2.1 Stereo Calibration - what am I missing?

[Dave the Rave]

Hey Folks, Thought I share my 2.1 stereo journey. Thanks to REW, have had a lot of changes over time mainly around speaker positioning and its response tweaking. As guided.... it was essential that I get the speakers to level match for any noticeable improvement to yield. I have been trying all sorts of variation using @serko70 Phase Inversion technique which is definitely superior to any filters/eq application in my experience.... Massive thanks to him for sharing his know-how. I can (modestly) say my stereo sound really really great now in spite of living room limitations - clarity across frequencies, sweet high, tighter bass and most importantly euphonic and engaging. I keep playing past tracks, stuck for hours on my couch (and often whisper wow after realising what i was missing).... Wonderful community here again. Thanks all.

 

[Wayne A. Pflughaupt]

Not familiar with phase inversion technique, but it looks impressive judging from your results. Can you point us to an information source?

Regards,
Wayne

 

[JStewart]

Not familiar with phase inversion technique, but it looks impressive judging from your results. Can you point us to an information source?

Regards,
Wayne

Hey Wayne, the procedure was developed by our member @serko70 and is documented on his YouTube channel Obsessive Compulsive Audiophile

Here’s a line to the first of his most recent two part series. The inversion method is in the second one. There were earlier versions, but I didn’t see them when I looked today.

 

[Dave the Rave]

@Wayne A. Pflughaupt I followed the recently updated PDF under the Youtube video

.
I did not apply step 4 (Width Cycle: 35) - but rather l did all steps at 1/24th Octave (under All SPL).
Also I linearized my speaker specific CrossOver ( as taught by Serkan). In the past, I tried fixing the Impulse manually in RePhase which always left some penny missing. The default speaker xo linearization gave the tightest and full bass. Amazing how such minor tweaks made significant sound signature changes.

 

[Dave the Rave]

Forgot to mention - though I followed most steps, I did not update my L and R speakers SPL Offset or adjusting the Impulse for both channels to 0. The SPL required +0.2 and -0.2 (nets to zero imbalance which was nothing). From Impulse analysis, my Right speaker required 27cm away from LP... I just pushed my speaker physically away. I found adjusting the L and R Impulse aggressively towards 0 created some artificial corrections taking away the analogue-like sound I currently enjoy.
For the Target curve, I visually choose the curve on a 1/24 graph - typically higher than REW automatically measured target.
I also save all my file and RePhase XO in 16 bits @44k as my DAC upsamples Redbook nicely.
Sharing some results in the Overlays

 

[sm52]

Sharing some results in the Overlays

Did it seem to me or is there a negative polarity in the left channel?

 

[Dave the Rave]

Not sure about the polarity... the Impulse is similar to the Youtube (i.e going on the negative side). My sub Phase is set at 180 deg as it integrates better with my 3-way speaker than at 0 deg.

 

[sm52]

going on the negative side

This is the negative polarity.

 

[Dave the Rave]

Ah ok.. thanks. Is it something I need to fix say by reversing the polarity and/or trying to get better result with the sub with 0deg.
Honestly I don't understand the technicality or impact of negative polarity but I have always been pleasantly surprised by little tweaks - all in the ever pursuit the next level. Hence most welcome to hear any suggestions.

 

[sm52]

reversing the polarity and/or trying to get better result with the sub with 0deg.

Listen to both versions. People and musical instruments begin to sing and play in positive polarity. Then it changes. But if one channel is in positive polarity at one point in time, and the other is in negative polarity at the same moment, they can greatly interfere with each other and create multiple cancellations of sound pressure.

 

[Dave the Rave]

Hmmm interesting... i looked into the L/R and combined Impulse as below. Both are negative but the stereo is positive. I am assuming this is normal. Prefer the sound as per current polarity

 

[sm52]

To analyze the L+R graph, you need to equalize the time of each. It is necessary to install the microphone exactly in the middle between L and R. But I wrote so that you do not look at the graphs, but listen to two options.

 

[Dave the Rave]

Point noted when measuring L+R.