In article , Phil
Allison wrote:

BTW; anyone familiar with the famous Crown DC300A ?

Both channels would emit a long squeal about 10 seconds after switch off
- it sounded much like a party balloon being let down while squeezing
the neck.


Yes.- I remember it well.

The Crown DC 300A was a ubiquitous studio workhorse in the UK.
I still have a copy of the manual:

Laboratory amplifier. 155W pc minimum RMS 1Hz to 20kHz.
FR +/- 0.1dB DC - 20kHz at 1W into 8 Ohms
FR +/- 1 dB DC - 100Khz
HD 0.001% 20Hz to 400 Hz increasing linbearly to 0.05% ar
20kHz at 150W RMS pc into 8 Ohms.
Output impedance 7 mOhms in series with 3uHenries

Unconditionally stable with any load including completely
reactive.

The IM and THD charts that come with the manual are blank
and marked "Disclosure prohibited 4.11.1974"

Our chief of maintenance described it as "a good amp,
incredibly reliable and clean as a whistle DC to daylight!" :-)

It was frequenty partnered with the Lockwood Major Monitor, a
studio speaker with a Tannoy 15" Gold. A very impressive
combination.

The Crown (Amcron in some territories) was also used as a vinyl
cutting amp, driven from a inverse RIAA preamp. It gave very
good results. Recorded Productions Ltd in London W1 had such
a set up.



Iain