Pretty cold in here.... nothing? Where's everyone eh....
18 responses Add your response
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.
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.
Thanks so much George ! My email id is firstname.lastname@example.org .
One more thing is there a Usher Version 1 and Version 2 ? I gathered this while talking to US based Usher dealer. Will that make a difference? If there's a difference then what is it and how do I differentiate cosmetically or internally between the v1 and v2?
Thanks George got you mail. Thanks very much indeed. Heard the amp extensively today and I can vouch that this amp will blow amps costing $6000 straight outta water. People looking for power amps should really check this Amp first before blowing money on Big Brands which are unnecessarily expensive for other reasons than the main reason ... The Sound.
I’m getting the R1.5 with a ss preamp later but a good preowned Shindo Auriges now .
So glad I found this thread. I have 2 Usher 1.5's and run (ran) them in mono to a pair of Usher Tower XL's.
One of my amps became noisy (right channel) and was shipped back to USHER for a replacement. Still waiting....
What I had learned was that Usher was setting the bias higher as it was discussed somewhere that the sounded even better at higher bias, and they already sound amazing. What a great amp and a beast. In mono it's stupid good.
But I don't know how to set bias :( So I guess I'll "probe" around, find a pot, and adjust till my hand starts burning?
But I don’t know how to set bias :( So I guess I’ll "probe" around, find a pot, and adjust till my hand starts burning?Say goodby to your amp!
Seriously, please get a tech to do it, as you need to put dmm meter probes on the emitter resistors, and that is a hairy place to be, as it’s very confined.
desalvo55I gave the circuit diagram to vvvinashhh above, on the condition he passes it on, email him and he’ll forward it to you.
Or send me your email,, and I'll send it, with the bias pot circled in red and the emitter resistors in red, which need to be monitored with a dmm when adjusting the bias pot
My mail id is right there and I have the schematics as George mentioned. What pre are you using desalvo55? I'm using a Cary Audio SLP03 and the results are pretty darn good. I have got to know that the factory Bias of the R1.5 is 500mA. So keep that as a reference point. These amps are simply fantastic and can be easily repaired by anyone who is experienced enough. Usher is going through a restructuring hence the delay.