300B solid state

Posted on Feb 4, 2014

Classic 6-Transistor circuit (many variations of this where around in the 1960`s & 70`s), NPN only output devices, fairly high level of Bias, single rail, input and output coupled via a capacitors (electrolytics - no less), clever feedback loop, bootstrapped load for the second stage, both voltage amp stages using some local degeneration too.

300B solid state
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I fixed so many of these, I could nearly draw out a circuit diagram from (> 15 Years old) memory. Nothing too unusual, it just sounded very good. Combined with an passive EQ circuit and a KSP215 8" Full Range driver these drove for example east german Radio/TV Monitors and these things where darn good. The later generation of Amplifiers in East Germany has the standard circuit (read Self if you want to know what i call standard) and DC coupled outputs etc. And they measured a lot better, had more power and all, but sonically they had a "typhical transistor sound" (in the negative sense), which the old outdated designs lacked and in a Studio where you can directly leave the studio and walk up to Mikes any significant deviation from subjective neutrality is easily heard. Too much generica out there that sounds in the main negative attributes as bad as the next (which is not to say all these amplifiers sound the same, they merely sound equally iriitating in different ways). Given that making an amplifier with low THD does not garantee that the resulting amplifier will sound better, more realistic, less coloured; whatever term you wish to use; than one with higher THD, what reason exist that could make any SENSIBLE person bother about THD as anything but an academic excercise Of course there are people who slink off with the spec sheet of their amp to the gents, oooohhh, the low THD, ahhhh the high power and all that, but if it...

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