What I'm about to ask could apply to cd players too but there are alot of companies marketing mains purification products and so on. I wanted to know what truth there is in the idea that sound quality varies thoughout the day because of the mains quality?
Have any of you who build amplifiers noticed such kinds of variations and has it been due to the mains?
Have any of you who build amplifiers noticed such kinds of variations and has it been due to the mains?
Mains purification is a solution to a problem that seldom exists. Years ago voltages and frequencies were unstable but these days you can almost calibrate your voltmeter and certainly your frequency meter with the mains supply.
Noise is another issue but, as SY indicates, attention to proper techniques will usually solve the difficulty.
Noise is another issue but, as SY indicates, attention to proper techniques will usually solve the difficulty.
There are whole books dedicated to that. Start with the Dave Davenport article posted on this site- he does a fine job of laying down the basics.
the only thing I noticed that affects the sound during the day is background noise. ie traffic, central heating, kids outside. The best for me is the fall and spring. Nice sunny warm days, no traffic during the day and the kids are at school and the wife at work. Grab a beer and listen ahhhhhhh
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When I used to do scientific research (in the UK, so using same grid as Prof. Smith) I found that the noise levels in my experiments had a strong dependency on the time of the day. It was not simply a case of noisy mains or a noisy earth either, but pick up of radiated noise by sensitive equipment.
I like the common mode choke suggestion, it's something that can be retro-fitted to many amplifiers rather easily if space permits. And it needn't be that expensive.
But as somebody else pointed out, the amplifier is but one piece of the system, the source and preamp (if used) may also be vulnerable.
Unfortunately, the mains isn't that great in some places. Susan Parker posted some notes about that awhile back - she's also in the UK and uses EI power transformers as they are more tolerant to bad mains. The frequency of the mains is pretty solid (or the generators would fall to pieces quickly) but the waveforms get distorted at remote parts of the grid by the myriad of local loads placed on them.
I like the common mode choke suggestion, it's something that can be retro-fitted to many amplifiers rather easily if space permits. And it needn't be that expensive.
But as somebody else pointed out, the amplifier is but one piece of the system, the source and preamp (if used) may also be vulnerable.
Unfortunately, the mains isn't that great in some places. Susan Parker posted some notes about that awhile back - she's also in the UK and uses EI power transformers as they are more tolerant to bad mains. The frequency of the mains is pretty solid (or the generators would fall to pieces quickly) but the waveforms get distorted at remote parts of the grid by the myriad of local loads placed on them.
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If the problem is the shape of the waveform or the voltage theres nothing I can do about it anyway. Supposedly, around tea/dinner time the voltage drops as people put on the kettle but during night the voltage stabilises, theres less noise and so on. The trouble is, the sound of my system does not vary according to this pattern. I have tried listening at night and the early hours of the morning and it has sounded bad. Conversely I recall it sounding good around dinner time on a number of occasions. There's no rhyme or reason.
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There may be no solution if you define it as a problem - because the other part of the system is our hearing and our emotional response to the sound. Somedays I like rock, others Jaz and what I enjoy one day maybe isn't enjoyable the next. If I listen to a song after first listening to rock and then listen to the same song after first listening to Jaz, then I find it sounds different. Same with the taste of food and many other things in life. So it's almost impossible to even decide if the sound is the same or not from one day to the next - which means you won't even be able to verify that you've 'fixed' the issue.
In this case, the solution is to stop regarding it as a problem, it's just how 'it' is.
In this case, the solution is to stop regarding it as a problem, it's just how 'it' is.
Perhaps the drop in the ambient noise is revealing some low level unhappiness in your system?
One way to get around the mains variation by the way would be to install a motor-generator set with a large flywheel. I'm surprised nobody has tried to sell one with the word "Audio" slapped onto it. Perhaps the profit margin isn't as good as some minerals in a cable
One way to get around the mains variation by the way would be to install a motor-generator set with a large flywheel. I'm surprised nobody has tried to sell one with the word "Audio" slapped onto it. Perhaps the profit margin isn't as good as some minerals in a cable
Variations on mains power variation
I was awaken by crazy clicking of my computer's UPS at 4 a.m. I tested the mains and here is what I captured on the scope. Not a very pretty picture. I am not talking about sound here, with such pulses there is a fair chance of equipment damage.
Moral of the story: Always use good surge prtectors (but of course you already know that)
I was awaken by crazy clicking of my computer's UPS at 4 a.m. I tested the mains and here is what I captured on the scope. Not a very pretty picture. I am not talking about sound here, with such pulses there is a fair chance of equipment damage.
Moral of the story: Always use good surge prtectors (but of course you already know that
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Irakli. That's just nasty!
I've read about high end systems in Japan that do exactly that. Never seen or heard one, tho. Have seen a lot of motor-generator sets in old cinemas. They were used to generate the 24VDC needed by the arc lamps. Massive things. Solid state rectifiers killed them off (hurray!)
Also seen a few smaller units that did 120V 60Hz in and 120V (I think) 400Hz out. That was for aircraft use. Military stuff.
I've read about high end systems in Japan that do exactly that. Never seen or heard one, tho. Have seen a lot of motor-generator sets in old cinemas. They were used to generate the 24VDC needed by the arc lamps. Massive things. Solid state rectifiers killed them off (hurray!)
Also seen a few smaller units that did 120V 60Hz in and 120V (I think) 400Hz out. That was for aircraft use. Military stuff.
Plating shops use the same process. Any DC or other anomalies in the line will have an adverse effect on the quality of plating. Whenever I went to plating shops and saw those big slow-moving flywheels I thought, "That would be cool to have in my living room with my audio system." Fat chance.
As for audio, it may be easier to use an isolation transformer with a common mode filter on the primary and keep the equipment power supplies simple, especially if you like to build and experiment with new stuff on a regular basis.
John
As for audio, it may be easier to use an isolation transformer with a common mode filter on the primary and keep the equipment power supplies simple, especially if you like to build and experiment with new stuff on a regular basis.
John
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what would be the specifications for a common mode choke ?
I assume lots of inductance is good, dc current rating is not so obvious to me. For Class AB there isn't much idle current, but I guess you have to worry about thermal heating of the choke if the average AC current flow exceeds the manufactuers dc rating ?
You can get this one in the UK for less than 5 quid, for dual rails you might want two per channel. And it's going to tame any r.f. from the rectifier diodes too.
Roxburgh EMC | Passives | Magnetics | Inductor Leaded | PCB Mount High Current |CMV20
I assume lots of inductance is good, dc current rating is not so obvious to me. For Class AB there isn't much idle current, but I guess you have to worry about thermal heating of the choke if the average AC current flow exceeds the manufactuers dc rating ?
You can get this one in the UK for less than 5 quid, for dual rails you might want two per channel. And it's going to tame any r.f. from the rectifier diodes too.
Roxburgh EMC | Passives | Magnetics | Inductor Leaded | PCB Mount High Current |CMV20
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partially this all post reminds me what good old times TV tech guys used to say to the costumers regarding that damage of their TV :
"it was a mains /voltage thing " so costumer is runing a way ready to have an argument with the electric company or looking for the rwrong method to protect the device ...such is a back up ups .... or a surge protector in a house or are that doesnt have proper or existing earthing system
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to me it is obvious that in a preamplifier or cd player neither voltage nor frequency variations ( with in reasonable limmits ) will ever effect the operations of the device as long that the AC voltage is supposed to be rectified filtered and regulated ....
By the same logic the same will happen to an amplifier when voltage is lower than supposed to total power will be less and if voltage is higher than supposed total power will be more than expecteted given as a fact that all the circuits of amplifier will capable of the variation ....
frequency variations will only effect the performance of the transformer ..
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the real problem will be in any surge,EMI ,and any noise that can be injected through the AC line to the transformer ( or the smps ) and there for even pass through rectifier or the regulator circuits
That will be the defination of the term of AC quality where how much voltage and how much frequency will be the less to bother with ....
"it was a mains /voltage thing " so costumer is runing a way ready to have an argument with the electric company or looking for the rwrong method to protect the device ...such is a back up ups .... or a surge protector in a house or are that doesnt have proper or existing earthing system
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to me it is obvious that in a preamplifier or cd player neither voltage nor frequency variations ( with in reasonable limmits ) will ever effect the operations of the device as long that the AC voltage is supposed to be rectified filtered and regulated ....
By the same logic the same will happen to an amplifier when voltage is lower than supposed to total power will be less and if voltage is higher than supposed total power will be more than expecteted given as a fact that all the circuits of amplifier will capable of the variation ....
frequency variations will only effect the performance of the transformer ..
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the real problem will be in any surge,EMI ,and any noise that can be injected through the AC line to the transformer ( or the smps ) and there for even pass through rectifier or the regulator circuits
That will be the defination of the term of AC quality where how much voltage and how much frequency will be the less to bother with ....
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