Post by solderdude on Jun 25, 2013 19:05:56 GMT
I measured the vintage Stax SR5 and despite it's age (about 30 to 40 years old) still performs quite well.
plots can be found here (scroll almost all the way down)
Stax SR-5 white with converted SRD6-SB energizer. The original energizer is of the so called Self-Bias type which means the bias voltage is generated by the audiosignal. a disadvantage of this is that you need to play it loud before you can start listening so the bias voltage is high enough. When playing soft for a while the bias voltage drops and so does the SQ. I converted the SRD-6 energiser so it is powered directly from mains. For an oldie (manufacturerd somewhere between 1970 and 1980) it doesn't sound that bad and if it weren't for the lack of bass extension it would give most headphones a run for their money.
Frequency response is fairly flat and well extended in the highs it only really lacks in the sub-lows. It sounds that way as well. Lows aren't even that bad but a drop-off below 60Hz is a bit meagre. When it is NOT played loud and the lows are compensated by a little boost it sounds quite full and well behaved. When playing louder it starts to distort in the bass though (as expected) as the membrane is tensioned pretty well, even after all these years. dropping the 10kHz slider on the EQ makes it sound even better !
CSD is remarkably clean with no obvious ringing anywhere .
Even at 500Hz it behaves extremely well.
Colour me impressed with what Stax could make already 40 years ago and still works well till today !
Thinking of making a filter for it on a dedicated power amp as these enegizers cannot be driven from a headphone amp but need a speaker amp.
The only annoying thing is the cable being quite microphonic.
plots can be found here (scroll almost all the way down)
Stax SR-5 white with converted SRD6-SB energizer. The original energizer is of the so called Self-Bias type which means the bias voltage is generated by the audiosignal. a disadvantage of this is that you need to play it loud before you can start listening so the bias voltage is high enough. When playing soft for a while the bias voltage drops and so does the SQ. I converted the SRD-6 energiser so it is powered directly from mains. For an oldie (manufacturerd somewhere between 1970 and 1980) it doesn't sound that bad and if it weren't for the lack of bass extension it would give most headphones a run for their money.
Frequency response is fairly flat and well extended in the highs it only really lacks in the sub-lows. It sounds that way as well. Lows aren't even that bad but a drop-off below 60Hz is a bit meagre. When it is NOT played loud and the lows are compensated by a little boost it sounds quite full and well behaved. When playing louder it starts to distort in the bass though (as expected) as the membrane is tensioned pretty well, even after all these years. dropping the 10kHz slider on the EQ makes it sound even better !
CSD is remarkably clean with no obvious ringing anywhere .
Even at 500Hz it behaves extremely well.
Colour me impressed with what Stax could make already 40 years ago and still works well till today !
Thinking of making a filter for it on a dedicated power amp as these enegizers cannot be driven from a headphone amp but need a speaker amp.
The only annoying thing is the cable being quite microphonic.