Why does my system sound so much better with a low xover?

Y

yepimonfire

Audioholic Samurai
There is huge difference between using a 50hz xover and 80hz xover, mainly in the tightness and transient response of the bass. Even though they measure identical, a 80hz xover sounds loose and sloppy, where as a 50hz xover sound tight and snappy. I took a few measurements and am at a loss as to why the sound is so different.

All of my speakers except for my height speakers manage -3dB @ 50hz in room. Originally I had my xover set to 80hz, because when I was using Klipsch R-15m's, there was a good deal of port noise above 85dB below 80hz, with my system now using Reference premiers, port noise is non existent with the tractrix shaped port. I get exactly the same frequency response with a 50hz xover vs an 80hz xover.


Keep in mind the wild dips and peaks are simply room interactions, which obviously change depending on the mic position.

Distortion @ 95dB (my max listening volume for movies, i.e. -10dB on the knob) is almost identical at 50hz as well, so I doubt either the sub or the speaker would do a better job at reproducing distortion free bass within their bandpass.


-10dB (95dB @ the listening position) on the receiver.
(keep in mind I didn't calibrate the spl on the mic)

I did not include center channel measurements because REW crashed when I went to save them, and I am far too lazy to redo it :p but the THD is .98% @50, likely due to dual woofers.

Any idea why it sounds so much better letting the speakers handle 50hz+?
 
TheWarrior

TheWarrior

Audioholic Ninja
There is huge difference between using a 50hz xover and 80hz xover, mainly in the tightness and transient response of the bass. Even though they measure identical, a 80hz xover sounds loose and sloppy, where as a 50hz xover sound tight and snappy. I took a few measurements and am at a loss as to why the sound is so different.

All of my speakers except for my height speakers manage -3dB @ 50hz in room. Originally I had my xover set to 80hz, because when I was using Klipsch R-15m's, there was a good deal of port noise above 85dB below 80hz, with my system now using Reference premiers, port noise is non existent with the tractrix shaped port. I get exactly the same frequency response with a 50hz xover vs an 80hz xover.


Keep in mind the wild dips and peaks are simply room interactions, which obviously change depending on the mic position.

Distortion @ 95dB (my max listening volume for movies, i.e. -10dB on the knob) is almost identical at 50hz as well, so I doubt either the sub or the speaker would do a better job at reproducing distortion free bass within their bandpass.


-10dB (95dB @ the listening position) on the receiver.
(keep in mind I didn't calibrate the spl on the mic)

I did not include center channel measurements because REW crashed when I went to save them, and I am far too lazy to redo it :p but the THD is .98% @50, likely due to dual woofers.

Any idea why it sounds so much better letting the speakers handle 50hz+?
Between the orientation of subs in the room vs listening position, and any type of processing done to the audio signal, your subs appear to be more capable operating in a narrow frequency range. And your towers can obviously play below 80 hz so this arrangement is bringing more value to your fronts by utilizing them more. Sweet!
 
everettT

everettT

Audioholic Spartan
Seems odd that crossing any speaker to sub at their 3db point would sound good. What is your lpf setting?
 
William Lemmerhirt

William Lemmerhirt

Audioholic Overlord
Well, taking the graphs out of the equation since sorting them was difficult for me, I'd guess that if the only change was XO, your speakers are just better in the mid bass than your sub. Also, I seem to remember that audyssey doesn't apply filters below where an XO is set. Only above, so if you lowered the XO after running Audyssey, that might change something too.
 
Y

yepimonfire

Audioholic Samurai
I don’t have audyssey or any sort of room correction.


Sent from my iPhone using Tapatalk
 
William Lemmerhirt

William Lemmerhirt

Audioholic Overlord
I don’t have audyssey or any sort of room correction.


Sent from my iPhone using Tapatalk
Then my guess is despite being around the f3 as Everett mentioned, the speakers are just better than the sub in that range. Positioning might have some effect but since the only change was XO, that's my guess. Iirc, you said flabby, so I'd attribute that to your subwoofer.
 
Pogre

Pogre

Audioholic Slumlord
I've been doing a lot of experimenting with this myself, though my problem is opposite yours. I have to use a 100hz crossover to get good results. I actually wish I had your problem.
 
KEW

KEW

Audioholic Overlord
Can you take an impulse response (and/or waterfall) in the 60Hz area to see how they compare?
 
S

shadyJ

Speaker of the House
Staff member
I've been doing a lot of experimenting with this myself, though my problem is opposite yours. I have to use a 100hz crossover to get good results. I actually wish I had your problem.
You are much better off with your problem. Your subs have way more dynamic range than your tower speakers. Everything else being equal, a higher crossover is better for you, so long as the subs can maintain that high frequency response (Hsu's subs are all pretty much good up to 200 Hz).
 
Pogre

Pogre

Audioholic Slumlord
You are much better off with your problem. Your subs have way more dynamic range than your tower speakers. Everything else being equal, a higher crossover is better for you, so long as the subs can maintain that high frequency response (Hsu's subs are all pretty much good up to 200 Hz).
Oh yes, I agree with you. In fact I don't really consider it a "problem" because everything sounds very good now. I'm leaving it right where it is.
 
Y

yepimonfire

Audioholic Samurai
Can you take an impulse response (and/or waterfall) in the 60Hz area to see how they compare?
The waterfall wasn’t terribly different, though I’m not an expert at interpreting it decay was slightly longer and louder with the sub, but what I did notice was there is a big group delay spike from the sub alone at about 66hz, crossing the speakers over at 80hz pushes this to ~75hz, and makes the spike even bigger. Using an xover at 60hz or 50hz eliminates the delay.

How would one accurately measure the impulse response of the speakers and sub? Room reflections would skew the measurements, and it cannot be windowed obviously. I do know the IR for the RP-150m has a rise and fall of less than one quarter of a millisecond, which is well below audible, since humans have a temporal resolution of around 6ms.

I’m fairly certain the sub design is high Q, considering it’s a ~ 4cu ft ported box with a 15” driver, if I’m not mistaken, this would cause it to be more resonant, ringing longer and louder.

I will say, subjectively speaking, pure sine waves above sub bass frequencies (60hz and above) sound better coming from my speakers vs the sub, below 60hz the sub sounds very clean and tight. It’s doubtful it has anything to do with room modes, because the two major modes are 47hz & 28hz. Could just be due to the fact it is a large, heavy driver that is unable to provide the same transient response above 60hz as it does below. I also have their sub 1000 with a 10” driver and it sounds more snappy at mid bass frequencies.

Not worried about my speakers having to handle 50-60hz on up, the box tuning is ~60hz, so from about 50hz-80hz the driver excursion and power consumption is minimal. They’re likely much more efficient at those frequencies than the sub, which has a 23hz tuning and a substantially lower sensitivity rating.


Sent from my iPhone using Tapatalk
 
Last edited:
TheWarrior

TheWarrior

Audioholic Ninja
The waterfall wasn’t terribly different, though I’m not an expert at interpreting it decay was slightly longer and louder with the sub, but what I did notice was there is a big group delay spike from the sub alone at about 66hz, crossing the speakers over at 80hz pushes this to ~75hz, and makes the spike even bigger. Using an xover at 60hz or 50hz eliminates the delay.

How would one accurately measure the impulse response of the speakers and sub? Room reflections would skew the measurements, and it cannot be windowed obviously. I do know the IR for the RP-150m has a rise and fall of less than one quarter of a millisecond, which is well below audible, since humans have a temporal resolution of around 6ms.

I’m fairly certain the sub design is high Q, considering it’s a ~ 4cu ft ported box with a 15” driver, if I’m not mistaken, this would cause it to be more resonant, ringing longer and louder.

I will say, subjectively speaking, pure sine waves above sub bass frequencies (60hz and above) sound better coming from my speakers vs the sub, below 60hz the sub sounds very clean and tight. It’s doubtful it has anything to do with room modes, because the two major modes are 47hz & 28hz. Could just be due to the fact it is a large, heavy driver that is unable to provide the same transient response above 60hz as it does below. I also have their sub 1000 with a 10” driver and it sounds more snappy at mid bass frequencies.

Not worried about my speakers having to handle 50-60hz on up, the box tuning is ~60hz, so from about 50hz-80hz the driver excursion and power consumption is minimal. They’re likely much more efficient at those frequencies than the sub, which has a 23hz tuning and a substantially lower sensitivity rating.


Sent from my iPhone using Tapatalk
Waterfalls are very pretty, but you have to choose between resolution of frequency or of time. Frequency response with phase at 1/24 octave is far more useful information.

Group delay of a single sub? You can adjust the delay of the sub. But group delay is calculated with phase data. Which is essential for dealing with frequency response below transition. No one seems to be posting that with their frequency response.

A ported sub couldn't work with a high Q driver. It would be the QTS parameter you'd be looking at to determine driver and enclosure pairing. Q takes on different meanings depending on how it is used.

You posted inaccurate room mode calculations in another thread. I suggest trying again.

1131/dimension (in feet) = room mode prediction

Higher order resonances (sound waves don't reflect once and dissipate) are logarithmic, so you would take each modal frequency and multiply x2/x3/x4 etc. I usually go to at least 3rd order. Your DSP inputs are proven truly effective when higher order resonances are eliminated.

Look over or post the minidsp inputs you've made and compare to your new room mode predictions. Perhaps even take new measurements, especially if previous ones were not a high enough resolution. But if you made minidsp inputs based on inaccurate predictions, I would clear the minidsp, take a baseline 1/24 octave measurement and start over.

It's alotta work but is well worth it!
 
Dale Doback

Dale Doback

Junior Audioholic
I've been doing a lot of experimenting with this myself, though my problem is opposite yours. I have to use a 100hz crossover to get good results. I actually wish I had your problem.
I had the same revelation recently. Set speakers to 'small' and left the X-Over at 120hz where MCACC Pro set it and YES! Sounds great. Fought this for quite sometime, since I have full range floorstanders, but, caved in to most advice I was getting and very glad I did. I have 4 10" subs (2 stacked on each side of center speaker). This may have something to do with my particular revelation.
 
j_garcia

j_garcia

Audioholic Jedi
I had the same revelation recently. Set speakers to 'small' and left the X-Over at 120hz where MCACC Pro set it and YES! Sounds great. Fought this for quite sometime, since I have full range floorstanders, but, caved in to most advice I was getting and very glad I did. I have 4 10" subs (2 stacked on each side of center speaker). This may have something to do with my particular revelation.
Similar finding here, though mine do sound good with an 80Hz x-over with them -3dB at 55Hz, I found it quite interesting that the my MC700 crossed mine at 110Hz and it sounded good.
 
everettT

everettT

Audioholic Spartan
Similar finding here, though mine do sound good with an 80Hz x-over with them -3dB at 55Hz, I found it quite interesting that the my MC700 crossed mine at 110Hz and it sounded good.
I cross my empires high also, sounds good wo any localization
 
Y

yepimonfire

Audioholic Samurai
Waterfalls are very pretty, but you have to choose between resolution of frequency or of time. Frequency response with phase at 1/24 octave is far more useful information.

Group delay of a single sub? You can adjust the delay of the sub. But group delay is calculated with phase data. Which is essential for dealing with frequency response below transition. No one seems to be posting that with their frequency response.

A ported sub couldn't work with a high Q driver. It would be the QTS parameter you'd be looking at to determine driver and enclosure pairing. Q takes on different meanings depending on how it is used.

You posted inaccurate room mode calculations in another thread. I suggest trying again.

1131/dimension (in feet) = room mode prediction

Higher order resonances (sound waves don't reflect once and dissipate) are logarithmic, so you would take each modal frequency and multiply x2/x3/x4 etc. I usually go to at least 3rd order. Your DSP inputs are proven truly effective when higher order resonances are eliminated.

Look over or post the minidsp inputs you've made and compare to your new room mode predictions. Perhaps even take new measurements, especially if previous ones were not a high enough resolution. But if you made minidsp inputs based on inaccurate predictions, I would clear the minidsp, take a baseline 1/24 octave measurement and start over.

It's alotta work but is well worth it!
The room mode calculations are from REW. The same calculation has been confirmed using numerous calculators online as well, and measurement near room boundaries confirms it, I get a 47hz peak along the side walls and a 28hz peak along the front/back walls. I’m not using a minidsp. I get a reasonably flat response either way.

Honestly I think it just boils down to the sub not being as “quick” in the mid bass frequencies as my Klipsch speakers. An 80hz xover doesn’t necessarily sound awful, just not nearly as snappy and tight as letting my speakers handle 60hz+.

Taking a measurement of the sub 1500 alone shows that it begins struggling above 100hz to remain linear.


Sent from my iPhone using Tapatalk
 
Last edited:
TheWarrior

TheWarrior

Audioholic Ninja
The room mode calculations are from REW. The same calculation has been confirmed using numerous calculators online as well, and measurement near room boundaries confirms it, I get a 47hz peak along the side walls and a 28hz peak along the front/back walls. I’m not using a minidsp. I get a reasonably flat response either way.
That's pretty disappointing to hear. That's the simplest calculation to make, and REW gets it wrong. Speed of sound divided by dimension. (or by frequency, equals dimension). If you made corrections on minidsp @ 28 hz, I'll bet that explains why you're finding better sound with a lower crossover. 28 hz could be, or very near, the resonant frequency of the driver. Or enough boost was applied, but either way, limits the drivers ability even an octave up.

Room modes/standing waves are created by sound waves interacting with room boundaries. Dimensions similar to wavelength see an increase in energy. That could still measure as a null because the mic/LP is out of phase with the pressure source, at that frequency. Point is that room modes don't have to measure as peaks, to still be identified as modes. If REW only treated peaks, then there's no telling how much better YOU could do, yourself!

My suggestion would still be to try again. This is Audioholics after all, ain't no rest for the obsessed!

Side note, already got a couple people on the 'Sound Reproduction' bandwagon. With the amount of effort you put in, and the passion you clearly have for sound, why not pick up Toole's Third Edition and give yourself a better source of information?
 
TLS Guy

TLS Guy

Seriously, I have no life.
There is huge difference between using a 50hz xover and 80hz xover, mainly in the tightness and transient response of the bass. Even though they measure identical, a 80hz xover sounds loose and sloppy, where as a 50hz xover sound tight and snappy. I took a few measurements and am at a loss as to why the sound is so different.

All of my speakers except for my height speakers manage -3dB @ 50hz in room. Originally I had my xover set to 80hz, because when I was using Klipsch R-15m's, there was a good deal of port noise above 85dB below 80hz, with my system now using Reference premiers, port noise is non existent with the tractrix shaped port. I get exactly the same frequency response with a 50hz xover vs an 80hz xover.


Keep in mind the wild dips and peaks are simply room interactions, which obviously change depending on the mic position.

Distortion @ 95dB (my max listening volume for movies, i.e. -10dB on the knob) is almost identical at 50hz as well, so I doubt either the sub or the speaker would do a better job at reproducing distortion free bass within their bandpass.


-10dB (95dB @ the listening position) on the receiver.
(keep in mind I didn't calibrate the spl on the mic)

I did not include center channel measurements because REW crashed when I went to save them, and I am far too lazy to redo it :p but the THD is .98% @50, likely due to dual woofers.

Any idea why it sounds so much better letting the speakers handle 50hz+?
Do you have the ability to measure impulse response?

I would bet this is time smear.

As you all know I regard subs as an evil you have to live with because of the falling low end response of most speakers.

The more you space speakers and subs the greater the smear. Sure you can time them for one location. However the time path will vary as you move listening location.

I can tell you that in a sub system there is easily seen separation of the impulse responses. Not good. Whilst moving subs may help with room resonances, it creates time smear. In my view in good low Q systems this time smear is easily audible, as I think you have found out.

As you know I have pointed at that there is a chasm in the view of the use of subs between the UK and USA.

The UK view is to set speakers to full range wherever possible and NOT cross them over. Just use the subs to gently supplement the roll off of the speakers.

My ears and measurements tell me the UK position is correct. And you know what, you don't then need gobs of power for your subs. In a well balances system they take little power.

I'm firmly and unashamedly in the UK camp on this and not the US.

And finally people who say time smear is not audible are just flat out wrong.

Yep, I think you have just found that it is.
 

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