delboyko
New Member
I've recently acquired mentioned Sony to see what's the fuss about.
Sony ES series was very popular in Germany back in the days so ads today are full of them and they're quite affordable. Mine is black with wooden side panels and NEW sticker on the front.
Inside was pretty clean with minimum dust and all caps looking brand new. Turning it on I learned that the transformer on these models tends to be almost audibly noisy and that the amp is free from hum/buzz noise.
I investigated the difference between TOTL model F808ES and F707ES and it is so minor that it can only be measured and not heard. They share the same service manual and all the PCBs have the same topology. The service manual is wonderfully written and the differences are nicely highlighted. I'll share them:
- Gold plated speaker terminals and all input connectors,
- The top cover is divided into two sections to minimize the vibrations,
- F808ES is rated 120W while the F707ES is 100W,
- F808ES has 15 000uf while the F707ES has 18 000uf filter caps,
- F808ES has a 3 significantly bigger caps on EQ board and different 3 transistors
- F808ES has a few narrower tolerance caps and resistors on driver board (same value)
- Visually some caps are of a different color but really just a few of them, and again mainly on the EQ board
That's about that. Except for the transistors from EQ board, all other are exactly the same and I'm actually quite surprised about 20W more power specs...??
The sound of these amps is known as super clear and precise and quite neutral... a true audiophile equipment with THD measuring only 0.004%. After listening for a few days I can agree. Comparing to my restored Sansui AU-717 I can say that the mids and highs are clearer and more detailed, while the bass is tighter but less highlighted. Saying all this I must exclaim that the all mentioned is barely noticeable and quite frankly I'm disappointed because I expected more! 15 years of audio engineering advantage and all those audio grade caps for this?
Switching back to Sansui I'm starting to value him much more. Sony is harsh, it's too precise, a little bit bright and to show off it needs careful paring. I got a pair of Klipsch Reference RF-52II.
Shortly after removing the cover I've noticed this:
4 burnt 15ohm fuse resistors near the filter caps. Other side of PCB is intact and the amp works perfectly but I'm really curious what could've caused this? I've monitored their temperature and they don't even get warm.
Amp features MOSFET PRE and POWER stage and gets really hot really quick. I found on some German HiFi forum that it draws ~95W just idling. I can't imagine that 100W can heat the heatsink so fast (minute) but everybody is complaining about how hot these amps are so I guess that's fine. When I say hot it means I can't hold my hand on the heatsink for longer than a second.
DC offset was 1mV on both terminals and BIAS needed a little bit of adjustment. One channel was 34mV and the other 24mV. Set them to 30mV in a heartbeat.
More pictures:
Sony ES series was very popular in Germany back in the days so ads today are full of them and they're quite affordable. Mine is black with wooden side panels and NEW sticker on the front.
Inside was pretty clean with minimum dust and all caps looking brand new. Turning it on I learned that the transformer on these models tends to be almost audibly noisy and that the amp is free from hum/buzz noise.I investigated the difference between TOTL model F808ES and F707ES and it is so minor that it can only be measured and not heard. They share the same service manual and all the PCBs have the same topology. The service manual is wonderfully written and the differences are nicely highlighted. I'll share them:
- Gold plated speaker terminals and all input connectors,
- The top cover is divided into two sections to minimize the vibrations,
- F808ES is rated 120W while the F707ES is 100W,
- F808ES has 15 000uf while the F707ES has 18 000uf filter caps,
- F808ES has a 3 significantly bigger caps on EQ board and different 3 transistors
- F808ES has a few narrower tolerance caps and resistors on driver board (same value)
- Visually some caps are of a different color but really just a few of them, and again mainly on the EQ board
That's about that. Except for the transistors from EQ board, all other are exactly the same and I'm actually quite surprised about 20W more power specs...??
The sound of these amps is known as super clear and precise and quite neutral... a true audiophile equipment with THD measuring only 0.004%. After listening for a few days I can agree. Comparing to my restored Sansui AU-717 I can say that the mids and highs are clearer and more detailed, while the bass is tighter but less highlighted. Saying all this I must exclaim that the all mentioned is barely noticeable and quite frankly I'm disappointed because I expected more! 15 years of audio engineering advantage and all those audio grade caps for this?
Switching back to Sansui I'm starting to value him much more. Sony is harsh, it's too precise, a little bit bright and to show off it needs careful paring. I got a pair of Klipsch Reference RF-52II.
Shortly after removing the cover I've noticed this:
4 burnt 15ohm fuse resistors near the filter caps. Other side of PCB is intact and the amp works perfectly but I'm really curious what could've caused this? I've monitored their temperature and they don't even get warm.
Amp features MOSFET PRE and POWER stage and gets really hot really quick. I found on some German HiFi forum that it draws ~95W just idling. I can't imagine that 100W can heat the heatsink so fast (minute) but everybody is complaining about how hot these amps are so I guess that's fine. When I say hot it means I can't hold my hand on the heatsink for longer than a second.
DC offset was 1mV on both terminals and BIAS needed a little bit of adjustment. One channel was 34mV and the other 24mV. Set them to 30mV in a heartbeat.
More pictures:
Last edited:
