Summer in The Netherlands is at it’s end, so it’s time too pick up my indoor hobby again. Which means its time for: Power Supply improvements: part 2.
As already stated by other inmates (Gstew, Reylands, Bertel, Theob, carcass93, Rayban, Sondale, fmak and many others) improving the power supply is a very worthwhile and very rewarding exercise.
Optimizations of the Operation System, Kernel and the BIOS all together do have a nice effect on sound quality, but I was really amazed what BIG IMPACT (!) a linear PSU on the P4-pin had on sound quality in my setup.
Note: my setup is a fully optimized PC as per Cics hard- and software recommendations. So my findings are based on a setup like this: see: http://cplay.sourceforge.net. With only 2 exceptions: I do not under-volt the FSB nor RAM . I over-volt both with + 0,2 V.
Improving the power supply to the P4 pin with a linear PSU turned out to be surprisingly easy (and also relatively cheap), Click on picture to see photo's in Picasa webalbum:
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| cMP2 project: Optimizing power with linear PSU to P4 power connector’ |
So I now would like to try optimizing the power to the P24 connector.
Just before summer (in june) more knowledgeable inmates who already tried to improve the power on the P24 (Bertel, Gstew and others) gave me a lot of suggestions and possible directions.
-> Bertel pointed out the importance of choosing good quality low-ESR smoothing caps but also and the use of low resistance wires (!).
“ to keep power supply as clean and quick as possible to keep the rise time between 0 and 1 ("no power" and "power", changing ever so quickly) at a minimum! IMHO this can best be done with caps sized the "right" way, plus cables from the caps to the board which are short, have a lot of internal conductors (that brings speed, e.g. I use AWG 6 which is 133*AWG27) and a very low internal resistance (<.5Ohm/1000ft, just to be safe - that's in the region of an average PCB's traces) “
-> Gstew suggested use a tweaked Pico PSU (extra smoothing caps) on the P24 pin.
So that’s what I did (wires and picoPSU) last week, with unexpected and very surprising results !!
* using LOW RESISTANCE internal power wires to P4 and P24.
Although Bertel already had pointed out to me the importance of using low resistance wires, I still wired everything together with standard computer wires (18AWG wire). Why? because its easy and I’m lazy. Standard computer 12 v power wires are constructed of 18 AWG and can simply be bought everywhere and they have already all the right plugs and connectors attached and in place. Regular wire to distribute power inside pc’s is: 18AWG = 6,5 ohm/1000ft. Bertel suggested to use 6AWG which is: 0,4 ohm/1000ft. http://www.interfacebus.com/Copper_Wire_AWG_SIze.html
Untill last Sunday. A suddenly cancelled social appointment left me with nothing much to do on a rainy Sunday afternoon. With electronic stores being closed on Sunday in The Netherlands, I had no other wire at hand than the type of wire that is used to wire the electricity in housing (with solid 2 mm copper conductor).
I braided 2 solid copper wires together until I had 1 meter of braided solid copper cable. With still 1 cm standard 18AWG computer wire left at the P4 plug I soldered the braided solid core copper wire to the P4 plug (a P4 plug has 2 black 18AWG wires + 2 yellow 18AWG wires)
I saw no other way than too solder the 2 mm solid copper wire to the P4 plug than trough leaving 1 cm of the original 18AWG standard wire attached to the P4 plug. The best solution would be to solder the low resistance wire directly to the metal-connectors inside the plastic plug. But I don't manage / don't know how, to get the metal-connectors out of the plastic plug.
Click on picture too see photo's of the solderingproces of low resistance multi-stranded wire to the P4 plug in the picasa webalbum.
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| cMP2 project: low resistance wire between linear PSU’s and P4 / P24 power connector |
I also braided 1 meter of 2 times 2 mm solid copper wire to also connect the picoPSU with this braided wire to the linear PSU that is feeding the picoPSU.
Working with this braided 1 meter 2 x 2 mm solid coper wire is a hassle. The braided wire is not flexible and one has to bend the braided solid copper wire in place all the way from the linear PSU, through the pc case, to the P4 and P24 connectors. Of course it’s much easier to use multi-stranded wire (6AWG or similar).
I didn’t expect much of this construction because there still was a bottle neck of 1 cm 18 AWG standard computer wire attached to the P4 plug. So I expected the whole wrestle with the stiff braided cable would probably not be worth the trouble.
But WHOW… I couldn’t be more wrong! It made big and massive impact!!
Bass, mids, treble everything changed dramatically. (I’m not writing this for effect purposes) Especially drum kicks, plugged strings, or any type of ‘explosive sounds’, where very much more heard and present. A drum kick, now sounds like a real drum kick !!!
The changes where that big, that I first thought, that there was something wrong. That I only added some kind of reverb like distortion. But after playing more and more music and tracks I started to realize that this was no distortion at all. This is probably how the music was recorded and mastered.
* Optimizing power to the 12Volt rail of the P24 with linear PSU + picoPSU.
- Chosing the right picoPSU model.
It turned out that not al picoPSU are made by the same concept. Some picoPSU models leave the 12 V line untouched and pas it straight on too the MoBo, where other picoPSU models don’t leave the 12 V line untouched and regulate the 12 V line.
So shit happens and I first bought the wrong picoPSU model. A PW-200-M w/P4-ATX. This model regulates the 12 V line which results in almost no sound quality improvement. So it’s not worth the trouble to change a ‘smoothing capped’ ANTEC ATX PSU for an PW-200-M w/P4-ATX.
By now I have ordered an other picoPSU model and installed it. The model picoPSU-150-XT leaves the 12 v line untouched and passes the 12 V line straight on too the MoBo. Now there is a very nice improvement in sound quality !
However a very nice improvement, it’s not as much as with a linear PSU on the P4 pin.
In comparison: a picoPSU-150-XT on the P24 gives about 1/3 of the improvement of a linear PSU on the P4 pin. (So improving the 5 Volt and the 3,3 volt power also needs to be done. Especialy the 5 v line. But thats for PSU improvements: part 3, because I haven’t made up my mind yet on how to do it the easy way). But although only 1/3, it’s still a worthwhile and recommended improvement !
So chosing the right picoPSU model (which leaves the 12v line untouched) is important ! Installing a picoPSU model that regulates the 12V line, it’s not worth the trouble IMHO.
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| cMP2 project: Optimizing power with linear PSU + picoPSU to 12V rail on P24 power connector’ |
* First question on internal power wires.
Are there any other inmates who swapped out the standard PC power wire type (18 AWG) and replaced these internal pc-power-wires for low resistance wires like Bertel suggests?
(AWG 6 wire or lower resistance)
Or, are there any inmates willing to experiment with low resistance type of wire between their linear PSU and the P4 pin and/or their picoPSU ? And report back there findings ?
* Second question on internal power wires.
If this would be analog audio, I could easily understand what is happening and understand the effect. But what is happening here ? Is this really the effect Bertel pointed at? “ keep the rise time between 0 and 1 ("no power" and "power", changing ever so quickly) at a minimum! ”
Any comments, suggestions, feedback is very much appreciated. Or even better: please try this at home and report findings back here at the forum !
Power supply improvements part 3, will on the P24 5 volt and 3,5 volt lines but I haven’t made up my mind yet on how do to this the easy way. Probably there is no easy way.
Note:
I don’t encourage anyone too use solid core 2 mm copper wires. It’s a hassle. I just had nothing else lying around at that time. But I do encourage to try multi-stranded 6AWG wire (or any other low resistance wire) between the linear PSU and the P4 / P24 connecter and report back the findings to this forum.
fully AOB optimized cMP2 PC -> Lynx AES16 -> XLR AES/EBU -> Lavry Black DA10 -> XLR Mogami Gold -> Klein & Hummel O300
