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In Reply to: RE: Harrassing Posters posted by Lew on March 31, 2008 at 10:51:16
Hi Lew! Nice to hear from you.
The following is for you to understand and question and does not purport to be anywhere near a complete discussion on this subject.
I named the attempt to design a power supply that would address the needs of ever-changing musical signals as a Low Storage Effect Supply.
If you place resistances between your power supply and its load, you are, in effect, blocking and impeding the natural flow of energy needed to fully track ever-changing musical events-- using the power supply as the energy source to do that. If you place items into this flow-path that contain too much resistance, too much iron losses, or too much copper losses, then you lose the "gestalt"-- the rhythm, flow, timing, and pace of actual musical events. You may still have plenty of power, but you will be making more heat and less music in the speakers voice-coil.
We know that rectifiers conduction AMOUNT rises and falls with the actions of the sine-wave A.C. power input to a rectifying system. We know that, at the trough of an energy sine-wave, there is an area known as "cutoff" where rectifiers are momentarily in a semi-non-conducting mode.
In designing amplifiers to drive low-efficiency speakers at high power levels, using inadequate power supplies, designers have resorted to STORING large amounts of energy in capacitors to "drive-through" these "time-outs" of the rectifiers-- when they are almost not conducting.
In order to achieve smooth, relatively constant current flow from such a power supply with large energy storage, engineers have also resorted to "critical value" chokes which makes power supply output smooth and well regulated.
Severe problems in trying to force actual musical events through such a system of bottlenecks and traps arise in such a supply, however.
Firstly, the excessive resistances of the "critical value" chokes literally CHOKES rapid WIDEBAND current delivery to the amplifier. A resistor here is a "bottleneck". Capacitor energy storage has to "plaster-over" this. Secondly, excessive size of the iron cores used also stores energy that must later be released-- of course it's out-of-time with musical events. In other words, this smooth, well-regulated, quiet power supply is hopelessly late in keeping up with actual musical events.
The large-value capacitors used limit bandwidth of the power supply, greatly slow-down response time, and also store energy which, at some point, must "let go"-- right when it IS NOT in the music.
All of this energy storage allows inefficient speakers to be driven-hard from capacitor and iron energy storage during times when rectifiers are contributing little to the power supply output. You get power, you DO NOT get high-fidelity.
Current draw always varies in relation to music-signal input regardless of class of operation of output devices. The individual classifications of operation are not fixed "over the cliff" definitions. Each-- for instance, Class A-- has an allowable range of operation and can still fall into that class of operation. Class A amplifiers may draw steadier power than Class B, etc., (they do), but music-signal input still modulates the power supply to a surprising degree.
In Single-Ended amplification, the power supply is one of three signal paths: these are-- (1) the "hot" signal path, as usual. (2) the entire amplifier and power supply grounding system, and (3) the power supply itself.
As you can see, single-ended amp design must design the entire amplifier as a wideband, modulated power supply.
To your question: If you wish to run low-efficiency speakers on a LSES supply, you engineer it as you would for super-efficient speakers. The whole thing is just a LOT LARGER. Everything in it!
What this means in practical terms is simple: If I choose to design a 100 watt P.S. to run a 1-watt amplifier (I do) making it so powerful that it needs virtually no energy storage, and is thus a really good musical reproducer, why can't I do it for a 10 watt amp?
You certainly can, and should. Your LSES power supply will be designed at around 750 watts or better. Its need for "critical" chokes will be nil, and its need for music-robbing fat-caps will also be nil.
Its voltage regulation will be pristine because it is simply too big to be pulled-down by the 10 watts.
Not Commercial? Controversial? Sure! I build them anyhow, and boy, do they work!
----Dennis----
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