prism orpheus and LP's
On 10/06/2015 06:12, Nate Najar wrote:
On Wednesday, June 10, 2015 at 12:23:06 AM UTC-4, PStamler wrote:
Congratulations on the good results. The instrument inputs on some interfaces will indeed work for this, as long as there are two of them (a lot of interfaces just have one). If you plan to do this again you might want to look up the input impedance of those instrument inputs and use a Y-connector to add some parallel resistance to bring it down to 47k, which is what the cartridge wants to see.
I just looked it up, it's 1meg. I didn't realize that cartridge wanted an impedance that low.
It does depend on the cartridge. Most, if not all magnetic cartridges
are designed to expect 47kOhms resistive load impedance, but on a deck
that age, it may have had a ceramic cartridge, which gave a flat(tish)
200mV response at a megohm or so, but also gave a similar response to a
magnetic cartridge when loaded to 47k.
The line inputs are 14.5K and the mic press are 5.5K
If you just pad the line inputs with a 33kOhm resistor, you'll lose some
level, but it may make the frequency response flatter. Or you can buy a
battery powered RIAA preamp for a few dollars, which takes care of the
matching and gives a (usually -10dB) unbalanced frequency compensated
output which will feed a 600 ohm line, and if you pay a bit more, you
can get one that gives you a 0dB, 600 Ohm balanced output. In the UK,
you can get a kit to build the preamp for about ten pounds, so the same
thing in the USA would be about 10 bucks.
Incidentally, the output from the cartridge may well not be connected to
earth at the turntable end, so you may be able to feed it to the line
inputs as a balanced source, with, if your impedance figures are
correct, a 15 kOhm resistor in each leg of the signal feed, then apply
the RIAA curve in the DAW.
iZotope RX has a pretty decent scratch and crackle treatment; start out with it set to about 1.2, and increase as needed.
that's good to know. I don't actually have the izotope software. I use a program called "sample manager" which uses the izotope algorithm for SRC.
The click remover in Audacity's not bad, either, and there are free or
paid for VST plugins to do the job better.
--
Tciao for Now!
John.
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