"Eiron" wrote in message
...
Dave Plowman (News) wrote:
In article ,
David Looser wrote:
"Dave Plowman (News)" wrote in message
...
In article ,
David Looser wrote:
Those sort of output impedances were common in valve days. Use a
video
or RF coax to your requirements. Maplin sell a range by the metre.

Hence the DIN idea of using a low input impedance at the other end of
the cable. A pretty crap idea (IMO) but as a way of reducing the HF
loss from cable capacitance it worked.
But only if you have an even lower source impedance. ;-)
Easy to do with transistors. With valves you need an extra stage.


Err.. no. The DIN system worked with high output impedences and low
input impedances. There was, of course, significant signal attenuation
in so doing with consequent S/N ratio implications, but it did reduce
the HF loss due to cable capacitance.

You've got me confused there. Thought low out high in was the rule. What
make would I be looking at for this? I had a Quad 3 series that used DIN
connectors throughout - but that was all low(ish) out high(ish) in.

Most domestic equipment in the sixties and seventies used DIN connectors
without following the DIN electrical standards.

--
Eiron.

That's right. DIN is both a standard for the connector and the electrical
signal. The electrical signal was effectively a current drive, going from a
relatively high output impedance (100k or thereabouts if I remember
correctly) into a relatively low (2kohm again from memory) input impedance.
Very few manufacturers applied this, Grundig and Philips comes to mind...I
had a Philips receiver with the tape ins and outs to the DIN signal standard
as well as connectors. Other manufacturers including Quad, A&R Cambridge and
Naim used the connectors but in a conventional low-out, high-in fashion.
S.