120 HZ crossover?

[kinggimp82]

I recently bought a pair of Sierra towers and am quite happy with their performance. When listening in stereo the detail and the imaging are excellent. However there is a null at 120 hz that makes the speakers sound bright and thin. There just seems to be a lack of warmth in the sound. When I switch to all channels stereo this was no longer the case but the imaging wasn't as good and the bass is a bit boomy. Listing to music is the only time this is in the issue. It doesn't bother me during movies. Currently I have all of the speakers crossed over at 80 hz. Would raising the crossover to 120 hz possibly possibly fix the null? And if so would it cause too much localization of the sub? I know I will need to experiment to see what sounds best to me. Just trying to get other people's thoughts of the situation.

[curtis]

The suckout at 120hz might be resolved with a slight change in place or room treatments. Are they an option?

I would definitely try raising the crossover. I don't think it will solve the problem, bit it can help.

[davef]

I recently bought a pair of Sierra towers and am quite happy with their performance. When listening in stereo the detail and the imaging are excellent. However there is a null at 120 hz that makes the speakers sound bright and thin. There just seems to be a lack of warmth in the sound. When I switch to all channels stereo this was no longer the case but the imaging wasn't as good and the bass is a bit boomy. Listing to music is the only time this is in the issue. It doesn't bother me during movies. Currently I have all of the speakers crossed over at 80 hz. Would raising the crossover to 120 hz possibly possibly fix the null? And if so would it cause too much localization of the sub? I know I will need to experiment to see what sounds best to me. Just trying to get other people's thoughts of the situation.

Have you taken measurements to confirm the null? Typically, a null at 120Hz is due to floor bounce or the "Allison Effect" but it shouldn't disappear when changing listening modes on your receiver, unless something is odd with Auto-EQ.

Are you using Audyssey? If yes, I would suggest going through the Audyssey measurement process again and be sure to use Audyssey's recommended microphone placement for each measurement.

http://www.willowville.net/ht/Audyssey%20Setup%20Guide.pdf

[kinggimp82]

The suckout at 120hz might be resolved with a slight change in place or room treatments. Are they an option?

I would definitely try raising the crossover. I don't think it will solve the problem, bit it can help.

Placement is pretty limited for me. I can move each speaker left and right a few inches. And forward or back. Right now the speakers are roughly 18 from the front wall.

[kinggimp82]

Have you taken measurements to confirm the null? Typically, a null at 120Hz is due to floor bounce or the "Allison Effect" but it shouldn't disappear when changing listening modes on your receiver, unless something is odd with Auto-EQ.

Are you using Audyssey? If yes, I would suggest going through the Audyssey measurement process again and be sure to use Audyssey's recommended microphone placement for each measurement.

http://www.willowville.net/ht/Audyssey%20Setup%20Guide.pdf

I have taken measurements to confirm the null. It's at least down 10 decibels from the other measurements near that frequency. Yes I have Audyssey. I will try running the calibration again with those microphone placement. Also what exactly is the Allison Effect? I've looked it up but could not really understand what it meant.

[Bruce Watson]

Placement is pretty limited for me. I can move each speaker left and right a few inches. And forward or back. Right now the speakers are roughly 18 from the front wall.

And your listening position -- can you move that as well? Sometimes all it takes is a little movement of the speakers and the listening position. 120 Hz is interestingly high for a null in my experience. But every room is different.

[Jaybeez]

You may consider and "override" of Audyssey and see what happens. In my HT space (where I listen to music on occasion) Audyssey gets me close, but I need a bit of manual tweaking (in the low end) to make up for what doesn't sound right to me.
At the end of the day your ears have a preference and should be happy with what you're listening to.

[davef]

I have taken measurements to confirm the null. It's at least down 10 decibels from the other measurements near that frequency. Yes I have Audyssey. I will try running the calibration again with those microphone placement. Also what exactly is the Allison Effect? I've looked it up but could not really understand what it meant.

Another test you should try is to turn the subwoofer off completely and run the speakers full range. This way you can be sure the suckout is not being caused by a phase issue with the sub.

The Allison Effect represents the interaction between speakers and nearby large boundaries. Depending on the distance to these boundaries, certain frequencies will be cancelled (1/4 wavelength distance away) while others will be amplified (1/2 wavelength distance away)

I suspect though that this is more of an issue with Audyssey since when properly run, Audyssey will correct for this.

[davef]

Placement is pretty limited for me. I can move each speaker left and right a few inches. And forward or back. Right now the speakers are roughly 18 from the front wall.

If the back of the speakers are 18" from the wall behind them, this places the woofers at approx 28" from the wall behind them. 28" represents a wavelength of ~ 480Hz. 1/4 of this wavelength = 120Hz, thus cancellation at 120Hz....

[kinggimp82]

If the back of the speakers are 18" from the wall behind them, this places the woofers at approx 28" from the wall behind them. 28" represents a wavelength of ~ 480Hz. 1/4 of this wavelength = 120Hz, thus cancellation at 120Hz....

Would you suggest I move the speakers forward or back? How far would you suggest moving them?

[davef]

Would you suggest I move the speakers forward or back? How far would you suggest moving them?

This depends, there are really a lot of variables at play. If you move them ~ 12" closer to you, you will lower this dip into the range where you cross to the sub which will help a lot. If you move them ~ closer to the wall such that the back of the speakers is ~8" from the wall, you will raise the frequency of the dip above 200Hz such that Audyssey will do a much better job of correcting for it.

My recommendation is to experiment with both options and report back. There are also side wall and floor bounce reflections to deal with so always best to try different positioning options.

[kinggimp82]

This depends, there are really a lot of variables at play. If you move them ~ 12" closer to you, you will lower this dip into the range where you cross to the sub which will help a lot. If you move them ~ closer to the wall such that the back of the speakers is ~8" from the wall, you will raise the frequency of the dip above 200Hz such that Audyssey will do a much better job of correcting for it.

My recommendation is to experiment with both options and report back. There are also side wall and floor bounce reflections to deal with so always best to try different positioning options.

Today I spent some time taking measurements with the speakers in two separate positions. First I measured with the speakers 18 inches from the wall with the crossover set to 80hz. In this first position when changing the crossover to 120hz or 150hz the measurements did not change. Here are the measurements for that first position.

80hz - 80.5
90hz - 79.5
100hz - 77
120hz - 63.5
150hz - 66.5
200hz - 74.5

Then I moved the speakers so there are 8 inches from the wall with the crossover set to 80. In this position 120hz increased slightly and 150hz dropped significantly lower yet. Here are those measurements.

80hz - 80.5
90hz - 79.5
100hz - 80
120hz - 66.5
150hz - 53
200hz - 74.5

Then in the second position I tried the crossover at 120hz. When I did this the reading jumped from 66.5 to 72.5 at 120hz. Then I increased the crossover to 150hz. This put 120hz at 72.5 and 150hz at 71.5. Without increasing the crossover to 150hz there is still the dip at 150hz. All of these measurements were taken with the receiver set to stereo. When I switched the mode to all channel stereo with the fronts center and surrounds playing together I could crossover at 120hz and could get 150hz to read 67.5. For reference I have the surrounds and center set with a crossover of 80hz.

After all of that I have been listening to music in stereo with the crossover set to 150hz. So far it seems good. I will leave it this way for a while to see how I like it and if i notice any localization coming from the sub.

[davef]

Today I spent some time taking measurements with the speakers in two separate positions. First I measured with the speakers 18 inches from the wall with the crossover set to 80hz. In this first position when changing the crossover to 120hz or 150hz the measurements did not change. Here are the measurements for that first position.

80hz - 80.5
90hz - 79.5
100hz - 77
120hz - 63.5
150hz - 66.5
200hz - 74.5

Then I moved the speakers so there are 8 inches from the wall with the crossover set to 80. In this position 120hz increased slightly and 150hz dropped significantly lower yet. Here are those measurements.

80hz - 80.5
90hz - 79.5
100hz - 80
120hz - 66.5
150hz - 53
200hz - 74.5

Then in the second position I tried the crossover at 120hz. When I did this the reading jumped from 66.5 to 72.5 at 120hz. Then I increased the crossover to 150hz. This put 120hz at 72.5 and 150hz at 71.5. Without increasing the crossover to 150hz there is still the dip at 150hz. All of these measurements were taken with the receiver set to stereo. When I switched the mode to all channel stereo with the fronts center and surrounds playing together I could crossover at 120hz and could get 150hz to read 67.5. For reference I have the surrounds and center set with a crossover of 80hz.

After all of that I have been listening to music in stereo with the crossover set to 150hz. So far it seems good. I will leave it this way for a while to see how I like it and if i notice any localization coming from the sub.

Please try taking the same measurements with the speakers running full range with Audyssey turned off and no subwoofer.

Also, please describe how you are taking these measurements... What equipment, mic and mic placement details.

thanks!

[kinggimp82]

Please try taking the same measurements with the speakers running full range with Audyssey turned off and no subwoofer.

Also, please describe how you are taking these measurements... What equipment, mic and mic placement details.

thanks!

I will take the measurements again following your suggestions.

I'm using a radio shack digital spl meter set to c weighting and slow. It is placed at my main listening position 10 feet away centered between the speakers. Im entering the measurements into a spreadsheet and using the corrections table for the meter to correct the raw data.

[davef]

I will take the measurements again following your suggestions.

I'm using a radio shack digital spl meter set to c weighting and slow. It is placed at my main listening position 10 feet away centered between the speakers. Im entering the measurements into a spreadsheet and using the corrections table for the meter to correct the raw data.

Sounds good so far... If you don't mind -- post a few pics of the front of the room and the spl meter placement. Also, keep in mind that those digital RS spl meters can be quite inaccurate and using steady state sine wave test tones can often be problematic. (music is not steady state)

You are much better off using room eq wizard paired with the Dayton Mic and a laptop for in-room measurements.

I look forward to your measurement results with no sub, no EQ and running the towers full range. This will help isolate the issue as I suspect what you are experiencing is some cancellation between your sub and the towers...

[Brady]

as someone who will be spending a lot of time dialing in a system shortly, I am learning a ton from this thread- thank you!

[kinggimp82]

You are much better off using room eq wizard paired with the Dayton Mic and a laptop for in-room measurements.

What is the model of that microphone? How much do they usually cost? Along with the laptop is that microphone the only thing I need to use REW?

[Mag_Neato]

What is the model of that microphone? How much do they usually cost? Along with the laptop is that microphone the only thing I need to use REW?

Here's the mic: https://www.parts-express.com/minidsp-umik-1-omni-directional-usb-measurement-calibrated-microphone--230-332

Or this one: https://www.parts-express.com/dayton-audio-emm-6-electret-measurement-microphone--390-801

I believe the laptop is the only other piece of hardware required along with the REW software.

[davef]

Here's the mic: https://www.parts-express.com/minidsp-umik-1-omni-directional-usb-measurement-calibrated-microphone--230-332

Or this one: https://www.parts-express.com/dayton-audio-emm-6-electret-measurement-microphone--390-801

I believe the laptop is the only other piece of hardware required along with the REW software.

Best option is the UMIK-1 since it is a USB mic and won't need an interface between the computer and the mic...

[kinggimp82]

Sounds good so far... If you don't mind -- post a few pics of the front of the room and the spl meter placement. Also, keep in mind that those digital RS spl meters can be quite inaccurate and using steady state sine wave test tones can often be problematic. (music is not steady state)

You are much better off using room eq wizard paired with the Dayton Mic and a laptop for in-room measurements.

I look forward to your measurement results with no sub, no EQ and running the towers full range. This will help isolate the issue as I suspect what you are experiencing is some cancellation between your sub and the towers...

I took the measurements again with the speakers full range no sub and Audyssey off. Here is the results.

8 inches from the wall
80hz - 70.5
90hz - 71.5
100hz - 75
120hz - 68.5
150hz - 57.5
200hz - 76.5

16 inches from the wall
80hz - 67.5
90hz - 67.5
100hz - 72
120hz - 66.5
150hz - 64.5
200hz - 75.5

I thought the measurements with the speaker 16 inches from the wall looked the most even so I decided to try measurements with the sub on with Audyssey still off and crossover set to 80hz. I took one set of measurements with the phase at 0. Then I took a second set of measurements with the phase at 180.

16 inches from the wall phase 0
80hz - 75.5
90hz - 73.5
100hz - 74
120hz - 66.5
150hz - 65.5
200hz - 77.5

16 inches from the wall phase 180
80hz - 70.5
90hz - 69.5
100hz - 71
120hz - 70.5
150hz - 65.5
200hz - 76.5

[jimb]

Interesting to follow your progress. I still need to do fine tuning of sub integration myself. I'm approaching mine using the receiver distance setting for the phase adjustment while keeping the knob on my F8 sub at 0 degrees. If I had your results, I'd expect to go with 0 degrees delay (or try other intermediate values) and reduce the sub level 3-5 db. Then expect Audyessy to handle the 150-200 irregularities. Ideally, you'd include the response a bit below the crossover point as well, say from 60 Hz. I'm looking forward to others' comments.

[davef]

I took the measurements again with the speakers full range no sub and Audyssey off. Here is the results.

8 inches from the wall
80hz - 70.5
90hz - 71.5
100hz - 75
120hz - 68.5
150hz - 57.5
200hz - 76.5

16 inches from the wall
80hz - 67.5
90hz - 67.5
100hz - 72
120hz - 66.5
150hz - 64.5
200hz - 75.5

I thought the measurements with the speaker 16 inches from the wall looked the most even so I decided to try measurements with the sub on with Audyssey still off and crossover set to 80hz. I took one set of measurements with the phase at 0. Then I took a second set of measurements with the phase at 180.

16 inches from the wall phase 0
80hz - 75.5
90hz - 73.5
100hz - 74
120hz - 66.5
150hz - 65.5
200hz - 77.5

16 inches from the wall phase 180
80hz - 70.5
90hz - 69.5
100hz - 71
120hz - 70.5
150hz - 65.5
200hz - 76.5

Measurements look great for an in-room response. +/- 5dB is very impressive without using any EQ. Now I recommend running Audyssey with the proper microphone placement for each measurement. This should help with some of the mild cancellation you are getting between the response of the speaker and the sub. Being that the sub and speakers do not occupy the same space, achieving perfect phase integration between the two at all overlapping frequencies is not possible without DSP correction.