Hallo everybody,
I'm searching for the mV value to reach on the emitter resistor on a Rega Luna (1997) clamshell 40watt to get a proper biasing.
On Rega.co.uk/service there's no info on this amplifier.
I can't find any REGA mail address either
And in Italy (where I live) the service center won't give any help, they will suggest me to ship them the amplifier.
I'm searching for the mV value to reach on the emitter resistor on a Rega Luna (1997) clamshell 40watt to get a proper biasing.
On Rega.co.uk/service there's no info on this amplifier.
I can't find any REGA mail address either
And in Italy (where I live) the service center won't give any help, they will suggest me to ship them the amplifier.
You are right domolo - I just checked the Elex circuit diagram and it uses 2SA1186/2SC2837 while Mira (2000) uses 2SC3519/2SA1386.
However, there won't be a lot of difference in this; just try a bias of ~ 10ma to start with (2.2mV over 2.2 ohm) and see how it goes. I had an Elex with similar issue.
BTW do you have the Luna curcuit diagram?
However, there won't be a lot of difference in this; just try a bias of ~ 10ma to start with (2.2mV over 2.2 ohm) and see how it goes. I had an Elex with similar issue.
BTW do you have the Luna curcuit diagram?
Hi Mashley,
I haven't the Luna diagram, I simply look at the output circuit and I see several things in common with the Elex. At the moment I'm using 100mA bias current. I've look at the datasheet and it seems the devices can handle such a current. The Rega get hotter but I can still keep my hand in contact under the transistor, below the clamshell (with the unit weights on my hand) without feeling pain at all. I choose an high value to have the channels as close as possible in biasing: my DMM give good reading only at the end of the scale. I don't notice clipping but I'm preatty sure several distortion in higher armonics can occur with such a idling current. The amp pulled toward a class A biasing has a more "live sound", but it loose that british "elegant feeling". I've replaced the 4x4700uF caps with 4x10000 Cornell Doublier, those are large cans with an high ripple current, the improvement has been outstanding 40.000uF is the maximum value that the 153VA trasformer can handle, over this sizing the bass becomes boomy and its control becomes poor. I wonder if I ever will find a 250VA transormer slim enough to replace the one in this slim clamshell.
I haven't the Luna diagram, I simply look at the output circuit and I see several things in common with the Elex. At the moment I'm using 100mA bias current. I've look at the datasheet and it seems the devices can handle such a current. The Rega get hotter but I can still keep my hand in contact under the transistor, below the clamshell (with the unit weights on my hand) without feeling pain at all. I choose an high value to have the channels as close as possible in biasing: my DMM give good reading only at the end of the scale. I don't notice clipping but I'm preatty sure several distortion in higher armonics can occur with such a idling current. The amp pulled toward a class A biasing has a more "live sound", but it loose that british "elegant feeling". I've replaced the 4x4700uF caps with 4x10000 Cornell Doublier, those are large cans with an high ripple current, the improvement has been outstanding 40.000uF is the maximum value that the 153VA trasformer can handle, over this sizing the bass becomes boomy and its control becomes poor. I wonder if I ever will find a 250VA transormer slim enough to replace the one in this slim clamshell.
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