> there is 30V across those two Rs
You are right. I read wrong. (WHY does THAT Corp have to use that grid-paper background???)
Seems inefficient to me to pull power out of the far rail when ground will do, and there is no crap involved to contaminate ground. But hey, only 15mW.
Ha, and it makes the arithmetic dead-easy. 27K plus a little extra, divided by (+/-15V)= 30V, is 1 milliAmp, near-nuff. So the 1.6K resistor drops 1.6 Volts. If you assume the transistor BE drops 0.6V, you have 1V across R21; if Vbe is higher then R21 gets slightly less voltage. 1V across 100 ohms gives 10mA, or maybe a very-little less if Vbe is a little more.
> we never selected equipment on the basis of how it sounded when we abused it!
I don't see where that point arises in this thread. The only abuse has been some LEDs.
I was a boy when low-low distortion at nominal levels became fairly common. But this clearly overlaps the period when electric guitarists were using overdrive as a tool on the artistic palette. As a small boy, few top-10 recordings featured heavy distortion on guitars, but there were a lot of non-pop players doing it. Just off the top of my head, "Telstar" was reverb-crazy but also overdriven. Later came the Stones' "Satisfaction", and the deriviative opening riff in "Inagadavida". Many early rock recordings were done low-budget and clearly pushing their boards far past the 0.5% IMD point, and that is part of The Sound. A few were beat to pulp: "Louie Louie" sounds like a bootleg from a wild party; Spector used layers of overdubbing because he liked what generation loss did to the base tracks. And never mind what was on records: in real performance, most bands had to push amps way into overdrive to cut through loud clubs, and vocal systems were usually putting out square-waves.
On the Fender guitar, the use of distortion is clear. Devoid of body resonances, with low inharmonicity, with frets to make string vibrato hard, the naked sound from a guitar is very plain and can be expressionless. Soft tube amps add a nice haze of low-order distortion, and a rise of distortion with level that is not unlike the change in un-assisted vocal timbre from normal to loud. (While some vocalists have large range of power, many have a limited range of fundamental power but increase the overtone power when speaking or singing "loud". Same is true of most woodwinds and brass.)
Whether from artistic intent or necessity, both musicians and listeners came to accept amplifier distortion as a musical tool. As precedent, think what Steinway would have thought of ragtime, honky-tonk, or the antics of Jerry Lee Lewis; or what Saxe would have thought of the way sax players "abused" his instrument in Swing and especially Jazz. W.E., Macintosh, Scott, Langevin and others worked to make amps clean and transparent at extremes; on the other hand musicians adopted the faults of amplifers as tools.
What has really changed is that the recording technician does less verbatim capturing of the band sound (that part is now easier), and is now expected to shape and flavor the work. This comes from people like Buddy Holley's recordist (see thread last week), the Beatles and George Martin in their Sgt Pepper days, the early Led Zeppelin. And adding just the right amount of distortion is now such an expected "spice" in many musical styles that a "perfect verbatim" recording won't do. Yes, the artists may have selected distortion in their guitar amps, but are at the mercy of a sound technician for vocal sounds.
And a problem I was just reminded of, on an all-percussion concert: smacked drums do not record well. Tape saturation is very helpful in getting a high average level and loud-sounding peaks without over-cutting the LP. Even then, a really fat drum sound needs help: that piece-of-crap Shure PA limiter has a following because Led Zeppelin used it to mash their drums onto tape and then LP. Drums can be manipulated (distorted) a lot without sounding distorted, because of their transient nature and the wide variety of sounds that can plausably come off a modern drum-set. I got my percussion concert mastered at an acceptably high average level (without tape) by pushing peaks to 0dB or +2dB FS. (At +2dB FS, on percussion, way less than 1% of samples are clipped.) But to make some of those passages hold-up against more steady state notes, or to get the obscenely high average level modern buyers and DJs think is "good", I woulda hadda put a clipper or limiter on the tracks.
