MakeMineVinyl
Major Contributor
Back in the 1950s and early 60s Stephens Electronics made an output transformerless power amplifier but it was meant to be used with their 500 ohm speakers.
But hey they were able to eliminate the output transformer - not that it matters with all the kludge circuitry they had to use to go about it. It makes me wonder how many output tubes would be required to make a real arc welder.OTL tube amps do exist... for some reason... But they're obnoxiously huge, use hilarious numbers of tubes (the Atma-Sphere MA-3 uses no less than forty-two 6AS7Gs per channel!)... and barely approach the distortion performance of a decent Class AB solid state amp.
Also not so huge headphone amps for electrostatic headphones.OTL tube amps do exist... for some reason... But they're obnoxiously huge, use hilarious numbers of tubes (the Atma-Sphere MA-3 uses no less than forty-two 6AS7Gs per channel!)... and barely approach the distortion performance of a decent Class AB solid state amp.
Accurate.If an imaginary speaker had no internal Reactance and behaved as perfect 8R resistor across the frequency spectrum, there would be little auditory difference between a valve and solid-state amp.
Not just cones - any speaker that uses a traditional voice coil does this.All cone speakers are highly Reactive and the Impedance varies over the frequency spectrum (approx 400%).
If by this one means "solid state amps are far less affected by impedance dips because of their lower output impedance than tube amps" I would agree. Noticeable, that entirely depends on the design.Therefore, because Valve and solid-state amps operate in opposite ways to how power is delivered into a changing Impedance, the resultant audible difference is very noticeable.
Absolute audiophool nonsense.With most cone speakers, solid-state amps appear to sound flat and lifeless, the bass and high frequencies appear dead, as if a blanket is put over the speaker.
Tubes and transistors aren't honestly very different in a linear region amplifier (i.e., not class D) - transistors are lower voltage, lower impedance, higher current. This doesn't make any sense at all.
- Valve amp power is directly proportional to speaker Impedance
therefore power increases as the speaker Impedance rises.
- Solid-state power is inversely proportional to speaker Impedance
therefore power decreases as the speaker Impedance rises.
Ultra-linear. The Screen acts as a second Grid modulating the gain of the valve in opposite phase to the Anode. This return path acts as an automatic Negative feedback that removes most if not all residual distortion created by the output valves and output transformer.
Yes, that's because the impedance of the speaker is reflected across the output transformer. Nothing crazy here. By the way, the most common UL tap is about 43%.Ultra-linear
This local feedback from the 50% primary taps to the Screen results in the speaker connected to the secondary being included in the UL feedback structure.
A remarkable result is that this reflected Impedance tends to naturally maintain constant power to the speaker, over the frequency spectrum, providing the ideal damping that enables the speaker to give the most pleasing musical sound.
Electrostatics are an entirely different can of worms. They're super high impedance and as such don't need an impedance matching transformer.Also not so huge headphone amps for electrostatic headphones.
So? It's still OTL. I own that particular model. As far as I can tell, the transformers are a greater part of the classic sound signature of vintage amplifiers than the tubes themselves. The Stax headphone amp is the best demonstration of that. Compared to Stax's TOPL solid state amp on offer at the time [1988], the Stax SRM T-1 was grainless, smooth but detailed on top. Much like the Topping L30 in that regard. Using the Stax energizer sans amplification, I hooked up the Marantz 8b. Smooth sounding top to bottom, but increasingly out of focus at the frequency extremes.Electrostatics are an entirely different can of worms. They're super high impedance and as such don't need an impedance matching transformer.
Yes, indeedy, thanks for throwing that into this goulash!Back in the 1950s and early 60s Stephens Electronics made an output transformerless power amplifier but it was meant to be used with their 500 ohm speakers.
Umm... no. No they don't.Valve and solid-state amps operate in opposite ways to how power is delivered into a changing Impedance
Not just cones - any speaker that uses a traditional voice coil does this.
Electrostatics are an entirely different can of worms. They're super high impedance and as such don't need an impedance matching transformer.
Yeah, I think so, too.I think he meant quite the opposite. Valve amps being less sensitive to speaker's changing impedance.
Then he's got it absolutely ass backwards. Nominal load impedance should ideally be at least 10x that of the source impedance for linear reproduction. Solid state amps have much lower Zout (generally in the ballpark of 0.1 ohms if not lower) than tube amps (generally around 1 ohm if not slightly less with feedback, quite a bit more without).I think he meant quite the opposite. Valve amps being less sensitive to speaker's changing impedance.
Pretty much.Yeah, I think so, too.
Which is part and parcel of what makes that article (or white paper or whatever) pretty darned hard to treat as anything but noise.
Yes, that's the point -- as long as the load impedance is (quite) high, a vacuum tube OTL amplifier becomes less of a Rube Goldberg contraption (viz. the aforementioned 500 ohm Stephens coax loudspeaker and its companion OTL "direct drive" amp).So? It's still OTL.
Thus tubes & horn speakers.Yes, that's the point -- as long as the load impedance is (quite) high, a vacuum tube OTL amplifier becomes less of a Rube Goldberg contraption (viz. the aforementioned 500 ohm Stephens coax loudspeaker and its companion OTL "direct drive" amp).
After they invited me to the front of the class a couple times for algebra and physics lessons, everyone in the class pretty much agreed their explanations were better suited to the audience because they were accessible, though admittedly fantastic.
Indeed.Then he's got it absolutely ass backwards. Nominal load impedance should ideally be at least 10x that of the source impedance for linear reproduction. Solid state amps have much lower Zout (generally in the ballpark of 0.1 ohms if not lower) than tube amps (generally around 1 ohm if not slightly less with feedback, quite a bit more without).
Equally - slightly off-topic but germane to our type of discussions - there were mixers and masterers who literally didn't know and didn't care what equipment they were using. I knew a multiple Grammy-winning engineer who couldn't have told you what monitors he worked on. He was staring at them 10 or 12 hours a day and the brand simply didn't register. That's how it was for non-superstar engineers, freelancers especially - it was like being a truck driver, showing up at the depot, getting handed a set of keys. You got what you got. The pickiness audiophiles show would have been regarded as weird.