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Context for quantifying SQ Improvements... muddying the waters!

Thinking more about what I wrote, I realized that one thing I did not highlight was the context of my cMP at the time of the two changes I mentioned... and as you'll see, the context is likely crucial to judging whether the changes will cause a similar impact with your setup.

At the time I implemented the Linear/Hybrid supply (Linear P4, Linear -> modified PicoPSU ATX-20/24), the state of my cMP was:

- cMP's Zalman case on compliant footers & some case-top weights & minimal motherboard damping
- HDD, USB, Zalman touchscreen powered via 2 Granite Digital SMPSs
- HDD mounted in the Zalman cage with minimal isolation
- Analog out via an un-modified Juli@

Initially:



After linear HDD/USB/Zalman monitor PSUs & some HDD isolation:



When I implemented separate power for my Juli@, the system state had changed significantly:

- cMP's Zalman case on compliant footers w/ some case-top weights & surface damping & slightly increased motherboard damping
- MoBo power via Linear P4, Linear -> modified PicoPSU ATX-20/24
- HDD, USB, Zalman touchscreen powered via hi-test linear supplies
- HDD resting on wooden slab with damping weight
- Analog out via a Juli@ modified with upgraded signal & power supply reservoir caps & 4 key regulators



And when I implemented the fully linear supply, the system state had changed even more:

- cMP's Zalman case on compliant footers w/ some case-top weights & surface damping on the top and sides & much greater increased motherboard damping
- HDD, USB, Zalman touchscreen powered via hi-test linear supplies
- HDD mounted to wooden slab with damping/stray-field-limited weight, ERS paper shielding, & compliant footers with carefully dressed connecting wires
- Analog out via a Juli@ digital w/add-on I2S connected AK4399-based DAC card & separate power



Until I implemented the separate power for the Juli@, any motherboard-connected power supply improvements likely made a larger impact on my cMP's sound quality than they would for a cMP with a separate DAC. This was confirmed when I powered the Juli@ from entirely separate supplies... The change made by upgrading the regulators, but still powered via the motherboard was noticable, but honestly disappointing in magnitude. But adding the separate power made the machine a whole new source (and this was probably magnified by the presence of the 'good' regulators).

How is this relevent to this discussion?

First, Playmate also uses a soundcard for his analog output. So he'll probably get results similar in magnitude to what I experienced if he does something similar. But not everyone will get similar results!

Second, to Mark's comments about HDD's & SSD's, first I have to ask Mark what is the current state of his cMP (sorry, I just don't remember or know all of it). I really can't comment with any authority until I know more (and likely not absolutely until I try an SSD), but I suspect that if Mark does not have as sophisticated a level of vibration control & power for his HDD/SSD, he may have gotten a greater improvement than I'll hear if I implement the same drive. Again, my trying it is the only way to know... And I may just have to do that. But an important data point is that the HDD isolation I've done makes a subtle, but very important difference in my system's SQ... if the HDD is touching a nearby structure or if the cables are not dressed correctly, the system will sound very dead, digital-ish, and not very tuneful.

***EDIT***

Mark, I see that you do describe a great deal about your system and how its powered in your SSD-question subthread. So the main thing I'm interested in knowing is how was your HDD and now how is your SSD mounted? Did you do anything to reduce the impact of vibrations from the HDD?


Third, I REALLY have to do a better job of detailing the context as I discuss changes I make to my cMP and their sonic impact... And ask that others do that too. I am pretty sure that someone using a separate DAC, especially one with galvanic isolation, would hear smaller differences if they implemented a linear/hybrid or fully linear supply than I experienced.

Finally, regarding the smaller difference I experienced when I implemented my fully-linear supply than when I implemented the linear/hybrid one... By the time I put in the fully linear, I had tweaked many other aspects of my system that would have been affected by that supply... Separate sound card power with very directly-powered DAC primarily, but not exclusively. If I took my system back to the state where it was when I first implemented the linear/hybrid supply & compared the two supplies then, I suspect I might hear greater or lesser differences in sound quality... Honestly, I am not sure which way it would go, but I'm pretty confident it would be different.

So where I end up is with greater clarity about how much less clarity we have in comparing sound quality impacts across our variously-different cMP systems. GACK, not what I expected to learn going down this path!

Greg in Mississippi

P.S. First, I won't be trying that experiment to take my system back to an earlier level and compare the two types of supplies... Sorry, just not enough time for that, at least not now. I will try to compare my modified Antec (additional filter caps, fan and extraneous cables removed) to the fully-linear and my system's current state as I'm getting ready to lend it out to a fellow inmate... I'm hoping that will be instructive.
Everything matters!


Edits: 01/27/11 01/27/11
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