Home Computer Audio Asylum

Music servers and other computer based digital audio technologies.

[ Follow Ups ] [ Post Followup ] Thread: [ Display  All  Email ] [ Computer Audio Asylum ]
[ Alert Moderator ]

How to Power the Memory - Part 1 Linear Regulator etc

Hi Serge and fellow members of this forum,

When we start to tamper with the PWM circuit on the MB, we begin to scratch its heart and soul. We are fully aware of the improvement brought about by implementation of full linear PS in place of the switching PS in ATX format.

Would a linear power supply for memory give a SQ enhancement, even if a full linear PSU for P24 and P4 is used? Perhaps I should rephrase the question in technical terms: "Would replacement of the on-board single phase switching power supply by a linear power supply enhance SQ?" I would say most definitely. Our full linear PS implementation has proven this. Nevertheless, improvement in SQ will largely depend on the quality of the linear power supply used. My experience is that whilst powering the MB with SLA batteries + 3-terminal reg., I then powered the memory with batteries resulting in good SQ improvement. Replaced by a LT1083 also improved SQ but not to the extent of battery. When powering the 5V rail with batteries I was in heaven. As Greg said, "Everything matters!" All minor improvement work add up. Don't know how it will sound when powering both 5V rail and memory by batteries at the same time.


With regard to implementation of memory power supply on H55/H61 series MB, as well as others, I have the following options in mind, in order of superiority:

1. NiMh battery (suitable for H61 MB)
2. Shunt regulator buffered by NiMh battery (suitable for H55/57/61/67 MB)
3. Shunt regulator alone (suitable for all MB)
4. Series regulator made of discrete components (suitable for all MB)
5. 3 terminal series regulator (suitable for all MB)
6. Onboard switching regulator buffered by NiMh battery (suitable for H55/57/61/67 MB)

So far, I have tried options 1, 5 and 6 on MBs. I have also tried 2, 3, 4 and 5 on other audio circuits. Hence I can tell the difference.

Application of the above options will largely depend on how desperate you wish to improve SQ, the ease of construction and MB model/electrical characteristics.

For H61 series MB, memory can run as low as 1.1V. Therefore, I will definitely go for NiMh battery(1.25V). However, there are some variations, e.g. whether to use 2-3 D size Nimh batteries or 1 Nimh battery backup by a large LifePo battery (2 more variations here in terms of backup battery connection - whether to use resistor or shunt regulator for voltage drop, the latter would be a combination of option 1 & 2 and may be a balanced approach in terms of maintaining purity of power supply and stability of voltage).

For H55M-UD2H, pure battery is not feasible, as memory won't work below 1.3V or so. Therefore, other options should be used. For G31 MB, the DDR2 memory runs at 1.8V and is therefore not suitable for battery operation.

It will be a long story. Hence, I will divide my writing into parts and start with the easiest options.

Option 6 - NiMh battery buffer for H55/57/61/67 MB

You only need a relay e.g. 12V, a diode, four wires and a C or D size Nimh battery in a holder with connecting terminals.

(a) No need to remove the choke powering memory
(b) Fix the battery/holder and relay somewhere on the MB near to the memory using double side adhesive tap.
(c)Connect the coil of relay to 12V and ground of P24 on MB, a diode 1N4001-4007 or similar in parallel to the coil(cathode towards P24 12V).
(d) Connect the negative of battery holder to P24 ground of MB.
(e) Connect positive of battery holder to the moving arm (COM) of the relay.
(f) Connect NO pin of relay to the output point of the choke




Upon MB startup, the battery will be connected, by the relay, in parallel to the on-board memory power supply. It is simple work which can be done in half an hour. The modification is safe, will improve SQ but won't hurt the MB, just be cautious about polarity. In addition, Ram voltage should not be set to 1.45V or above, use the lowest voltage possible to run the ram. The battery acts like a capacitor under this config. and I found this buffer better sounding than bypass caps. Of course, quality caps should also be added.

Option 1 - NiMh batteries for H61/67 MB

The connection is similar to option 6 above but the choke should be removed. More batteries connected in parallel are needed for longer playing time.

A stock battery charger can be put/stick inside the case. Negative terminal of charger to Gnd of MB, Positive connected to the NC pin of relay. When MB is power off, it will charge the batteries provided that it is always connected to the AC mains.


Option 5 - 3 Terminal Linear Regulator for all MB

I'll take some photos to illustrate the construction. Please feel free to ask any question. See you in part 2.



Edits: 11/23/11 11/23/11
This post is made possible by the generous support of people like you and our sponsors:
  Crux Audio  

Follow Ups Full Thread
Follow Ups
FAQ

Post a Message!

 Forgot Password?
Moniker (Username):
Password (Optional):
  Remember my Moniker & Password  (What's this?)    Eat Me
E-Mail (Optional):
Subject:
Message:   (Posts are subject to Content Rules)
Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:  Automagically notify you when someone responds.

[ Top Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]
[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]