Power generation using electric motors

[rajupatel]

Hi, I am a novice. I have very sensitive high end audio equipment. I want to power them up from an independent source. I was contemplating using a electric motor driven generator. I want to do this to supply cleanest power to the equipment/electronics. My power requirement is about 5 KVA. I am planning to make three such sets of 2KVA each to supply to my three sets of amplifier's. I do not want to use any fuel based prime movers.
I would appreciate any suggestions.

 

[bipolar]

What is the "Normal Source" that you want to be independent from?

Need to know more about the existing source and identified problems before even making a guess.

Removing any "fuel based" motors pretty much eliminates all viable options, other than running a portable nuclear reactor, unless that too is "fuel based".

In a country with a stable electric grid, you won't find a cleaner source of power than the grid.

 

[rajupatel]

my normal source is the grid. But. as usual, many electric items are connected to my home power source (both inside and outside) which do carry electrical noise. Hence I want a dedicated power source to run just my audio equipment. and nothing else will be connected to it.

 

[bipolar]

The AC power is filtered, converted to DC and heavily filtered more to eliminate the 120Hz Ripple. These steps make any noise on the AC line isolated from the audio signal. If the power is stable enough to run a PC, Display, etc, the AC line is OK.

If there is audible noise from the power in the audio output, the power supply in the amplifier needs repair.

 

[rajupatel]

i agree. but i have heard amplifier running on an dedicated power source and it sounds so much more cleaner with a much lower noise floor. The transients in the music are more pronounced and impactful. If i understand right the more components there are in a circuitry more is the contamination in the signal path. though i cannot get rid of the components in the signal path, the least i can do is to supply a pure sine wave power which makes the components in the signal path less obstructive... pardon me if my concepts are out of context, as i have no knowledge of electronic circuitry...

 

[Integral]

How do you know that the differences you heard were due to the power source? Did you listen to the same system with both grid power and the independent source? If not then how do you know the difference was due to the power?

Read Bipolars posts, if you do not understand what you are reading please ask questions.

 

[rajupatel]

yes i have heard the same system on both power sources separately. Hence the observation. "Bipolars posts" = where? link?

 

[bipolar]

Any transients/noise floor that are audible are due to the internal amp power supply, or a different location/position of the amplifier and system, and not related to the power source.

As I stated, if your household source did have enough noise to get past a properly designed amplifier power supply, then your computer would not run.

Please read http://sound.westhost.com/cables-p4.htm#power for some more information regarding supply quality and AC related to audio amplifiers.

 

[Phrak]

Hi, I am a novice. I have very sensitive high end audio equipment. I want to power them up from an independent source. I was contemplating using a electric motor driven generator. I want to do this to supply cleanest power to the equipment/electronics. My power requirement is about 5 KVA. I am planning to make three such sets of 2KVA each to supply to my three sets of amplifier's. I do not want to use any fuel based prime movers.
I would appreciate any suggestions.

Way cool dude. Peddle power you drums, man. Maybe, like, instead of a dancing chorus, you could have a peddling chorus.

 

[Averagesupernova]

Don't you guys know to never argue with an audiophile?

 

[Pumblechook]

I can't really believe someone has actually been taken in by that pure supply nonsense.

A local generator will produce a noisy spikey output anyway.

Do you spend £20 a metre for speaker cable as well?

A fool and his money...

 

[mgb_phys]

The AC power is filtered, converted to DC and heavily filtered more to eliminate the 120Hz Ripple. These steps make any noise on the AC line isolated from the audio signal.

If it was designed/built correctly

If the power is stable enough to run a PC, Display, etc, the AC line is OK.

PCs used switch mode PSUs that will run on absolutely anything.

If there is audible noise from the power in the audio output, the power supply in the amplifier needs repair.

Probably true, or an Earth loop, or a bad ground.

If you are really fussy cut out the AC power supply and run the amplifier directly from a 12V battery

 

[chroot]

I'd say the first step should be to put the DC output of your amplifier's power supply on a scope, and measure the noise, transients, ripple, etc. that's present. After you've proven the power supply to be inadequate, then you can work on a solution to improve it.

Throwing money and effort at a perceived (but unproven) problem is silly. If you're into high-end audio, you're probably already used to doing this, unfortunately, since that's the essence of the entire hobby -- making yourself feel better about your equipment by throwing money at problems you can't really perceive and don't really understand.

If you really want to spend money to improve your music-listening experience, I'd suggest some insulating wall coverings, or maybe just a rum and coke. Enjoy.

- Warren

 

[Averagesupernova]

Throwing money and effort at a perceived (but unproven) problem is silly. If you're into high-end audio, you're probably already used to doing this, unfortunately, since that's the essence of the entire hobby -- making yourself feel better about your equipment by throwing money at problems you can't really perceive and don't really understand.

- Warren

You hit the nail on the head here. The audiophile community likes to perceive problems that cannot be proven whether or not they really exist. This way, there is an endless amount of money or effort that can be thrown at the perceived problem. If you cannot prove with instruments that the 'problem' has been fixed, then technically it's still there. Those of us who claim that there was no 'problem' to begin with don't seem to count.

 

[Pumblechook]

The blind tests .. Monster Cable for speakers versus wire coathangers was amusing. The hi-fi nuts couldn't tell the difference. Coathangers are not even low oxygen copper, not even copper but mild steel.

http://www.monstercable.com/mseries/speaker_cables.asp

 

[chroot]

Pumblechook,

There are many, many audiophiles who claim that electronic measurement equipment cannot detect the subtle qualities of music that are affected by, say, power conditioners. Despite the clear and obvious truth that the electronic measurement equipment is far, far more sensitive than human ears, they wish to rely on their ears alone as a guide for spending their hard-earned money.

What's really shocking is that there are many audiophiles who further reject the notion of double-blind testing. This means they not only distrust electronic measurement equipment, they also distrust their own ears -- the same ears they are supposedly trying to please in the first place.

After rejecting the results of both measurement equipment and double-blind testing, audiophiles are no longer vulnerable to any rational argument. Instead, they follow their instincts and collect vast amounts of shiny, overpriced nonsense. The enjoyment of music eventually becomes confused with something even more fundamentally human: the pride of ownership.

If all you seek is pride in ownership, you'll always get what you pay for.

- Warren

 

[Bob S]

If your equipment is properly designed and built, the power supply connections to all your low level stages should come from regulated DC supplies and be bypassed locally with caps to ground. The audible hiss should be only broadband noise, with no 60 Hz or harmonics. Also, the only noise or hiss should come from your first stage ( e.g., 12AX7) wih open input. Unplug it and the noise should go away. I had to run the filaments on my first stage with DC to minimize the hum.

 

[bassplayer142]

What about interference coming through the air and not necessarily through the electrical system. Interference could come from anywhere and then re enter the system after amplification or anywhere. Shielding the wires and amp might help.

 

[Bob S]

All low level signal amplification stages should be totally enclosed in metal enclosures (aluminum, except maybe copper at loweest frequencies), and all power leads shoud be bypassed (capacitor to ground) at the entry point. Input and output signals should be on coax cables with the shields well grounded. For loud (ground shaking) music, I would also isolate the amplifier stages mechanically so that vibrations do not shake the grid of your amplifier tube (e.g., 12AX7) and modulate the gain. Or I would use a low noise JFET instead.

 

[rajupatel]

Hi Guys,
Thanks for the great "eye openers". I am better informed now. And incidentally I AM NOT AN AUDIOPHILE. This was an idea that was thrown to me and i do make it a point to research well before i take the plunge. and that includes talking to professional's in the field too. And I did read bipolar's link. Thank you guys. Incidentally i have corrected the room acoustics problem before i ventured in upgrading to any equipment. My head is on my shoulders! unlike "AWED-DIOPHILES". Thanks again

 

[Pumblechook]

Learn about the nuts and bolts of electronics. Never read Hi-fi magazines unless you want a laugh.

I do not see the point in using valves (tubes) these days, certainly not in the low power stages of amplifiers.

Transistors of various types are used as low noise amplifiers right up to 100 Ghz or so. So why on Earth people use valves at audio frequencies beats me.

I was a BBC engineer for 17 years.

 

[Bob S]

I do not see the point in using valves (tubes) these days, certainly not in the low power stages of amplifiers.

Transistors of various types are used as low noise amplifiers right up to 100 Ghz or so. So why on Earth people use valves at audio frequencies beats me.

I totally agree. The only reason I ever used 12AX7's was because when I worked at Hewlett Packard 1954-58, they had a box of reject vacuum tubes that employees could take for free, and we would occasionally find Telefunken 12AX7's, which were known to be among the lowest noise hi-gain preamp vacuum tubes available. I switched to discrete solid state about 10 years later.

 

[mgb_phys]

Transistors of various types are used as low noise amplifiers right up to 100 Ghz or so. So why on Earth people use valves at audio frequencies beats me.

Supposedly the idea is that the valves output changes near saturation and so sounds like the 50-60s era guitarist did on stage.
Sony used to do a fancy DSP based home amp that you could program to simulate the overload on various old guitar amps - and it meant you could listen to the distortion without blowing out the windows!

 

[Bob S]

Sony used to do a fancy DSP based home amp that you could program to simulate the overload on various old guitar amps - and it meant you could listen to the distortion without blowing out the windows!

I changed to 100% discrete solid state audio amplifiers the moment my push-pull final stage (Mullard EL-34's, which glowed red due to the high plate current) arced over and literally blew the voice coil completely out of one of my speakers.

 

[bipolar]

I changed to 100% discrete solid state audio amplifiers the moment my push-pull final stage (Mullard EL-34's, which glowed red due to the high plate current) arced over and literally blew the voice coil completely out of one of my speakers.

Heh, I've done that with Transistors.

 

[rajupatel]

If it was designed/built correctly

PCs used switch mode PSUs that will run on absolutely anything.

Probably true, or an Earth loop, or a bad ground.

If you are really fussy cut out the AC power supply and run the amplifier directly from a 12V battery

We have 240V 50Hz supply voltage. To run my audio setup, how much battery power would i need? Would it be ok if I use an inverter? I am told that that the amps will need a 5 amp supply and consumption on stand by is 50W and at peak output it is 800W. I have six amps. Other equipment consumption is 250W all put together.

 

[russ_watters]

I'm not clear on your numbers: you have 6 amps at 800W apiece? That's 5050W altogether, including the other equipment.

I don't know the efficiency of a typical inverter, but if it is around 90%, that's 5050/.9 = 5611W.

You probably don't want to exceed about 10 Amps of draw from the car battery. The capacity of a car battery is rarely stated, but if you have a 100 A-H batter, that'll give 10 hours of charge.

For 6300W at 12 V, that's 5611/12=467A = 47 batteries. You might be ok with halving that to pull 20 amps peak, but I wouldn't go any smaller than that.

 

[rajupatel]

Thanks russ,

800 W is peak drawing. i rarely operate at peak (high SPL's) levels. But a guess would be, that for the amps i would be drawing around 250W at above normal listening levels. This is because i operate amps at -12dB levels. Guess that would mean 250X6=1500W and add another 250W to make it 1750. Say max 2000Watts.
So accordingly to your calculations it would mean
2000/.85 = 2352W

Hence for 2352 at 12V, it is 2352/12 = 196A = 20 batteries.

I hope I got it right.

Thanks again

 

[meat5000]

Ok you lot. Raj is on to something and you know it. After reading the posts I understand what he is getting at. He is not saying his power source is noisy but he IS saying that when other devices are connected to the supply the noise levels are greatly increased as the noise generated by the other devices is somewhat feeding back through the power lines. If you ever looked at mains power with a scope you will see that the sinewave is far from perfect and is indeed crammed with noise.

I can give you a case to confirm this, which a lot of you can try.
When your modem/router is connected to the supply go to some pingtesting website and get it to calculate your pings and jitters. Try the router in its own socket, then try it plugged into a plugbank with other noisy devices. Measure the pings/jitters in both cases and try again with TV's fridges etc switched off.

You should find that when alone there will be more noise (hence more ping/jitter) than when the router shares a close and common ground (the difference in one length of cable is large as more interference can be picked up).
**In my own home experimenting with various positioning and layouts of equipment and sockets produces a ping difference of up to 300ms, which in todays broadband terms is quite profound. This is ALONE a noise issue. **

Good power equipment will handle certain levels of line based (through power cable) noise well but only if the noise levels are constant. It will not perform so well on spurious transitions. Examples of this are when the boiler kicks in and you get that awful crackling noise through your radio/speakers.
Most components will pick up some kind of field energy (cars starting outside for example). The only way to prevent this is a faraday cage.

There are a few types of noise and different types are easier to deal with than others. I learned from professors but you can equally well learn this from Professor Google.

So, that is something for you lot to chew on for a while. In the meantime my suggestions ARE:

1) Invest in an Isolating Transformer
or
2) Invest in boat-type leisure battery and inverter.

Two ideas that are cheaper than a Genny. BTW motor based gennies will poo all over your audio; don't bother.
You can use the isolator in two ways. Put your audio straight through it or put your highest power (and motor based) equipment through it (which is probably better). The latter helps prevent noise from fridges etc leaking back onto the line. Most likely you will use the former as boilers etc are usually wired directly into some fused/switched box meaning they cannot be run through said transformer.

For all you sceptics : rectifier circuits do not work on miracles.