Linear Power Supply for an external HDD?

[blownsi]

I'm wanting to try a linear supply on my external (music) drive. Would I simply buy a linear supply to replace the wall wart without opening up the case or would the internal supply "dirty" the power? If I were to open the case and bypass the factory power altogether would I need two supplies (one 5v and one 12v)? Or some kind of splitter with a 12>5v stepdown?

[blownsi]

240 views and no responses so I've either asked a very good question or a dumb one:) Either way I have found a few articles online of people just replacing the wall-wart of an external drive with a similar linear supply. None of them clearly indicate whether any improvement was heard. They just seem to be making sure that's not a source of issue. There is also an example of a guy custom building a linear supply that provides both 5v and 12v taps and the entire unit is packaged into a box that looks like an audio component. This guy refers to it as his audiophile hard drive if you'd like to google it for yourself.

[wwaldmanfan]

I'm wanting to try a linear supply on my external (music) drive. Would I simply buy a linear supply to replace the wall wart without opening up the case or would the internal supply "dirty" the power? If I were to open the case and bypass the factory power altogether would I need two supplies (one 5v and one 12v)? Or some kind of splitter with a 12>5v stepdown?

 

A simple test would be to copy some music files to a RAM disk, then unboot the external HDD, and play them. If you really want to get nuts, unplug the wall wart from the AC supply after you unboot the drive. If you don't hear any improvement in SQ, then don't bother changing anything.

[blownsi]

A simple test would be to copy some music files to a RAM disk, then unboot the external HDD, and play them. If you really want to get nuts, unplug the wall wart from the AC supply after you unboot the drive. If you don't hear any improvement in SQ, then don't bother changing anything.

 

I have no doubt that a ram disk is better than an external hdd. I also can hear a difference between SSD and spinning disk. The issue is what to do with the entire collection as it will not fit on either medium. With all that said, unplugging the wall wart gives me an idea to try it on battery. I can simply use an appropriate SLA battery to see if a difference is realized. While I have heard that SLA is not the best battery to use for audio, this would allow me to test a different power source on the external drive. So thank you for the inspiration.

[jabbr]

I have no doubt that a ram disk is better than an external hdd. I also can hear a difference between SSD and spinning disk. The issue is what to do with the entire collection as it will not fit on either medium.

 

Just buffer/copy your current playlist into the ram disk. Then just listen vs. unplug HDD and listen (ymmv)

[fatihakin]

HDplex has a 100W linear power supply with discrete 19/9/12/5V outputs. This may be an option. But there is no detail about your external disk; does it have an external switching psu or just a wall plug and internal psu; where to connect external power leads...etc. Some DIY work may be required.

[iago]

240 views and no responses so I've either asked a very good question or a dumb one:)

 

Not a dumb question, but your project might need a bit more research ;-)

 

Your disk (assuming a standard 3.5" magnetic disk) uses +5V and +12V internally. If I remember correctly, the 12V rail is used for the motor, the 5V rail supplies the electronics. The additional electronics necessary to adapt the internal interface (e.g. SATA) to the external one (e.g. USB or Firewire) probably use CMOS logic, which implies a 3.3V supply voltage. This would be generated internally with a regulator.

 

I owned enclosures with a four pole mini DIN connector (looked like the old PS/s mouse keyboard plug, but had fewer pins). I never bothered to check what went over this interface, but the probabibility is very high that it supplied both voltages. My current enclosures use a barrel type connector and a standard 12V PSU.

 

So probably your enclosure uses a single 12V PSU, routes this voltage directly to the drive, and generates 5V and 3.3V from this input voltage internally.

 

You might start with the simple replacement of the original PSU and see if you like the result. Before you go further, check how the other two voltages are generated. Replacing the standard voltage regulators with something more appropriate might be less effort than using separate supplies.

[blownsi]

Not a dumb question, but your project might need a bit more research ;-)

 

Your disk (assuming a standard 3.5" magnetic disk) uses +5V and +12V internally. If I remember correctly, the 12V rail is used for the motor, the 5V rail supplies the electronics. The additional electronics necessary to adapt the internal interface (e.g. SATA) to the external one (e.g. USB or Firewire) probably use CMOS logic, which implies a 3.3V supply voltage. This would be generated internally with a regulator.

 

I owned enclosures with a four pole mini DIN connector (looked like the old PS/s mouse keyboard plug, but had fewer pins). I never bothered to check what went over this interface, but the probabibility is very high that it supplied both voltages. My current enclosures use a barrel type connector and a standard 12V PSU.

 

So probably your enclosure uses a single 12V PSU, routes this voltage directly to the drive, and generates 5V and 3.3V from this input voltage internally.

 

You might start with the simple replacement of the original PSU and see if you like the result. Before you go further, check how the other two voltages are generated. Replacing the standard voltage regulators with something more appropriate might be less effort than using separate supplies.

 

Wow. Thanks for such a detailed response and yes your assumptions are very much correct. The drive I am thinking of experimenting with is a simple Seagate 5tb external from the black friday sale. Inside of it is a typical 3.5" drive.

 

Yes I believe I will start with a simple SLA battery to barrel connector. Then move onto a simple laptop type power supply that is linear. Obviously neither of those are "audio grade" but they will allow me to see if I'm on the right track. No sense buying a true audio linear power supply for hundreds of dollars if the electronics inside the box are the culprit.

[iago]

Yes I believe I will start with a simple SLA battery to barrel connector. Then move onto a simple laptop type power supply that is linear. Obviously neither of those are "audio grade" but they will allow me to see if I'm on the right track. No sense buying a true audio linear power supply for hundreds of dollars if the electronics inside the box are the culprit.

 

The lead acid battery should work, but don't leave the drive connected when you charge it, the voltage (13.8V) is slightly too high.

 

Using a single PSU might already achieve the desired effect by diminishing the coupling between devices over the power rail - it's probably just as bad as unintended coupling via the ground plane, You do want the galvanic coupling, but you don't want your signal to feed forward into adjacent circuits. JohnSwenson posted something related to this topic last month.

 

A separate power supply could simply be realized with a regulator and a few additional components as part of a SMD design, so the generation of the two additional voltages inside your enclosure needs not necessarily be bad. It just depends on the performance of the components used.

 

HiFiDUINO maintains a list of popular low noise regulators.