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In part because the temperature difference between on and off is so great, the sound does change as the components warm up. (Obviously, designers work to optimize the sound after warm up, not during.) Keep them on, and you won't have to wait for the amps to warm up for an hour and stabilize every time you listen. |
I used to own a big Class A amp that I left on continously for three years. Doubled my electricity bill and warmed my placed in winter (nice) and in summer (unpleasant). Sound was great, though. Now I have a Pass X350 that can be switched to standby mode. So far I have not found much difference in sound whether I leave it on continously or switch to standby. Just not sure what the cycles of heating and cooling could do to the amp.. |
It's your call Ferrari!, I have class A monoblocks, and they genearate a lot of heat! But they sound good if you leave the power on all the time.. |
Personally, I have had Plinius SA-100 mk3 amps, and I would not leave them on in Class A idle. First they suck up electricity. Second, the hotter the temperature of an amp, the less lifespan it has. Temperature affects amplifiers like everything else, it decreases the lifespan of the amp.
KF |
Both tube and solid state amps can reach a stable operating temperature in about 15 minutes. I see no reason to leave the amp on when no one is listening just to save the warmup time. The electricity alone is enough to justify this. Didn't your parents teach you to turn off the light when you leave a room? Same goes here (and probably multiplied by a small factor if your amps are like mine: BAT VK-60). Just a few years ago we were all worried about using up the earth's resources. Whatever happened to that?
If you want to speed up the warmup process, just put a space heater under the amp. Then you only need to wait five minutes. |
Hehehe, John, doesn't space heater use electricity? ;-) |
We in California get our electricity from hamster power, and it is very expensive. :-)
Turn the Class A stuff off... It's not like we need heaters ;-)
KF |
I keep my solid state amps on 24/7 unless I am going out of town. The soundstage really opens up after they have been on about an hour. I turn off my tube pre-amp between sessions. It seems to warm up fairly quickly, plus I don't want to burn up my NOS tube set.
If you notice a difference and don't want to wait then leave them on all the time. If you have heat/power concerns or ocassional listening habits, then you may want to switch them on in advance of your session.
Be aware that warm up can also be significant when auditioning new equipment.
On a side note, I have 22 Bryston amps at my work that have been on for 10 years straight without failure.
hope this helps,
Stewart |
From a lifespan viewpoint, any heat is bad. Thermal cyclic failure is logrithmically dependant on power (half the power = 100 times more cycles before failure) so especially high power amps should not be turned on and off too often. But, if it is on all the time, the cycling effect is decreased because when you turn the volume up from idle, the device temp is not starting from room temp which increases your device lifespan compared to cold starts. The happy median point is very hard to find due to its dependancy on many factors like circuit design, layout, device type, bias, heatsink, size, weight, etc.
That said, some designs (like emitter-follower and low or zero feedback) can have thermal issues after being on for a long time like bias error which will degrade performance over time especially if extreme care in hotspot minimization was not taken. I would ask the manufacturer as to what to do (although they may be reluctant to tell you that they did not design for full thermal steady-state). If everything was taken into account in the amp design - there should be no problem in leaving it on all the time, save higher electric bill.
But as for me, I stay away from class A due to thermal problems (as I said - any heat is a problem) and because designers who like the concept of "pure" class A often tend to oversimplify the circuit to the extent that it cannot take care of itself in the long run or in extreme situations. I am always amazed how many high-priced amps have little to no protection circuits in the name of clean and pure sound, which I think is a very dumb idea. Arthur |
I could be wrong about this but I thought that class A amps were least efficient when not driven. If I'm wrong I'm sure you good souls will correct me. If the first premise is true, I would think that leaving a class a amp on all the time would needlesly shorten the life of the amp, waste more electricity than any other component (perhaps as much or even more than the rest of the system combined) and have a negative effect on the enviornment. Perhaps a suitable compromise is in order. |
I am an Aleph user and the class A operation on the 5 uses 300 watts, that's a lot of heat/electricity, when turned on regardless of whether there is program material.
The Aleph 5 seems to take 1 hour to warm up and become most musical and fluid, so I turn it on when I plan to listen and turn it off when not in use for longer than 6 hours. The heating and cooling cycles are no different than leaving it on continuously 24/7 I assume and quite likely better than frying forever.
As the Pass website says the aleph series like like the sun will burn brightly and when it is finished it is all over!
Enjoy... |
Nelson Pass expects 20 years or so from the Alephs because they "run hard". As energy consumption is also importantly an issue, I too try to flip my 30 amp switch on my ACME cry0-outleted junction box with my toe about an hour or two before listening...or listen to FM background before CD.
I'm hoping that this 10-15% on-time leverages my Aleph MTBF to at least 25 years (I'll be 75). We'll see....
Sometimes I think it takes mybe 2-3 hours for the Aleph 2 monos (300w idle each) to get liquid and VERY resolving.
But it could be my (our) hearing apparatus acclimating to the listening environment, like occurs at a live concert.
Yeah, I guess I could afford to leave them on 24/7, especially in the winter, but I'd still feel like they'd age due to thermal load. I have them each sitting in holey
plastic 1 ft-cube milk cartons, hanging a foot under the basement floor joists, so they get convection cooling from UNDERNEITH, too. Hope it helps.... |
Many thanks to all the respondents of this thread. I have found this one draws 1 amp and 120 Watts at idle. According to the manufacturer,(I just found out)Can be turned on and off as well as left on constantly. If possible keep turned on. If going on vacation or away for a period of time turn the system off. |
Leave them on and make sure that they have adequate airflow. Sean
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Based upon advice here and from other sources. The amp has been on for a solid ten days now. There is no comparision between turning off and leaving on. Clearly Class A amps,whose output operates in Class A definitely sound better being left on. This amp has really come into its own now and is quite impressive to say the least. |
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After reading all the threads posted I agree that leaving the amp on is the way to go sonically. I have a Audible Illusions S-120 and it sounds great when left on. However I would like to turn the tube pre(AE-3 Cary) off to keep the Sylvania's in top shape. My question is how do I turn the pre off while not damaging the amp. Dosen't the amp need to see a load while on? Many thanks. |
South43, be REALLY CAREFULL when you turn on the preamp. I know a gentlemen, damage his speakers because he left the power amp on, and turn of the pre the way you do. When you turn on the pre the load will goes through the power amp and out to your speakers. I damage my speakers twice because the power disrupted. |
From "Audio Power Amplifier Design Handbook" 2nd ed. by Douglas Self page 362 final paragpraph:
"Readers of hi-fi magazines are frequently advised to leave amplifiers permanently powered for optimal performance. Unless your equipment is afflicted with truly doubtful control over its own internal workings, this is quite unnecessary. (And if it is so afflicted, personally I'd turn it off now) While there should be no real safety risk in leaving a soundly constructed power amplifier powered permanentley, I see no point and some potential risk in leaving unattended equipment powered; in Class-A mode there may of course be an impact on your electricity bill." |
No offense Ezmeralda, but Doug Self can listen to his system how he wants. Regardless of who has how many books published, his thoughts and opinions on the subject are simply that, his thoughts and opinions. Personally, i think that he is FAR more hung up on measuring things than to listening to them. Personally, i do not know how well his designs work, as i've never used, heard or even seen one of them.
I suggest that one try leaving the system powered up and listening as you normally would. One should obviously take precautions when leaving the system unattended, but one should do that anyway. If you don't notice any difference after a few days ( at least 72 hours of continuous power ), then go back to powering it up and down as needed. Nothing lost except for a small amount of electricity and a few pennies.
My findings are that very richly biased AB amps and those that truly are Class A sound best after 2 - 3 days of continuous power. Amps of low bias AB design or models using some type of switching supply typically sound as good as they are going to get after a half an hour or so.
As far as tubes go, i would put preamps into standby mode and leave them on. Tube power amps should be powered down and fired up as needed unless the system is used most of the time.
Obviously, these are only suggestions based on past experience, just like those of Mr Self's. Sean
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No do not leave them on all the time. The heat generated will lead to pre mature failer.I have owned several Class A biased amps and they need about an hour of warm up to sound good.Also youd be wasting electricity. |
Does "standby" count as being on? I've left mine in standby mostly since I did not want to run the internal fans continuously. I figure that these would be the first bits to go. Any thoughts? |
Well, I have tried leaving my Aleph 5 on for extended periods after all of this discussion and I must add that...
It is incredible how removed the amp becomes and music forward after one, two and even three days of power on. I am now sold on not turning off the amp overnight and only turning off for longer than 36 hour periods.
Other than the power bill the only downside I have come to experience is the desire for more dynamics that micro fade after extended power up periods.
In a word how does the Class A Aleph 5 perform after extended periods of power up, Incredible! |
Sayas: Thanks for the follow-up. Hopefully, your posting of honest findings based on first hand experience will encourage others to check things out for themselves. It is good to see that, even though you initially thought your system sounded quite good, it sounds even better now. As you've found, it sometimes pays to have an open mind and experiment : )
As to the slight fading of dynamics that you are experiencing, i have to wonder if your amp is receiving adequate aiflow. It sounds as if the amp is running TOO hot, which can make them sound dynamically constricted in my experience. How much open space do you have on top of and around the amp ? I know that the Aleph's are all heat-sink, but anything that you can do to let the heat naturally dissipate through convection will only help the matter. Sean
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Sean, the 5 is in a basement on concrete, underpad & carpet and marble slab with nothing surrounding it for 4'. Airflow, cool air is as good as it gets. The listening room is 70F or cooler.
I am confident that the convection factor is as good as I can make it. |
Leave them on...most decent Class A amps are designed with this in mind...if you have reservations....and want to turn them off...give them 10-15 minutes of "warm UP" when turning back on...and dont stack other componets on top!
If you have the old MF A1...you can make some chicken fajitas while listening to Mahler..awesome! |
continuing this conversation after a time gap of roughly 19 years....
I recently acquired a Sumo nine class A power amp and Sumo Athena preamp. The preamp has a on/off switch that works but the powr amp on/off switch is broken. I currntly have them plugged into two independent surge protectors. I turn them on an hour or two before listening.
These Sumo amps are 40 years old. I have no idea of their history.
I want to leave them on all the time, but of course they do not have standby mode.
I am afraid to leave them on while unattended.
But also worried about turning them on once every day, the sudden inrush current could damage the powr supply in the amps.
Any advise what to do in this sitatuion? Are there any reaaonably priced slow start/safe start for home audio? I only find lots of different options for surge protectors and power conditioners. Do these surge protectors and power conditioners protect against sudden spike in current while turning the switch on?
Thanks. |
A class A amp has a pretty high steady state current load on the power supply, so the caps have a fair amount of current flowing in and out all the time when the unit is powered up. I think this puts a lot more stress on the caps than a couple of cycles during power on.
Most well designed amps will have some kind of soft start circuit which will reduce the start-up current during power up. This is to protect the transformer more than the caps. When a transformer is first energized, it can draw a LOT of current until the magnetic field in the transformer is established. I don't know whether your amp has a soft-start, but assuming it does, this will also limit the initial current flow into the caps.
So, from a cap lifetime perspective, I think you are way better off turning the amp off when you aren't using it.
A surge protector is not the same thing as a soft-start. It is designed to protect against over-voltage on the AC line, and will not help during start-up. I have not seen a soft-start circuit built into a separate enclosure, but such devices may exist. |
I don’t think there is any need to have a class A amp on permanently, after 15-30 min it should be 95% there sound vise, and after an hour I would not think it would get any better. |
@unsound : you are correct! A true Class A amp (like a Bedini 25/25) will get quite hot by 30 minutes after turn-on. Playing music for an hour will then lower its temperature significantly as the speaker load absorbs current. That is the mark of a true Class A circuit! If the amp temperature remains hot it is going into Class B past a few watts of Class A power! How do I know this? I owned a Bedini 25/25 for 10+ years as my "daily driver"! The Sumo Nine mentioned here is Class A only for the first 15 watts! After that it goes to Class B for a maximum of 60 wpc! Audio magazine had a test report on it back in the 80's. True Class A amps are most efficient when they are driving a load/speaker. |
My Sumo Andromeda (another James Bongiorno design like his Nine) is Class A for the first 15 watts. Then it goes to Class B for 200 wpc! It still sounds excellent at the higher power range - a mark of an excellent design! I turn it off at day's end! |
Pass Labs XA60.5 that I put in standby when not playing music. Yes, they did increase power consumption slightly, but with solar panels, I don’t have an electric bill so no problem. :-) |
If your Class A amp doesn’t have a standby mode, turn it off over night. If it doesn’t sound good enough 30-60 minutes after powering on, or into Class A, get another amp.
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Turn on 1 hour before listing only. |
I could be wrong about this but I thought that class A amps were least efficient when not driven.
This is correct, a pure class-A or very heavy biased A/B still draws the same current from the mains driven or when at idle. Both amps at idle gives off more heat from it’s heatsinks than they do when driven, but when driven some of the energy that causes the heatsinks to get hot is then diverted to the speakers driver coils instead. All the pure class-A and heavily high biased class-A amps that I have built, all sounded their best after around 1/2hr of being turned on. Cheers George |
op
answer to your query is no
as others have stated, turn on when listening or a few minutes before
amp will come up to temp pretty fast as they run hot, music should sound very good before long
nice to save some energy too |
Thank you @jjss49
@jasonbourne52
@ebm
@wrm57
@georgehifi
@gryphongryph
@jaytor
@audiojan
Thanks for the detailed replies.
As advised I will turn it on hour before listening and turn it off for the night.
The preamp I will keep it on 24/7, Sumo Athena preamp, also super old roughly 35-40 years old. Preamp does not have standby. But the user manual says "where possible keep it on all the time".
One day the setup sounds great, but the next day sounds little bit harsh. I am using JBL L5 floor standers.
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@nebulae
if your equipment is 30-40 years old it is worth having a good tech check them out look for degraded capacitors etc etc... replacing worn or degraded components can dramatically improve the sound of a good old piece of gear
good luck |
Thanks @jjss49
Sure I will do that.
Thanks. |
