Subject: Re: [linux-audio-user] [OT] recording fom turntable (ripping LPs)
From: Jan Depner (eviltwin69_AT_cableone.net)
Date: Tue May 04 2004 - 22:35:37 EEST
On Tue, 2004-05-04 at 13:41, Aaron Heller wrote:
> There are further considerations beyond RIAA equalization and gain.
>
> Moving magnet phonograph cartridges are designed to work into a specific load, typically 47k ohms and 250 pF (e.g., see "Recommended Load" for a Shure V15 on http://www.shure.com/v15vxmr.html), which is significantly different than the load presented by a microphone preamp. The wrong load will change the frequency and transient response of the cartridge.
>
> Phono preamps are designed to present the correct load to a phono cartridge. Good ones have switchable loads to accommodate different cartridges and to compensate for the capacitance in the connecting cable. In high-end gear, it is common practice is to modify the input circuitry of the preamp to specifically match the cartridge and cable in use.
>
> There are also moving coil phono cartridges, which have different requirements.
>
> By contrast, professional microphones typically have source impedance of about 150 to 200 ohms and are designed to be loaded with a pure resistance in the range of 1 to 5 k ohms. (here are the specs for a Neumann U87 http://www.neumann.com/infopool/mics/en/u87ai_t_data.htm).
>
> If you are serious, my recommendation would be to use a dedicated phono preamp. There are some very good ones for around $150 like the Parasound PPH-100, which handles both MM and MC cartridges.
>
Why would I want to spend $150 on a preamp? I get almost exactly the
same sound from the mic preamps and JAMin EQ that I get from my stereo
amp (with built in phono preamp). After I record it I'm going to encode
it in ogg vorbis. I seriously doubt that I would be able to hear the
difference between the $150 phono preamp and the combination mic/line
preamp and JAMin.
Jan
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