If I put my notes here, I might be able to find them again later!
Technics SE-9060
There was a series of relatively slim (2U chassis rather than 4U), upmarket audio separates put out by Technics in 1977: the ST-9030T tuner, SU-9070 preamplifier, and SE-9060 amplifier. They are two degrees of separation from the top of the line models at the time, the range went 9600>9200>90x0.
I recently acquired the tuner (more on that some other time) and have the others in my sights.
For educational purposes, the amplifier schematic for the SE-9060 is shown below. The input stage and voltage amplifier was driven from regulated 55 V supplies (Va+ Va-), while the driver stage was powered directly by the rectified DC at about 50 V (Vb+ Vb-) filtered with 18,000 uF per rail per channel.
Note that there were 9060 and 9060II as well as 9070 and 9070II models in Japan, but the export model of the preamp which sold as the 9070 was actually the 9070II rather than the 9070 domestic version. Likewise the SE-9060 shown below (from a European service manual) equates with the Japanese SE-9060II rather than the SE-9060.
I recently acquired the tuner (more on that some other time) and have the others in my sights.
For educational purposes, the amplifier schematic for the SE-9060 is shown below. The input stage and voltage amplifier was driven from regulated 55 V supplies (Va+ Va-), while the driver stage was powered directly by the rectified DC at about 50 V (Vb+ Vb-) filtered with 18,000 uF per rail per channel.
Note that there were 9060 and 9060II as well as 9070 and 9070II models in Japan, but the export model of the preamp which sold as the 9070 was actually the 9070II rather than the 9070 domestic version. Likewise the SE-9060 shown below (from a European service manual) equates with the Japanese SE-9060II rather than the SE-9060.
Total Comments 2
Comments
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This technique of separates supplies for power and rest of the circuit in the output stage are used for other amps, as the Sansui AU-217/217 MKII, you can download the service manual here:
Sansui AU-217 Manual - Stereo Integrated Amplifier - HiFi Engine
Perhaps the champions are the series L-2XX from Luxman, with separates supplies for the power, the VAS and the differential input:
Luxman L-215 Manual - Duo Beta Stereo Integrated Amplifier - HiFi Engine
I think that some Rotels, the RA-840, also use separated supplies.
RegardsPosted 19th May 2014 at 02:06 AM by raul_77
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Indeed the L-215 has two regulated positive rails, one for the input and one for the VAS, as well as the split unregulated lines for the output. Pity its all shared between channels. The Technics 9060 actually has two power transformers, one on each side of the unit, and the construction is almost completely dual mono.Posted 19th May 2014 at 05:04 AM by rjm
