because I'm using a conventional 125 wpc AVR (for dual purpose music-and-movies) rather than a beefy dedicated 2-channel HiFi Amp. And I bought a subwoofer (Rythmik F25) that has a few extra knobs/control capabilities I can turn, including the ability to "roll off" at 24 db/octave above 80 Hz rather than 12... which I think helps.
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