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Old 11th April 2003, 06:18 PM   #1
eclam is offline eclam  Canada
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Default Standby mode for Aleph series...

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.
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Old 11th April 2003, 09:11 PM   #2
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eclam,


I donīt 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
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Old 11th April 2003, 09:23 PM   #3
Bricolo is offline Bricolo  France
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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
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Old 11th April 2003, 09:59 PM   #4
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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
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Old 12th April 2003, 05:01 AM   #5
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Quote:
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.
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Old 12th April 2003, 05:16 AM   #6
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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
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Old 19th April 2003, 10:31 AM   #7
Bricolo is offline Bricolo  France
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Quote:
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?
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Old 19th April 2003, 03:48 PM   #8
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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
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Old 19th April 2003, 07:44 PM   #9
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I think Iīve read somewhere that only the powersupply is "on" in standby mode. This probably enlarges the caps lifespan cause the hard charīges during startup are reduced.

william
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Old 2nd April 2012, 06:03 PM   #10
oltos is offline oltos  United States
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Default Standby mode & thermal electric conversion for Aleph 30?

I'm a newbie with limited circuit design knowledge. I don't own the Aleph 30 but if I did I'd love it to have a standby mode (like the XA30.5 does). Has anyone perfected a way to add this feature to the Aleph 30? If yes, does it work as well as , if not better, than the one in the XA30.5?

If not, has anyone perfected a way to reduce the Aleph 30's heatsink temps by converting the heat it emits to another form of energy? How about to light?

I found this firm Our Products Menu : Thermoelectric Coolers : Generator : Peltier Cooling : Seebeck : CustomThermoelectric.com and spoke to Andy, their apps engineer. He was friendly and took the time to explain how it could be done: Using an inexpensive chip similar to this one 12711-5L31-03CL (but I think the one Andy specified had
4 leads), you basically just connect one (input lead to the Aleph 30's heat sink and the other lead to a "thermal ground", which Andy said would need to be another standalone heatsink-the lower its thermal resistance the better. The other pair of (output) leads would connect to a load, say a bank of LEDs (and the appropriate series current limiting resistors?). Andy didn't specify but I imagine that the input leads could either be soldered to drilled holes in the chassis and standalone heatsinks, if not connected together with thermal conductive tape like this http://multimedia.3m.com/mws/mediawe...lxtU4x2v4x_Gev
7qe17zHvTSevTSeSSSSSS--

Ideally, this scheme would at least reduce the chassis heatsink temp from not being which "... comfortable to touch for more than a moment or two...." (manual, p. 4)
to no problem doing so. But this may be asking too much from the thermal electric device and/or the amount of affordable standalone heatsink.

If anyone has a stock (not a clone) Aleph 30 and has or add at least one of these two features to it that work perfectly, and wants to sell it, I may be interested. Thanks.
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