Musings on Switching Power Supplies (LPS for Oppo / DirecTV/ Radiance)

Okay, so what’s next.  There’s still those switching power supplies in my DirecTV receiver and Radiance video processor.  Upon investigating, I can see that the switching power supply adapters clearly show voltage specifications:

Radiance:  12V DC, 2.5A

DirecTV: 12V DC, 4A

The Radiance uses an industry standard DC plug (5.5mm outer diameter / 2.1mm inner diameter).  However, the DirecTV uses a very proprietary 2-pin DIN connector.  The 2-pins are off center at a weird angle with the DIN notch at top.  I could not find an industry standard connector for this, so I knew I was going to have to chop the DirecTV adapter.  I just ordered another DirecTV adapter from ebay ($10 for a spare EPS44R0-16, you can buy these all day long on ebay).

So I started looking for external linear power supplies and came down to Teradak as a solution.  Now, I could have gotten two separate linear power supplies for the DirecTV/Radiance.  There were a 12V 3A supply and another 12V 5A supply.  I also saw Teradak had a dual 12V / 6.5A power supply.  It would have been more money to buy the individual power supplies.  I am also a fan of oversizing power supplies to ensure completely smooth DC.  Additionally, I would only have to worry about one extra power cord instead of two extra power cords.  So I decided on this unit from ebay:

TeraDak dual 12V / 6.5A chord hugo Hifi DC-200W Linear Power Supply

It had two individual 12V / 6.5A DC outputs, which was perfect for me.  The TerDak power supplies on ebay are often marketed for a specific piece of equipment (“chord hugo”, “auralic aries”, “Logitech squeezebox”, etc.).  This makes it easy for those consumers because the power supply is “plug-n-play” with those devices because it uses the proper DC voltage and DC connector.  However, these are just linear power supplies and can be used in other types of equipment, as long as the DC voltage is correct and you attach/wire-in the proper DC connector.  In any event, this item came with the same 5.5/2.1 connector used in my Radiance, so it was plug-n-play for that.

On the extra DirecTV adapter I bought from ebay, I cracked open the adapter case using a chisel/hammer.  I could see that there was a center white conductor that was +12V.  The shield wire (or black conductor) was ground.  Easy-peasy.  I could not find out the type of connector used on the Teradak unit itself, so I just un-soldered the existing connector and soldered that onto the DirecTV wires.  Make sure that you connect the right wires to the right points – verifying with a multimeter several times!!  It would be really bad to cross-wire your DirecTV power and damage the unit.

Okay, looking at the TeraDak unit itself.  It is very well built for a Chinese product.  Nothing cheap here.  All the solder connections looked really nice!  Very well made!  The electrolytic capacitors could be better.  They did use 105 degree caps (which are not as good for audio in my opinion).  The description in ebay indicates they use Panasonic capacitors, which is a good thing.  I did not spend the time trying to validate this.  This dual 12V external linear power supply is still $100 cheaper than the OPPOMOD LPS, so who am I to argue.  I will say that testing this showed that it was light years better than the stock switching power supplies, so I win in the end in any event.  I did not think it was worth it to try to get some of the higher end $500+ linear power supplies (such as Teddy Pardo, Paul Hynes, etc.)

This next step in the process came about a day after the Teradak was in the mix, during burn-in period.  I found that the audio had suddenly become a little bright/harsh again.  After extensive testing, what I found was that the fuses and power cords for the Oppo as well as the Teradak/DirectTV “digital transports” were influencing the audio coming from the Krell HT Processor.  In additional, a fuse in one source transport was influencing the sound from another source transport, even though it wasn’t selected as an “active input”, or was put in standby mode.  The DirecTV Genie receiver is always powered up and running even when it’s in “standby” mode (internal computer and DVR are 24/7).

This discovery came when I decided to remove the Hi-Fi Tuning silver fuse from the Oppo and put in a 2A PADIS fuse instead.  The result was, even though the Oppo was powered off and in “standby-mode”, the sound from DirecTV was not as bright, but just did not sound right in the end.

At that time, the Oppo had the PADIS fuse, but had a power cord that uses cheap braided 20awg solid-core Radio Shack copper with Furutech rhodium connectors.  In other testing, I found this Radio Shack copper sounded good, but it was too warm with rolled-off highs.  Interestingly enough, this power cord on a digital HDMI source was affecting the sound from a separate DirectTV digital HDMI source through the Krell HT processor.  I switched the power cord on the Oppo to a much better braided 20awg solid-core OCC copper teflen Neotech cable wit Furutech rhodium connectors.  The sound quality improved immediately.  Weird!  In research, I think there are two wires in the HDMI cable that could contribute to this result:

Pin 18 - +5V DC

Pin 17 – Ground

Pin 18 is +5V that is supplied by the source device to power external items that do not have an external power source (this would be something like active cables or external headphone DACs or something else).

Pin 17 is ground, which is the ground plane shared across all devices in the equipment chain).

Since the +5V DC voltage is generated by the Oppo or Teradak, I believe it is making its way into the Krell processor (through the HDMI input) to the normal 5V power rail.  This will definitely influence the character as the DAC href uses this +5V voltage for generating it’s DC output voltages (among other things in the circuits).  The ground plan can influence sound as well between devices.  It could also be that the power supply on the transport is affecting how good the digital signals are (voltage levels, jitter, etc.).

So, under testing, putting a warmer fuse into the Teradak (such as an Isoclean) definitely contributed to making the audio sound warmer in the whole system.  In the end, I ended up with Furutech fuses in both Oppo and Teradak and Audioquest NRG-4 power cables with Furutech Rhodium plugs.  In the end, that was the best combination as the Furutech fuse / OCC solid-core cables are my reference in all applications.  Both the video quality and audio quality are absolutely amazing for me now.

To sum it up, the argument that “switching power supplies are not bad for digital circuits” is completely wrong for me.  I can hear the difference!  It’s amazing to me that many high end audio equipment pieces still use switching power supplies for digital sections (even though they may use linear power for analog sections).  Emotiva started on a crusade a few years ago when they started touting “switching power supplies as the future”.  I believe they were paving the way for consumer belief so that they could put in switching power supplies and make the item lighter/cheaper for shipping.  I have also read many electrical engineer statements that switching power supplies are perfectly fine as long as you have a good filter in them.  I strongly disagree!!  In fact, one of the reasons I love my Krell S1200 is that it does not use switching power supplies at all!  It uses linear power for everything.  In fact, it actually uses a fully discrete shunt regulator circuit for the +5V DAC vref, and a normal LM7812 regulator for 12V required for some digital circuits.

So, new project on my list for next year is to upgrade my computer power supply (upstairs computer audio system) to a Teredak Computer Linear Power supply and upgrade the DAC to something that uses non-switching power supply (maybe LKS MH-DA004).

Yep, and the 203 no longer support Netflix streaming, which I use a lot!

I have seen that Clones Audio power supply as well and it looks like a very nice one indeed!  Unfortunately, like you said, they don't make one for the older 103 models.

There are a bunch of Oppo LPS on ebay from China that are all less than $130 each. These all have smaller amounts of capacitance and I'm not sure how well these actually operate, but I have no regrets with my OPPOMOD LPS.

I have also seen that Furutech + Mundorf wire update.  Yes you could make your own, but you would have to find the proper plug/connector for the main board, or just chop the stock one.  I was considering this after I did the LPS, but after my experience with silver fuse, I'm not going to introduce any silver elements into the mix.  I might upgrade the IEC inlet sometime in the future.  I have an AC-1001 rhodium filtered IEC inlet sitting here that was used in a previous project.