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MiniDSP SHD vs Pioner VSX-LX505 : noticeable difference in sound quality

I recently purchased a Pioneer VSX-LX505 to see if I could move from a stereo to 7.1.2 setup. I made a head to head comparison, using the same amplifier and speaker, and with all processing off (Pure Direct on AVR, Dirac off on Minidsp). Both speakers were placed right next to each other and same channel was used. I used pink noise and a UMIK-1 to make sure they are both producing SPL within 1db of each other.

Setup was
Apple TV -> Pioneer -> TV -> TV Optical Out -> Minidsp SHD -> Hypex NC502MP Amp Channel 1 -> Speaker (Wharfedale Linton)
Apple TV -> Pioneer -> Pre Out -> Hypex NC502MP Channel 2 -> Speaker (Wharfedale Linton)

I can distinctly make out that the Pioneer Pre-outs lack as much attack and detail as the SHD. I also took a recording of both and performed an ABX test in Foobar, and got 16/16 (test.txt).
Are you sure that all “sound-enhancing” functions are deactivated on the TV? Maybe not everything on the TV can be deactivated.
Please eliminate the TV and go these two ways.

Apple TV -> Pioneer Optical Out -> Minidsp SHD -> Hypex NC502MP Amp Channel 1 -> Speaker (Wharfedale Linton)
Apple TV -> Pioneer -> Pre Out -> Hypex NC502MP Channel 2 -> Speaker (Wharfedale Linton)
 
Are you sure that all “sound-enhancing” functions are deactivated on the TV? Maybe not everything on the TV can be deactivated.
Please eliminate the TV and go these two ways.

Apple TV -> Pioneer Optical Out -> Minidsp SHD -> Hypex NC502MP Amp Channel 1 -> Speaker (Wharfedale Linton)
Apple TV -> Pioneer -> Pre Out -> Hypex NC502MP Channel 2 -> Speaker (Wharfedale Linton)

That would be good but I am not sure if the Pioneer LX505 has optical output, if it has, he would/should have done just that, I would think...
 
1707838068004.png


it does not have an optical output, only analog pre-outs.

For this test to work properly, the source should have a pair of digital outputs with one feeding the miniDSP and the other feeding the AVR.
Then both devices should be volume matched with the output voltage on the pre-Outs matching to within 0.1V or closer.
Those should then feed into the amplifier for headphones/speakers, etc.


Alternatively, because a microphone recording of speakers playing music in a regular room will almost always come with great variance in sound, OP should consider running a null-test first.
Feed the signal into the amplifier and take the output (from pre-outs) to measure.
Source (e.g. Computer via optical) - Input AVR - output from AVR - Source (computer RCA input) and see if the output is equal to the output. (in Pure Direct, that should be the case, with any DSP active, not)
 
Are you sure that all “sound-enhancing” functions are deactivated on the TV? Maybe not everything on the TV can be deactivated.
Please eliminate the TV and go these two ways.

Apple TV -> Pioneer Optical Out -> Minidsp SHD -> Hypex NC502MP Amp Channel 1 -> Speaker (Wharfedale Linton)
Apple TV -> Pioneer -> Pre Out -> Hypex NC502MP Channel 2 -> Speaker (Wharfedale Linton)
My Pioneer avr doesn’t do optical out, only hdmi
 
If I’m redoing the tests, would it make sense to use pink noise rather than using a recording?
 
If I’m redoing the tests, would it make sense to use pink noise rather than using a recording?

If you want to compare the AVR to the miniDSP, it would make sense to first do a null test to see if there's any difference in the signal at all.
But only after eliminating all devices that aren't necessary for the test.

for your actual test:
You want both to be in the identical chain, that's why I suggested using a source with optical and coax out that lets you quickly switch, running one into the AVR, and the other into the miniDSP.
From there, you want them level matched using a digital voltmeter (those are 10-20 bucks at the hardware store), using the pre-outs on both that then go into an amp of your choice
 
From the title it looks like the test is between the Minidsp SHD and Pioneer 505 as preamp. Everything else should be eliminated for an equal comparison including turning off all DSP. Might need a different source than the apple tv. maybe computer using usb in on both.

Source> Minidsp SHD> Hypex amp>speaker
Source> Pioneer pre out> Hypex amp> speaker
 
If I’m redoing the tests, would it make sense to use pink noise rather than using a recording?
I would just use REW sweeps, simple and easy, and much more reliable than going by ears.
 
If I’m redoing the tests, would it make sense to use pink noise rather than using a recording?

The last time I tried comparing amps, I got the following using REW sweeps:

I tried by ears first, couldn't tell a difference at normal listening level, let alone which one sounded better, then I do the REW FR sweeps and while there were visible differences, but at 1/24 smoothing it is hard to tell which is which either. That's for average 90 dB spl, at higher level such as 100 dB average, there were very visible differences in the range below 100 Hz, I tried to find the graphs but couldn't find them yet.

I could use the same method to compare my external dacs, or between ext. dacs and an AVR/AVP preamp outputs.

1707920585794.jpeg
 
I did another test.

List of changes
1. Chain is now PC -> MiniDSP -> Pioneer AVR -> Amplifier -> Speaker
2. MiniDSP was connected digitally (COAX) as well as with RCA to the AVR. I also tried one test with MiniDSP connected directly to the Amp.
3. AVR was run in Pure Direct and Direct modes. My understanding is that 'Pure Direct' disables any bass management, room correction etc. while Direct will not introduce any artificial surround, but bass management etc. continue to work.

minidsp vs pioneer.png


Observations:
1. 'Direct' mode seems to be turning on bass management as expected, reducing the SPL below 100 hz significantly. This is both when using the AVR as a DAC or MiniDSP as DAC feeding the AVR.
2. 'Pure Direct' behaviour is not consistent. When MiniDSP is used as a DAC feeding the AVR, bass management is turned off. However, when the AVR is being used as a DAC, Pure Direct is till engaging bass management. This could be a bug in AVR firmware.
3. MiniDSP connected directly to the Amp produces the same behaviour as MiniDSP acting s DAC and feeding AVR in 'Pure Direct' mode.
4. Minimal effect on frequencies above 100 Hz (this is probably because my Sub x-over in the AVR is setup at 100hz).

.mdat file attached.
 

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Last edited:
I did another test.

List of changes
1. Chain is now PC -> MiniDSP -> Pioneer AVR -> Amplifier -> Speaker
2. MiniDSP was connected digitally (COAX) as well as with RCA to the AVR. I also tried one test with MiniDSP connected directly to the Amp.
3. AVR was run in Pure Direct and Direct modes. My understanding is that 'Pure Direct' disables any bass management, room correction etc. while Direct will not introduce any artificial surround, but bass management etc. continue to work.

View attachment 349814

Observations:
1. 'Direct' mode seems to be turning on bass management as expected, reducing the SPL below 100 hz significantly. This is both when using the AVR as a DAC or MiniDSP as DAC feeding the AVR.
2. 'Pure Direct' behaviour is not consistent. When MiniDSP is used as a DAC feeding the AVR, bass management is turned off. However, when the AVR is being used as a DAC, Pure Direct is till engaging bass management. This could be a bug in AVR firmware.
3. MiniDSP connected directly to the Amp produces the same behaviour as MiniDSP acting s DAC and feeding AVR in 'Pure Direct' mode.
4. Minimal effect on frequencies above 100 Hz (this is probably because my Sub x-over in the AVR is setup at 100hz).

.mdat file attached.

these massive differences in the bass look more like the subwoofer being active/inactive.
You can nicely see the gigantic room modes, too. (And I would suggest placing the subwoofer somewhere else and crossing over at maybe 80Hz to get rid of that null at 100Hz and flatten the null at 165 or so Hz.

iirc, Direct mode doesn't do "bass management", but rather keeps the crossovers and lets you use the subwoofer alongside the speakers, whereas Pure Direct only plays stereo. (which makes no sense if I see the two blue lines correctly in your measurements)
bc orange, green, and bright blue look like bookshelf speakers with no subwoofer. whereas brown and dark blue look like there's a subwoofer active.



All that said, there shouldn't be any audible differences between the miniDSP and the Pioneer based on FR and levels.
 
I did another test.

List of changes
1. Chain is now PC -> MiniDSP -> Pioneer AVR -> Amplifier -> Speaker
2. MiniDSP was connected digitally (COAX) as well as with RCA to the AVR. I also tried one test with MiniDSP connected directly to the Amp.
3. AVR was run in Pure Direct and Direct modes. My understanding is that 'Pure Direct' disables any bass management, room correction etc. while Direct will not introduce any artificial surround, but bass management etc. continue to work.

View attachment 349814

Observations:
1. 'Direct' mode seems to be turning on bass management as expected, reducing the SPL below 100 hz significantly. This is both when using the AVR as a DAC or MiniDSP as DAC feeding the AVR.
2. 'Pure Direct' behaviour is not consistent. When MiniDSP is used as a DAC feeding the AVR, bass management is turned off. However, when the AVR is being used as a DAC, Pure Direct is till engaging bass management. This could be a bug in AVR firmware.
3. MiniDSP connected directly to the Amp produces the same behaviour as MiniDSP acting s DAC and feeding AVR in 'Pure Direct' mode.
4. Minimal effect on frequencies above 100 Hz (this is probably because my Sub x-over in the AVR is setup at 100hz).

.mdat file attached.
Thank you for putting in the effort and doing the capture again. There's definitely something strange going on!
 
these massive differences in the bass look more like the subwoofer being active/inactive.
You can nicely see the gigantic room modes, too. (And I would suggest placing the subwoofer somewhere else and crossing over at maybe 80Hz to get rid of that null at 100Hz and flatten the null at 165 or so Hz.

iirc, Direct mode doesn't do "bass management", but rather keeps the crossovers and lets you use the subwoofer alongside the speakers, whereas Pure Direct only plays stereo. (which makes no sense if I see the two blue lines correctly in your measurements)
bc orange, green, and bright blue look like bookshelf speakers with no subwoofer. whereas brown and dark blue look like there's a subwoofer active.



All that said, there shouldn't be any audible differences between the miniDSP and the Pioneer based on FR and levels.
The subwoofer is turned off. My speakers can play down to 45Hz in room. So the difference is that Pure Direct when Pionner acts as a DAC vs when it is receiving Analog. Only Analog is 'Pure Direct' in the true sense of the word as it disengages the sub crossover at 100hz
 
Performed the same test for Right Channel with same results. When the AVR acts as a DAC, even 'Pure Direct' does not turn off the sub x-over.

minidsp vs pioneer R.png
 
Performed the same test for Right Channel with same results. When the AVR acts as a DAC, even 'Pure Direct' does not turn off the sub x-over.

View attachment 350322
A very interesting interpretation of the words "pure" and "direct"!
 
did you set the front to "Double Bass" per chance?

What I find incredibly strange is your alleged 100Hz crossover... that should be a 12 or 24dB/octave filter, yet that looks absolutely not right.
The frequencies below 100Hz are barely reduced in SPL.. why?!
 
did you set the front to "Double Bass" per chance?

What I find incredibly strange is your alleged 100Hz crossover... that should be a 12 or 24dB/octave filter, yet that looks absolutely not right.
The frequencies below 100Hz are barely reduced in SPL.. why?!
How do you setup double bass? I haven’t found that option
 
How do you setup double bass? I haven’t found that option
That's in the speaker setup menu. (page 134 in the manual)
1708326738886.png


From looking at your measurements, I'd say that you aren't seeing the crossover enabled, but rather a bass boost present with the miniDSP.
Because you get roughly 45 Hz at -3dB in Direct mode.. (compared to the 63dB at 1kHz)
It looks terrible because of the room modes interfering so much, but you chose almost no smoothing there.

Could also be that you have intense room gain and your speakers in-room response is all the way down to below 30Hz without EQ, but that really doesn't seem reasonable if they only get 45Hz in room, according to you?!
Also, you feed the Pioneer an analog signal from the MiniDSP, then put out pure direct? Is an EQ in the miniDSP active for bass?

Because I cannot quite wrap my head around the differences.
Green, teal, and lilac look "correct" for a setup with "smaller" speakers and no subwoofer.
blue and red look like there's a subwoofer playing, or at least a massive boost in the bass. (+15 dB at 35Hz is just crazy!)
 
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