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Bass Management

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Ron Texas

Ron Texas

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OK, I noticed in REW there is a phase measurement. In my system it was around -175 degrees. I changed the phase switch on the sub to 180 and now the phase measurement is +5 degrees. It sounds better. Did I get it right?

One other thing. If you have a topping D30 using USB input make sure the Windows volume control is set to 100. Some wonky measurements are leading me to believe the digital volume control in the D30 has loudness compensation.

I would need some different hardware to have multiple subs with separate EQ. It's just not something I want to try right now.
ASR is really great. There are bunches of smart and knowledgeable people here.
 

edechamps

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OK, I noticed in REW there is a phase measurement. In my system it was around -175 degrees. I changed the phase switch on the sub to 180 and now the phase measurement is +5 degrees. It sounds better. Did I get it right?

No, that's a red herring. To set the phase on your sub, look at the transition region in the frequency response where the sub crosses over to the mains. Pick the sub phase settings where the frequency response looks the flattest. (If you plan to EQ afterwards, it might be a better strategy to use the setting which has the fewest dips, and then EQ away the peaks.)

The point of the sub phase setting is to make the sub sum up correctly (i.e. in phase) with the mains near the crossover frequency. It doesn't have anything to do with absolute phase per se.
 
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Ron Texas

Ron Texas

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No, that's a red herring. To set the phase on your sub, look at the transition region in the frequency response where the sub crosses over to the mains. Pick the sub phase settings where the frequency response looks the flattest. (If you plan to EQ afterwards, it might be a better strategy to use the setting which has the fewest dips, and then EQ away the peaks.)

The point of the sub phase setting is to make the sub sum up correctly (i.e. in phase) with the mains near the crossover frequency. It doesn't have anything to do with absolute phase per se.

Thank you. Time to get out the microphone. There is definitely a learning curve here. I have been EQ'ing peaks.

Update:
Phase of 90 looked flatter than 180. Phase of 0 and phase of 90 had about the same area above and under the target curve, but 0 had smoother transitions from above to below the target and back.
 
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g29

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Thank you. Time to get out the microphone. There is definitely a learning curve here. I have been EQ'ing peaks.

Update:
Phase of 90 looked flatter than 180. Phase of 0 and phase of 90 had about the same area above and under the target curve, but 0 had smoother transitions from above to below the target and back.

FWIW, here is my OB dipole sub integration (1/24 octave smoothing) with a dipole planar magnet speaker and no EQ/room correction other than phase, level and the sub's low shelf filter. Symmetric XO is at 40Hz with 48dB slopes. Noticible room nodes @ 52Hz and 140Hz both with and without the sub.

Left 20.1 with OB Sub.jpg
 
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DonH56

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The quick and dirty method is to play a test tone at the crossover frequency and adjust the phase until the signal is loudest (using ears, SPL meter, whatever) when measured at the listening position. That is where the sub and mains will be in phase. You can adjust delay in the AVR, phase on the sub (my sub has continuous phase control, a nice feature), phase in the crossover if possible (e.g. miniDSP or similar), and/or move the mains and sub(s) relative to each other to find the best alignment.

HTH - Don
 
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Ron Texas

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It's funny, but the settings and placement I am using now on my sub are the same ones I was using before I started with REW. One breakthrough was discovering the D30 hardware digital volume control had loudness compensation. I don't know if it can be turned off. The solution is set the Windows volume to maximum and use software volume controls. It's taken me a while to understand REW. It's only in the last few days that I realized what individual boost and overall boost meant.

For a lot of folks integrating a sub is a daunting task. There are some around here who really know their way around these problems and they say it is easy. Others will say they got tired of fiddling with their sub and ditched it or only use it for movies. I probably fit somewhere in the middle at the start. I am a hobbyist willing to do whatever it takes in terms of time and effort to get a good result. Knowing what I know now, I could do it a lot faster. The end result was definitely worth the effort and modest cost of the ML Dynamo 1000W and UMIC-1.
 

Ultrasonic

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As @Ron Texas as said, it would be a waste to use the 2x4 HD with a low distortion amplifier. And I would like to feed my Yamaha a low distortion balanced signal. On the other hand I feel that the advantages of DSP outweigh the disadvantage of a 90dB SINAD which isn't all that bad. This system certainly isn't worth the cost of a minidsp SHD and I don't want to spend that much. Is there any other products out there that can do these things? Have you bought anything new Ron?

One factor to bear in mind when considering distortion figures is distortion caused by your speakers likely dwarfs that of the electronics.

I'm tempted by an SHD due to the better DAC performance and actually the display to show volume and selected source. I'd be paying a lot for DIRAC and streaming features I don't want though, and would lose the FIR functionality of the 2x4 HD. I'm hoping miniDSP may come out with a new product that fills the gap between the two.

(I'll update this thread with details of the main/sub integration I've achieved with my 2x4 HD when I have more time. It works well though.)
 

daftcombo

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Should EQ for bass management (for instance -8dB, Q=4 at 42 Hz to deal with a room mode) be applied with a minimum phase or a linear phase filter?
 

Julf

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Should EQ for bass management (for instance -8dB, Q=4 at 42 Hz to deal with a room mode) be applied with a minimum phase or a linear phase filter?

Doesn't really matter.
 
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