Audio Research SP9 MK II Tube Hybrid Stereo Preamplifier





For your consideration; a beautiful AR SP9 – MK II Tube Hybrid Preamp with NEW Amperex Bugle Boy tubes.  This unit is in excellent condition and sounds great.

To purchase contact us for a discounted shipping quote(763) 575-7447 or       

SP9 MKII (1991)

The SP9 Hybrid Stereo Preamplifier represents a further evolution of the innovative electronic design first embodied in the widely acclaimed Audio Research SP11 Stereo Preamplifier. The SP9 is not a “stripped-down” version of the SP11, but rather represents an adaptation of some of the SP11’s patented hybrid technology to a simpler, more economical single-chassis format.

Using just two 6DJ8 vacuum tubes (one in the phono section and one in the high-level stage) in intermediary gain stages, the SP9 expresses the musicality and natural “rightness” vacuum-tube preamplifiers have been noted for, yet it does so with the quickness and dynamic vigor of the best solid-state designs.

Technically, the Mark II version of the SP9 preamplifier includes a group of 14 different improvements, utilizing 61 component and wire changes. These combine to provide enhanced reliability and flexibility, in addition to the sonic improvements.

– In the CD unit the gain has been reduced by 12 dB, allowing operation of the gain control in its mid rotation or high positions, while still leaving all other inputs with normal gain for lower input program sources.

– Low-level hum in the line section is reduced 10-20 dB, which is noticeable primarily in systems with high-efficiency speakers, small “live” rooms, high-gain power amps, or low-noise CD program sources.

– The power supply and phono sections are “beefed up” to prevent accidental damage if a CD source is mistakenly connected to the MC phono inputs and is played at a high level, even with the mute on.

Although the SP9 contains an on-board power supply (as opposed to the SP11’s isolated supply), it is a highly advanced, tightly regulated design employing a shielded toroidal power transformer to minimize any potential problems of mechanical noise or hum. Location of this transformer in relation to special low-hum input circuitry has been optimized within the SP9 chassis layout to virtually eliminate transformer-related noise. (Note that while outboard power supplies have become a popular design trend among high-end audio manufacturers, simply isolating the power supply from the main chassis has little benefit if the basic design of the supply itself is second-rate. In such cases, outboard isolation may be little more than a cosmetic cure for more serious deficiencies.)

While the SP9 is designed to provide superb playback from phono records, its high-level circuits have also been optimized for other popular input sources, including compact discs. In this respect, the SP9 is virtually overload proof, insuring maximum enjoyment of today’s most dynamic program material. And, with two tape monitor loops, the SP9 offers the tape dubbing flexibility so many listeners want but seldom find in an audiophile-grade preamplifier.

Of course, all controls and switches used in the SP9 have been carefully specified and selected to insure minimal sonic degradation – as have the other active and passive components used in the construction of the SP9.

Return Policy

All units are sold with a 90 day warranty  period in which you can exchange them for full the purchase price (less any shipping charges) towards any other unit we have in stock.  Any unit which proves to be defective within ten days of delivery can be exchanged for the same model or a suitable replacement. In the event a replacement unit is not available, we will refund the purchase price. We will pay the shipping costs for replacement merchandise. Any non-defective merchandise returned for credit will be subject to a 15% restocking charge, with the buyer paying all shipping charges. Please call us at (763) 575-7447 for a return authorization number. No returns will be accepted without a valid return authorization number.

Equipment must be repacked exactly as it was packaged when it was originally shipped to you; all packing materials intact double boxed, etc., in order to avoid shipping damage. Equipment initially returned as defective, where the defect cannot be verified, will incur a 15% restocking charge.