Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Power supply upgrade

There are different "DC-filter boards" -thats after the SPS.
The 861 have only one amp maybe for power on or temperatur control.
The 800 Dc board have a 3 pin voltage regulator.
all other circuits are passive on that board.
The new PS is the
ECM40UT31 from XPPower
link to PS data
Its a 40 Watt switching PS and have 1% peak to peak hum/noise thats at 12VDc are 120mV.That sounds good in the first impression and look to the older PS this is better.When you calculate that is a signal/noise ratio of 100(1%) and thats 40dB-that is "not impressive".
Of coarse the DC-filter board improve that,but I want just give a "feeling" for data here.The hum/noise is one factor,more important is the "impedance".Thats is the resistance with different frequencies.So the best would be, that for every frequency the resistance is equal, then you have no or equal influence to the frequency response.That is important in every amplifier as the current flow is starting from the PS over the preamp and further the power amp circuit(all in one device ) further to the speaker and back to the PS.So the PS and the AC/DC circuit determinates HOW the current is influenced(beside all other componenets in the chain).
What I want to say here is, that not only the hum/noise is the important factor to select a "better" PS.
SPS generates do their function more noise(switching), but that are basically easier to controll. Linear PS not only generate line frequencis as it mybe sounds logic,they are generate also high frequency noise.The transformer,diode(rectifier) and charge capacitor are a oscillator-there are good explainations for that on the net. So finally the construction itself and selecting proper parts(what should be included in a "good design") determinates the sound quality besides their basic goal to supply a stable and noise free DC voltage.
Impedance you dont get from a datasheet and they are not really helpfull as allways there is a circuit behind that in summary with the PS, is the impedance what the "audio circuit" will "see".
Select a battery is not "easy",watch here for the Impedance,depending on the type(Pb,NiCd,Lithium...) and HOW their inner construction is), there are big differencies here.
So working trustfull,you have to look for the spec,have to make fastidiously measurement(which expensive equipment),
but finally your ear/musical taste decide what you like....
I know the whole post mabe not practical helpfull, i just want to make a little sensitive about that sophisticated chapter.

Robert