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Choosing a Phono Stage

Choosing a Phono Stage

There is an endless stream of mediocre phono stages which have great reviews, so your range of choice is enormous. We have heard a good number and even some award winners do not come close to those listed on this page. Life is too short to consider everything so we have distilled what we consider to be among the very best at their particular price points.

Before making any decision on brand or budget you may do well to consider a number of factors. Firstly your phono stage can easily make or break a vinyl based system. The stage of phono pre-amplification is absolutely crucial – more so than the pre-amp or amplifier stage – if you have any doubts about this we urge you to get a demonstration of something like the GSP Audio or Puresound phono stages. The reason for this importance is that the phono stage carries out, up to a massive 95% of your total signal amplification from cartridge to speakers. This is too much to entrust to a feeble £1 chip used in many integrated and pre-amps.

To clarify why the phono stage is special, you know that the signal output from a cartridge is around 0.5mV for a moving coil and around 5mV for a moving magnet cartridge. Your CD player, DVD player, streamer, etc. can produce around 1Volt of signal (approx. 200 to 2000 times higher than a cartridge). The phono stage therefore amplifies a very low-level signal by an enormous amount. The fragility of this extremely low-level signal is often severely underestimated along with the amplification quality needed to produce a good sound.

The way in which your amplifier handles these extremely low signal levels (thousandths of a volt) from the cartridge is critical – information is more easily lost or distorted at this stage than later on in the signal path. Information lost can never be regained and any distortions and colourations are amplified thousands of times. It is not difficult to appreciate why this area has so much potential for improvement and is often the weakest link in a system.

Why upgrade to a stand alone phono stage?

Many amplifiers neglect the phono stage. With a focus on CD replay, many companies produce amplifiers with no phono input at all. The solution is to add a phono stage and then use interconnects to plug it into a spare input socket on your amplifier such as an aux, tuner or tape input socket.

If an amplifier does have a moving magnet or moving coil input, it is often assumed that all is well. The problem is that many phono inputs often use budget integrated circuits costing less than £1 as a cost cutting solution. Expertise in the area of RIAA equalisation and cartridge amplification is not an area that many amplifier manufacturers have the time or resources to invest in. For this reason a well researched and properly designed phono stage is a huge upgrade.

There are theoretical advantages for a separate phono stage

The power supply is separate and uncorrupted by the drain of larger current circuits. If the supply is separate, the sensitive circuitry is not susceptible to stray fields from the large transformer inside most amplifiers.

Should I use a step up transformer?

Step up transformers are used to increase the voltage of moving coil cartridges. They connect between your cartridge and a moving magnet phono stage. This is necessary because a Moving Magnet Phono stage can only accept higher signal levels to work properly.

Step up transformers tend to be favoured by Valve amp designers (possibly because of a bias against solid state). The drawback is that they have severe problems in matching impedance loads required by different cartridges. Many deny this or are unaware of the problems. After a lot of experimentation, we have found that unless a step up transformer is designed for a specific cartridge (not just the load), you are highly unlikely to get a perfect tonal balance. The alternative is to use a solid state active stage such as the GSP Elevator. These work perfectly even with valve phono stages.

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