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In Reply to: RE: cMP - the open source high-end Memory Player posted by cics on December 30, 2007 at 05:42:01
I was reminded of that tonight. I was moving my gear around to make room for one of my turntable setups, none of which have been run for several years.
Most of the work was in re-cabling / re-shelving my DVD & VHS players (yah, my system is also a sorta AV setup... But most of the time, the AV stuff is all unplugged and it mostly acts as a very hair-shirt stereo).
But I did move the cMP2 around a bit while doing the other stuff. This takes some care as my harddrive and all my linear supplies are just sitting in the case (with some care to control vibrations), but not secured.
I put it all back together (after spending some time watching/listening to couple of movies through both the DVD and VHS players... They sound pretty good when the audio output is going directly through that hair-shirt stereo setup!). And it didn't sound right... Bright, splattery, conjusted, bass didn't flow. Since I moved it around, likely stuff shifted inside. I open it up and the HDD is no longer on it's damper feet (I have the drive mounted to a block of bamboo, wrapped in ERS cloth, sitting on three Herbie's feet, and weighed down with a VPI brick-substitute made from an old laminated transformer core). I put it back in as it should be, fire it up, and the sound is back to snuff.
I'm debating moving the drive outside the case if I can come up with a good mounting setup.
I'm also breaking in a couple of Hammond chokes in the AC for the dirty supplies... They're about a week into the break-in, I hear that they'll continue to change for at least another week, but I immediately heard some improvements in background blackness and bass detailing when I put them in and that has improved with break-in time. Remember, these are the dirty supplies... HDD, LCD, and the one active USB port for the mouse and touchscreen! They ARE serious linear supplies (oversized transformers & regulators, good diodes and caps, and 47,000uf caps on the raw DC) going through a 16'-long Ryland's-inspired braided extension cord to a separate AC circuit in my house as specified by cics. Shouldn't make much of a difference, huh? But it does and improving the AC filtering took it up another notch.
Some people want to use their computer to play music. They install some music software, maybe network it to other systems in their house, surf the net on it, run antivirus, let their kids use it for playing games, etc. They get one level of sound quality from this.
Other people want to setup a computer to play music. They build up a cMP2 or setup one of the many computer music playback configurations, PC, MAC, or Linex, XP, Vista, or Windows 7, whatever. They may select specific software and hardware, spend some time configuring the system to optimize it a bit, and likely use it only for music playback. They get a higher level of sound quality.
And a few people want to use a computer as component in a digital playback system. Here, they start to do the things that one would do to build a high-end CDP/DAC combo... Vibration control, optimized power supplies, radical system configuring, selected hardware, paying attention to connecting cabling, etc. I hear a lot of rewards in going this way... I won't be able to do a comparison between my cMP2 and my vinyl setup for a few more weeks, but my cMP2 is definitively besting all of my previous digital playback setups in every way. Yah, it's really nice to have my entire CD library on a harddrive and accessable with a few clicks of a mouse, but it's the sound quality that makes it really worthwhile.
And at this level, virtually everything matters. God is in the details!
Lotsa fun!
Greg in Mississippi
If you haven't yet, read Theob's post about the impact converting the 3.3v on his Juli@ to battery made on his sound quality. Remember, in his setup, this is just powering the chips that receive the digital signal from the processor via the PCI buss and convert it to SPDIF. He says it made the largest impact of any single change he's made to his setup... and my experience with upgrading power supplies has me understand what he's talking about.
If the cMP2 setup with cPlay makes a PC-based digital playback sound good, upgrading the power supplies takes it to another realm entirely. I had a similar experience to Theob's when I powered my Juli@ from independent linear supplies with high-quality regulators... in my setup, only one other upgrade's sonic differences were in that realm of magnitude and that was when I added a linear supply to the P4 and the linear/hybrid supply with the modified PicoPSU to the ATX24.
As I've been listening to my system over the past several days (after putting the GA-G31M-S2L back from the comparison to the ES2L), I am struck by a couple of things:
1. My collection of music has gotten larger. Strange, huh? But recordings that were dogs before sound ok or sometimes pretty good now. Good recordings sound phenomenal. And really good recordings still sound phenomenal. The range of levels of sound quality has shrunk... the poorer ones are smoother, more detailed, more musically satisfying & involving then they ever were with any of my CD setups.Good ones still sound very good and have improved too, but not to the level of magnitude that the poorer ones have improved. So I now have a bunch of recordings that were 'bottom of the pile' that are now interesting both sonically and musically.
2. I'm much more interested in listening to music than fiddling with hardware or software. I have a BUNCH of things lined up to test:
- More stringent comparison between my linear 'dirty' supplies and the original Granite Digital units to determine if one particular dirty unit makes more difference than the others.
- Adding caps on the Granite Digital units to see what difference that makes.
- Comparing my Ryelands-inspired seriously-braided extension cord to the 'dirty supplies' to the cheap store-bought unit I used before to better access the differences.
- Assessing the impact of the now-broken-in choke filters on the 'dirty supplies' AC and if the inline filter I used before still makes a worthwhile difference with the chokes.
- Further motherboard comparisons... GA-G31M-S2L vs GA-G31M-ES2L vs GA-EG45M-UD2H with additional configuring on the two new boards.
- Further memory comparisons... ValuRAM vs HyperX vs Mushkin.
- cPlay 2.0b27 vs 2.0b26... in my setup, at first listen, I preferred b26 as it gave more PRAT and musical involvement. But I never spent the time to try and optimize the settings on b27.
- SOX. I'm still using SRC and haven't even tried SOX yet.
- Battery on the Juli@ 3.3v line. I did get one of the 3.3v LiFePO4 cells to try here... heck, I have a ton of serious high-current/high-capacity LiPo packs from my model airplane hobby and I really need to try battery power on various rails on this thing. I know good results can be achieved with either battery or AC power... but it'd be nice to reduce the sonic difference I get from the varying quality of the AC line during various times of the day.
Plus I have a bunch of projects lined up around my cMP... Main among them are trying Bertel's switched-over linear supplies using relays and building a custom case. Plus my I2S DAC sounds like it should really be here in the next week or so and I'm getting some different and highly-regarded regulators to try out on the Juli@. Also I want to try comparisons of my custom linear supplies to some of the lab linear supplies others have used... and I'm very interested to hear what hfavandepas finds out about whether the lower-power PicoPSUs do a direct pass-through of the 12v.... this is possibly a good, easy-to-implement improvement.
Some of these will help us understand what's important in a cMP2.... others will help determine what hardware is best to use, especially that some parts are no longer easily available... some have the promise of further catapulting the sound quality of a cMP2 to the another level. I'm a tweak and I should be jumping up to run through all of them!
But right now, I just want to go and listen to my system and discover those recordings that I didn't pay much attention to before because they sounded bad or weren't musically interesting.
Such is the sound of greatness peeking through!
Greg in Mississippi
P.S. Many thanks to all the heros and pioneers in this saga... cics for the concept and all the hard work developing this, Rick Mc for being the pioneer who championed this to me, Ryeland, Bertel, hfavandepas, and Peter Daniel (from the DIYAudio list) for their work in improving the system's power supplies, and abysstw for working out the basic BIOS settings on the GA-EG45M-UD2H. Thanks all, I haven't had this much fun in audio for many, many years.
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