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AHB2 Mono v Stereo - what is audible?

pjug

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According to benchmark article at
https://benchmarkmedia.com/blogs/ap...KwHM2ZqkqRlb7LVNrQNXnHOC2-OKx3nRoCMagQAvD_BwE....

0.2db is at the threshold of audibility. 0.5db gives "red" color in the example Excel worksheet.

So, "just 1db" supposed to be so obvious that no abx is needed, at least for those who can still hear 20khz.... : P
Maybe, to me the question is whether the rolloff is starting at low enough frequency to be audible. Anyway here is the EQ filter. A lot of calculations and in the end it is essentially just a gentle rolloff!
 

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preload

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Here is what I am getting. I included 10 feet of 12 AWG cable (20 ft round trip). Since the AHB2 has a high damping factor at low frequencies, the cable resistance is the main cause of the deviations of FR (the bigger difference is at high frequencies, where the AHB2 DF comes down and the F208 impedance is also lower than with the simulated speaker). So not much difference between mono and stereo except at higher frequencies. The delta is what should be applied as EQ for an ABX test (correct?), but I can't imagine there is any audible difference in the bass, which is the OP claim. I think any bass difference would have to be from something else besides output impedance effects. I am not sure doing ABX with a filter made from this FR delta is worthwhile to do. Recording speaker voltage would be better.
View attachment 136363
edit: remade the chart to see effects better
Woah hang on a sec. Where are you getting the ahb2 output impedance vs frequency data from?
 

pjug

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I should mention I normalized the EQ filter for 0dB at 1KHz. Applying filter and checking spectra delta confirms the filter shape. Diff is ~-67dB.
1624045090667.png
 
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preload

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Soundstage review gives damping factor vs freq.
Oh very nice thank you. The delta in the FR curves just from adding in more output impedance in the last few octaves seems like it’s a lot more than expected. Actually I should probably ask what was the output impedance in the last octave?
 

pjug

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Oh very nice thank you. The delta in the FR curves just from adding in more output impedance in the last few octaves seems like it’s a lot more than expected. Actually I should probably ask what was the output impedance in the last octave?
Here is another view showing up to 20KHz. Someone should check my work; I was doing a few things back and forth so could have made errors. I am heading out for the weekend now, will be able to check the site but not crunch numbers.
1624046915334.png
 

Pdxwayne

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Maybe, to me the question is whether the rolloff is starting at low enough frequency to be audible. Anyway here is the EQ filter. A lot of calculations and in the end it is essentially just a gentle rolloff!
Thanks for doing this!

Do let us know about your own abx results with this new filter.
 

pjug

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The delta in the FR curves just from adding in more output impedance in the last few octaves seems like it’s a lot more than expected.
And more than it seems like it should, to me, when I compare the F208 impedance to the Stereophile simulated load. I wonder if I made a mistake somewhere.

Edit: Ugh! Something went wrong with my trace of the damping factor. It says DF=12 at 20Khz . DF should be about 30 at 20KHz. I will have to redo. Maybe Sunday I can get to it. After I get that fixed I will attach the xls file in case anyone wants to go over it.
 
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Pdxwayne

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And more than it seems like it should, to me, when I compare the F208 impedance to the Stereophile simulated load. I wonder if I made a mistake somewhere.

Edit: Ugh! Something went wrong with my trace of the damping factor. It says DF=12 at 20Khz . DF should be about 30 at 20KHz. I will have to redo. Maybe Sunday I can get to it. After I get that fixed I will attach the xls file in case anyone wants to go over it.
So, the db difference at 20Khz will be bigger or smaller? It does not really matter for me at 20Khz as I am not able to hear above 16khz anyway....

I tried your latest filter. I think I can sense the difference pretty good, but not perfect.

Delta of spectra of the test files:
delta_of_spectra_with_filter_2.PNG


ABX results is 13/16. It was not easy....I think I got a bit of ear fatigue at the end, listening to higher freq sound, and got last two wrong....
mono_vs_stereo_ahb2_abx_result_filter2.PNG
 

pjug

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So, the db difference at 20Khz will be bigger or smaller? I
It will roll off much less. I imagine the stereo curve at the high frequencies will be much closer to the Stereophile simulated speaker curve. I might try to fix it tonight since I decided not to leave town until the morning. Sorry for the f***up! That's pretty good 13/16. If you can do similar when I fix the curve maybe we are getting at something.
 

Pdxwayne

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It will roll off much less. I imagine the stereo curve at the high frequencies will be much closer to the Stereophile simulated speaker curve. I might try to fix it tonight since I decided not to leave town until the morning. Sorry for the f***up! That's pretty good 13/16. If you can do similar when I fix the curve maybe we are getting at something.
At least now you know someone out there can hear a difference with "only 1db" slope.
: )

Looking forward to your next filter.
 

pjug

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At least now you know someone out there can hear a difference with "only 1db" slope.
: )

Looking forward to your next filter.
Indeed I am learning a lot. Here is the corrected filter. I guess uploading xls is not allowed. I can make it a text file or csv but will lose calculations. I guess best thing will be google drive if anyone wants it. Here is the DeltaWave shot of the curve, after I filtered a track and compared.
1624060076098.png
 

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restorer-john

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I guess uploading xls is not allowed.

The file I uploaded is an .xls. I just changed the extension to .pdf to upload it successfully. Change it back to .xls after downloading and it's fine.
 

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Blumlein 88

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You also can upload as a zip file I think.
 

Pdxwayne

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Indeed I am learning a lot. Here is the corrected filter. I guess uploading xls is not allowed. I can make it a text file or csv but will lose calculations. I guess best thing will be google drive if anyone wants it. Here is the DeltaWave shot of the curve, after I filtered a track and compared.
View attachment 136389

This is more difficult. But I think I still do pretty good? Not easy to find song with lots of high frequencies over 10Khz. If you have a good candidate, let me know.

delta_of_spectra_with_filter_3.PNG


12/16 correct....not easy

mono_vs_stereo_ahb2_abx_result_filter3.PNG


Edit:
The test clip spectrum:
plot_spectrum_original_song_for_filter_3_test.PNG
 
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pjug

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You also can upload as a zip file I think.
The file I uploaded is an .xls. I just changed the extension to .pdf to upload it successfully. Change it back to .xls after downloading and it's fine.
Thank you. I will go back and give it another extension. I thought about that but wondered if amir set it up that way to prevent large files. It is only something like 250KB even if I keep a graph though.
 

pjug

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This is more difficult. But I think I still do pretty good? Not easy to find song with lots of high frequencies over 10Khz. If you have a good candidate, let me know.

View attachment 136395

12/16 correct....not easy

View attachment 136397
Nice job. I haven't tried it yet, maybe Sunday night or next week. So 4% probability that your success is just by chance, is that what the p-value indicates?
 

Pdxwayne

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Nice job. I haven't tried it yet, maybe Sunday night or next week. So 4% probability that your success is just by chance, is that what the p-value indicates?
Yeah, I think it means about 4% chance of getting the score by random guessing.

I also updated the spectrum of the test clip. If you find better songs with better high frequencies, please let me know.
 

pjug

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Yeah, I think it mean only 4% chance of getting the score by just random guessing.

I also updated the spectrum of the test song. If you fine better songs with better high frequencies, please let me know.
What is the title? Might as well try the same one, or at least that one among others.
 

Pdxwayne

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What is the title? Might as well try the same one, or at least that one among others.
It was a gift from my friend. I think you won't find it in tidal....

It is called "Spirit Of The Glen - The Ultimate Collection". From "The Royal Scots Dragoon Guards".

I cut out 15 seconds with good amount of high freq from song number one, "Amazing Grace".
 
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