On Thu, 05 Mar 2015 00:55:31 +0000, Sumatriptan
wrote:
What do you mean by the 'deck'?
I meant how is the deck powered, by mains AC, or low-voltage DC from a
wall-wart or inlne PSU block, but you've answered that below.
The interface between tt and PC is a
single unit containing pre-amp and RIAA eq. and a ADC followed by a USB
interface. It is powered via the USB from the PC.
With tt input disconnected from the pre-amp front end, hum/noise is too
low to be measurable using Audacity. S/N ratio is given in the specs as
89 dB @1 kHz
So, that would seem to make it the actual deck then - nothing else
seems to fit the facts.
1) Is the deck powered by a wall-wart or an inline unit and
low-voltage DC actually coming into the deck, or is it mains coming in
and its motor works directly off it? If the former, I'd suspect the
PSU.
Motor is mains. If this mains supply is disconnected the hum level falls
by about 5 dB
Do you mean actually pulling the plug out of the wall, or just
switching off, which might leave the deck still attached to neutral?
(I can't remember for sure whether power-points have double-pole
switches, but I think not.)
That also suggests that the hum may have two, or more, sources, and by
doing that you are fixing a less important one.
2) What sort of PC is it? A desktop, or a laptop powered by a
wall-wart or inline unit as described for the deck?
Desktop powered by mains.
Wouldn't have expected problems with that, though ISTR that Jim thinks
PC PSUs are noisy, electrically-speaking. Nevertheless I've digitised
stuff via a SB Live soundcard on a standard, homebuilt PC without any
difficulty. However, thinking about it, that may mostly have been
using an optical input, as described in the previously linked post, or
another of around that time, and that of course wouldn't hum!
Java Jive: ROT: PC Audio Recording & Playback (was: Holst and a
Headache), 6/12/11
https://groups.google.com/d/msg/uk.t...k/a7R64KmusM8J
I just had a quick skim and your mention of laptops reminded me that I
do have a laptop available that I could try on battery power.
Certainly worth a try.
I am aware of the headshell contact issues with this turntable so will
be looking at that when I get more time to play.
Good luck.
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