The time between charging pulses is only 8.3 milliseconds. For a 20A load (80 volts at 4 ohms), 40k uF will produce at most 4V of ripple, assuming the reactance of the trafo is "low". That's in an affordable and practical cap range - and most any large amp can handle this. And why you see about this much cap - give or take a factor of 2. You actually get less ripple if the trafo's reactance is higher, but the voltage drops like a stone - approaching 63% of no-load if the diodes go into continuous conduction. But then an 80V rail can swing wildly between 80 and 50V under the varying load, and that's not going to do good things for the sound. Larger caps will tend to mitigate this, but anyone who has experience in high power car audio will tell you that this is just a band-aid.
vifa PL26W09 8 ohm driver demands for short term power of 600watts..
http://www.audioalchemy.ro/difuzoare/vifa/pl26wr09-08e.pdf
so in this case I can reduce the trafo size? like for a 100rms x 8 ohms
but can 2 x 2SC1943 can give this current output?
http://www.audioalchemy.ro/difuzoare/vifa/pl26wr09-08e.pdf
so in this case I can reduce the trafo size? like for a 100rms x 8 ohms
but can 2 x 2SC1943 can give this current output?
This depends upon the transformer regulation.
If it is a typical value of 15% then a 100V. rail will drop to 85 at full load.
If it goes down by this amount in 20ms. it delivers 12J to the load.
An on line calculator indicates that a .1F. capacitor will do this, so split between two rails its about 50e3 micro Farad per rail.
rcw
If it is a typical value of 15% then a 100V. rail will drop to 85 at full load.
If it goes down by this amount in 20ms. it delivers 12J to the load.
An on line calculator indicates that a .1F. capacitor will do this, so split between two rails its about 50e3 micro Farad per rail.
rcw
That is a calculation based upon a 1000VA with 15% regulation.
he on line calculator is the one at hyperphysics and shows that the first Joule is provided when the capacitors discharge by 15 Volts, you can use a smaller transformer by using more capacitance, this has the effect of increasing the peak to average ratio.
rcw
he on line calculator is the one at hyperphysics and shows that the first Joule is provided when the capacitors discharge by 15 Volts, you can use a smaller transformer by using more capacitance, this has the effect of increasing the peak to average ratio.
rcw
so the trafo should not go less than double the power ratings of the amp.
But if the music has very complex bass track and heavy soundtracks with very big pulses in a very short period of time then?
have a look at krell amp.. Krell Industries, Incorporated, America's premiere manufacturer of high-end audio equipment: award-winning amplifiers, preamplifiers, CD players, DVD players, surround/sound processors, loudspeakers
they have stated>>
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Blessed with a power supply outfitted with a 2,500 VA power transformer and 163,200 µF of capacitance, the Evolution 3250e is a powerhouse. Power output of 250 W per channel into 8 ohms and 500 W per channel into 4 ohms will drive any loudspeaker to its full dynamic capability.
_______________________________________
they are using 10 times the power ratings of the amp...
But if the music has very complex bass track and heavy soundtracks with very big pulses in a very short period of time then?
have a look at krell amp.. Krell Industries, Incorporated, America's premiere manufacturer of high-end audio equipment: award-winning amplifiers, preamplifiers, CD players, DVD players, surround/sound processors, loudspeakers
they have stated>>
_______________________________________
Blessed with a power supply outfitted with a 2,500 VA power transformer and 163,200 µF of capacitance, the Evolution 3250e is a powerhouse. Power output of 250 W per channel into 8 ohms and 500 W per channel into 4 ohms will drive any loudspeaker to its full dynamic capability.
_______________________________________
they are using 10 times the power ratings of the amp...
The speaker manufacturer doesn't say what it means by that and it is easy to show that it will run out of excursion a long time before anything like that power, especially at low frequencies, gets into it.
Model it in win isd and look at what cone excursions you are getting and that is the power limit, domestic drivers run out of cone excursion long before voice coil dissipation, so maximum linear cone excursion should be your guide.
As I have already said you can increase the peak power by using a transformer with more regulation and slightly larger capacitors, but just don't go over the top. In the amplifier you cited they use the components they do more for marketing hype than any real benefit. I don't know if they are using a capacitance multiplier but with such an over sized transformer it is usual to do so because the capacitors are basically there as filters and you can increase the effective filter effect greatly by so doing, but you can't multiply the energy content of the capacitors with such a device.
Overall in ordinary music reproduction the transformer that is rated say 1.3-1.5 times the power output of the amplifier and has a rail voltage that sags 10-15% at full average power is about right.
There are many that will differ on this but all you do is to spend extra money for no practical audible results if you do much outside this range.
rcw
Model it in win isd and look at what cone excursions you are getting and that is the power limit, domestic drivers run out of cone excursion long before voice coil dissipation, so maximum linear cone excursion should be your guide.
As I have already said you can increase the peak power by using a transformer with more regulation and slightly larger capacitors, but just don't go over the top. In the amplifier you cited they use the components they do more for marketing hype than any real benefit. I don't know if they are using a capacitance multiplier but with such an over sized transformer it is usual to do so because the capacitors are basically there as filters and you can increase the effective filter effect greatly by so doing, but you can't multiply the energy content of the capacitors with such a device.
Overall in ordinary music reproduction the transformer that is rated say 1.3-1.5 times the power output of the amplifier and has a rail voltage that sags 10-15% at full average power is about right.
There are many that will differ on this but all you do is to spend extra money for no practical audible results if you do much outside this range.
rcw
If you want a truly stout power supply a transformer with 3% loses and minimum capacitance after the rectifier is a much better choice IMHO. We investigated this question when developing our line of guitar amplifier power and output transformers. Google O-Netics to see our customers opinions of the results.
These power transformers utilize a passive self demagnetization construction and duplicate the rise and settling time of transient power draw of power from toroids. Unfortunately they have large EMF bloom and physical shake and so are not suitable for typical single chassis audio reproduction use. You want to specify regulation loses and loaded voltage to a transformer manufacturer, or when trolling their catalogs. Assuming "double the VA" is meaningless. You want the exact VA with specified losses as a specification.
Bud
These power transformers utilize a passive self demagnetization construction and duplicate the rise and settling time of transient power draw of power from toroids. Unfortunately they have large EMF bloom and physical shake and so are not suitable for typical single chassis audio reproduction use. You want to specify regulation loses and loaded voltage to a transformer manufacturer, or when trolling their catalogs. Assuming "double the VA" is meaningless. You want the exact VA with specified losses as a specification.
Bud
Yes , but also sized for the power output at the lowest load it is going to be used at..
A s I have pointed out all of that type of stuff is totally unnecessary, and simply over the top excess for people for whom that sort of thing is impressive.
If you want to know what is needed and is enough so that you can't actually hear any difference between it and that sort of badly engineered audiophile rubbish then look at the ESP site.
rcw
If you want to know what is needed and is enough so that you can't actually hear any difference between it and that sort of badly engineered audiophile rubbish then look at the ESP site.
rcw
I have to agree with RCW here. You do not need 1000 times power needed for 1 watt output. It's unlikely you need 100 times, so long as between capacitive draw cycles, the transformer can support any increase needed for the next draw cycle. This is where the 3% or better regulation makes the difference. It can repeatedly provide transient draw increase, but only if it is designed to do so. Even typical E/I transformer builds in the 3 % regulation range will suffice, a Toroid is better and so is an E/I transformer built to audio grade standards, with excellent core material, low dielectric constant dielectric barrier materials and again, better than 3% regulation. You just do not need any better than this.
As for materials in capacitors and "how they sound" you want electrolytics in a power supply for a whole bunch of good reasons. If you must feel better about this, choose Nichicon Gold Muse electrolytics and by pass the stack with a poly prop and film of 1/100 the value and a glass passivated device of 10 Pf. Use capacitors as you do now, for taste and color, in the signal series and parallel to ground locations.
Bud
As for materials in capacitors and "how they sound" you want electrolytics in a power supply for a whole bunch of good reasons. If you must feel better about this, choose Nichicon Gold Muse electrolytics and by pass the stack with a poly prop and film of 1/100 the value and a glass passivated device of 10 Pf. Use capacitors as you do now, for taste and color, in the signal series and parallel to ground locations.
Bud
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