Usher R1.5 should I buy?
vvvinashhh Usher R1.5 and R2.5 were almost direct copies of the Threshold Stasis S200 and S300. I showed Nelson Pass the circuits of the Ushers, and the only difference was they had one extra gain stage transistor in them, which Nelson replied was what he would have done if he did a re-design of them. So your in good company as I owned an S300 mkII and it was a very nice smooth amp with plenty of grunt. Cheers George |
vvvinashhhI might also add the ones I've played around with, were under biased,, and needed to to be adjusted a bit higher to get the Class A bias of the Thresholds, "as Nelson palm detector adjustment", enough bias to keep the palms of you hand on a fully warmed up heatsink for at least 6 seconds, (bricklayer exempt from this test) Cheers George |
I had the circuit, but it’s long gone now, but if you warm it up with the lid on for at least an hour, and if still not warm enough (use Pass palm test) Monitor the bias across the emitter resistors (yes they used them the same way as NP did, collectors drove the speakers) with a DMM and increase 10mV at a time till you get the right heatsink temp, both channels. And yes more cap uF the better on the power supply, but many small ones are better than big ones, as they can release their storage quicker and give you far better transient response. PS: Just found the circuit of the Usher 2.5 send a PM if you want it with your email address. Cheers George |
