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How to Power the Memory - Part 2.2 : Three Terminal Linear Regulator

In Part 2.1, I built a regulator board attached to H55M-UD2H to power the memory, but I never listened to it singing because I used batteries.

In this Part, an external regulator board is built for general use with all Mobos. A GA-G31M-ES2C Mobo is used for the test. For your interest about the listening test, it is at the bottom of this page and I recommend you read about the results first.

Construction

1. Prepare components, mark position/holes with a pencil and dill holes.



2. Circuit diagram and components layout




0.1uf cap should be added to all caps. You can also add the cap that I crossed out for even better filtering effects.









3. Remove the choke from the Mobo. May need to use solder iron to press out the choke from the solder side.



4. Connect wires from P24 3.3V and Ground, as well as from the choke output.





5. To power the DDR2 ram, tune the VR to maximum resistance, i.e. 50 ohm combined.

6. Connect the wire to the regulator board. If you're not sure whether the regulator will work, connect it to a power source e.g. a 6V battery or other power supply and check the output.




Listening test.

SSD powered by batteries, Antec Earthwatt 430, battery powering USB isolator and stock Musiland 01USD, battery driven AD1865 DAC, 45-tube power amp. CPU running at 960Mhz, forgot what CPU was used, must be a low-end one. Bios optimized.


The Mobo with DDR2 Ram booted up when the regulator was about 1.53V, with power taken from P24 3.3V. I miscalculated the resistor values(this set of resistors, i.e. 200/50 ohm, will output 1.53V not 1.8V), but never mind, it booted without problem.

Few day ago, I listened to this Mobo while doing some tests and I wasn't pleased with its SQ at all. Last time I assessed some Mobos, I graded this Mobo slighting above my Atom Mobo and the H55-UD2H was much better sounding.

With the implementation of linear regulator for memory, it sounded so much better than I could image, it is way out of expectation. Running the ram at lower voltage (1.5V) has some bearing on SQ(standard is 1.8V).



I further reduced the voltage to 1.3V whilst CMP was running. Power off
and then power on again. It booted up without problem at 1.3V. Current was about 2.3A.



At 1.3V, I was getting better music. Some noticeable improvement, minor details was clearer and background noise was lower. Under this set up with standard switching PS, no separate P24 12V and stock USB converter, I would rate the Mobo (modified with bypass caps) sounding very close to stock H55M-UD2H or perhaps better in some aspects.

I strongly recommend building a linear regulator for the memory of your Mobos. Theob, you should try. It is not complicated at all but it really makes a difference and you will be paid off. I believe the memory power circuit is more important than the rest in the mobo e.g. CPU core and graphic, it is because wave files are loaded to the memory for playing and it is the source of what we will be hearing. Therefore, a noise free environment is paramount.

Boards like H67M-UD2H-B3 also has a single phase switching power circuit, albeit using low RDS(on) Mosfet, hence will sound better. Nevertheless, it is still a switching regulator with that particular sound signature. The 2 chokes before and after the regulator help filter out much of the switching noise and listening was enjoyable, even when no linear regulator was used in the front end. Powering the regulator by P24 3.3V is convenient but not mandatory.

In Part 3, I will skip Option 4-"Series regulator made of discrete components" as I never have liked it. Instead, I'll go to Option 3 to build a sub-voltage shunt regulator(my favour), to power the memory. The design goal is an adjustable shunt regulator capable of delivering voltage as low as 0.6V to 1.3V and with more than 2A of current delivery capability. I've sourced the necessary components and is waiting for its arrival.






Edits: 11/26/11 11/26/11 11/26/11 11/26/11
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