Who uses them?
Whos your preferred manufacturer?
What do you use them for? How much is too much?
Ive been reading anout the many wonderful things these PS can do for our audio! Snake oil? Or just good science?
Im a non engineer looking for some education. Thanks to all that reply.
Let's start with a basic explanation of what makes them different:
LINEAR POWER SUPPLIES = TRANSFORMER = Usually, a relatively large, wire-wound Transformer, which "steps-down" the Voltage from the Primary AC (115/120 VAC in the USA) down to something a bit higher than what is needed at the Output (Usually 24-Volt Power Supplies will have a Transformer that puts-out around 28 VAC).
When used for specialty Audio applications - the "high-end" stuff usually has a Torroidal Transformer - which means that the Primary and Output windings are built around a "doughnut"-shaped core.
(Most "conventional" transformers are wound around rectangular cores, laminated from layers of thin metal.) I do not fully understand the reasoning for this.
Regardless of the type - this Transformer has a few benefits, including:
- Isolation from Electrical Noise
(There is no "hard" Electrical connection from the 120 VAC Circuitry to the Low-Voltage Output - Only the internal Magnetic Fields connect the High and Low-Voltage windings.)
The Transformer Output is then fed-into Rectifier and Regulator Circuitry, which turns the Low-Voltage AC Power into (mostly) DC Power
WHEN LINEARS NEED TO "DUMP" ENERGY (High-Current Demand) Energy stored in Filter Caps usually gets "dumped" into high-current Regulators in more of a continuous flow like a River
When the Rectifier / Regulator circuitry fails - they CAN bleed significant amounts of AC Power into their Output
SWITCHER POWER SUPPLIES = TRANSFORMERLESS = (what often LOOKS like a small transformer is a choke / Filter to reject unwanted frequencies / harmonics at their Input).
The in-coming AC Waveform is "chopped-up" into small segments, and each such segment is Rectified and either knocked-down or brought-up to the desired DC Output Voltage. The process of "chopping-up" the AC Waveform usually is done at a VERY high speed, and internally generates high-frequencies which can cause interference or noise on sensitive Audio Circuitry (IF such circuits are not properly isolated / protected).
When the Voltage is HIGHER than desired - some energy is stored, and is used to ADD Energy to the segments where the Output would otherwise be Lower than desired (rather than being "wasted")
When the Voltage is LOWER than desired - some of the previously stored energy is ADDED to the segments
This process occurs to a lesser degree within the Rectifier and Regulator circuits of a Linear -
Switchers do a better job of Storing un-used Energy and Re-Using it as needed, rather than wasting it as HEAT)
WHEN SWITCHERS NEED TO "DUMP" ENERGY (High-Current Demand) Energy stored in Filter Caps usually gets "dumped" into each Output Segment in more of Big Scoop-By-Scoop method
When Switchers fail - from what I've seen, they tend to simply "go dead"
COMPARISON:IF DONE PROPERLY - Many would say that they are (or CAN BE) Equal, in terms of Output Voltage and Current
ADVANTAGES OF LINEAR POWER SUPPLIES:
-Less tendency to introduce Noise (since the highest frequency used within them is usually 50 or 60 Hz = Fundamental Frequency of Line Voltage)
-Better Electrical Isolation from Primary AC Source (less potential, unintended "coupling" to other equipment fed from same AC Source / Circuit)
-MAY (if properly designed) be able to better handle certain types of high-current loads
ADVANTAGES OF SWITCHER POWER SUPPLIES:
-Less Weight (when they have large outputs - those Transformers used in Linear Supplies get BIG = Heavy)
-Less Weight = Lower Shipping Costs
-More Energy Efficient (hey, the whole world wants to be more "green"...)
-Less Heat to get rid-of
Who uses them (LINEAR)? = That's a loaded question. The General answer is "fewer and fewer companies" - due to their relative inefficiency and higher weight.
But there ARE cases where a well-designed, well-regulated Linear is clearly the better choice
Typically, cases where the desired Signal being processed and/or amplified is miniscule - where ANY source of unintentional noise can become significant.
(Such as sensitive, Low-Level Audio Circuit like a mic or phono pre-amp, where the potential introduction of any small high-frequency noise outweighs the precautions required to prevent that from happening / could get coupled into the Output)
If I were BUYING instead of MAKING my own Power Supplies - I have the following general observations, per my experience in the Low-Voltage Systems arena (which is different from Audio)
A GOOD LINEAR POWER SUPPLY = Will deliver its rated Output with the wind in its face, on a rainy day, going Up-Hill
A GOOD SWITCHER POWER SUPPLY = Will deliver its rated Output with the wind at its back, on a sunny day, going Down-Hill....
(More than this requires a CUSTOM / EXCEPTIONAL Switcher.)
Preferred Manufacturer / Use? = That would depend upon what Voltage and how much Current do you need / what is the application?
I have spent many years in the Low-Voltage Building Systems arena (Security / Fire Alarm / Nurse Call and lots of other stuff)
I have used / specified Linear Power Supplies from companies called "Condor" and "Power One" (their International Series) - [You can look them up on Digi-Key and Mouser]
SOME Low-Voltage (consumer-grade) Audio equipment that requires low-current MIGHT benefit from disconnection of their internal "cheapo" Switcher Power Supplies and replacing them with a better Linear Power Supply. However, doing that is usually beyond the capability of the average "Joe six-pack" and may void U.L. and/or FCC Listings for the associated equipment.
Alarm-Saf makes units for Fire Alarm, etc. that are "built like tanks" - but more and more of their stuff is turning to Switch-Mode Power Supplies
