Does Class A really need to be on for days...

[Masterlu]

Does Class A really need to be on for days to sound it's best?

Great article, but the thought of leaving the system on for days to sound it's best is a turn off.

http://www.accuphase.com/review_pdf/...0_02_2013e.pdf

I've heard atleast one Boulder owner say he leaves his Boulder 1060 on 24/7 to achieve the best sound, but that is a class a/b amp. My Vitus in Class A mode reaches normal operating temperature within about 1-1.5hrs. Leaving a class A amp on all day , or 24/7 means it is constantly thermally cycling which can prematurely wear out caps and other areas of the amp. Not to mention the huge power bill! I'd question if that is all with if for maybe 2% difference??

[imprezap2]

My E-560 takes less then 1 hour to fully blossom, my Wadia 381i and Ayre DX-5 I have to leave on (or standby), when I come back after 4 weeks working it takes them 2/3 days before I have he magic back. (sound sticks to the speakers and the soundstage is gone)

Olaf

[tdelahanty]

Originally Posted by Bodhisattva

I've heard atleast one Boulder owner say he leaves his Boulder 1060 on 24/7 to achieve the best sound, but that is a class a/b amp. My Vitus in Class A mode reaches normal operating temperature within about 1-1.5hrs. Leaving a class A amp on all day , or 24/7 means it is constantly thermally cycling which can prematurely wear out caps and other areas of the amp. Not to mention the huge power bill! I'd question if that is all with if for maybe 2% difference??

I don't understan what you mean by thermal-cycling when your class A amp is turned on constantly ??? Just the opposite occurs when left on. Solid-state devices reach thermal equilibrium and become heat-soaked to a uniform level of conduction and perform their best.

Thermal cycling occurs when turned on and off after each use, the internal, microscopic elements expand and contract (as they heat & cool) which causes them to move. Eventually this causes mechanical fatigue and they fracture.

I leave my system on 24/7.

Originally Posted by tdelahanty

I don't understan what you mean by thermal-cycling when your class A amp is turned on constantly ??? Just the opposite occurs when left on. Solid-state devices reach thermal equilibrium and become heat-soaked to a uniform level of conduction and perform their best.

Thermal cycling occurs when turned on and off after each use, the internal, microscopic elements expand and contract (as they heat & cool) which causes them to move. Eventually this causes mechanical fatigue and they fracture.

I leave my system on 24/7.

Hi Tdelahanty, I was referring to a fixed biasing scheme (ie: basically crank up the bias and let it run hot). Such a biasing scheme can lead to unreliability when it heats and cools cyclically - eventually the solder joints everywhere crack and fail after repeated thermal expansion and contraction. This is why you see so many old Krell amps die so often and one of the reasons the old Levinsons fail. No i'm not saying every Class A amp has this biasing scheme. Boulder for example manage the bias at all times with a circuit that monitors current draw, voltage draw and load and adjusts the bias accordingly for the level of signal being passed. That's how they can keep a 1,500 watt amp operating in Class A without it charring whatever touches it. They go through a lot of effort to maintain thermal stability and eliminate rapid cycling, all of which is very, very expensive to implement - and by this I don't mean shiny metalwork.

[Masterlu]

I was just starting to strongly consider a pair of A200's. I would never leave them on for days though.

[imprezap2]

The Accuphase class A amplifiers heat up quickly, if you switch them on half an hour before listening it should be ok.

A-200 or M-6000, I know which ones I would order

[tdelahanty]

Originally Posted by Bodhisattva

Hi Tdelahanty, I was referring to a fixed biasing scheme (ie: basically crank up the bias and let it run hot). Such a biasing scheme can lead to unreliability when it heats and cools cyclically - eventually the solder joints everywhere crack and fail after repeated thermal expansion and contraction. This is why you see so many old Krell amps die so often and one of the reasons the old Levinsons fail. No i'm not saying every Class A amp has this biasing scheme. Boulder for example manage the bias at all times with a circuit that monitors current draw, voltage draw and load and adjusts the bias accordingly for the level of signal being passed. That's how they can keep a 1,500 watt amp operating in Class A without it charring whatever touches it. They go through a lot of effort to maintain thermal stability and eliminate rapid cycling, all of which is very, very expensive to implement - and by this I don't mean shiny metalwork.

I had an ARC D52B which was 50 watts fixed bias class A, it ran so hot the heat-sinks would burn your hand. I owned it for 7 years and never turned it off, not so much as a whimper !!!

Originally Posted by tdelahanty

I had an ARC D52B which was 50 watts fixed bias class A, it ran so hot the heat-sinks would burn your hand. I owned it for 7 years and never turned it off, not so much as a whimper !!!

It's not a pre-requesite.

[jdandy]

Ivan.......After reading the article I don't think the writer was suggesting the A200 sounded bad when not left on. He simply pointed out that there was a difference in the sonic signature when shut off and turned back on versus being left energized continuously. We already know this as it is also true of our Class AB amplifiers. If I owned a pair of Accuphase A200 Class A amplifiers, there is no way I would leave them on 24/7. I might develop the habit of turning them on an hour or so prior to any serious listening, but I would not want the constant heat being released into my room or the constant energy waste. It is also interesting to note the the 230 volt version on the A200 automatically switches itself off after 120 minutes of inactivity. Accuphase calls this Eco Mode.