Single Power Exreme 14 amp model
Includes the following tubes:
1 Sylvania 6sl7gt
2 IBM 5998
2 RCA JAN 6as7g
Purchased April 2008, barely used (less than 500 hours). No pets or smokers in the home.
pics of the insides when I opened it up 2 months ago:
spx - a set on Flickr
The transformer (Hammond model 266PA14) is clearly pictured, despite my poor photography. I have left the transformer cover unattached, because it's a tremendous pain to attach it the way Mikhail originally did. It can easily be reattached with some duct tape or other hackery.
After opening it up, my electrical engineer friend (he builds satellites, not audio gear) inspected it and verified the transformer’s wiring. The output side of the transformer is wired in parallel (per mfg. spec); however, Mikhail definitely wired the input side against the manufacturer’s recommendation. The second primary winding is used (basically as another output winding) to supply the high side voltage to the power tube. By doing this, the transformer’s output rating of 7V @ 12 A for a parallel connection is now only good for half that or 6A for total filament current. Analyzing the tube datasheets shows the combined filament current of approximately 5.5 amps. The output side of the transformer supplies the heater filament voltage to the tubes and measures at 7V and stable after transformer has warmed up.
As you can see from the pics, the transformer shows no signs of overstress or overheating. The solder joints are all clean and shiny (no signs of cold solder joints). All visible capacitor and part markings confirm them as properly rated for the applied voltages.
I have never had any problems with this amp, and it sounds great to my ears. I'm selling it because I rarely listen to music at home these days.
I am asking $1000 for pickup in the SF bay area. You're welcome to come by and audition it.
Includes the following tubes:
1 Sylvania 6sl7gt
2 IBM 5998
2 RCA JAN 6as7g
Purchased April 2008, barely used (less than 500 hours). No pets or smokers in the home.
pics of the insides when I opened it up 2 months ago:
spx - a set on Flickr
The transformer (Hammond model 266PA14) is clearly pictured, despite my poor photography. I have left the transformer cover unattached, because it's a tremendous pain to attach it the way Mikhail originally did. It can easily be reattached with some duct tape or other hackery.
After opening it up, my electrical engineer friend (he builds satellites, not audio gear) inspected it and verified the transformer’s wiring. The output side of the transformer is wired in parallel (per mfg. spec); however, Mikhail definitely wired the input side against the manufacturer’s recommendation. The second primary winding is used (basically as another output winding) to supply the high side voltage to the power tube. By doing this, the transformer’s output rating of 7V @ 12 A for a parallel connection is now only good for half that or 6A for total filament current. Analyzing the tube datasheets shows the combined filament current of approximately 5.5 amps. The output side of the transformer supplies the heater filament voltage to the tubes and measures at 7V and stable after transformer has warmed up.
As you can see from the pics, the transformer shows no signs of overstress or overheating. The solder joints are all clean and shiny (no signs of cold solder joints). All visible capacitor and part markings confirm them as properly rated for the applied voltages.
I have never had any problems with this amp, and it sounds great to my ears. I'm selling it because I rarely listen to music at home these days.
I am asking $1000 for pickup in the SF bay area. You're welcome to come by and audition it.