All,
It’s nice to get so much interest and thanks for the comments. I have tried to answer some of the questions below, its only based on my setup eg USB in to a Transit card but I hope it helps...
I will post some pics but the system is not pretty, its spread out like a bad electronics project on the bench, the problem is its never finished
. I am on holidays right now so will take the shots next week and post them.
The fans I use areCPU fan
http://www.quietpc.com/gb-en-gbp/products/intelcooling/cnps7000cThe fan comes with a little in line voltage controller to adjust fan speed, I set it quite slow, from a 3 or 4 feet away its hard to hear. You need a bit of clearance above the CPU though as the copper fins are quite tall.
Case fan
http://www.ebuyer.com/product/97858These Akasa have worked well.
Power Supplies
I use Audiocom linear supplies these are very high quality and designed specifically for digital and analogue audio. Place then as close to the PCI board circuits as possible. I have about 12 X Q-Powers in total (now discontinued) and 3 of the invisius supplies (these are extreamly good but quite expensive. I looked into making my own but done have the test kit needed to ensure they can meet the standards of the Audiocom kit.
Invisius 2 regulators
http://www.audiocominternational.com/product_detail.asp?id=14I have been doing audio power mods for a few years now on audio and these things really are more than the sum of the parts.
Lab Bench Supplies
The first one I had hanging about just a 2 amp 0-30 volt, single rail old but nice, I use this one for the M-Audio Transit Audiocom supplies.
The second is a Maplin supply, I bought this in a hurry to see what could be done powering the PC. I probably would go for the third supply below though now.
http://www.maplin.co.uk/Module.aspx?ModuleNo=5925The third is the nicest bench supply it’s a bit big but has 2 X 0 to 30v and 1 X 5v supplies. One thing to be aware of is that it has thermal cut in cooling fans which are quite loud. They cut in from time to time. At the volumes I listen at this is not much of a problem but they are quite loud (I keep meaning to see it I can replace the internal fans with some Akasa ones) .
http://cgi.ebay.co.uk/New-Triple-Output-DC-Bench-Power-Supply-0-30V-0-3A_W0QQitemZ320370820851QQcmdZViewItemQQptZUK_BOI_Electrical_Test_Measurement_Equipment_ET?hash=item4a9796c6f3Leifchristensen
From my experience I would not go down the mobo USB route. I have tried onboard USB on 4 laptops 3 mobos and most have not been as good as the Startach NVidia chipset USB card. On board looks hard to upgrade so for what the Startech card costs (circa £20) I would give it a go.
http://www.startech.com/item/PCI625USB2I-Value-6-Port-USB-20-PCI-Card.aspxI have found USB cables to have quite an effect on sound quality. I tried quite a few but in the end I bought a few meters of 0.5mm pure silver wire and PTFE insulation and made one up. You only need to have the quality wire for the USB signal and the signal earth (the USB +5v from the PC is best not used down stream at all but the cable wiring can just be hook up wire). I hacked the connectors from some cheep USB cables and platted the silver wire (two cores at lease for signal +ve and earth). The cable is un-shielded but is works lots better than standard cables
For power supply upgrades I generally work in this order;
1) Replace the bypass capacitors on the boards with Black Gates or OsCons. Both are getting hard to get now as black gate have stopped producing. IMO they are the best you can get for Audio particularly the red / purple N and Nx types well worth the extra cost.
2) If I can work out how to do a clock upgrade (eg apply an Audiocom Supper clock) this almost always has a good effect.
3) For a basic upgrade I try isolate the existing supply on the card (I usually just break the relevant PCB track) and apply the smoothed supply across the bypass capacitors for the power rail. Take care this can be point of no return stuff as broken surface mount PCB tracks are hard to reconnect
4) For the PCI cards I have worked on it seems fine to power these separately before the PC supply is switched on. When the PC boots everything seems to sync up fine.
5) Next a bit of research, I look out the data sheets for the USB board / Transit Card / DAC chips in my system components. It helps to get a reasonable idea of what to go for, I usually concentrate on the boards Crystal clock / PPLs (phase lock loops) / digital line drivers (eg AES outputs) where I can work out where these are. For clever proprietary DSP ICs the chances are that the data sheets are not going to be available so then your back to looking at the existing power arrangements to work out where to break in to the supplies.
6) I have found quite a lot of PC boards and Digital Audio boards are implemented with a view to keeping cost down. Reading the data sheets can throw up some interesting simple things. For instance my DAC AD1865 really responds well to separate earths for its digital and analogue rails. This is specifically mentioned in the DAC application notes data sheet but was not well implemented in my DAC.
The PCI Bus pin out for the power pins to look at is here.
http://en.wikipedia.org/wiki/PCI_Local_BusWith regards to mobo’s I have done the following based on part personal experiment and part reading what others have done.
I run a ASRock board. At the time the approach was to keep the system as simple as possible and to have plenty of horse power to spare for the music. In the end I went for;
1) The simplest onboard video adaptor I could find (I read that sound cards seem to be bad news for Audio and experience has born this out to some degree).
2) PCI bus expansion for my PCI USB card
3) Generally a simple board because most of the extras were just going to be turned off and would only create RF and use processor and Bus time (eg minimum expansion slots etc etc)
4) Bios with good level of control over the mobo systems as I want to turn most off them off. In particular turn off clock spreading on the CPU and this is like deliberately adding jitter to the CPU clock – doesn’t seem right for Audio .
5) Finally I wanted a Bios that can load multiple configs as I wanted to rune dual boots one for audio with absolutely everything turned off and one for normal use.
6) I did look at the mobo power supply (as far as possible from pics). I know that some are better than others but I already knew that I was going down the route of supply upgrades.
This is what I went for, its cheep but seems to put in a good performance.
http://www.asrock.com/mb/overview.asp?Model=G43Twins-FullHDI have not gone as far as a separate mobo power plan (so far )but I would not be surprised to hear that it worked for sound quality. Certainly for my system turning everything off either by bios setting and or by disconnecting if it’s not used works (eg CDROMS, A Drive, Additional Hard Drives etc). Using the lab bench supplies for fans the remaining hard drive and PCI USB card is also good for sound.
Best Regards,
Nick.
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but musicaly rather good to listen to.
