Is it possible for a power supply to affect sound quality?

[One and a half]

An SMPS conducts noise 100kHz upwards, which capacitively couples to the power supply and the network within an amplifier or DAC, doesn't matter. Floating heatsinks 'conduct' noise to ground planes, depending on the atmosphere, can change and is very difficult to control. SMPS only advantage is its small physical size, for audio SMPS is a nuisance, don't use them.

 

Battery. Well, you can use them, their internal resistance changes, so their source impedance will also change, which may affect noise paths. Batteries also need to be regulated and charged, so I find 

 

So a linear power supply is quiet electrically, so why not use them. Rectifiers can cause noise, mitigated by Schottky diodes, or just plain caps across them. Regulation is nice but not essential to be within 0.0001%, typically +10-15% like most mains rated equipment. Unless probably in some DACs the clock circuit is critical, but that's a DAC designer's issue, not ours and cannot depend on a customer's supplied unit (see Lumin thread on 3rd party power supplies).

 

What's important for a linear supply is the recovery caused by rectifier pulses and sudden load changes, The voltage shouldn't sag and swell over milliseconds, this leads to instability and load malfunctions. Some linear power supplies, like the Uptone JS-2  and the Acopian have sensing terminals that monitor and adjust the output voltage due to long lead length, I use the Acopian Gold Box at 9V sensing cable to an ifi Micro USB3, works well over a 3m cable length.

 

I've included a paper from Acopian which discusses SMPS and Linear supplies as well as how noise is created not only from SMPS but circuit elements, transistors, CPU, MOSFETS, gates,  where the noise comes from in the first place. 

 

 

An Overview of Chip Level EMC Problems - IEEE Santa Clara Valley ...032010Radu.pdf Trouble_with_wallwarts.pdf Wurth Electronic Product_Training_CMC_100728.pdf Linear-Vs-Switching-Power-Supplies-Whitepaper.pdf

[One and a half]

18 hours ago, Summit said:

 

This is not correct IMO. SMPS's advantage are its small size, low weight, high efficiency, low heat radiation and most important low cost per watt.

 

It’s not that simple that a linear power supply is always quiet electrically. Many LPS are sensitive to DC offset and both hum and radiate a lot of EMI.

 

Am not saying that SMPS is better sonically, but a quality SMPS is normally better than a low quality LPS for the same watts and price.

 

To answer the OP question, can a linear supply actually make any difference? Yes it can, but that it is linear is no guaranty. If it was, no respectable hifi manufacturer would use SMPS.

 

 

Transformers are sensitive to DC offset, not the bits after the transformer secondary. A transformer manufacturer doesn't expect the power source to contain enough notches to cause hum, a transformer expects a clean zero transition, it's up the consumer to provide a clean notch free voltage or IOW 'connect the transformer to a suitable power supply".

 

SMPS can comply to EMC rules within themselves, but connect them to a load and that certification is shot, that's clear in the added pdf.

 

Magnetic interference can be controlled with design techniques for the transformer, ask any tube amplifier designer.

 

Respectable hi fi manufacturers (some) that I could think of...

Here's a list of amplifier manufacturers that use linear approaches to the main drive and in their pre-amplifiers:

 

Adcom

Accuphase

Ayr Acoustics

Bricasti

Macintosh

Luxman

Soolution

Pass

and countless more thousands

 

Here's a list of some amplifier manufacturers that use SMPS approaches to the main drive:

 

Benchmark

Hypex

90% of modern AV amps

 

[One and a half]

2 hours ago, SJK said:

But then, being a designer of power and control systems for industrial machines - not stereo gear, I thought there might be a topic for discussion, and the premise was simple.

You should be aware then of the implication of noise on serial communications, shielding and grounding techniques for cables, and noise coupling from one voltage system to the other. Audio is really no different, if you start with a poor power supply full of noise, then that noise is propagated through the machine's system where it can affect the operation of sensing equipment.