REW Sweeps Using XOver 40htz vs 250htz Settings

[408Revo]

Hi, I'm a newbie with REW and trying to understand how the different crossover settings affect a single speaker. Using a Denon with Audyssey turned off and my speaker set to large, I ran two sweeps, one with the crossover set to 250 and another set to 40. I noticed that with a XO at 250, there are more lower frequencies getting through to my speaker than when set to 40 XO. I'm I missing something? From the little I know, my understanding is that when you set a speaker to a certain XO frequency, the dBs start dropping by each octave. I would assume that if I have my XO set at 250, by the time I'm around 30htz I should be close to -24db (assuming its a 12dB/octave)? At 30htz the 250 XO setting is around 6dBs higher than when the setting is set to 40htz.

Am I doing something wrong in REW when taking the measurement? Any help is greatly appreciated. thanks

 

[JStewart]

Your understanding of how a crossover works is correct.
Measure one speaker at a time.
Any DSP settings must be off (upmixers, downmixers, double bass type settings, whatever else is on that thing!)
Start with full range (no crossover set)
Then do with crossover engaged to compare.
Be sure any sub or subs can’t play a signal.

 

[408Revo]

All DSP settings are off and speaker set to large. It's probably just me not able to read the graph correctly or I have a setting on REW that is not allowing to measure? Why would I have higher dBs at 30htz with a 250 XO than 40?

 

[JStewart]

Clearly something is not as it should be.
This is probably a matter of semantics ,,,

All DSP settings are off and speaker set to large.

but just in case… a speaker set to large has no XO. Speakers set to “small” utilize a XO.

 

[sm52]

Why would I have higher dBs at 30htz with a 250 XO than 40?

In the first graph there is no response to the filter, neither at 250 Hz nor at 40 Hz. On the second there is a reaction only at 40 Hz. You need to clarify how the filters created in REW work.

 

[408Revo]

Clearly something is not as it should be.
This is probably a matter of semantics ,,,

but just in case… a speaker set to large has no XO. Speakers set to “small” utilize a XO.

why am I getting similar results when I run my speaker set to small?

 

[408Revo]

In the first graph there is no response to the filter, neither at 250 Hz nor at 40 Hz. On the second there is a reaction only at 40 Hz. You need to clarify how the filters created in REW work.

To clarify, I'm not using any REW filters. This is just me disabling any DSPs in the receiver and taking sweeps with different receiver crossover settings and with speakers set to small or large. I'm trying to understand what these receiver settings are actually doing to the speakers by using REW to test these changes. That's why I think that I'm doing something wrong in REW, I see almost no difference. Not sure if I'm making any sense, and do apologize in advance for any confusion to my question. I'm just really trying to understand.

 

[ddude003]

My guess would be that the large dip at ~225 to 250ish is a room mode... Not an easy fix with EQ... If you have your speaker(s) set to large you should not be using a crossover... If your speakers are set to small then you would want to crossover 10 to 20 Hz above where your small speaker starts to run out of juice (read the speaker specs)...

This might help... https://www.svsound.com/blogs/svs/should-speakers-be-set-to-large-or-small-on-an-av-receiver

It might help if you told us a bit more about your kit... Fill in the "More" part of your Account Details...

 

[408Revo]

My guess would be that the large dip at ~225 to 250ish is a room mode... Not an easy fix with EQ... If you have your speaker(s) set to large you should not be using a crossover... If your speakers are set to small then you would want to crossover 10 to 20 Hz above where your small speaker starts to run out of juice (read the speaker specs)...

This might help... https://www.svsound.com/blogs/svs/should-speakers-be-set-to-large-or-small-on-an-av-receiver

It might help if you told us a bit more about your kit... Fill in the "More" part of your Account Details...

thank you for your response, much appreciated. I agree, the dip in the 200s is a room issue. To further clarify, I'm so new to all this that I don't really know anything on what the different settings really do or even how to use REW. With REW, I'm comfortable to say that I'm able to run a sweep and look at a graph to see what my speakers are actually doing (at lease I think I do but might not even be doing that correctly). What I'm trying to do, is figure out how setting a XO at a certain frequency affects a speaker. I understand what it should do in theory but want to confirm with data. I think that if I have a better understanding how everything works, I can then be better at getting the best results with what I have. Please let me know if what I'm doing is an incorrect way to figure out what the XO settings are doing to a speaker? Thank you for the link, I will check it out.

 

[sm52]

Your goal makes sense and you are correctly testing the effect of receiver settings on the result. And this is useful for correct coordination in time and frequency response of all speakers in the system. But there are times when you change something, the numbers in the receiver are already different, but they are not really applied. For different reasons.

 

[sm52]

This is just me disabling any DSPs in the receiver and taking sweeps with different receiver crossover settings and with speakers set to small or large.

If your receiver has auto-calibration, then turning off the DSP may still leave the equalizer active. The large mode disables filters for the main speakers, the small mode enables filters.

 

[408Revo]

If your receiver has auto-calibration, then turning off the DSP may still leave the equalizer active. The large mode disables filters for the main speakers, the small mode enables filters.

All DSP settings are off

 

[408Revo]

I went and tried a different speaker. Settings: Audyssey on, speaker set to small, and tried XO at 40 and 250. What am I doing wrong? Blue line is XO at 250 which shows 5 dBs higher at 40htz.

 

[sm52]

If Odyssey is turned on and the speakers are turned to small, then at any XO from HF to XO frequency the main speakers will work, below the sub. The graphs show how the docking occurs, worse or better. You choose a 45 hertz pit + 90 hertz hump or a 250 hertz pit. To see separately each speaker from the 'speaker + sub' pair, physically disconnect one of this pair during measurement, and the other during the second measurement.

 

[JStewart]

With respect to the measurements not showing the XO you have set, are you measuring using Direct or Stereo mode? I believe direct mode and/or Pure Direct modes bypass the bass management, so no XOs in these modes. Stereo will work or its multi-channel equivalent. And as @sm52 said, turn the sub off for a speaker measurement.

 

[408Revo]

I feel smart. The whole time when running sweeps the subs were also in the mix. I never thought that when running a sweep on a individual speaker the subs would be included. Greatly appreciate everyone's help on this. Lesson learned, turn off sub when running sweeps on individual speakers. thanks