Cans of Air I think that has been done already!
Perri Air in Mel Brook's Spaceballs
I recon jneutron pretty much nailed it although it still don't fully explain Engelbert Humperdinck. Spiraling lectrons can always be lassoed with a ground loop but all is undone by neglecting cable lifters. These should always be the same height as your speaker terminals to avoid the roller coaster effect which obviously causes time smear issues.
btw why don't they just make the whole CD out of green plastic?
btw why don't they just make the whole CD out of green plastic?
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Hang on. We still have not discussed the effect of the coils eddy currents and how 2nd harmonic distortion in the resistor is generated due to increased skin effect on every 2nd half of the output waveform. In layman terms, every alternate half of the output waveform either pulls electron flow along the surface of the resistor metallization layer, or drives it deeper (another good reason we have found to stick with carbon composition resistors that completely avoid this effect)
Further, the harmonic phase is also dependent upon on the hemisphere you are located in - positive in the Southern Hemisphere (Dan can expound further on this) and negative in the Northern Hemisphere.
Ok, I'm outta here !
Sigh, so wrong.....
ps. Bonsai, we should start a company. We could probably sell cans of air..
The company would have to be called Future Audio Research Technology
It's a great acronym for a high-end audio company.
I worked at a studio called Good Audio Sense years ago, that gave us a laugh too...
Hmmm.
You are actually describing what I believe I will be writing on in a future LA, which hinges on me actually wanting to build some inductors with embedded bucking coils to show this effect in copper coils.
I assume I will eventually have the desire to make hardware again given time.
John
Hmmm.
You are actually describing what I believe I will be writing on in a future LA, which hinges on me actually wanting to build some inductors with embedded bucking coils to show this effect in copper coils.
I assume I will eventually have the desire to make hardware again given time.
John
I have a variable inductor.... made this way but rotates within another. Cool thing.... just had to buy it even with no use for it. Yes, commercially made.
THx-RNMarsh
Well, my computer died, keeping me from making any further comments on the output inductor discussion.
Some amps can be made stable without an output inductor. Not all topologies can, at least not without knowing exactly what you're doing. But the fact is, the compensation that achieves this just causes the amp to emulate an inductor. If you want you can measure this inductance, and see whether it is more or less linear than an air core inductor. Almost always it does a very bad job in comparison.
As for the resistor, it does damp the coil but it does more than that, it compensates the amplifier which is a somewhat different function.
Some amps can be made stable without an output inductor. Not all topologies can, at least not without knowing exactly what you're doing. But the fact is, the compensation that achieves this just causes the amp to emulate an inductor. If you want you can measure this inductance, and see whether it is more or less linear than an air core inductor. Almost always it does a very bad job in comparison.
As for the resistor, it does damp the coil but it does more than that, it compensates the amplifier which is a somewhat different function.
All amplifiers act inductive at the output. OL gain inevitably decreases with frequency in any amplifier so the output impedance increases. More stages then the faster it decreases with frequency. (A good argument for folded cascode.)
Closed loop amplifiers with limited stability margins may become unstable when the load eats internal gain, especially when its capacitive, and that stability margin is gone.
The output inductor is a way to limit the load effects at high frequencies along with the resistor that keeps the load as a positive resistance (motors like speaker drivers can go negative which can be a real problem). However the RL will interact with the speakers impedance and the cable so what you get at the driver may be different from a pure voltage source. This interaction is probably why some speakers need specific amps to function as intended. The Sigma drive is a way around that, but it needs great care to work. I think Cello tried that as well. But it will backfire if the speaker needs some HF impedance for the optimal tweeter balance. Remote sensing gets very difficult (read impossible) at very high frequencies. Where really needed (RF test systems) you put a power sensor at the load to "level" the system. Audio does not work that way.
Closed loop amplifiers with limited stability margins may become unstable when the load eats internal gain, especially when its capacitive, and that stability margin is gone.
The output inductor is a way to limit the load effects at high frequencies along with the resistor that keeps the load as a positive resistance (motors like speaker drivers can go negative which can be a real problem). However the RL will interact with the speakers impedance and the cable so what you get at the driver may be different from a pure voltage source. This interaction is probably why some speakers need specific amps to function as intended. The Sigma drive is a way around that, but it needs great care to work. I think Cello tried that as well. But it will backfire if the speaker needs some HF impedance for the optimal tweeter balance. Remote sensing gets very difficult (read impossible) at very high frequencies. Where really needed (RF test systems) you put a power sensor at the load to "level" the system. Audio does not work that way.
The falling nfb using a VFA topology gives a rising Zo and appears AS IF there was an equivalent inductor on output. And the stability issues that accompany the Zo change etal is dealt with in normal ways. However, the CFA doesnt have this characteristic to same degree and may be one of the reasons I find easier to have stable running circuit with real loads. Wha chu tink?
BTW - I have the new high SR CFA amp on my office desk at factory ... took two young men to carry it.... mostly due to the huge power transformer.... the bane of analog. Nice of them to give me a nice big office there to use when in town. I only tested to 10W so far and the THD numbers are great..... next week go back and run further tests with it to 200W and into various loads. Sounded wonderful on the QUAD 989's I sent over... imaging is fantastic, too.
This is a CFA topology and not using CFA-B topology. May try the CFA-B, at some point in time as an alternative for balanced input.
Will send pictures and some data asap. Then shipping it to Calif and trying it out on the new JBL M2's for comparison with a very different amp topology (Crown). Building more of the CFA amps of course. Running high bias and heat sinks are barely warm.
THx-RNMarsh
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Looking forward to the media. You sure you want to risk shipping? Why not put it in your carry on?
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Well, I doubt I could lift it over my head.... or off the floor. Weighs in almost as much as I weigh. Probably cost me, via company discount, about $500 to ship it. But it is well worth 500 to have at home to listen with... would be the cheapest ultra high performance amp I've owned. Even with parts, build costs.
Makes a good excuse to go back to calif. Otherwise, I just got my renewed Visa - good for another year.
Oh! My girls arrived at the airport. Got to go.
THx-RNMarsh
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