I would be a little hesitant to use something like this.
Not sure exactly what the TO-3 transistor is for, but it's either to measure the AC or control the output.
Regardless, there are three common methods of regulating AC:
First is to rectify to DC, and invert back to AC. Some use straight square wave inverter, some are stepped (quasi) sine, and others are full PWM sine. All three of these are rich in some spectrum of harmonics, which are usually not friendly for audio. Side note: the first two products are great for most non-audio devices, that rectify the square wave back to dc.
Second method is SCR or triac phase control. Simple, down and dirty, and horrible for audio, due to steep wavefronts and all around nasty harmonics.
Third method is ferroresonant, which of any has some potential, but they have drawbacks also. The sine wave is not necessarily a clean sine wave, but is typically a little flat-topped. This may actually be a benefit with rectification, but I do not have the experience to have tried it with an audio device. Their source impedance is quite bad, implying you would need a very overrated unit to provide a suitable source for your circuit. I think the worst part of these units are the incredible expense, weight, and heat.
I would put your picture in some unknown version of the third method, but it's not completely ferroresonant. I can't really tell what the large device in back is.
There are some other esoteric methods such as paraformer and eddy current, but those are rare.
Not sure exactly what the TO-3 transistor is for, but it's either to measure the AC or control the output.
Regardless, there are three common methods of regulating AC:
First is to rectify to DC, and invert back to AC. Some use straight square wave inverter, some are stepped (quasi) sine, and others are full PWM sine. All three of these are rich in some spectrum of harmonics, which are usually not friendly for audio. Side note: the first two products are great for most non-audio devices, that rectify the square wave back to dc.
Second method is SCR or triac phase control. Simple, down and dirty, and horrible for audio, due to steep wavefronts and all around nasty harmonics.
Third method is ferroresonant, which of any has some potential, but they have drawbacks also. The sine wave is not necessarily a clean sine wave, but is typically a little flat-topped. This may actually be a benefit with rectification, but I do not have the experience to have tried it with an audio device. Their source impedance is quite bad, implying you would need a very overrated unit to provide a suitable source for your circuit. I think the worst part of these units are the incredible expense, weight, and heat.
I would put your picture in some unknown version of the third method, but it's not completely ferroresonant. I can't really tell what the large device in back is.
There are some other esoteric methods such as paraformer and eddy current, but those are rare.
Actually there are pure sine power sources for audio applications, for example the Powerstation series from PS Audio.. They are rather expensive, but they are clean and very tightly regulated. <1% no load to full load. Most models are also frequency agile over a limited frequency range.
I have a close friend who uses one in conjunction with his pre-amp, a Sony SCD-1 and a few other odds & ends. Occasionally I feel motivated to clone something similar, but the amount of work involved is too considerable.
Not sure how much merit the approach has, I have always preferred good line filtering, but have not been able to A/B in my own system..
Currently I have dedicated power feeds less than 10' from the panel and limited to non existant filtering.
Of course YMMV..
I have a close friend who uses one in conjunction with his pre-amp, a Sony SCD-1 and a few other odds & ends. Occasionally I feel motivated to clone something similar, but the amount of work involved is too considerable.
Not sure how much merit the approach has, I have always preferred good line filtering, but have not been able to A/B in my own system..
Currently I have dedicated power feeds less than 10' from the panel and limited to non existant filtering.
Of course YMMV..
I have a small collection of ferroresonant transformers around my place. I use a few of them for audio, but you are heavily limited in power obviously. I don't use them for amplifiers, but have tried them on CD transports, turntables, etc.
They are nice for regulating line level problems and eliminating lots of noise. Only really useful I find with equipment that has problems with line level variation.
They are nice for regulating line level problems and eliminating lots of noise. Only really useful I find with equipment that has problems with line level variation.
A number of years ago, a buddy of mine bought a huge new-surplus AC regenerator. I don’t recall the brand, but it was good for many, many kilowatts. It might have been from Square D or GE. It was about the size of a dishwasher, without exaggeration. This device, obviously not designed for audio, rectified his 240 volt two-phase line power, created a crystal-controlled 60 Hz oscillation which was amplified by powerful internal amplifiers. He planted this beast in a distant spare bedroom on a pallet since it had noisy cooling fans. He ran what looked like dock-to-ship power cables from this room, down the hall, to his stereo in the great room. His stereo at that time consisted of a pair of stripped Quad 63s with a variety of tube and transistor amps. Needless to say, he was single. I mention all this because the difference this regenerator made to the sound of his system was rather alarming. It was a lesson for me. This guy always knew how to throw together a good-sounding system, but I had never heard Quads play with that kind of pristine clarity and sparkling detail before, and I knew his equipment well from before the AC regenerator took up residence. My friend moved out of town a few years later and we’ve lost touch unfortunately. But that experience made a believer out of me regarding very serious power regeneration. I haven’t attempted to match that level of power conditioning in my own set-ups yet, but in an upcoming new house building project, I may make provision for something like this in the plans.
Look at my thread on "power suppy idea" in the Pass Audio area.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=89750
Apply the same to each rail of a balanced AC line. A pair of large chokes should do it.
First, apply such to the PS side of your emitters in a given preamp or amp circuit. It is literally 15 minutes of work to check it out for yourself.
Once you hear it....It might make your brain smoke a bit, until you go back to propogation theory combined with AC inductor theory. Then you'll get it.
You may decide that massively re-generated AC isn't worth it at that point. This solution may be good enough. And likely, far cheaper. Possibly more effective. It sure is effective on the emitter +PS rail. whooo-eee!
And some of those oddities proposed in the arena of electrical circuits that we hear about every now and then..might start to make sense.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=89750
Apply the same to each rail of a balanced AC line. A pair of large chokes should do it.
First, apply such to the PS side of your emitters in a given preamp or amp circuit. It is literally 15 minutes of work to check it out for yourself.
Once you hear it....It might make your brain smoke a bit, until you go back to propogation theory combined with AC inductor theory. Then you'll get it.
You may decide that massively re-generated AC isn't worth it at that point. This solution may be good enough. And likely, far cheaper. Possibly more effective. It sure is effective on the emitter +PS rail. whooo-eee!
And some of those oddities proposed in the arena of electrical circuits that we hear about every now and then..might start to make sense.
How about getting a bog 200W silicon amp, one of those cheap module things, then putting 50/60hz oscillator on the front, then connect a transformer to the output?
if you take a 200 watt amp, what would the output voltage swing be? 20/30 volts, put that into the secondary of a toroid, and ergo, mains voltage at the other side, or what ever voltage you want.
just a daft idea, but an idea none the less!!!
just a bit of fun
if you take a 200 watt amp, what would the output voltage swing be? 20/30 volts, put that into the secondary of a toroid, and ergo, mains voltage at the other side, or what ever voltage you want.
just a daft idea, but an idea none the less!!!
just a bit of fun
pinkmouse said:
not really, the important bit is that with most of these amps there is a big capacitor in the output, so that there should be no dc short.
So say the amp is designed to run into a 4 ohm load, you make the effective reflected Z of the power supply transformer and it's load look like 4 ohms!
Amps don't generally mind higher impedances, it's the lower ones that cause the problems!
So say that the amp op is 4 ohms, at 200W, that's an rms voltage of approx 28v. stick that into a transformer with a suitable turns ratio, say 10:1, and you will get 280v, now as long as you don't 'suck' the well dry by pulling out more than 200W, including allowing for losses in the transformer, it should work. There is of course no regulation, but you could fit a feedback loop from the derived power supply, to a gain stage/nfb loop in the amp, so to maintain the voltage levels.
just an idea, not fully formed as you can see. It's very late here.
kind regards
bill
I blew up a 100W amplifier this way. The problem is that uisng a mains transformer as an output transformer, they usually have insufficient primary inductance and although the rather nasty current drawn from the mains when connected the right way around isn't a problem, it is to a fragile flower like a transistor amplifier.
Using rugged old PA amplifiers and toroids can work pretty well. Some of the bigger Crown amplifiers will swing enough voltage in bridged mono mode to dispense with a transformer altogether. (120V mains only, 230V will require a 2:1 stepup or 2:1 step up variac to do it.)
The key to long life is to size the amplifier such that the maximum continuous load power is around 1/3 or less of the continuous rated power which is what the FTC pre-conditioning test requires an amplifier to survive for an hour before testing commences. IME even home hifi amplifiers generally will run continuously at this power level with adequate cooling.
As an example using a 100W amplifier with a 24V/120V toroid stepup you would generally want to stay at 30W or less on the secondary side to allow for transformer losses..
In some instances you might be able to get away with more since the output voltage is fixed and presumably delta across the devices is relatively small. Just need to watch the SOA and load PF (power factor)..
Dissipation in a class AB/B ss amplifier is usually worst somewhere around 1/4 of rated power with an equal amount to the delivered power being dissipated in the output stage, it generally improves at higher powers.
This all assumes the PF in the transformer and load is around 1, i.e. voltage and current in phase - not always the case and this will affect SOA adversely particularly with highly capacitive loads..
Another very robust approach would be to use one or a pair or more (they can be paralleled) of National's Spike series monolithic amplifiers on a large heatsink driving a toroid. IMO The LM3886 would be well suited. You can build high quality, high power inverters, and they are pretty indestructable as long as you add clamp diodes from the outputs to the supply rails in case of load dump. (Turning something off with the supply operating, etc.) With some care in design the transformer can be included inside a global feedback loop for good voltage regulation.
Note that it has been years since I did anything of this sort, and some patient tinkering, blown up parts, etc. will be required to get it to work.
As always YMMV..
The key to long life is to size the amplifier such that the maximum continuous load power is around 1/3 or less of the continuous rated power which is what the FTC pre-conditioning test requires an amplifier to survive for an hour before testing commences. IME even home hifi amplifiers generally will run continuously at this power level with adequate cooling.
As an example using a 100W amplifier with a 24V/120V toroid stepup you would generally want to stay at 30W or less on the secondary side to allow for transformer losses..
In some instances you might be able to get away with more since the output voltage is fixed and presumably delta across the devices is relatively small. Just need to watch the SOA and load PF (power factor)..
Dissipation in a class AB/B ss amplifier is usually worst somewhere around 1/4 of rated power with an equal amount to the delivered power being dissipated in the output stage, it generally improves at higher powers.
This all assumes the PF in the transformer and load is around 1, i.e. voltage and current in phase - not always the case and this will affect SOA adversely particularly with highly capacitive loads..
Another very robust approach would be to use one or a pair or more (they can be paralleled) of National's Spike series monolithic amplifiers on a large heatsink driving a toroid. IMO The LM3886 would be well suited. You can build high quality, high power inverters, and they are pretty indestructable as long as you add clamp diodes from the outputs to the supply rails in case of load dump. (Turning something off with the supply operating, etc.) With some care in design the transformer can be included inside a global feedback loop for good voltage regulation.
Note that it has been years since I did anything of this sort, and some patient tinkering, blown up parts, etc. will be required to get it to work.
As always YMMV..
something i have been interested in for a little while has been green energy. my dad is also quite interested in it and he plans to set up a solar/wind system at our cottage. the cottage is currently connected to the grid and it will continue to be because of high-draw stuff we have there(electric heat, window air conditioner, stove, and water pump) but the power would be drawn primarily from the solar/wind setup, only dipping into the grid for higher draws. we went to a store around my cottage called the solar power store....it deals in installing custom solar and wind power systems for all kinds of applications. why i mention this is because the power generated this way is extremely clean and smooth, as you have your own sinewave invertor, but still have the power to use everything you normally would. if you were installing it with audio in mind you could possibly have a seperate line which draws strictly from the solar grid or the array of batteries that come with it. then have a seperate set of plugs in your listening room or even throughout your house for it.
not a cost effective solution at any stretch, but if you're interested in having your own green power system and being self-sufficiently powered, even if you're in the city, it's a nice fringe benefit for audio purposes. maybe one day i'll have something like that.
not a cost effective solution at any stretch, but if you're interested in having your own green power system and being self-sufficiently powered, even if you're in the city, it's a nice fringe benefit for audio purposes. maybe one day i'll have something like that.
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