Time alignment vs. frequency response: Is the battle real?

[Sancus]

Obviously you have strong opinions but very little facts. The problem is not the bass driver but rather the room itself. Below 200 Hz or so, the room is very dominant. The additional subs are to reduce the effects of the modes in the room. Please read up on the subject. The information is readily available.

Probably best not to feed trolls of this type.

To add something to the discussion... Does the X4400 not support the multeq app? It makes way more sense to me to use the app to manually change the sub EQ than to try to trick Audyssey about how many subs there are.

 

[Spenav]

... and actually measure the behaviour of a single sub in your room, at your listening position, and various other locations. It becomes very obvious very quickly once you see the frequency response graph staring you in the face.

Actually, he should move around his room and just listen in different locations to quickly understand that the bass is very different from location to location. This is a very simple experiment that requires zero additional instrument.

 

[Spenav]

Probably best not to feed trolls of this type.

To add something to the discussion... Does the X4400 not support the multeq app? It makes way more sense to me to use the app to manually change the sub EQ than to try to trick Audyssey about how many subs there are.

You are correct. My bad.

 

[617]

I'm not sure what your assumption here is, but it is worth mentioning that the eq for different LF sources will be different. Basically you make one suck as little as possible, then you add another in, filling in some of the gaps from the first, then you add a third. Fourth makes much less difference, which is why 3 is the recommended number of subs.

 

[Bullwinkle J Moose]

Obviously you have strong opinions but very little facts. The problem is not the bass driver but rather the room itself. Below 200 Hz or so, the room is very dominant. The additional subs are to reduce the effects of the modes in the room. Please read up on the subject. The information is readily available.

I have read everything I needed to build a better system

I invented the 3 channel home theater experience before Dolby ever heard of it

The original is still the best

There is none better!

 

[Bullwinkle J Moose]

... and actually measure the behaviour of a single sub in your room, at your listening position, and various other locations. It becomes very obvious very quickly once you see the frequency response graph staring you in the face.

That is entirely incorrect

My sweet spot is the entire room

Yours changes millimeter by millimeter

 

[seedragon]

Probably best not to feed trolls of this type.

To add something to the discussion... Does the X4400 not support the multeq app? It makes way more sense to me to use the app to manually change the sub EQ than to try to trick Audyssey about how many subs there are.

It does support that app, which is what I use. But the app doesn't allow you to change settings for your subs independently, even if you connect your subs independently and run Audyssey. In fact, after MultEQ X32's SubEQ HT extension sets the level and delay of your subs independently in the first pass of calibration, it sends them the exact same sweep at the same time for each pass thereafter because Audyssey wants to apply a global EQ to both subs summed.

So I'm not so much "tricking" Audyssey into thinking it's working with one sub so much as I am setting the delays myself to prioritize a smoother FR over correct time before I let Audyssey EQ the summed response. The problem that I'm highlighting is that when I set the delay myself, I am optimizing for even FR, whereas Audyssey is optimizing for correct time (which creates a terrible FR that drops off a cliff after 40hz). What I ideally want is to optimize for both.

 

[BDWoody]

I am the only one with the facts!

Yeah...
Thread ban.

 

[fieldcar]

I recently played around with doing a sub crawl for my 2x 550p's and 1x SB-2000 pro.(I know, I shouldn't mix and match, but I'll get another SB-2000 pro eventually). Don't forget to disable audyssey when doing this to remove the room correction.

I ended up using 'this youtube test track' to sweep from 20-65Hz while I did the sub crawl. Instead of just listening by ear, I used spectroid on my android phone to watch how a few good sub crawl locations would work out. Some locations had bass fall off from 20-25Hz, and others had a nice extended low end. Since I have two separate subwoofer models, I redid the crawl for each type.

I'll probably re-arrange and try again just for the heck of it, but here is what I got with my last audyssey test. I'm happy with the results.

 

[seedragon]

I recently played around with doing a sub crawl for my 2x 550p's and 1x SB-2000 pro.(I know, I shouldn't mix and match, but I'll get another SB-2000 pro eventually). Don't forget to disable audyssey when doing this to remove the room correction.

I ended up using 'this youtube test track' to sweep from 20-65Hz while I did the sub crawl. Instead of just listening by ear, I used spectroid on my android phone to watch how a few good sub crawl locations would work out. Some locations had bass fall off from 20-25Hz, and others had a nice extended low end. Since I have two separate subwoofer models, I redid the crawl for each type.

I'll probably re-arrange and try again just for the heck of it, but here is what I got with my last audyssey test. I'm happy with the results.

View attachment 122421

Thanks for chiming in, but did you measure your actual room response after running Audyssey? That "AFTER" plot is what Audyssey thinks your room response is after correction, but I've never seen it be anywhere near reality. Run a measurement with REW and I think you'll be surprised by what's actually going on...

 

[fieldcar]

did you measure your actual room response after running Audyssey?

No. I've eyed up the UMIK-1, but haven't taken the plunge yet. I'm pretty satisfied with the broad correction that Audyssey applies. There are peaks/dips, but the general tone is where I want it for now.

That "AFTER" plot is what Audyssey thinks your room response is after correction, but I've never seen it be anywhere near reality. Run a measurement with REW and I think you'll be surprised by what's actually going on...

Yeah. I've seen some of the posts showing a sweep from REW after audyssey correction. My jbl 590's are fairly linear before the correction, so I'm not too worried. I would like to nail down room correction a bit further though, since I only have a backwall absorber at the moment.

Good luck nailing down the sound in your system!

 

[Sancus]

So I'm not so much "tricking" Audyssey into thinking it's working with one sub so much as I am setting the delays myself to prioritize a smoother FR over correct time before I let Audyssey EQ the summed response. The problem that I'm highlighting is that when I set the delay myself, I am optimizing for even FR, whereas Audyssey is optimizing for correct time (which creates a terrible FR that drops off a cliff after 40hz). What I ideally want is to optimize for both.

Yes, I understand, what I'm saying is it's probably better to let Audyssey's delays stand and then adjust the EQ to fix the cliff. I'm really skeptical that just manually adjusting delay to produce a smooth FR is a good idea. Of course, you can adjust phase slightly to deal with dips, but if you're adjusting delay significantly then you're going to produce more than slight phase differences...just doing manual adjustments seems like a pretty bad idea unless you have a lot of experience with that and a deep understanding of FR vs phase and delay tradeoffs.

If the cliff is not just a null, I'm not sure what could be going on tbh as I've never seen an Audyssey result that created a rolloff before.... but honestly I've never seen a detailed examination of Audyssey's behaviour with more than 1 sub, so who knows what it's doing.

At the end of the day, the most proper solution if Audyssey isn't doing the job for whatever reason would be to get a MiniDSP and use Multi-Sub Optimizer(as previously suggested) since it's a much more sophisticated form of bass management. Short of getting a much more expensive AVR with Dirac's new bass module, I think that software produces the best multi-sub results out there.

 

[seedragon]

Yes, I understand, what I'm saying is it's probably better to let Audyssey's delays stand and then adjust the EQ to fix the cliff. I'm really skeptical that just manually adjusting delay to produce a smooth FR is a good idea. Of course, you can adjust phase slightly to deal with dips, but if you're adjusting delay significantly then you're going to produce more than slight phase differences...just doing manual adjustments seems like a pretty bad idea unless you have a lot of experience with that and a deep understanding of FR vs phase and delay tradeoffs.

If the cliff is not just a null, I'm not sure what could be going on tbh as I've never seen an Audyssey result that created a rolloff before.... but honestly I've never seen a detailed examination of Audyssey's behaviour with more than 1 sub, so who knows what it's doing.

At the end of the day, the most proper solution if Audyssey isn't doing the job for whatever reason would be to get a MiniDSP and use Multi-Sub Optimizer(as previously suggested) since it's a much more sophisticated form of bass management. Short of getting a much more expensive AVR with Dirac's new bass module, I think that software produces the best multi-sub results out there.

What you say makes sense, which is why I'm having a lot of difficulty with this situation. However, when I let Audyssey control the delay, my FR was something like -30 dB below 40 hz. I'll need to run the measurement again to recall what the drop off was exactly, but I knew that it wouldn't be correctable with EQ. That's why I opted to adjust the delay myself to recover that band--which mostly worked except for a -5 dB dip between 20-40 hz--and let Audyssey EQ it from there. That has produced a workable FR, but now my issue is that Audyssey's curve editor doesn't appear to have any affect on FR.

miniDSP does look like the next step!

 

[Chrispy]

Factoid of the day:

A Single Sub is always the best solution!

LOL thanks for the laugh!

 

[Zedly]

I had a single sub for supper tonight, and to be fair, it was a pretty good solution (to hunger).

 

[holbob]

Yeah but if you get another one you'll have a rounder curve....

 

[Elfsberg]

All frequency response sums up in phase below 100 Hz, pretty much. I would NEVER let an automatic system like Audyssey calibrate my setup. Not ONCE have I seen it actually improve a setup.

1) frequency
2) phase
3) distortion



THX standard of 80 Hz crossover is based upon work done at the national "Swedish Television". The author of the work, Ingvar Öhman, is not at all dogmatic in his own setups but rarely recommends people using a XO below 75 Hz - on the contrary I've seen him recommend crossing over wherever well above 100 Hz if that solves your problems.
Noone localises a properly setup subwoofer system crossed at 80 Hz in a room, the data is crystal clear on this fact. If the subwoofers is located in the front the matter is totally different.

If you can localize a proper setup crossed at 80-120 Hz my guess is that you're localizing physical artifacts of resonance in your room/house/building.

Ingvar fits his own subwoofer systems with feet similar to these:

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