The SR3, SR5 and SR7 all use the same basic regulator topology, which is a proprietary design fabricated from discrete components. The error amplifier wideband noise spec is 0.5 nanovolts root Hz with a noise corner of 1 Hz. Gain bandwidth product >100 MHz.
The 21 suffix relates to the output voltage although all three Technics SL1200/SL1210 supplies can be adjusted up to 27 volts to allow use as a pre-regulated power supply driving the TDR21 internal regulator upgrade providing a double layer of mains interference suppression. The current ratings are all based on 21 or 27 volts output setting.
The SR3 uses the best UK “off the shelf” mains transformer I have found and is rated at 60 VA. The SR3-21 has a continuous current rating of 1.2 amps but can deliver a short duration transient exceeding 20 amps.
The SR5 uses a 160 VA custom-built mains transformer built to my specification with a regulator module that is the equivalent to the SR3 regulator with higher power rectifiers and output stage to allow a continuous current rating of 3 amps, >40 amps transient. This is a special application psu for the SL1200 that does not have the large external heatsink used with the SR7 power supplies as the SL1200 does not draw a lot of current.
The SR7EHD uses a 240 VA custom-built mains transformer built to my specification with a regulator module that is further ruggedised with higher power rectifiers and output stage than the SR5as well as additional energy storage to a higher transient current delivery allowing a continuous current rating of 5amps, >80 amps transient.
The sound quality just gets better with progression up the range. The easiest analogy for most to understand is to go from a family saloon to a VW Golf GTI (or Mustang if you are in the USA) to a Bugati Veyron. They will all get you where you are going but do it in very different ways. No prizes for guessing which one I would choose.
Regarding the sonic performance of the power supplies, there are a number of reports about these power supplies in a variety of applications on the internet.
Regards
Paul
