"GregS" <zekfrivo@[EMAIL PROTECTED]
> wrote in message
news:fu5er5$kqc$2@[EMAIL PROTECTED]
> In article
> <bp6dnaD1DdylpZvVnZ2dnUVZ_hmtnZ2d@[EMAIL PROTECTED]
>, "Arny
> Krueger" <arnyk@[EMAIL PROTECTED]
> wrote:
>> " Frank" <noreplay@[EMAIL PROTECTED]
> wrote in message
>> news:HqCdnfNQSajugJzVnZ2dnUVZ_tCrnZ2d@[EMAIL PROTECTED]
>>
>>> By the 1960s we had both tubes and transistors.
>>
>> True for many applications, but not for others.
>>
>>> The
>>> transistor than was very mature as it was invented in
>>> 1947 and much of the physic were been worked out years
>>> ago.
>>
>> Depends which end of the 60s, you're talking. In 1960
>> there were no competitive mainstream solid state power
>> amps, receivers or integrated amps. By the end of the
>> 60s, there were, but power ratings above 200 wpc were
>> still in the next generation.
>>
>> The first stereo amp reviewed by Stereo Review was the
>> Knight kit KG-870, in 1965. It was not competively
>> reliable. The first stereo amp reviewed by High
>> Fidelity was the Knight KN400, in 1961. It had low power
>> and was not competively reliable. By 1966 some SS gear
>> with adequate power and reliability crept onto the
>> market. Really high-powered SS amps waited until 1973 or
>> later.
> I just pulled out my 61 catalog. I must have built a SS
> amp sometime later.
> It was a smaller amp with germanium transistors and
> transformer interstage
> driver. It had that great clear SS sound.
Sounds like the same RCA Transistor Manual amp schematic that also graced
the Heath AA-22 which I owned for a while. I sold it and went back to Dyna
tubed amps after I fried the second set of output transistors.
The transistors were as I recall 2N2147 germanium transistors. Plenty
fast,
good beta, but only 25 watts dissipation and wildly insufficient SOA.
The first commercial SS amps with reasonable power and reliability used
silicon outputs (2N3055) in the much-maligned but actually really pretty
good "Quasi Complementary" design. The secret of their reliability were
some
SOA limiters that were based on a few cheap parts including a couple of
$0.35 small signal transistors.
> Doesn't look like they used the KG- etc in 61 year. They
> just said 40 watt amp or something like that.
There was another Heath SS amp, the AA 21 I think, that used the same
output
devices, 4 per channel, in what they called the "totem pole"
configuration.
Totem poles came back in the silicon era in amps like the Dyna 400, which
used 8 devices per channel. But now we're talking 1974-1975.
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