Switching and linear power supplies in hi-fi

Nighthawk- nice to hear from someone that understands
the potential of a SMPS when proper filtering and regulation
are applied. FYI- on the input side, these supplies also benefit from better prerectification AC line filters,high speed diodes and faster primary filters.

Andy2- if your digital equipment uses a SMPS, reducing its' output noise will make a major improvement in sound quality. The more digital devises that are in the circuit
path, the greater the potential improvement.

Andy2, sorry for such a cryptic question, but I wasn't sure if you were interested in switchers because of marketing hype or had a technical reason. I see you DO know something about the technical differences between the two types.

You are quite correct in saying linears are less noisy than switchers. However, you can still use a switcher in low noise analog circuits. The basic technique is to filter the switcher output, then use a low-dropout linear regulator to post-regulate the filtered output. The output of a linear regulator when used in this manner can be just as quiet as an all-linear power supply. The reason for the filter is most linear regulators are quite poor in rejecting the typically 100KHz to 1MHz switching noise on the switcher's output.

Digital applications still have analog output stages so they still need quiet supplies.

Nighthawk, I was just trying to find out what people are using in their high-end equipment. But linear regulators are much better in term of noise control which is I guess pretty important in analog circuits.

Switching are probably used much more in digital application since they have better efficiecy and noise is less of an issue.

Andy2, do you perceive switchers to be more desirable than linears, or vice versa, and why?

Most use linear regulators but in the next two years that might be changing due to additional EU import restrictions. The EU will be requiring 'zero phase angle' power supplies in all electronics imported to the EU. Switching power supplies are the only thing that can do that. My guess is that temporarily, at least, it will mean a degradation in sound.

Obviously the restriction is political- untilities have been dealing with power factor/phase angle issues for 80 years and now all of a sudden this is an issue?? Politics.

Andy2 - I think the majority of digital front end equipment
use SMPS units, but most analog devises are still running
on linears.

With good design and quality parts, SMPS units can perform
very well. Their lower cost, weight and lower power consumption makes them very attractive.

David Berning has used high-speed switching power supplies in his products since the late 1970's.