Hi, I was very lucky to find a deal on an New-Old-Stock sealed in original box "Samson Servo 170" studio amplifier, also before purchase I was considering either an ART SLA-1 or a Samson Servo 120a(the latest Servo versions) but the internal quality/parts of those amplifiers where questionable to me, however looks like the last production/batch of this early/old Servo 170 amplifier didn't used complementary output stages due the transistor obsolesce/shortage and I'm worried about sound quality and stability issues.
This amplifier will be used only for tweeter duty only and I probably shouldn't be worrying at all but I want suggestions if a VAS upgrade is worthy or not, here below are the amplifier output stage info and my VAS upgrade considerations:
Servo 170 originals(Obsolete):
2SB688 (Ib: 1A, Ic: 10A, 10MHz) <--- OK
2SD718 (Ib: 1A, Ic: 10A, 12MHz) <--- OK
Last Servo productions?(Obsolete):
2SB688A (Ib: 1A, Ic: 10A, 10MHz) <--- OK
2SC5197 (Ib: 0.8A Ic: 8A 30MHz ) <--- ???
Replacements(I'm considering this ones):
2SA1943N
2SC5200N
Replacements(They has high output capacitance):
NJW3281G
NJW1302G
Regards!
This amplifier will be used only for tweeter duty only and I probably shouldn't be worrying at all but I want suggestions if a VAS upgrade is worthy or not, here below are the amplifier output stage info and my VAS upgrade considerations:
Servo 170 originals(Obsolete):
2SB688 (Ib: 1A, Ic: 10A, 10MHz) <--- OK
2SD718 (Ib: 1A, Ic: 10A, 12MHz) <--- OK
Last Servo productions?(Obsolete):
2SB688A (Ib: 1A, Ic: 10A, 10MHz) <--- OK
2SC5197 (Ib: 0.8A Ic: 8A 30MHz ) <--- ???
Replacements(I'm considering this ones):
2SA1943N
2SC5200N
Replacements(They has high output capacitance):
NJW3281G
NJW1302G
Regards!
It will likely work with any modern output pair. The onsemi 0281 and 0302 (smaller versions) are the closest to any of the Toshiba or Sanken types. Those are the ones recommended by folks chasing that last ounce of performance.