Cross at 60 vs Cross at 100

[Chrispy]

The LFE channel carries a very wide bandwidth.

The LFE channel is normally limited to 120hz, altho can be higher but rarely is....at least that's my understanding.

 

[Chromatischism]

The LFE channel is normally limited to 120hz, altho can be higher but rarely is....at least that's my understanding.

True. Thinking about my comment again, it isn't the LFE channel that is the problem for most movies. The biggest problem is the redirected audio from all of your speakers.

 

[Chrispy]

True. Thinking about my comment again, it isn't the LFE channel that is the problem for most movies. The biggest problem is the redirected audio from all of your speakers.

That coiuld be different. I don't have particular issues with the redirected bass either otoh.

 

[Acerun]

But when you cross against a subwoofer you need to match the slopes. A sealed enclosure has 12 dB/octave which will be 24 dB/octave with the standard AVR filter of 12 dB/octave. This will be matched to the AVRsub slope of 24 dB/octave. The ported response of the Revel is rather complex as you can see from measurements, not easy to match.

Well, I'm at a bit of a loss with that analysis. See my latest reading. I tested the L and R sealed and the response dropped like a rock. Am I supposed to turn my subs down about 8db to hit the 60 crossover?

 

[boxerfan88]

I tested the L and R sealed and the response dropped like a rock.

It looks like when in sealed mode, the response starts falling from 150Hz thereabouts. The rolloff slope from 150Hz is less steep... which is consistent with sealed behavior.

 

[Acerun]

It looks like when in sealed mode, the response starts falling from 150Hz thereabouts. The rolloff slope from 150Hz is less steep... which is consistent with sealed behavior.

So where should I be aiming the crossover? I'd have to drop it about 8 to 10db to get it crossed at 60, no? That doesn't seem right.

Am I reading it right that perhaps crossing at 100 is the play?

 

[poxymoron]

The frequency response plot for the track "Sixteens Tons" is shown below. It shows a large amount of bass energy in the 36–46 Hz region.
View attachment 347177

The frequency response plot for the track "Limit To Your Love" is shown below. This has some strong tonal information in the 18–30 Hz frequency range.
View attachment 347180
The frequency response plot for the heartbeat at the beginning of Pink Floyd's "Dark Side Of The Moon" album shows a strong, broad peak at 31 Hz. It's interesting to listen to it as it builds in intensity.
View attachment 347193

If the subwoofer's ability to reproduce very low frequency content in music is of particular interest, then the track "Bass I Love You" provides a lot of low-frequency content at 9 Hz and 18 Hz, as well as 31 Hz. That should help test out most subwoofers quite nicely. The frequency response plot is provided below.
View attachment 347194

What software are you using for this? Audacity?

 

[Acerun]

What software are you using for this? Audacity?

Yes. MultiEQ-X. More I think about it. If I go down this path I would have to take all new measurements with the mains sealed wouldn't I?..

 

[Acerun]

What software are you using for this? Audacity?

Sorry I was on mobile. You were asking someone else this question.

 

[Chromatischism]

To add additional complications- I use digital crossover foo_subwoofer. I found out that crossover slope steepness has a subtle impact on sound (upper bass) quality where the subs-mains transition. So does mains-subwoofer delay settings therein.

Correct. Higher crossovers need a steeper slope to avoid sound quality degradation. To add, there is some crossover into the discussion on localizability of bass:

If we reference Floyd Toole in Loudspeakers and Rooms for Stereophonic Sound Reproduction, and Loudspeakers and Rooms - Working Together we find:

• Tests where bass transient signals were used support 60Hz being the limit of localizability.
• Tests where 2nd order slope crossovers are used support 60Hz.
• Tests where 4th-8th order slope crossovers are used support 80Hz.
• The early research on woofer localization used bass transients, bass sine waves, and music for blind testing as well as for measurement. Conclusion: bass transients over 60Hz can be localized. For sine waves, it is higher.
• The AES Technical Council notes in the Multichannel surround sound systems and operations document AESTD1001.1.01-10 that in small rooms, bass transients under 80Hz cannot be localized to the subs when steep crossovers are used.

 

[boxerfan88]

So where should I be aiming the crossover? I'd have to drop it about 8 to 10db to get it crossed at 60, no? That doesn't seem right.

Am I reading it right that perhaps crossing at 100 is the play?

Based on your measured mains FR amplitude response, these are my thoughts:

• if you're aiming to crossover in the 60-80Hz region, leave the mains as ported.
• if you're aiming to crossover in the >100Hz region, you can experiment with the sealed setup.

 

[Acerun]

Based on your measured mains FR amplitude response, these are my thoughts:

• if you're aiming to crossover in the 60-80Hz region, leave the mains as ported.
• if you're aiming to crossover in the >100Hz region, you can experiment with the sealed setup.

Right. That's what I thought I was seeing as well. Thanks.

 

[a2Thompson]

The lower output below 50 hz for the 80 and 100 crossovers makes no sense to me. Why would that happen? Unless most of the lower frequency energy is being supplied by the mains and not the subs.

 

[Hayabusa]

The lower output below 50 hz for the 80 and 100 crossovers makes no sense to me. Why would that happen? Unless most of the lower frequency energy is being supplied by the mains and not the subs.

indeed, that was also my conclusion, something is very wrong with that...

 

[jhaider]

View attachment 347475I’m not facile with this sort of thing, so please excuse my crude attempt, but what I’ve included here is a screen shot from the Rythmik L12 site. It shows that the FR bandwidth is different when using the Line In input vs. using the LFE input.

I went back to the thread and you are correct. However, even the limited upper bandwidth through LFE input - basically the same as JL E110 on first impression - qualifies them IMO as an “advanced users only” kind of product.

Certainly, they’re not a sub for someone looking to explore a wider range of crossover frequencies.

So, the reason Amir’s graph shows the sub’s response rolling off above 90Hz is not because of some technical limitation of the servo design, but rather because of an optional design feature intended for a specific use case.

Well…look at Erin’s review showing the driver good out to something like 800Hz. Take that and add the xmax Erin measured, and you have a very good drive unit!

Brian Ding has commented a few times about this compromise in his design. He thinks the tradeoff of lower bass distortion for limited top end is worthwhile.

 

[Acerun]

The lower output below 50 hz for the 80 and 100 crossovers makes no sense to me. Why would that happen? Unless most of the lower frequency energy is being supplied by the mains and not the subs.

A MultiEQ-X room adjustment? I have no idea, I took all of those readings back to back.

 

[ROOSKIE]

You have M126Be's. How do you cross them?

Sorry about delay. I'm really sick.

About 90hrz.
60hrz is to low for really high output levels in my space but it would be fine for most times.
Still I'd much rather have the subs handling the bulk of the 50-90hrz range vs a pair of 6.5s.
They are much more suited to delivering those frequencies.
I've used with a few different subs.
8's 10's 15's of various design.
Bear in mind I am mainly a 2 channel listener so this is a music system. No movie, LFE, rather miniDSP and ability to very easily make adjustments and blend subs and mains.

Fwiiw I don't think there is any benefit to sealing the M126be. Unless there is midrange leaking from the port. (Which I've never heard is an issue with this model) The drivers are not meant to be sealed in a box that 'big'(it would be about 1/3 that size if designed as such) you are likely losing powerhandling & output & gaining nothing back.

Changing the crossover is not the only variable. Each time you adjust you may have to tweak in relationship to other variables. Also there are room modes, SBIR, Subwoofer(s) location, location of mains to walls ECT.

I also use a different target for the bass region room responce vs the flat slope you posted.

I also apply PEQ/room adjustments above about 150hrz to each L & R channel independently. Below that I generally apply globally.

But when you cross against a subwoofer you need to match the slopes. A sealed enclosure has 12 dB/octave which will be 24 dB/octave with the standard AVR filter of 12 dB/octave. This will be matched to the AVRsub slope of 24 dB/octave. The ported response of the Revel is rather complex as you can see from measurements, not easy to match.

Howdy, I don't agree.
I don't find this is the same as matching something like a tweeter and midrange.
Blending the sub is not delicate, it is almost a bit of brute force crude endevor.
The wavelengths are enormous and nearly 100% omni(unless crossing high to say make a diy 3way) and blend together very easily. They do not need to matched like the ideal on paper especially as they absolutely to do not behave that way in rooms.
Then the many, many different room effects are massive and much room correction is used below 150hrz relative to other regions.
I've never had a problem getting superb blending with a little time involved to try a few different things. Though with miniDSP that is easier vs most AVRs still I could certainly get a good blend in the bass and especially if any PEQ or RC is going to be used.
Just measure with every adjustment and take some time.

 

[jbattman1016]

I have a few questions, like why you are not using the built-in aps of the 8500H, but some tips for getting better sound.
Modify the sound curve via the JSON file from the multi-EQ app, I'm using the Toole+bass curve from AVSForum.
Disable the following surround parameters from the denon (Cinema QE and Loudness).

Changing the audyssey adjustment frequency just means the frequencies above that are going to remain as is and not touched by the target curve. I have this set to 500Hz as well.

I set my crossover to 60Hz for my system and this sounds good, but did run it at 90Hz for a while. Still testing.

Some details here on how to manually edit the curve: https://www.avsforum.com/threads/an...r-tweaking-audyssey-multeq-app-files.3006886/
The last couple of pages show how to edit the curve in a browser/JSON editor so you don't need to use the software.

 

[Thomas_A]

Sorry about delay. I'm really sick.

About 90hrz.
60hrz is to low for really high output levels in my space but it would be fine for most times.
Still I'd much rather have the subs handling the bulk of the 50-90hrz range vs a pair of 6.5s.
They are much more suited to delivering those frequencies.
I've used with a few different subs.
8's 10's 15's of various design.
Bear in mind I am mainly a 2 channel listener so this is a music system. No movie, LFE, rather miniDSP and ability to very easily make adjustments and blend subs and mains.

Fwiiw I don't think there is any benefit to sealing the M126be. Unless there is midrange leaking from the port. (Which I've never heard is an issue with this model) The drivers are not meant to be sealed in a box that 'big'(it would be about 1/3 that size if designed as such) you are likely losing powerhandling & output & gaining nothing back.

Changing the crossover is not the only variable. Each time you adjust you may have to tweak in relationship to other variables. Also there are room modes, SBIR, Subwoofer(s) location, location of mains to walls ECT.

I also use a different target for the bass region room responce vs the flat slope you posted.

I also apply PEQ/room adjustments above about 150hrz to each L & R channel independently. Below that I generally apply globally.


Howdy, I don't agree.
I don't find this is the same as matching something like a tweeter and midrange.
Blending the sub is not delicate, it is almost a bit of brute force crude endevor.
The wavelengths are enormous and nearly 100% omni(unless crossing high to say make a diy 3way) and blend together very easily. They do not need to matched like the ideal on paper especially as they absolutely to do behave that way in rooms.
Then the many, many different room effects are massive and much room correction is used below 150hrz relative to other regions.
I've never had a problem getting superb blending with a little time involved to try a few different things. Though with miniDSP that is easier vs most AVRs still I could certainly get a good blend in the bass and especially if any PEQ or RC is going to be used.
Just measure with every adjustment and take some time.

I treat integration and room effects separately. Having sealed speakers or speakers where ports can be plugged getting that ≈12 dB/octave slope and crossing at 80-100 Hz with the standard 12/24 filter is the start. Using a separate DSP is another solution for integration. Then use parametric EQ to dampen room modes.

 

[sigbergaudio]

I'm not sure I understand most of these measurements. There are massive differences even very low in frequency between them. In this graph for instance they're not at all at the same level say at 30hz. Why?

Can we get a graph with just the difference between 60, 80 and 100 for instance, in the same graph, taken at the same time, and only showing 20-200hz on the X-axis? (no point in seeing the full frequency range). And no smoothing.