[plug] Altering Gains on Multiple Audio Files

Daniel Pittman daniel at rimspace.net
Fri Apr 3 13:13:07 WST 2009

Jason Posavec <jasonposavec at iinet.net.au> writes:
> Daniel Pittman wrote:
>> Kev <kdownes at bbnet.com.au> writes:
>>> You can purchase, from Jaycar, a neat little pre-amp (model# PA-928 -
>>> RIAA I think is the standard) for, from memory, about $16.00.  Inputs
>>> are switchable between phono and aux.  There is also a similar item
>>> available in kit form from Altronics.  Such a device might just do
>>> what you want.
>> Really?  What makes you think that, and not that this will make the
>> situation worse by applying an inappropriate amplifier to a mismatched
>> set of electrical signals?
>> Seriously.  Are you saying that the headphone output is comparably to a
>> record player in terms of preamp (and RIAA response curve) needs?
>> Alternately, are you suggesting that the electrical mismatch between the
>> line level socket on the amp is going to be any less an issue with the
>> mismatch of the line level input on this preamp?
> Just the part where it's switchable between aux and phono gives me the
> impression that the device is doing some kind of magic inside,
> depending on what the specific input is.

Sure.  It switches between line-level input (aux) and phono input run
through a phono pre-amp.

The phono stuff is ever stranger than the headphone / line level stuff,
because there is a  RIAA specified set of assumptions about the response
of the phono preamp — which is not flat — literally baked into the vinyl
of the record.

> If it wasn't, then it wouldn't care what was being plugged into it?

Sure it would: it will be assuming their line-level on aux, or phono
level on phono.

> And wouldn't need a switch? I'll have to look further into it.

I could be wrong, and it could be doing magic; as I noted elsewhere the
Jaycar website refused to divulge any details of the device, even a
price, under any search I made.

So, my answers are guesswork, but reasonably informed guesswork since
the labels (aux and phono) have very specific meanings. :)


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