PS AUDIO GCPH PHONO PREAMP
Product Description
 The
very first product PS Audio ever built and sold to customers, way back
in 1973, was a high-end phono stage. It was an immediate an unequivocal
success and launched PS Audio into the world of high end audio products
for the next 30 plus years. Built around a passive RIAA curve and dual discrete class A gain stages, this unique standalone phono preamplifier set the standard for outboard phono stages for many years to come. The GCPH, our latest effort at a high-end phono preamplifier is designed for the highest quality phono reproduction possible. It is based on PS Audio’s unique Gain Cell Technology and over 30 years of designing state-of-the-art phono stages. The GCPH is built around the same design philosophy all PS phono preamplifiers have enjoyed over the last 30 years: a passive RIAA curve and fully discrete class A gain stages. It is our finest work to date and should again set the standard for standalone phono amplification for many years to come. We've also managed to make some serious improvements to our original design techniques in the GCPH, by adding a dual mono, balanced signal path and dual mono power supplies. Separating the signal paths and the power supplies into, essentially, mono paths adds a wonderful level of separation in the audio chain and helps lower the noise to nearly imperceptible levels. This is truly a state-of-the-art phono preamplifier that can be used as an add on to your preamplifier or all by itself feeding your power amplifier directly! The RIAA Curve The RIAA curve is a specification for the correct playback of vinyl records, established by the Recording Industry Association of America (RIAA). The purpose of the equalization curve is to permit greater playback times, improve sound quality, and to limit the physical extremes that would otherwise arise from recording analog records without such equalization.  The
RIAA curve has operated as a de facto global industry standard for the
recording and playback of vinyl records since 1954. Prior to that time -
mainly between 1940 and 1954 - each record company applied its own
equalization; there were over 100 combinations of turnover and rolloff
frequencies in use, the main ones being AES, LP, NAB and FFRR. The RIAA
standardized the EQ curve for records and hence the majority of vinyl
LP’s are recorded to this standard.Before 1940, most records were cut flat. This included broadcast recordings and motion picture recordings before sound-on-film. If you play a pre-WWII 78rpm record through a modern preamp, you will effectively be playing it with a scratch filter whose cutoff begins at 2200Hz, giving lack of high frequencies and muffled voices. RIAA equalization is a form of pre-emphasis on recording, and de-emphasis on playback. A record is cut with the low frequencies reduced and the high frequencies boosted, and on playback the opposite occurs. The result is a flat frequency response, but with noise such as hiss and clicks arising from the vinyl surface attenuated. The other main benefit of the system is that low frequencies, which would otherwise cause the record cutter to make large excursions when cutting a groove, are reduced so grooves are smaller and more can be fitted in a given surface area, yielding longer playback times (hence the term “LP” or Long Play records). RIAA equalization is not a simple low-pass filter. It carefully defines roll-off points in three places, 2122 Hz, 500 Hz and 50 Hz.  There
are multiple means of achieving this curve in a phono preamplifier, but
the two main implementations are active and passive. Active means the
RIAA curve is in the feedback loop of the preamplifier and passive means
it is outside any feedback loop. PS Audio has always believed the best
performance will be achieved when the curve is outside the feedback loop
of the internal amplifier because the amplifiers’ performance will
change with frequency. This is because at high frequencies the negative
feedback of the phono preamplifier will be very high and at low
frequencies, relatively low. Our design philosophy of preamplification
has always revolved around the notion of keeping negative feedback low
and uniform at all frequencies. Thus, a passive RIAA curve is “just
what the doctor ordered”.Whatever method is employed, it is absolutely critical the curve be as exact as possible. Deviations of more than a tenth of a dB are unacceptable. The GCPH is flat to the RIAA standard by less than 0.1dB. The RIAA Curve is only the beginning The second most critical aspect of a perfectionist high-end phono stage is the gain stages themselves. They must be low noise, high gain and low distortion. A tall order indeed, but nothing too difficult once we employ our unique Gain Cell technology to the preamp. The GCPH is built around two discrete and fully class A balanced gain stages: a high gain, low noise input stage and a Gain Cell for the output stage, with the passive RIAA curve between the two stages.  This
unique topology permits an unheard of flexibility for users to adjust
the gain of the phono preamplifier to their specific cartridge and
system. Coarse gain settings are handled by rear mounted controls that
adjust the input stage to the proper level for each cartridge and fine
adjustments are handled via a volume control like knob on the front
panel. The front panel gain adjustment also allows the GCPH to be used
as a standalone phono preamplifier, feeding the purest phono signal
possible directly into your power amplifier. Making the most of a passive RIAA curve design The superiority of a passive RIAA curve can best be utilized by adjusting the gain of each of the two gain blocks to take advantage of the lowest possible noise levels and the highest possible overload characteristics of any one stage. Regardless of the type of cartridge you are using on your turntable, the first step in utilizing the GCPH is to adjust the gain of the input stage. Here we want as much gain as possible without overloading the stage on transients from the record. What comes into this stage is a “pre-equalized” signal, so the high frequencies are considerably louder than the low frequencies from the vinyl. We adjust the rear mounted gain switches to best match the cartridge output to this first stage requirements. Typically, a majority of the gain we need will be here, in this first stage. The signal is then passed through the passive RIAA curve. This is perfect because the curve will lower the residual hiss and noise from the first stage and, at the same time, get all the highs and lows from the  vinyl
disc in proper order.At this point, we have a low noise and properly equalized phono output and we feed this into the second stage, the Gain Cell. Gain Cells are unique in that we can adjust their gain without changing their characteristics and without attenuating the incoming signal. You get only the gain you need from a Gain Cell and it is adjustable from the GCPH front panel. Using the front panel gain adjustment control on the GCPH, you can set the Gain Cell for the perfect gain to feed your preamplifier or maintain absolute control from zero gain to any other gain and feed your power amplifier directly from the GCPH! This is a vinyl lover’s dream come true. Complete control over any cartridge and it can act as a complete system or an outboard phono preamplifier to feed your preamplifier directly. Available gains and impedances From the rear panel you can adjust the gain of the GCPH to 48dB, 54dB, 60dB and 66dB. You can then adjust the Gain Cell for even more gain from the front panel. In short, the GCPH will provide enough gain for just about any phono cartridge ever made. Impedance setting are equally flexible. You can choose, 100 Ohms, 500 Ohms, 1000 Ohms or 47K Ohms regardless of what gain setting you are using. Many vinyl lovers use a moving coil cartridge at the standard  moving
magnet impedance setting of 47K and adjust the turntable’s VTA such that
the increase in overall system brightness is reduced. The combination
of proper turntable setup and higher impedance for Moving Coil
cartridges can result in some incredibly dynamic and open music on your
system.Point is, the GCPH stands ready to give you everything you need in terms of gain and resistive settings for cartridges. Huge power supply Last, but not least, one thing we’ve learned over the years is that you need a healthy power supply for a phono preamplifier to sound its best. We were the folks that introduced the notion of a high current power supply for low current draw products, and the GCPH is no exception. Within the chassis is a huge toroidal transformer feeding giant capacitors and multiple regulators. All designed to give you the finest performance a phono stage can possibly offer. Inputs and outputs The GCPH is a true balanced design from input to output. It features the highest quality connectors and you can feed your preamplifier or your power amplifier with either single ended RCA or balanced XLR connectors for best sound. The GCPH is a true high end state of the art preamplifier, designed specifically for the demands of vinyl and the wants and needs of music lovers the world over. You simply will not find a better phono preamplifier at any price. Period.
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