Your Power Supply is TOO NOISY

[opus101]

3 hours ago, Speed Racer said:

The AHB2 is better, but shouldn't it be for the price? Is that a result of using a switching power supply? Is noise the only drawback of a switching power supply? What does a switching power supply throw out onto the AC mains?

 

It puts out a whole slew of common-mode noise at ultrasonic frequencies. Which I rarely see mentioned in articles praising the merits of SMPSUs (which are undoubtedly real merits).

[opus101]

1 hour ago, Ralf11 said:

does this say anything about power supplies for DACs?

 

What it says to me is - if your DAC has a switching supply you'll do well to ensure it has a balanced output and your amp a balanced in. Use unbalanced and you're likely to run into SQ issues.

[opus101]

I have a suspicion that the failure to adopt balanced has something to do with the huge margins available to dealers on unbalanced tweak-o-rama interconnects. Its simply not profitable enough for balanced to become the default IC.

[opus101]

That Elberoth post looks to be concerning a powerline noise meter which measures the normal-mode noise (i.e. between line and neutral), not the common-mode noise. The latter is a much more difficult measurement to make as its context dependent. The next best thing I guess is a normal mode measurement as there's bound to be some degree of correlation between the two.

[opus101]

6 hours ago, firedog said:

As far as noisy, I don't think the issue would be that you are hearing noise - it would be is the PS making some type or level of noise that makes your setup less revealing, sound not as good, etc.?

 

 

Precisely. The subjective effects of ultrasonic noise ingress are often harshness and annoyance (in large quantities) - at moderate quantities sibilance and loss of dynamics and spatial cues.

[opus101]

53 minutes ago, One and a half said:

 

 

For instance, a 100W load, a 100VA transformer would work well, maybe 5-10% regulation. By increasing the rating of the transformer to 200VA or even higher, won't guarantee that the regulation will improve. The regulation needs to designed into the transformer from the get-go. The only advantage of using a higher rated transformer is it won't be as hot as the 100VA, however if you run the transformer at little load, the losses become the overriding load, and the transformer gets warm... no free lunch.

 

 

A 100W DC load if continuous requires a higher than 100VA transformer due to power factor considerations - the RMS current from the trafo is higher than a purely resistive load as the rectifier diodes aren't conducting for most of the time. A 100VA transformer's regulation is poorer than '5-10%' - and that's just the AC with resistive load, once the ripple on the DC supply and the power factor is included in you'll be looking at more like 20%.