Bias mods to a Continuum, absolutely necessary if the bias is to be set into Class A. The sensor now measures the output device temperature, not the heatsink, and therefore responds around 200 x faster to changes. Without this mod the outputs overheat.
Pile of switches from two 705′s and a Continuum. These were very low quality and I change them as a matter of course as they will fail at some point, it’s just a matter of when. Shafts get replaced with metal parts that fit properly.
Crappy OE switch on the left, quality branded part on the right. Price differential is around 8 times which is probably why SS went for the el cheapo option.
Main board now has new switches, uprated rail caps, upgraded preamp chips, bias adjusters, new control shafts, gain mods so it can be used with horns. More to follow next week.
The casing has a sheet of Polyamide / kapton to insulate the power devices but let the heat into the heatsink. When we increase the bias on the front channels we need a thermally better interface, so the Kapton sheet is removed where the 4 channel outputs go.
Board is now ready to fit into the chassis. Special Boron Nitride filled insulators are fitted to the 4ch outputs, and thermal compound to all the other parts.
Channels 3&4 set up for the horns. Sensitivity has been dropped so they don’t play too loud, and distortion is very low. With horns being so efficient 1 watt will be very loud, typically 105dB.
Distortion residual is clean.
As promised, this is a standard Continuum straight out of the box, just as it arrived. Distortion is ball park for a SS reference series amp. Compare with the modified result though reduced by approx 92%
This shows the jagged distortion residual caused by underbiased outputs in the stock amp. The output stage biasing modifications detailed above all need to be done so this can be virtually eliminated. Picture taken at the same settings as above.