DrTebi
Active Member
Recently I acquired a Technics SH-9010 parametric equalizer to help compensate for the low frequency loss in my open baffle speakers.
This 1978 EQ is in quite good shape. It was advertised as "serviced", which seems to have been done well, but was limited to cleaning and de-oxidizing switches and trim pots (while the sliders were left alone). None of the electronics appear to have been touched.
However, when I put it into the tape loop of my pre-amp, and switch back and forth between tape and source, with the EQ set to the "off" position, I notice that it sounds different. "Muffled" is probably exaggerated, but it sure sounds just a bit less alive when the EQ is in the chain.
I am sure there can be numerous reasons for that, but my first thinking is, why not start to re-cap this guy a bit... after all, it is now 40 years old, and chances are the caps are not quite up to spec anymore.
There is a total of about 50 caps in there I figured I start with the power supply, and probably the "logic circuit" and input circuit. I started to make a list of caps that I would need for the power supply... and now finally to the questions:
1) As far as I know, a higher voltage rating of a capacitor can do no harm, and may even be preferred. Correct?
2) Since the replacement capacitors won't cost much, does it make sense to order multiples, and check their values in order to get the best matching capacitors?
3) Should I stick to one brand? I wanted to use all Nichicon FG caps, but it turns out that some values are not available in the correct µF/V, or too small/too large to fit. I would mix in some from the KW series (for the large 470µF caps).
4) When a capacitor is specified as "audio grade", would that make a difference to the audio if the cap is in the power supply section?
Here a list of the values that I need for the power supply section:
Any suggestions are greatly appreciated.
This 1978 EQ is in quite good shape. It was advertised as "serviced", which seems to have been done well, but was limited to cleaning and de-oxidizing switches and trim pots (while the sliders were left alone). None of the electronics appear to have been touched.
However, when I put it into the tape loop of my pre-amp, and switch back and forth between tape and source, with the EQ set to the "off" position, I notice that it sounds different. "Muffled" is probably exaggerated, but it sure sounds just a bit less alive when the EQ is in the chain.
I am sure there can be numerous reasons for that, but my first thinking is, why not start to re-cap this guy a bit... after all, it is now 40 years old, and chances are the caps are not quite up to spec anymore.
There is a total of about 50 caps in there I figured I start with the power supply, and probably the "logic circuit" and input circuit. I started to make a list of caps that I would need for the power supply... and now finally to the questions:
1) As far as I know, a higher voltage rating of a capacitor can do no harm, and may even be preferred. Correct?
2) Since the replacement capacitors won't cost much, does it make sense to order multiples, and check their values in order to get the best matching capacitors?
3) Should I stick to one brand? I wanted to use all Nichicon FG caps, but it turns out that some values are not available in the correct µF/V, or too small/too large to fit. I would mix in some from the KW series (for the large 470µF caps).
4) When a capacitor is specified as "audio grade", would that make a difference to the audio if the cap is in the power supply section?
Here a list of the values that I need for the power supply section:
Code:
Part No. Voltage µF Quantity
C701-C704 35 470 4
C705-C706 25 47 2
C707-C708 25 10 2
C709-C710 25 100 2
C711 25 33 1
Any suggestions are greatly appreciated.