Transistors have advanced since the 1970s. Back then it was a big deal if the output of the amp had complementary symmetry.
The distortion of the 70s gear was often higher than that of later years and often higher than rated. But a lot of it doesn't sound all that bad as it has more 2nd harmonic than later designs have, owing to the large amount of single-ended circuitry present in the voltage amplification circuits.
There are other things causing colorations- such as inappropriate use of tantalum capacitors for coupling and extensive use of carbon film resistors. Many of them had poor grounding technique, often using a corner of the circuit board used for mounting the board to the chassis doubling as ground for that circuit board as well. So when I see equipment like this one thing I do right away is tighten all the circuit board mounting screws.
As long as you don't push them too hard they don't sound that bad. They've never struck me as all that three dimensional though!
The distortion of the 70s gear was often higher than that of later years and often higher than rated. But a lot of it doesn't sound all that bad as it has more 2nd harmonic than later designs have, owing to the large amount of single-ended circuitry present in the voltage amplification circuits.
There are other things causing colorations- such as inappropriate use of tantalum capacitors for coupling and extensive use of carbon film resistors. Many of them had poor grounding technique, often using a corner of the circuit board used for mounting the board to the chassis doubling as ground for that circuit board as well. So when I see equipment like this one thing I do right away is tighten all the circuit board mounting screws.
As long as you don't push them too hard they don't sound that bad. They've never struck me as all that three dimensional though!