Bauhausler
Rational Subjectivist
Below is a photo of a Sumo Polaris 310 power amp, an Athena MM/MC preamp and an Aurora tuner. I received these pieces in semi-working condition with the recent purchase of a Transcriptors turntable. They are all working now and I'm leaving them to cook in my bedroom system for a week to see if they blow up before selling them off.
I got two of the power amps, both of which were said to be dead. There is no, repeat NO documentation available on these. Luckily, each of the stereo power amps had one dead channel and one live one. Removing 2 screws detaches the channel and its heat sink from teh side of the chassis. It was a moment's work to shuffle the modules and produce one working stereo amp and one entirely dead one.
The power amp clips at 120WPC simultaneous into 8 Ohms and 175W into 4. It's a very beefy common power supply with a large PT and a pair of 15,000uf 80V caps. It's a MOSFET design with 2 pairs of output devices/channel.
I listened to the power amp in my main system for 2 days. The bass amazed me. It is very solid and palpable with great pitch and control. That's compared to my favorite vintage amp, the great Accuphase P-300. I was amazed at how good the Polaris was. The highs were more recessed than the Accuphase, with a distinct 'sweet' presentation. Maybe a little detail missing, but super listenable.
The preamp gave me fits. I immediately found there was a fault in the power supply's regulator section. The bipolar regulator circuit uses 8 transistors, 9 diodes, 8 caps and a batch of resistors. After several nights of fooling around I found a shorted 15V zener and replaced it, but not until I had already replaced 4 transistors (twice each), 3 caps and 2 resistors. The circuit board for this is the size of a legal pad and has over 70 transistors plus associated components. There are traces on both sides and plated through holes transferring signals and current from one side to the other. The component lead holes are plated through, with solder on both sides. This makes it impossible to neatly remove a sensitive component. much less without destroying it. You just can't heat three transistor leads sufficiently and simultaneously to melt solder on both sides of the board. I was one the verge of making a discus out of it when I gave it one last try and fixed it.
I like the tuner. It has worked since I got it. Great sensitivity, and I immediately liked the sound.
The ergonomics are so so. I like the LEDs that indicate the function selected, but the tiny dark gold printing on black requires good light and close squinting to read.
These would be keepers if they were not irreparable orphan pieces. I like the sound a lot, but I don't want to be the owner when they quit.
I got two of the power amps, both of which were said to be dead. There is no, repeat NO documentation available on these. Luckily, each of the stereo power amps had one dead channel and one live one. Removing 2 screws detaches the channel and its heat sink from teh side of the chassis. It was a moment's work to shuffle the modules and produce one working stereo amp and one entirely dead one.
The power amp clips at 120WPC simultaneous into 8 Ohms and 175W into 4. It's a very beefy common power supply with a large PT and a pair of 15,000uf 80V caps. It's a MOSFET design with 2 pairs of output devices/channel.
I listened to the power amp in my main system for 2 days. The bass amazed me. It is very solid and palpable with great pitch and control. That's compared to my favorite vintage amp, the great Accuphase P-300. I was amazed at how good the Polaris was. The highs were more recessed than the Accuphase, with a distinct 'sweet' presentation. Maybe a little detail missing, but super listenable.
The preamp gave me fits. I immediately found there was a fault in the power supply's regulator section. The bipolar regulator circuit uses 8 transistors, 9 diodes, 8 caps and a batch of resistors. After several nights of fooling around I found a shorted 15V zener and replaced it, but not until I had already replaced 4 transistors (twice each), 3 caps and 2 resistors. The circuit board for this is the size of a legal pad and has over 70 transistors plus associated components. There are traces on both sides and plated through holes transferring signals and current from one side to the other. The component lead holes are plated through, with solder on both sides. This makes it impossible to neatly remove a sensitive component. much less without destroying it. You just can't heat three transistor leads sufficiently and simultaneously to melt solder on both sides of the board. I was one the verge of making a discus out of it when I gave it one last try and fixed it.
I like the tuner. It has worked since I got it. Great sensitivity, and I immediately liked the sound.
The ergonomics are so so. I like the LEDs that indicate the function selected, but the tiny dark gold printing on black requires good light and close squinting to read.
These would be keepers if they were not irreparable orphan pieces. I like the sound a lot, but I don't want to be the owner when they quit.
My memory is fuzzy, and I just remembered there was SOME connection, but obviously none of the details (hence, my stupid question). Maybe I have strange taste, but I always thought the appearance of Sumo gear was pretty cool, as far as black colored gear is concerned
I wish I could afford to take them off your hands!!
