Description
Hand built hi definition hybrid tube preamplifier with separate (isolated) power supply. I bought this from a family of a HiFi enthusiast who passed away in Los Angeles CA last year. It had been in storage for years. I had the components tested and replaced 2 power supply capacitors with OEM ARC caps. I replaced the feet with original ARC feet supplied by Greg Christenson at ARC. The unit sounds outstanding and does everything well. The components are very clean and well presented. I wanted to keep the units for years but I have switched to a PS Audio Direct Stream II DAC which doubles as a preamp. I cannot afford both so the ARC has to go. Id keep it if I still used vinyl as the phono stage is second to none. In defense of the ARC it makes a LOT more volume than the PS Audio so if you like your music loud on occasion you need a preamp. The DAC cant make adequate output to raise volume above loud conversational level. The umbilical cord is as new. Audio Research SP15 Review by James Leahy.Source: Dr Hi.Fi. House Calls – Since 1984 – Found at:http://www.drhifi.net.au/Reviews/ARC%20SP15%20Review/1.htm The Audio Research SP15 was introduced to the world in 1988 and is a full functioning Pre-Amplifier with Inbuilt Phono Stage. As can be seen from the pictures, the SP15 is constructed on Two (2) Chassis, utilizing Aircraft-Quality Connectors and an Interconnect Cable Forty-Eight (48 ) Inches long. The Unit is divided into an Active Amplification Chassis (SP15) And A Power Supply Chassis (SP15PS).A Custom Interconnect Cable of longer length is available from Audio Research at additional cost, although some degradation of performance will occur as the Cable lengthens.The Power Supply is in the pictures, as well as the Control Section.If you are a Control Freak, this is the Pre-Amplifier for you. It has a plethora of functions to play with and is the ultimate in flexibility.The Power Supply has Two (2) Controls, One is the Main Power and the other is the Auxiliary Power Outputs for various other components that can be Switched On or Off via the SP15.There is a five level attenuation control that is designed to equalize source levels and give a huge range of volume control to the pre-amplifier. It is graded in 6dB increments and is adjustable down to -24dB.The Volume Control is the usual Analogue Pot with Graduated Positions being used for this Multi-Ganged Heavy Gold Platted Unit designed to minimize Sonic Degradation of Microvolt Level Analogue Signals.There is a Balance Control that is useful in some poor acoustical environments.There is One (1) Pair of Balanced Outputs as well as Two (2) Pairs of Single Ended outputs. As always, I recommend using the Balanced Output to connect up to your Power Amplifier, if it has this available too.The SP15 has Mono, Stereo, Left, Right and Reverse listening modes.The Phono Circuit has impedance settings of 3, 10, 30, 100, and 47 K ohm.There is also a Direct Mode that in the Bypass position, directly connects the Attenuator to the Output of either the RIAA Compensated Phono Amplification Circuitry or a selected Line-Level Source (such as CD…),The Balance, and Mode Controls, as well as the Monitor Switch are removed from the Active Circuit path when this Switch is in operation.The Bypass Switch is provided for use with Audiophile-Quality Program Material or whenever Maximum Fidelity to The Input Signal is desired.There are Three (3) 6922 Vacuum tubes used in Intermediary Gain Stages in the Phono Section of the SP15.Each of the levels of Circuitry Amplification is provided with its own electronic regulation in the form of a Capacitance Multiplier, providing essentially zero impedance power supplies with essentially infinite isolation between circuit sections. Thus, the active circuitry is allowed to operate near theoretical performance levels.The separate Active Chassis contains both the High-Gain, RIAA Equalized, Magnetic Phono Preamplifier and the Line Level Circuitry, plus all of the Inputs, Outputs and various Function Controls.Extensive use has been made of State-Of-The-Art Audio Materials, including such items as Polypropylene And Polystyrene Dielectric Capacitors, Metal Film Resistors, Wire-Wound Resistors, proprietary Point-To-Point Internal Wiring, Gold-Plated Input and Output Connectors, Heavily Gold-Plated Switches, and other high-quality components.The SP15 is The Ultimate Pre-Amplifier even to this day that has an inbuilt Phono Section. The improvements over the much loved but not forgotten SP11 are as follows:Like the SP11, the new SP15 is a Hybrid Preamplifier using both Vacuum Tubes and Semiconductors as gain devices.However, the SP15 uses only three (3) tubes compared to the SP11s six;and whereas the SP11s tubes were employed in both phono and line sections, the SP15s tubes are confined to the Phono Section alone.As in the SP11, these tubes are not required to be selected, low-noise types.The changes in the SP15 line section (as compared to the SP11) are not limited to choice of gain devices. Resistance to input overloads, reduction of inherent noise levels, resistance to inter-input crosstalk and dynamic headroom have all been achieved as a result of circuit redesign in this area.Convenience features and controls remain similar to the SP11, but with some significant additions. The familiar Gain control has been replaced by a 5-position Attenuator switch having 6dB increments, resulting in better sonics while maintaining a useful selection of settings to match the output characteristics of both phono cartridges and CD players.Tape and dubbing functions remain identical to the SP11.On the back of the SP15 are new provisions for either Conventional (i.e. Single-Ended) or Balanced Output connection(s). Balanced connections can be made via the RCA jacks labeled Direct and Invert, or by using the new industrial XLR connector provided.Like the SP11, the SP15 is a Two (2) Chassis design isolating Power Supply functions from sensitive Preamplifier Circuits, reducing the opportunity for magnetic field effects to degrade sonic performance.A Toroid Power Transformer minimizes mechanical buzz and hum. See Installation Instructions for details on proper placement of the Two (2) chassis relative to one another.THE INSTALLATION INSTRUCTIONS AND THE OWNERS MANUAL ARE PDF AND INCLUDED IN THIS SALE VIA EMAIL.The SP15 reflects a further evolution and refinement of the idea that state-of-the-art preamplifier performance can be combined with real-word user convenience and system flexibility.Care has been taken to optimize the sonic performance of a variety of popular input options -- video, compact disc, tuner and analogue tape, as well as unsurpassed phono reproduction.Sonic Evaluations:The SP15 was fired up with Kim Carnes timeless classic Bette Davis Eyes from the Mistaken Identity album (EMI Records, 1981). The soundstage was both wide and deep. I was more than a little impressed with the sonic maturity of this product even by todays standards.The SP15 had an impressive level of drive and slam compared to the LS15 that I reviewed at the same time.The SP15 was in a different class sonically and had a marvelous top end that was not harsh or brittle. The midrange was smooth without any obvious flaws or trouble spots. Bass extension was well defined and quick.On the whole it is a very worthwhile unit with great features that would surpass all in the SP line up that I have heard. Even the latest SP16 that I have tried and did not take to.For all those who wish to know about the quality of the Phono Stage in the SP15, read on.The internal phono stage of the SP15 is the best that I have heard in an integrated component. However this is not saying much.I have done extensive comparisons with the SP15 and the separate Audio Research PH5 Phono Stage and the difference in quality is huge.As I would have expected, I was just not prepared for the level of difference that could be heard when I paired up the SP15 with the PH5. It was JAW DROPPING. If you are into your vinyl then the PH5 is a must have as you can by-pass the phono section in the SP15 while still maintaining use of all the other great benefits of this wonderful classic unit.Audio Research Corporation3900 Annapolis Lane NorthPlymouth, MN 55447-5447www.audioresearch.comPLEASE NOTE:INCLUDED IN THIS SALE ARE THE FOLLOWING:1. Two original ARC boxes with factory inserts. One (1) Set of Vacuum Tubes (Previously Used). I will remove the Tubes, prior to shipment and professionally wrap them separately from the Two (2) Amp Chassis.
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