SPL Phonos MM/MC Phono Preamplifier

Moving Magnet

Moving magnet pickups generate a small voltage by moving a magnet between copper coils. MM pickups have a very high inductance and impedance. The Phonos offers a choice of three capacitors to correct the linearity of the frequency and phase response. The capacitances are 150 pF, 220 pF and 330 pF. In the off-position the capacitance is determined by the capacitance of the cable.

Moving Coil

The MC pickup is also a small electromagnetic generator, but with the magnets firmly anchored and the coils moving between them, i.e. exactly the opposite of the MM pickup.

The output voltage, however, is very low at only a few hundred microvolts and is therefore more sensitive to noise and induced hum. This makes preamplifier design a challenge, because the very low output voltage must be pre-amplified extremely noise-free. Phonos offers one of the most powerful phono preamplifiers for MC systems with up to 71.5 dB preamplification. Thanks to the 120V technology, the preamplifiers are extremely low-noise, linear and phase-locked. MC pickups have a very low inductance and impedance. 

This means that the effects of cable capacitance (from turntable to preamplifier) are negligible. The impedance, however, is relevant and can be set in six positions: 100, 220, 470, 2.2 k, 4.7 k, and 10 kOhm.

If there is any doubt as to which impedance matches that of the pickup, the impedances can also simply be switched through until the linear frequency response is acoustically determined.

Perfect level

The gain control can be used to determine the amplifier power, in other words, the output level of the Phonos. There are three values to choose from. In the “Norm” position, the gain is +46 dB for MM systems and +67 dB for MC systems. With the switch set to “-10”, the gain is reduced by 10 dB (MM = +36 dB, MC = +57 dB). This is optimal in combination with standard HiFi equipment that works with a reference level of -10 dBV. If the switch is in the “+4” position, the gain is increased by +4 dB (MM = +50 dB, MC = +71 dB). So the output level is about as loud as that of modern DA-converters at a reference level of 0 dBfs = 15 dBu.

Subsonic Filter

The rumbling of the turntable’s drive mechanism is also amplified by the high amplification of the bass range due to RIAA equalisation in playback. The Phonos offers a switchable subsonic filter to remove this rumble.

Connections

Gold-plated RCA sockets are available for connecting the turntable and for outputting to a preamplifier such as the Director Mk2 or the Elector. A ground connection for the turntable is designed as banana plug socket. The ground lead can be either clamped or plugged in.

RIAA Equalisation

The specification for the recording and playback of records proposed by the Recording Industry Association of America (RIAA). The RIAA equalisation curves introduced a global de facto industry standard for vinyl records in 1954.

RIAA equalisation uses pre-emphasis to reduce low frequencies and boost high frequencies when the record is cut (blue RIAA curve). The bass is reduced by up to 20 dB to provide more space and longer record play time. The high frequencies are boosted by up to 25 dB to increase the signal-to-noise ratio between the noise of the record media to the audio signal.

During playback, exactly the opposite happens in the Phonos. The de-emphasis filter (red RIAA curve) compensates for the pre-emphasis and the result is a linear frequency response.

Douglas Self Design

The RIAA equalisation of the Phonos was developed according to the recommendations of Douglas Self. Idea: Many small capacities instead of a few large capacities. Advantages: The capacitors charge and discharge faster, which results in better resolution and faster impulse response. Only audiophile Styroflex capacitors are used in the entire RIAA equaliser. Douglas Self is a British electronics engineer with a strong penchant for audio. He holds honorary degrees from Cambridge University and teaches psychoacoustics at the University of Sussex.

We endeavour to despatch same day for orders placed up to 1pm on available stock items (items with stock message "Usually dispatched within 24 hours"). Please remember to check with us first for a physical stock check if next day delivery is important to you. Any items with stock message "Usually dispatched within 72 hours" are items that we do not hold in stock but order in from the importer or manufacturer as soon as a customer order is received. Occasionally these may be delayed beyond 72 hours due to importer/manufacturer stock levels but we will inform you as soon as we can if this is the case.

UK Orders

We despatch the bulk of our UK mainland items on a 24 hour service – Free of Charge. Non Mainland locations - Isle of Man, Isle of Wight, the Scilly Isles, the Scottish highlands and Islands, the Channel Islands and Northern Ireland may take a day or so longer and are not Free of Charge. Smaller items are delivered using Royal Mail 24 or special delivery. Larger items are delivered using a courier service such as DPD or UPS.

International Orders

Due to the nature of our products and brand restrictions we are only able to send certain items internationally. Smaller items are delivered using Royal Mail Small Packets Airmail with International Tracked and/or Signed depending on value of item and availability of the service. Larger International shipments are sent by insured and tracked services using UPS. If there are any delays due to specific customs regulations, etc, you will be contacted by Hifisound or by the courier with a request for any further information required. Customs duties can apply for shipments to any countries outside of the UK depending on where the product you have bought is made. Customers are responsible for all taxes and duties incurred when the items enter their country.

Collect in Store or Home Install

At the request of the manufacturer some items cannot be supplied by mail order but you can click and buy them and then elect to collect them from our store or arrange a home install (if applicable). Applicable items clearly state that they are Collect in store or home install. Once ordered you will receive a message prompting you to contact us by phone or email to arrange for us to deliver and install or to reserve and collect from our store at your convenience, you will also be advised of the delivery time / stock availability as not all Home install / collect in store items are held in stock.