Many Class A amps require a certain about of time to warm up to ideal listening levels. It can be annoying to wait for your amp to warm up, and it can be problematic to leave a fully-biased Class A amp running when you are not using it. Would it be beneficial to include circuits to reduce the amps bias to some intermediate level when not in active use to minimize warmup time when next needed?
My general practice is to power up my VFET amp first thing in the morning, and shut it down before going off to sleep. If I forget to turn it off, no big deal. I used to leave my Aleph J on 24/7, because it sounds best that way. All the rest of my audio system stays on 24/7.
Whether a Class A amp can be modified to have a faster warm up time depends on the mechanism for setting the bias current in the output devices. The F6 can be modified this way. The F5 comes this way already. Hint: look for negative thermal coefficient in the bias setting circuit. The M2 and Aleph J are what they are.
Whether a Class A amp can be modified to have a faster warm up time depends on the mechanism for setting the bias current in the output devices. The F6 can be modified this way. The F5 comes this way already. Hint: look for negative thermal coefficient in the bias setting circuit. The M2 and Aleph J are what they are.
My class A amp inspired by the De Lite needs about 15 seconds to "warm up" because I use tubes to drive the MOSFET. I assume it would be under 1 second if I was using a solid state driver...
A thoughtful question.
It depends on the amp. You could introduce a circuit that could run many amps in a "stand-by" mode of sorts at X% Iq. There are also some "mods" that help some amps reach electrical / thermal equilibrium a bit more quickly. Those two things are not mutually exclusive.
What I'd recommend is having someone you trust run a blind A/B test with you with each amp that you care about. It's highly likely that you won't notice the difference between 2 mins and 20 mins of turn-on time. I'll speculate that 2mins is OK for you to wait. If you have to wait longer than 20 to get to a stable operating point, it may be less than ideal. Many people leave their amps on 24/7. Many turn them off between uses. Nelson Pass himself discusses this in many manuals/articles. I choose to not get into the fray of benefits / detriments of either practice.
For you and you only - If you notice a meaningful (to you) sonic difference with verifiable results between 2 and 20 minutes (or time periods of your own choosing), then you'll know if it's potentially worth your time/effort/expense.
Another thing to consider - It's not often the best indicator, but it certainly can be a decent indicator.... look at your favorite commercial (and even DIY) amplifiers and see if they have anything like this implemented. If so, then "the market" has likely determined this to be beneficial at least in some cases. For commercial FW amps, none that I know of have a feature like you describe.
tl;dr - Yes, it can likely be done. Is it worth it (beneficial)? Only you can know. "Heated" discussions (pun intended) have erupted over the energy efficiency of Class A amplifiers both when in-use and at "idle".
It depends on the amp. You could introduce a circuit that could run many amps in a "stand-by" mode of sorts at X% Iq. There are also some "mods" that help some amps reach electrical / thermal equilibrium a bit more quickly. Those two things are not mutually exclusive.
What I'd recommend is having someone you trust run a blind A/B test with you with each amp that you care about. It's highly likely that you won't notice the difference between 2 mins and 20 mins of turn-on time. I'll speculate that 2mins is OK for you to wait. If you have to wait longer than 20 to get to a stable operating point, it may be less than ideal. Many people leave their amps on 24/7. Many turn them off between uses. Nelson Pass himself discusses this in many manuals/articles. I choose to not get into the fray of benefits / detriments of either practice.
For you and you only - If you notice a meaningful (to you) sonic difference with verifiable results between 2 and 20 minutes (or time periods of your own choosing), then you'll know if it's potentially worth your time/effort/expense.
Another thing to consider - It's not often the best indicator, but it certainly can be a decent indicator.... look at your favorite commercial (and even DIY) amplifiers and see if they have anything like this implemented. If so, then "the market" has likely determined this to be beneficial at least in some cases. For commercial FW amps, none that I know of have a feature like you describe.
tl;dr - Yes, it can likely be done. Is it worth it (beneficial)? Only you can know. "Heated" discussions (pun intended) have erupted over the energy efficiency of Class A amplifiers both when in-use and at "idle".
I found it actually more problematic to cycle my hot running (not a pass design) amp on/off, and have had better reliability since leaving on for the last 2-3 years. Prior to that there would be failures at about the one year mark.
With most other equipment it’s around an hour, but my headphone amp gets better after a few hours(?)
Your results may vary…
With most other equipment it’s around an hour, but my headphone amp gets better after a few hours(?)
Your results may vary…
All this continual running of amps makes the power companies very happy.
As for me, I don't buy into that stuff, I hit the handy dandy OFF switch when I'm done using something.
Never had a problem, nor a big electric bill. 😀
As for me, I don't buy into that stuff, I hit the handy dandy OFF switch when I'm done using something.
Never had a problem, nor a big electric bill. 😀
I recall Papa saying 30 minutes or so of warmup was required before the circuit became fully stable in some of his articles, I'd have to go back to see which ones. That's the whole basis I have for even considering such a thing important. I would be interested to know if running an amp at 50% Iq would reduce the time needed to reach stability, and if so by how much. I'll have to research the topic more so I can do some tests, once I finish my build.
If there's a negative thermal coefficient element in the bias circuit and that element is in thermal contact with the HS / output devices, then it's a temperature regulator. Bias and power dissipation starts out high, goes down as temperature goes up until a setpoint is reached.
Such a circuit will warm up faster than a static bias and should track the temperature of the environment the amp is running in. A cooler room will drive bias somewhat higher.
Such a circuit will warm up faster than a static bias and should track the temperature of the environment the amp is running in. A cooler room will drive bias somewhat higher.
This situation of being "fully stable" and the people that suggest such things are IMO just a long-running type of old wives tale passed around.
And as well, it likely stems from amps being unstable in the first place, a sign of poor design.
Decades ago, before solid state amps, tube amps were well-designed, and didn't need such attention nor discussion about warm-up times.
Anyone can go back and look at literature/operating manuals from those days, and nothing was ever mentioned about the things that currently intrique and worry people today.
There were no "standby" switches on amps, except for musicians devices, and that was only to lessen the time to use them during performances after breaks.
It is true, however, that during warmup, small, actually insignificant noises happen - pings, crackles, from the tube elements as the elements expand due to heating.
That perhaps takes about 1 to several minutes to settle, but not hours, unless a tube is less than ideal manufacture, as some currently seem to be these days.
Better to look for the potential causes of "less than perfect" operation and having to wait forever to enjoy the music.
Stop needlessly wasting energy 😱🙄
You're also putting lots more hours onto the components, I often see kit that's been on 24/7 because the owner were told (or read) that it's better ... this is even on solid state stuff.
All you're doing is prematurely ageing the product and wasting electricity.
24 hours power up in every day instead of 4 or 8 makes a product design that might have lasted 10 years without intervention only last 2 or 3
Valve kit should be fully up to temp within 30 minutes or so, solid state - 10 minutes.
whatever I'm doing and no matter how much in hurry I am, listening the music isn't exactly Take money and Run! operation to me
I'm enjoying the music pretty much every minute of my awake state, and sole forbidden place for that is Bedroom, simply because Boss doesn't like noises while sleeping
was thinking of gonna rid of Boss, but I can't, chose too wisely
I'm enjoying the music pretty much every minute of my awake state, and sole forbidden place for that is Bedroom, simply because Boss doesn't like noises while sleeping
was thinking of gonna rid of Boss, but I can't, chose too wisely
It only matters what it will do to your energy bill / house temperature, and more importantly if it will be a meaningful difference to you. You've built an amp I take it. Measure before and after.
Each of your amps has a known / quantifiable energy consumption. You should know what you pay per KWh. Calculate the cost to run the amp.
My rooms don't go up a single degree. Why? Because I have an actively monitored and controlled HVAC system. One could speculate that I may spend a bit more on energy to cool the room when my system is running in "the summer". It might be a slightly lower cost in "the winter".
See if you can find the average heat dissipation of a human. How much do you heat the room... how about if you have a friend over? How does that compare to the heat dissipation of the amps you're wondering about?
Again - thoughtful questions, but others' experiences, while providing some context won't replicate your experience with your amp(s) in your room at your energy costs.
tl;dr - energy bill likely higher. Temp - likely irrelevant if the home has active temperature control. If not... then likely higher. Again, is it a meaningful difference? Only you can decide.
Looking at the use of electrolytics at least in the power supply, sometimes also in the amp section itself: those thingies have a guaranteed operational life between 2,000 and 10,000 hrs. A year, 24/7, has 8,760 hrs.
Just another data point at leaving stuff on 24/7… 😉
Just another data point at leaving stuff on 24/7… 😉
To keep the whole household cost and CO2 emission neutral, but still running Class A amps, Mr. Pass' method is reducing the frequency of driving his big truck to post office.
Since building and running Class A amps, I reduce consuming steak consistently, from twice a week to once a week to pay my electricity and keep my CO2 foot print same.
Since building and running Class A amps, I reduce consuming steak consistently, from twice a week to once a week to pay my electricity and keep my CO2 foot print same.
My class A amp draws about 400W from the wall and makes about 5W/channel. It makes my tube amps look efficient 😀
You can read by it though, so there's that.
You can read by it though, so there's that.
Amazing..... I'm surprised that most of us Geezers could even hear the difference betwixt a just turned on and after a warmup.... sound.
I can't .. well in truth there is a slight difference but it... IS ...slight (and temporary 🙂 Is it really that important on a 10$ recording?
I can't .. well in truth there is a slight difference but it... IS ...slight (and temporary 🙂 Is it really that important on a 10$ recording?
It’s in a naturally cool basement room, and have not noticed my new heat pump working any harder.
I’m sure pleased to not have to rebuild the thing every few months though, what’s that worth?
I’ve never had an inclination to operate equipment this way, but I’ve never had equipment that sounded as good, yet deteriorated with regular use either. I just found a way to make it last in my situation…