Hi,

In message , Keith G
writes

Guilty about the ludicrous number of gardening mags she consumes, Swim
bought me a couple of hifi comix yesterday (I'm actually so 'off them',
these days!) and in one of them I saw a mention that attenuation of signals
for computer recording purposes should be done 'pre-computer' because the
software 'volume sliders' wreck the sound quality.....???

That sounds likely. A lot of sound cards these days don't have any
analogue attenuation on the inputs, so they take whatever you feed them,
digitise it, and then perform any gain changes digitally. Digital gain
changes on cheap sound cards can be a bad thing, and if the analogue
input is too hot for the card, then it can be difficult to avoid
clipping.

Anyone care to confirm or deny this and would this mean it is best to leave
the sliders 'maxxed out' if one is attenuating 'pre computer'?

That's what I do. I use a low end Spirit Folio mixer between the source
(RIAA preamp) and the card inputs. I set the levels on the mixer, while
keeping an eye on the level meters of the sound card. The metering on
the Folio is almost worthless anyway, and I only use it to get the
signal levels vaguely right.

My signal path goes TT Gram amp Folio (stereo in) sound card.
The Folio has a couple of RIAA preamps but they aren't very good, so I
avoid them.


Anyhoo, moot AFAIAC, as I can not get a recording from my vinyl setup
without having the slider set at the absolute minimum or I get clipping, as
anyone who has bothered to listen to any of the wacky clips I post from time
to time**, will tell. So I'm plotting to construct a little attenuator which
I envisage as not much more than an Alps pot in a little box with phono
sockets IN and OUT, wired accordingly.

That will probably be fine. It will introduce a change in the input and
output impedances, but if you pick the right value pot I doubt you'll
have any problems. It will probably depend on how fussy the preamp
feeding the pot is about the load it sees.

Too simple? Am I missing summat here? (Like everything you buy seems to have
a tiny little resistor stuck in it for some reason!)

Simple is good :-)

If it was me, I'd try it and see. Worst case I reckon you might need to
add a couple of resistors if the preamp output wants to see a high
impedance load. Have a look at
http://www.users.bigpond.com/aagreen/passive01.html (just for circuit
ideas - some of the parts comments are silly), or you could always ask
Mr. Pinkerton nicely if he'll share his passive attenuator circuit with
you...

**On that subject, I notice no-one has had a go at my truncated'name that
tune' clip:

http://www.apah69.dsl.pipex.com/keit...aughtybits.mp3

Too obscure or just too ****ty a recording, eh?

Too obscure! Maybe Donizetti on amphetamines?

--
Regards,
Glenn Booth