I'd not want to dismantle the mixer, it might just kill it off, its rather
elderly but functional nonetheless. I like what I'm used to as modern stuff
if not just software is often not tactile enough for me.
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Johnny B Good" wrote in message
...
On Wed, 05 Jul 2017 20:31:26 +1000, Trevor Wilson wrote:

On 5/07/2017 4:23 AM, Brian Gaff wrote:
Humph, well i thought it was me.
a single transistor stage with, say an emitter follower would suffice
though these days the over designers would probably use an Ic.
Brian


**And just to nit-pick: With a single transistor, operating as emitter
follower, you have a Voltage gain of less than 1. Just sayin'. I think
you mean 'common emitter'.

Brian has a point, assuming he's aware of the difference between the DIN
system and the phono plug based system, namely DIN's use of Hi-Z sources
driving Lo-Z sinks versus the use of Lo-Z voltage sources driving Hi-Z
phono inputs.


An OP amp is very, very easy, cheap and simple to implement. Distortion
is almost non-existent too.

The less than unity gain of an emitter follower is typically 95 to 98
percent of the input voltage, depending on the emitter load resistance
and the beta gain of the transistor used. Even with a gain of only 0.90,
interposing such an amp between a 100K DIN output and a 10K phono input
will provide a 20dB boost in signal level (even when both are 50K,
there'll still be a good 5dB advantage).

Using an op-amp circuit with non inverting Hi-Z input unity gain will
only add a dB or so boost at most to the classic emitter follower
amplifier solution so there's not a lot to choose between them other than
the fact that adding a simple variable resistor to the op=amp circuit
provides variable gain from unity upwards (say a 6 or 12dB boosting range
of adjustment).

A single PP3 (or, optionally-but not essential, two PP3s in the case of
the op-amp solution) should be able to provide dozens, if not hundreds of
hours of fun between changes of battery with such a self contained
boosting amplifier module.

If a more permanent battery-less solution is desired, I'd say the best
option would be to fit it inside the mixer box and provide the additional
phono socket(s) alongside of the existing DIN socket, rather than use a
seperate 9 to 12 volt noise free wallwart psu.

--
Johnny B Good