Standby mode for Aleph series...

[eclam]

I was wondering if builders out there have contemplated
incorporating a standby modes for the Aleph series.

One idea I had was to reduce lower the +/- rails by 80%
of their "ON" value.

It would keep the FETs warm until a full power on. This
would save on energy and lower the heat disappated by
the heat sinks.

The other idea would be to have a second bias point
setup for standby and a relay would switch between
the operating bias current and the standby bias current
value.

I don't like the idea of waiting 1-2 hours for peak sound, but
at the same time, I don't want to leave the unit on all the time
heating the room.

[wuffwaff]

eclam,


I don´t know why but somehow the warmup time of my Aleph has shortened from more than an hour to almost nill.

There are still gains over the first hour but they are not really big anymore compared to when the amp was new and you can really listen to the amp from cold.

william

[Bricolo]

If Nelson come here, he'll correct me if I'm wrong:

on the new AX series, there is a standby button, that switches off the output mosfets, but keeps the diff pair's bias

[cocolino]

Hi eclam,

I think lowering the rails would be quite difficult and is not very practical.
I like Your second idea better. Furthermore it would be very handy to switch the relay automatically depended of the presence of an audio signal. When there is no signal for a certain time the relay is activated and the bias lowered - after a signal is detected the relay flips back to the normal operating bias.

I thought about something like this:
Amplifier-Timer

[Nelson Pass]

Originally posted by Bricolo
on the new AX series, there is a standby button, that switches off the output mosfets, but keeps the diff pair's bias

Actually, we found it necessary to shut down the diff pair also, otherwise the outputs go to the negative rail. This does not appear across the load, but scares the cows anyway.

[Mark A. Gulbrandsen]

Why not just lower the bias??? A smaller value for R19 on one position of a switch and then the normal value(or none) on the other position.....make before break contacts on the switch.....
Mark

[Bricolo]

Originally posted by Nelson Pass

Actually, we found it necessary to shut down the diff pair also, otherwise the outputs go to the negative rail. This does not appear across the load, but scares the cows anyway.

so, what stays on when the amp is in standby mode?

[Mark A. Gulbrandsen]

I don't quite get it either unless the only important part to keep warm is the constant current sources......I would think the input differential pair would be the most important to keep warm though....
Mark

[wuffwaff]

I think I´ve read somewhere that only the powersupply is "on" in standby mode. This probably enlarges the caps lifespan cause the hard char´ges during startup are reduced.

william