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Do I need a phono stage ( amplifier ) for my System?

by: dappletoft( 17731Feedback score is 10,000 to 24,999) Top 5000 Reviewer
31 out of 33 people found this guide helpful.
Guide viewed: 2795 times Tags: phono | stage | amplifier | cartridge | amp


WHAT DOES A PHONO PREAMP DO, AND WHY DO I NEED ONE?


Unlike line level audio sources you connect to a stereo (DVD/CD players, tape decks, TV audio, minidisc, etc.), the output from a magnetic cartridge installed in a good quality turntable is MUCH lower, and requires an additional stage of amplification to bring it up to the same volume as the other sources you listen to through your stereo.

This additional amplifier stage, the phono preamp, is built-in to most older receivers and amps, allowing direct connection of a turntable.

However, newer stereo equipment (including virtually all mini-systems and home theatre units, as well as many stereo receivers and amps), have NO phono input (this because records and turntables are supposedly obsolete in today's world dominated by CDs and DVDs).

In order to utilise the inputs such units DO have (Aux, Tape, Line, Video, CD, etc.) to connect a turntable, you need to first pass the signal through an external phono preamplifier to bump up the level.
 
The same level increase is needed if you're connecting a turntable to a computer sound card's line input so you can make CD-Rs from LPs; again, the external phono preamplifier provides it.

WHAT IS RIAA EQUALIZATION?


Because of limitations in the LP recording process, an equalization curve must be applied to the music or other sonic content prior to it being cut onto Vinyl, so as to reduce backround noise and sibilance.

Reversing this equalization effect (the RIAA curve) and restoring the music's original frequency response curve during playback is a VITAL part of the phono preamp's job and differentiates it from other preamps used for microphones and musical instruments, which usually provide gain but no other modification of the original sound quality.

Proper RIAA re-equalization during playback is a must in faithfully producing the original musical content without coloration or distortion.

WHICH PHONO PREAMP IS BEST FOR ME?


Obviously, the more money you invest, the better the performance and sound quality of the preamp you buy will be.

Signal-to-noise ratio is the most important criteria; the higher the number, the lower the backround hiss level will be.

This may not be particularly crucial if the overall playback system's quality is low (a cheap minisystem or sound card, for instance; both may generate enough hiss in their own right to obscure any added by the preamp), but matters a great deal when comparing LP fidelity to other sources like CD on a good playback system.

Ability to faithfully correct RIAA equalization is another important sonic quality. Additional features like mike inputs and a power indicator may be useful to one user but not to the next; buy only what you need.

WHAT DO I DO WITH THE GROUND WIRE ON MY TURNTABLE?


Most (but far from all) turntables have a ground wire which provides shielding and hum reduction.

Not connecting the ground wire will result in 60 cycle hum (often sufficient in level to obscure the music).

If no ground wire is present, none may in fact be needed; but always look to make sure no one's amputated or unplugged it!

On older amps and receivers having a built-in preamp, the ground point to which the turntable ground wire attaches is clearly labelled.



Phono Amps for Sale

The Black Box 1 has no dedicated ground terminal; try connecting the wire to the preamp's metal back plate using any means available. A better solution is to strip the end of the ground wire (1.5-2 inches will do) and create a "lasso" which you then loop tightly around either the preamp's left or right input jack BEFORE you plug the turntable's RCA cable in. Pushing the RCA plug in should then securely hold and connect the ground wire to the input jack's outer sheath. We've found that this arrangement provides a reasonably hum-free connection regardless of what the preamp is connected to. This technique should work with any preamp lacking a ground terminal...

WHAT'S THE DIFFERENCE BETWEEN MOVING MAGNET AND MOVING COIL CARTRIDGES (and which do I have)? WHAT'S A CERAMIC CARTRIDGE?


Moving magnet (MM) cartridges are the common variety, characterized by high output impedence (typically 47k ohms) and a removeable, replaceable stylus (what most people call a needle); these are the cartridges most phono preamps work with. Moving coil (MC) cartridges, on the other hand, are low impedence devices (anywhere from 10 to 1000 ohms) which require a step-up transformer or "pre-preamp" to connect. MC cartridges rarely have replaceable styli, and can cost more than than most of us spend for our entire stereo systems. If you have a moving coil cartridge, chances are you know it.... Ceramic cartridges are the cheap, primitive type found on kiddie and fold-up record players, as well as the console stereos which were common before component stereo. Usually they have a "flip-over" needle (LP on one side, 78 on the other) and horrendous fidelity. One play with a ceramic cartridge will ruin a record for good, so never lend your LPs out!

HOW DO I RECORD LPs ONTO CD-Rs?


Mechanically, no problem. Connect your turntable to the input on any phono preamp, and the preamp's output to the line input on your computer sound card or laptop (many, if not most phono preamps come with the required connectors). Your CD burner software does the rest. There are tons of resources on LP to CD-R recording on the web; a Google search using the keywords "CD-R" and "vinyl" will yield plenty of results


Guide ID: 10000000004216437Guide created: 16/08/07 (updated 17/08/08)

 
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