I would appreciate any advice on leaving a tube preamp always powered on whilst minimising safety hazard and shortening of tube life.
I am thinking of an "idle" setting which leaves the preamp ready for use rather than having to go through a warmup period.
Would lower heater or HT voltage/current work?
Another application would be for preamps with line and phono stages where the phono stage is only used occasionally but is on all the time the line stage is being used. This seems to be a waste of tube life.
The preamps I am using are all small tubes - 12AX7, 6922 etc.
Thanks!
I am thinking of an "idle" setting which leaves the preamp ready for use rather than having to go through a warmup period.
Would lower heater or HT voltage/current work?
Another application would be for preamps with line and phono stages where the phono stage is only used occasionally but is on all the time the line stage is being used. This seems to be a waste of tube life.
The preamps I am using are all small tubes - 12AX7, 6922 etc.
Thanks!
Thank you Tweeker.
Another reason I want to leave the preamp on is because I use a transistor power amp, which is always on, and turning the preamp off produces a speaker destroying thump. I have to turn the power amp off, preamp off and then turn the power amp on again which is a pita.
If I cut off the HT completely would this make a thump?
Another reason I want to leave the preamp on is because I use a transistor power amp, which is always on, and turning the preamp off produces a speaker destroying thump. I have to turn the power amp off, preamp off and then turn the power amp on again which is a pita.
If I cut off the HT completely would this make a thump?
It could still thump badly depending on how quickly the B+ rises at restoration of power, and how slowly it falls when it goes into standby.
I am not completely sure about this, but I think your pre-amplifier standby scenario could lead to problems of cathode interface (loss of cathode emission) with some commonly used audio tubes. Instant on tv sets in the 1960's often used tube types with somewhat improved cathode chemistry to try and reduce this problem. (IIRC many of these sets seemed to have worse tube life, and my dad, an EE educated in the tube era, disabled the feature on our set because he maintained that it shortened tube life.)
Edit
I reread your post and noted you leave your solid state amplifier on. Regardless of power consumption/component life issues, I assume it sounds better when warm? In this scenario it seems like relay muting (shunt) at the pre-amplifier output would be the best choice. It should only unmute the pre-amplifier once warmed up, and should mute the pre-amp just prior to shutoff. This is the technique I used with ss amps and tube pre-amps. Another interesting option is a transformer coupled pre-amp - this also eliminates the issue.
I am not completely sure about this, but I think your pre-amplifier standby scenario could lead to problems of cathode interface (loss of cathode emission) with some commonly used audio tubes. Instant on tv sets in the 1960's often used tube types with somewhat improved cathode chemistry to try and reduce this problem. (IIRC many of these sets seemed to have worse tube life, and my dad, an EE educated in the tube era, disabled the feature on our set because he maintained that it shortened tube life.)
Edit
I reread your post and noted you leave your solid state amplifier on. Regardless of power consumption/component life issues, I assume it sounds better when warm? In this scenario it seems like relay muting (shunt) at the pre-amplifier output would be the best choice. It should only unmute the pre-amplifier once warmed up, and should mute the pre-amp just prior to shutoff. This is the technique I used with ss amps and tube pre-amps. Another interesting option is a transformer coupled pre-amp - this also eliminates the issue.
Thanks Kevin and billy pilgrim.
Yes, I can and probably should add the output relays. It would also be handy if I do leave it on and there is some sort of fault condition.
But I'm still interested in ways to leave a pre on without wearing all the tubes out. What about connecting it to a variac and turning the supply voltage down when not in use? This would obviously reduce both the ht and heater voltages. The pre would still need to work well enough for my wife to listen to the radio in the morning etc and then when I wanted to do some serious listening I could wind the voltage back up.
What do you think? Crazy?
By the way one of my pre's has just failed. It's an ARC SP12 and I am about to start a new thread because it has a strange arrangement of the heater supply.
SP
Yes, I can and probably should add the output relays. It would also be handy if I do leave it on and there is some sort of fault condition.
But I'm still interested in ways to leave a pre on without wearing all the tubes out. What about connecting it to a variac and turning the supply voltage down when not in use? This would obviously reduce both the ht and heater voltages. The pre would still need to work well enough for my wife to listen to the radio in the morning etc and then when I wanted to do some serious listening I could wind the voltage back up.
What do you think? Crazy?
By the way one of my pre's has just failed. It's an ARC SP12 and I am about to start a new thread because it has a strange arrangement of the heater supply.
SP
If you have a copy of "Valve Amplifiers," there's a lot of detail on running the tubes in standby using reduced voltages; basically, you want to switch off the high voltage and run the heaters at a reduced voltage/current. The variac might be a problem since it reduces the heater voltage while keeping high voltage (albeit somewhat reduced) on the plates.
That said, I keep my preamp going 24/7 and go many years between tube changes.
That said, I keep my preamp going 24/7 and go many years between tube changes.
Leaving my pre-amp on standby
Hi All
I am not expert by any means but I was lead to believe that if you turn the ht off and leave heaters running you are likely to poisoning the cathode, which results with it no longer working.
Another thing worth mentioning, I know so many of us and our amps use dc for the heaters, this has a tendency to shorten the valve life too, for reasons which I can not remember.
The only other thing is why do you need to leave them on anyhow, given current trends with global warming etc, you are just wasting energy and resources.
Most amps warm up within 15 minutes or so anyhow and I was lead to believe that there was no advantage in leaving them on anyhow.
Some months ago i stopped leaving my amps on and turned them off, just as well I did as the Musical Fidelity Typhoon power amp made some most interesting noises some months back.
I attributed the creakign to the normal heating up but it was not some time after switching on there was a sudden hum in the left channel and I turned round to see there was a load of smoke coming out of the amp. Of course i switched off, the whole thing was very very hot, had i not been here and had I not ceased to leave mine on standby, i would now be homeless.
Not wishing to put you off but my advise forget the idea, did you know you invalidate your household insurance by leaving it on, as you do with other items such as washing machines should something happen and you left them un-attended then you would be able to claim nothing.
Well it is only my opinion but a worthy one I feel.
See you
Steve in the U.K.
Hi All
I am not expert by any means but I was lead to believe that if you turn the ht off and leave heaters running you are likely to poisoning the cathode, which results with it no longer working.
Another thing worth mentioning, I know so many of us and our amps use dc for the heaters, this has a tendency to shorten the valve life too, for reasons which I can not remember.
The only other thing is why do you need to leave them on anyhow, given current trends with global warming etc, you are just wasting energy and resources.
Most amps warm up within 15 minutes or so anyhow and I was lead to believe that there was no advantage in leaving them on anyhow.
Some months ago i stopped leaving my amps on and turned them off, just as well I did as the Musical Fidelity Typhoon power amp made some most interesting noises some months back.
I attributed the creakign to the normal heating up but it was not some time after switching on there was a sudden hum in the left channel and I turned round to see there was a load of smoke coming out of the amp. Of course i switched off, the whole thing was very very hot, had i not been here and had I not ceased to leave mine on standby, i would now be homeless.
Not wishing to put you off but my advise forget the idea, did you know you invalidate your household insurance by leaving it on, as you do with other items such as washing machines should something happen and you left them un-attended then you would be able to claim nothing.
Well it is only my opinion but a worthy one I feel.
See you
Steve in the U.K.
I am certainly sure that leaving equipment power-on increases power bills. Personally, I'd prefer to have my power-amp switch off when not in use, and the same applies to my preamp.
What I have found best is to switch on the preamp, then go make a cup of tea, get a beer, feed the dogs, whatever. Come back in a couple of minutes and switch on the main amp, then decide which CD to play and go get it. Anyway, by the time I've done all this, my system is usually pretty warmed-up. Maybe if I allowed it to warm up for a couple of hours, I may notice a difference in sound quality, although I feel that it may be more subjective.
A second reason for powering-down equipment is that during the long Arizona summers, it is very difficult to keep the house below 80F (27C) and it can add to the heat induced depression to think of the preamp tubes adding extra heat into the room
Charlie
What I have found best is to switch on the preamp, then go make a cup of tea, get a beer, feed the dogs, whatever. Come back in a couple of minutes and switch on the main amp, then decide which CD to play and go get it. Anyway, by the time I've done all this, my system is usually pretty warmed-up. Maybe if I allowed it to warm up for a couple of hours, I may notice a difference in sound quality, although I feel that it may be more subjective.
A second reason for powering-down equipment is that during the long Arizona summers, it is very difficult to keep the house below 80F (27C) and it can add to the heat induced depression to think of the preamp tubes adding extra heat into the room
Charlie
Leaving my pre amp on
Hi
I know it does not use much power that is not really the issue here, it is one of safety.
However, I do think the hole in that argument that it only uses a little power, is the same as the one for leaving all equipment on standby, I know this is slightly off topic but, I do think it is valid.
A television left on standby uses 80% of the power it uses when it is fully switched on, there is no advantage in doing this, the same with microwaves, why do you need those switched on too.
The point I am trying to make is that it might use only a little power but it is power wasted, that costs money, adds to global warming and if we all do it all those little bits of wasted energy add up to whole lot.
Equipment does not need to be switched on for that long for it come on song, it might take a little longer in colder climes but those houses are usually well insulated, as stated in another reply, in parts of the world it is a case of it is too hot indoors.
That one is a double whammy, you wasted the electricity lets say in "Nevada" to keep the amplifier on song and then you had to pay again as the air conditioning had to work harder to keep the house cool.
It is only my opinion but one I feel strongly about, it is a waste of time, energy and resources, not to mention a hazard to your long term health should the thing go into meltdown while you are sleeping or you come home to find the house has burnt down.
Let me put it another way, I take it that most of us that use valves also have a lot of vinyl and we have spent years collecting looking this album and that album ahh but I think I will see if I can get it by the other artist too, ahh but that is a rare and expensive copy......then how do you think you would then feel about the house burning down, not mention all the family items that would be lost too.
Have nice day!!!
Stevie in the UK
Hi
I know it does not use much power that is not really the issue here, it is one of safety.
However, I do think the hole in that argument that it only uses a little power, is the same as the one for leaving all equipment on standby, I know this is slightly off topic but, I do think it is valid.
A television left on standby uses 80% of the power it uses when it is fully switched on, there is no advantage in doing this, the same with microwaves, why do you need those switched on too.
The point I am trying to make is that it might use only a little power but it is power wasted, that costs money, adds to global warming and if we all do it all those little bits of wasted energy add up to whole lot.
Equipment does not need to be switched on for that long for it come on song, it might take a little longer in colder climes but those houses are usually well insulated, as stated in another reply, in parts of the world it is a case of it is too hot indoors.
That one is a double whammy, you wasted the electricity lets say in "Nevada" to keep the amplifier on song and then you had to pay again as the air conditioning had to work harder to keep the house cool.
It is only my opinion but one I feel strongly about, it is a waste of time, energy and resources, not to mention a hazard to your long term health should the thing go into meltdown while you are sleeping or you come home to find the house has burnt down.
Let me put it another way, I take it that most of us that use valves also have a lot of vinyl and we have spent years collecting looking this album and that album ahh but I think I will see if I can get it by the other artist too, ahh but that is a rare and expensive copy......then how do you think you would then feel about the house burning down, not mention all the family items that would be lost too.
Have nice day!!!
Stevie in the UK
Re: Leaving my pre amp on
It certainly doesn't. Televisions certainly use more than they ought in standby because they only have the one switching supply and run it at very inefficiently to provide the small amount of power needed to monitor the remote control, but it's <10W.
I'm afraid quite a lot of equipment does take quite a while to warm up properly. This might not be covered in electronics lectures, but electrolytic capacitors in particular take time to stabilise their leakage current after power is applied. Technically, this is nothing to do with temperature, but such phenomena tend to be lumped together under the catch-all of "warm-up". Read the specifications for an oscilloscope - they will almost certainly say that at least 20 minutes warm-up is required before measurements can be taken.
I certainly appreciate your point about conserving energy but it is important that you have the correct facts to hand when you venture into such a contentious area. Of course, if we were really, really concerned about energy, we'd be using Class D silicon amplifiers...
Stevie342000 said:
It certainly doesn't. Televisions certainly use more than they ought in standby because they only have the one switching supply and run it at very inefficiently to provide the small amount of power needed to monitor the remote control, but it's <10W.
I'm afraid quite a lot of equipment does take quite a while to warm up properly. This might not be covered in electronics lectures, but electrolytic capacitors in particular take time to stabilise their leakage current after power is applied. Technically, this is nothing to do with temperature, but such phenomena tend to be lumped together under the catch-all of "warm-up". Read the specifications for an oscilloscope - they will almost certainly say that at least 20 minutes warm-up is required before measurements can be taken.
I certainly appreciate your point about conserving energy but it is important that you have the correct facts to hand when you venture into such a contentious area. Of course, if we were really, really concerned about energy, we'd be using Class D silicon amplifiers...
Leaving my pre amp on
Hi
Yes your right I had forgotten to mention that even in something as old as my Vortexion CBL6H Reel to Reel that it mentions switching on for 15 minutes or so before commencing recording.
But any more than that is a waste of time in my humble opinion, it is a contentious issue I know.
But think if you left equipment on how much more it costs you in the back pocket, now what other uses can you think of for the money that you have saved.
All the things that we do in our homes such as leaving televisions on standby (the cause of lot of household fires too just behind the chip pan), I still feel is on one of personal safety, you don't go out and leave the gas oven on just because it would bake a better cake when I come home. So why do it with electrical equipment, it is a con we have bought into, with a lot of electrical goods such as televisions, microwaves etc.
There might be advantages to leaving audio equipment on but for me they are out weighed by the cons rather the the pros.
Have a nice day
steve in the UK
Hi
Yes your right I had forgotten to mention that even in something as old as my Vortexion CBL6H Reel to Reel that it mentions switching on for 15 minutes or so before commencing recording.
But any more than that is a waste of time in my humble opinion, it is a contentious issue I know.
But think if you left equipment on how much more it costs you in the back pocket, now what other uses can you think of for the money that you have saved.
All the things that we do in our homes such as leaving televisions on standby (the cause of lot of household fires too just behind the chip pan), I still feel is on one of personal safety, you don't go out and leave the gas oven on just because it would bake a better cake when I come home. So why do it with electrical equipment, it is a con we have bought into, with a lot of electrical goods such as televisions, microwaves etc.
There might be advantages to leaving audio equipment on but for me they are out weighed by the cons rather the the pros.
Have a nice day
steve in the UK
TECHNIQUES TO EXTEND THE. SERVICE LIFE OF HIGH POWER VACUUM TUBES.
Walter Johnson, Voice of America, Technical Material Support Division.
Walter Johnson, Voice of America, Technical Material Support Division.
Leaving my pre amp on
Hi
I agree wholeheartedly that there are times when valves should be left on and transmitter valves are indeed one instance.
They do not benefit at all by being switched on and off, think about what sort of heater amps are involved here and the impact that has on the filament each time it is switche on.
The 833 for instance does that not run at 10v or 5v but uses 20A to power its heater, now that is one awful surge of power, turning these on and off will probably shorten their life to.
But for the average tube/valve I am not sure I can see an advantage, in my humble opinion it should only take about 20 minutes for most amps to warm up, this time could be covered by going to make a pot of coffee and emptying the dishwasher, while it idles away playing some radio station for background, then sit down, enjoy a nice coffee and a muffin or G & T if that it is that time of day for you.
It is at the end of the day personal choice but I for one can see no advantages, the dangers to me outway the pros, it has taken me years to collect my vinyl much of which is irreplaceable and would take me how to long to re-collect and at what cost should the house burn down.
But really guys don't get me wrong I am into Hi-fi and High Fidelity but I feel sometimes we can take things too far and we jump at the latest whim or fad...stop worrying and just enjoy the music or some folks say wake up and smell the coffee.
No matter how hard we try we are not going to approach the sound of a live concert, the conditions are wrong, so is the equipment, situation, listening room, etc. It just ain't gonna happen, like is said sit back and enjoy the music stop worrying about what is ultimately unattainable and does not exist.
A recording is just that a recording, it in no way bears any resemblance to the live performance or the sound on the master tape...ooops they do not use that any more do they? I had a professional reel to reel a Studer B62 mid/late 60s tech.....the recordings I made from the radio bore no resemblance to the original source....somehow there there was a lot more dynamics and scale, where did that come from it was not what i heard when I made the recording.
To hear the original perfomance you would need to be in the studio, a physical impossibility, however we should do our best to try recreate the most favourable conditions in our home systems but it is horses for courses otherwise we would all be using the same equipment.
Your or mine opinion on what is the right or the wrong way to go about this or that or the other is just that our opinion, there will be no overall agreement there. At the end of the day it is all down to personal choice, mine is given the risks then it is of no advantage for me to leave the equipment on.
It is your choice if you disagree with this, there is no point in any of us falling out over what is personal choice, it will not affect the outcome one way or the other.
Have a nice day the sun is still shining for now!!!
steve in the uk
Hi
I agree wholeheartedly that there are times when valves should be left on and transmitter valves are indeed one instance.
They do not benefit at all by being switched on and off, think about what sort of heater amps are involved here and the impact that has on the filament each time it is switche on.
The 833 for instance does that not run at 10v or 5v but uses 20A to power its heater, now that is one awful surge of power, turning these on and off will probably shorten their life to.
But for the average tube/valve I am not sure I can see an advantage, in my humble opinion it should only take about 20 minutes for most amps to warm up, this time could be covered by going to make a pot of coffee and emptying the dishwasher, while it idles away playing some radio station for background, then sit down, enjoy a nice coffee and a muffin or G & T if that it is that time of day for you.
It is at the end of the day personal choice but I for one can see no advantages, the dangers to me outway the pros, it has taken me years to collect my vinyl much of which is irreplaceable and would take me how to long to re-collect and at what cost should the house burn down.
But really guys don't get me wrong I am into Hi-fi and High Fidelity but I feel sometimes we can take things too far and we jump at the latest whim or fad...stop worrying and just enjoy the music or some folks say wake up and smell the coffee.
No matter how hard we try we are not going to approach the sound of a live concert, the conditions are wrong, so is the equipment, situation, listening room, etc. It just ain't gonna happen, like is said sit back and enjoy the music stop worrying about what is ultimately unattainable and does not exist.
A recording is just that a recording, it in no way bears any resemblance to the live performance or the sound on the master tape...ooops they do not use that any more do they? I had a professional reel to reel a Studer B62 mid/late 60s tech.....the recordings I made from the radio bore no resemblance to the original source....somehow there there was a lot more dynamics and scale, where did that come from it was not what i heard when I made the recording.
To hear the original perfomance you would need to be in the studio, a physical impossibility, however we should do our best to try recreate the most favourable conditions in our home systems but it is horses for courses otherwise we would all be using the same equipment.
Your or mine opinion on what is the right or the wrong way to go about this or that or the other is just that our opinion, there will be no overall agreement there. At the end of the day it is all down to personal choice, mine is given the risks then it is of no advantage for me to leave the equipment on.
It is your choice if you disagree with this, there is no point in any of us falling out over what is personal choice, it will not affect the outcome one way or the other.
Have a nice day the sun is still shining for now!!!
steve in the uk
Leaving my tube pre amp on
Hi All
That was an interesting read on the transmitter tubes, but can it really be transferred to the audio tube world that we live and is it really that relevant or that important.
There are other issues at hand here such as the wasted power and the risks associated with meltdown, which I feel outweigh any benefits.
Can someone tell me in laymans terms what the Miller-Larson effect is? I tried to google it but got the document that is listed here already, I did not read all of it so forgive me if it is contained in there.
Are there not other issues here such as cathode or heater poisoning, which i thought was caused by such things as running heaters on d.c. and leaving them switched on.
Is this Miller-Larson the same Miller as in the Miller effect which is to due with the capacitance of triodes and self oscillation or instability in triode amplifiers, did i get that right?
Have a nice day
steve in the UK
Hi All
That was an interesting read on the transmitter tubes, but can it really be transferred to the audio tube world that we live and is it really that relevant or that important.
There are other issues at hand here such as the wasted power and the risks associated with meltdown, which I feel outweigh any benefits.
Can someone tell me in laymans terms what the Miller-Larson effect is? I tried to google it but got the document that is listed here already, I did not read all of it so forgive me if it is contained in there.
Are there not other issues here such as cathode or heater poisoning, which i thought was caused by such things as running heaters on d.c. and leaving them switched on.
Is this Miller-Larson the same Miller as in the Miller effect which is to due with the capacitance of triodes and self oscillation or instability in triode amplifiers, did i get that right?
Have a nice day
steve in the UK
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