2. tech-talk
  3. 131860-80335

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

So, this whole story begins about a couple months ago when I was watching a satellite television show on my HT system.  While I was watching, I noticed that my Oppo bluray player was still on (I often turn everything on in the beginning to warm stuff up and/or listen to music).  Well, I hit the remote button to turn off the Oppo and a weird thing happened.  The sound got a little bit better.  It lost a small bit of that digital “solid-state” harshness / brightness.  I then thought, “wait a minute, something is going on here”.  The next thing I did was, even though my Oppo was powered off in “stand-by” mode, I went and just unplugged it completely.  The sound actually got a tiny bit better after that.  Now I have read postings that say switching power supplies can cause noise in other devices when they share the same circuit/outlet.  I never really gave it much thought, but apparently this is definitely a thing.  My Oppo is plugged into the same outlet as me left surround amp, which is a completely different circuit than my HT processor and other amps.  However, the switching power supply in my Oppo BDP-103 was still causing havoc in the system!

I have four dedicated 20 amp circuits for my HT equipment.  I also had two other devices that still contain switching power supplies:  DirecTV Genie satellite receiver and a Lumagen Radiance video processor.  My DirecTV was plugged into the right surround outlet and the Radiance was plugged into the same outlet as my Krell S1200 HT processor.  So the next step was to pull those out and connect them to regular house outlets (which are different circuits and not even in the same subpanel).  I could see immediately that I lost some of the video quality through HDMI.  The picture was not as sharp and it introduce a little bit of noise into the image.  However, it did improve the sound even more (got rid of more of that digital harshness).

So what to do next?  Well, of course get rid of all these switching power supplies and, somehow, implement linear power supplies!

auxinput
retiredaudioguy
57 posts
 

I am VERY late to this party but I think that, as usual, it all depends.  A good SMPS will beat a poor LPS, and can at best beat a good LPS.

Notably, Benchmark uses SMPS exclusively to lower the noise floor.  The LA4 pre is silent, at full volume, no input, output is zero.

Also, Sutherland, no slouches in engineering quality, use commercial Meanwell LRS series supplies in the Duo phone stage - not their top of the line model but very close in performance.  Once again silent background.

My (contentious) opinion is that if the performance of a piece of equipment can be affected by its fuse (e.g.) its PS was badly designed/implemented.  I use a power filter and then filtered MIT power leads on most components because of noise on the power line to my rural home - but I maintain I should not need to!

toddalin's avatar
toddalin
351 posts
 

...Or better yet..., get rid of the 103 and get a 95, 105, 105D, or 205.  The power supply is where the differences lie.

 

I can't imagine that any "audiophile" would purchase a "3" when they could have bought a "5".

auxinput OP
2,921 posts
 

I don't read this forum anymore, but willing to respond to this.

As far as SMPS power supplies go, they can be decent.   The "measured" noise of these power supplies can be very excellent and the audio performance can be good.  However, I have listened to a LOT of different power supplies, both linear and SMPS.  In all instances, the SMPS generally had something lacking.  Most of the time, it is a lack of deep bass power, but can also be a lack of smoothness in the overall tones/music.  That's my argument.   I understand much of this is personal preference and the idea that "SMPS is always superior" (or that "linear is always superior").

 

Not going to get into an argument about fuses.   Been there, done that.   Rinse repeat on this forum.

 

As far as the choice of 103 went, I only wanted a digital transport to provide HDMI (and/or S/PDIF) to my Krell processor.   If you really pull apart the 95/105/205 units, you will find the linear power supply, but that is only supplying the analog circuits.   There is a SMPS underneath that still powers all digital circuits (transport, DSP, HDMI output, etc.).  The 95/105/205 unit is no better than the 93/103/203 units in regards to a digital transport.   That is where the linear power supply upgrade really helps and takes out the "glare" of the stock unit digital signal.  It also cleans up the digital signal to give you a much cleaner purer sound (when using a digital processor such as the Krell S1200 - or any other ultra-high end processor).

More to discover