ToTo Man
the band not the dog
In preparation for the return of my Revox B77 I have rescued my Technics SH-8065 from the wardrobe and intend to put it back into service on the playback leg of my analogue source, so that I can mimic the EQ settings I use with my digital source. The setup will be as follows:
Amp Line Out -> Revox B77 Line In
Revox B77 Line Out -> Technics SH-8065 Line In
Technics SH-8065 Line Out > Amp Line In
The SH-8065 was the second from top model of EQ from Technics and has a switch on the back to change the input sensitivity between 150mV and 1Vrms. Lower models in the range don't have this ability, AIUI they are fixed at 150mV.
I'm struggling to source an owners manual but did find the following info on Ken Rockwell's site:
"An unusual feature is an adjustable gain structure that optimizes the SH-8065 for two different signal levels. The gain is unity in either position, however noise and maximum output are optimised.
The signal level, volume or gain is not changed by this switch; it merely optimizes the equalizer for different signal levels.
Technics says to use the HIGH (1V) setting if you use this between a preamplifier and a power amplifier, and the LOW (150mV) setting if you 're using this in tape-monitor or external processing loops, or between anything else other than a power amplifier.
I didn't make any noise measurements, and never heard any noise in either setting.
To my surprise, the maximum output level at clipping at 1 kHz was 3.00 V RMS in the HIGH (1V) position, but was 8.5 V RMS at clipping in the LOW (150 mV) position!
As I use this for low-level signals (not fed directly to a power amplifier), I'm keeping it at LOW (150mV).
This almost makes sense, as if Panasonic is mis-naming these on purpose. Power amplifiers would be clipping long before they are fed 3V, so it makes perfect sense to optimize the SH-8065's HIGH range for levels not to exceed 3V. In other words, in the HIGH setting, your power amp will clip long before the EQ does.
On the other hand, at low levels, if you slam the sliders up to +12dB as fed from a typical CD or other player, you easily can need the 8.5 V maximum output level. It just so happens that the full-scale output of most CD players is 2V RMS, and the SH-8065's measured maximum output of 8.5 V RMS is conveniently +12.6 dB above 2 V RMS, meaning that Panasonic knows what they are doing.
Measured noise is also higher in the LOW setting, so I think someone reversed these."
I'm still not sure from the above comments whether I should select 150mV or 1V sensitivity, but I'm swaying towards 150mV given the apparently greater headroom. Having said that I'm not going to be boosting frequencies only cutting them, so the output voltage leaving the EQ won't be any higher than the input voltage, if anything it will be slightly lower. So I guess it them comes down to what the maximum output voltage from the B77 is?
Amp Line Out -> Revox B77 Line In
Revox B77 Line Out -> Technics SH-8065 Line In
Technics SH-8065 Line Out > Amp Line In
The SH-8065 was the second from top model of EQ from Technics and has a switch on the back to change the input sensitivity between 150mV and 1Vrms. Lower models in the range don't have this ability, AIUI they are fixed at 150mV.
I'm struggling to source an owners manual but did find the following info on Ken Rockwell's site:
"An unusual feature is an adjustable gain structure that optimizes the SH-8065 for two different signal levels. The gain is unity in either position, however noise and maximum output are optimised.
The signal level, volume or gain is not changed by this switch; it merely optimizes the equalizer for different signal levels.
Technics says to use the HIGH (1V) setting if you use this between a preamplifier and a power amplifier, and the LOW (150mV) setting if you 're using this in tape-monitor or external processing loops, or between anything else other than a power amplifier.
I didn't make any noise measurements, and never heard any noise in either setting.
To my surprise, the maximum output level at clipping at 1 kHz was 3.00 V RMS in the HIGH (1V) position, but was 8.5 V RMS at clipping in the LOW (150 mV) position!
As I use this for low-level signals (not fed directly to a power amplifier), I'm keeping it at LOW (150mV).
This almost makes sense, as if Panasonic is mis-naming these on purpose. Power amplifiers would be clipping long before they are fed 3V, so it makes perfect sense to optimize the SH-8065's HIGH range for levels not to exceed 3V. In other words, in the HIGH setting, your power amp will clip long before the EQ does.
On the other hand, at low levels, if you slam the sliders up to +12dB as fed from a typical CD or other player, you easily can need the 8.5 V maximum output level. It just so happens that the full-scale output of most CD players is 2V RMS, and the SH-8065's measured maximum output of 8.5 V RMS is conveniently +12.6 dB above 2 V RMS, meaning that Panasonic knows what they are doing.
Measured noise is also higher in the LOW setting, so I think someone reversed these."
I'm still not sure from the above comments whether I should select 150mV or 1V sensitivity, but I'm swaying towards 150mV given the apparently greater headroom. Having said that I'm not going to be boosting frequencies only cutting them, so the output voltage leaving the EQ won't be any higher than the input voltage, if anything it will be slightly lower. So I guess it them comes down to what the maximum output voltage from the B77 is?
Last edited: