> everybody else that uses the resistor idea (Airbrake variety) has a fixed value of 8 ohm and then mismatches to 4 or 16.
Yet a pentode output sounds very different under-loaded or over-loaded. A too-low Z probably preserves the "sound" best (but may heat the tubes). And with impedance-variation, both types of limiting can happen. OTOH, a transistor amp (some folks use them) may get very sick with a low-Z load (OTOH, most sound the same at any impedance above their minimum).
So you could push a 4Ω version for tube-amps and a 16Ω job for tranny-heads, but that isn't really any simpler.
> autotransformer, we're playing around
Yeah, I really can't think of an affordable part. I happen to be blessed with a pair of JBL-branded irons with 4/8/16Ω taps rated 200 Watts above 30Hz and really very flat and clean 20-20KHz. I'd fearlessly put these between any 100Watt guitar-amp and any load, and expect "audibly perfect transformation". Probably take 400 Watts of guitar without audible distress. But these must have been frightfully expensive, between the size and the logo.
If you are shopping for samples, Dave here has ordered custom iron from Edcor. They do a lot of big audio iron. Hmmmm... standard part 300 Watt Auto Transformer 70 volts with 4 ,8, & 16 ohms $47.16. (This is really just 4/8/16: 70V at 300W is 16.33Ω!) But Dave says they wound his custom sample wrong the first time (they quickly got it right) so you should bench-check before you wail. (The company has an interesting history.)
> I can't talk about it yet.
Understood. There is a whole nasty branch of US law about pre-announcing products; ask IBM, Altair, and Gibson. Intel and Dell can give limited "advanced briefings" after a dozen lawyers map the minefield, but you can't afford the lawyers. Also even when you have a final product, you want to leak it to dealers in a way that they won't get stuck sitting on stocks of an "old" model.
Yet a pentode output sounds very different under-loaded or over-loaded. A too-low Z probably preserves the "sound" best (but may heat the tubes). And with impedance-variation, both types of limiting can happen. OTOH, a transistor amp (some folks use them) may get very sick with a low-Z load (OTOH, most sound the same at any impedance above their minimum).
So you could push a 4Ω version for tube-amps and a 16Ω job for tranny-heads, but that isn't really any simpler.
> autotransformer, we're playing around
Yeah, I really can't think of an affordable part. I happen to be blessed with a pair of JBL-branded irons with 4/8/16Ω taps rated 200 Watts above 30Hz and really very flat and clean 20-20KHz. I'd fearlessly put these between any 100Watt guitar-amp and any load, and expect "audibly perfect transformation". Probably take 400 Watts of guitar without audible distress. But these must have been frightfully expensive, between the size and the logo.
If you are shopping for samples, Dave here has ordered custom iron from Edcor. They do a lot of big audio iron. Hmmmm... standard part 300 Watt Auto Transformer 70 volts with 4 ,8, & 16 ohms $47.16. (This is really just 4/8/16: 70V at 300W is 16.33Ω!) But Dave says they wound his custom sample wrong the first time (they quickly got it right) so you should bench-check before you wail. (The company has an interesting history.)
> I can't talk about it yet.
Understood. There is a whole nasty branch of US law about pre-announcing products; ask IBM, Altair, and Gibson. Intel and Dell can give limited "advanced briefings" after a dozen lawyers map the minefield, but you can't afford the lawyers. Also even when you have a final product, you want to leak it to dealers in a way that they won't get stuck sitting on stocks of an "old" model.
