Audio Research LP1 Phono Preamplifier
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Audio Research LP1 Phono Preamplifier
479 South Broad Street
Glen Rock NJ 07452
Tube phono preamp from Audio Research which provides 47db of gain, good for all MM cartridges and High Output MC cartridges.
Tough to beat at this price range, specially for a tube unit.
"The LP1 is a departure for us in both size and series designation.
The chassis is a compact 13” wide, by 8.6” deep, by 4.5” high. The front panel has the inset Audio Research logo with an engraved line completing the panel, but no handles. There are simply two switches for Power/Off and Mute/Operate. The entire chassis is silver, and the front panel is only available in Natural.
The LP1 has 47dB of gain, perfect for higher output (>1.0mV) MM and MC cartridges. It is a hybrid design utilizing one 6H30 tube, special low noise JFETs, custom Audio Research designed power transformer (made in the U.S.), and multiple stages of regulation. There is no overall feedback, and it is noninverting. Inputs and outputs are single-ended.
The LP1 simply sounds wonderful, with great transparency and a lovely tonal balance. Typically Audio Research, the LP1 has dynamic life, passing gobs of information and sorting out the most complex musical passage. Airy on top, resolute on the bottom, the LP1 is fun to listen to and distances itself from the competition. Put it in any system at hand and have a great time with your favorite vinyl."
Audio Research continues its dedication to unparalleled musical expression and crafting components of the highest quality and lasting value for its customers. Our long-term dedication to service is peerless in this industry (Audio Research, with few exceptions, can repair anything ever produced during its entire history). We continue to seek out new and exciting ways to make music more real and more enjoyable. More than just a name or a marketing tool, Audio Research has come to represent exceptional performance and long-term value. Experience Audio Research – experience High Definition®.
RCA inputs and outputs, IEC power cord. Grounding Lug.
Smooth, uncolored, undistorted natural and clean
8/10 = Very Good. Excellent front faceplate, one minor flaw on chassis side or top.. See our detailed rating description here.
Working perfectly and tested in our lab and listening room.
Unit, manual, and power cord.
Will be packed using our highly developed in-house process and custom packing materials.Reviews:
FREQUENCY RESPONSE: ± 0.3dB of RIAA, 10Hz to 20kHz.
DISTORTION: Less than .019% at .5V RMS SE output.
GAIN: 7dB at 1kHz.
SWITCHES: Power, Mute.
INPUT IMPEDANCE: 47k ohms (0.7 to 7mV high output cartridge recommended).
OUTPUT IMPEDANCE: 5.5k ohms Single Ended (Single Ended RCA connectors). 60k ohms minimum load and 100pf maximum capacitance.
OUTPUT POLARITY: Non-Inverting.
MAXIMUM INPUTS: 40mV RMS 1kHz, 100mV RMS 10kHz.
RATED OUTPUTS: .0.5V RMS Single ended into 100k load (maximum output 15V RMS at 1% THD at 1kHz).
POWER SUPPLIES: Electronically-regulated low and high voltage supplies. Automatic 40 sec. warm-up/brown-out mute. Line regulation better than .01%.
NOISE: 0.4μV RMS IHF weighted equivalent input noise, shorted input 74dB velow 2mV RMS 1kHz input).
TUBE COMPLEMENT: (1) 6H30 dual triode.
POWER REQUIREMENTS: 100-135 VAC 60Hz (200 - 270VAC 50/60Hz) 35 watts maximum.
11.3" (33 cm) W x 4.5" (11.4 cm) H x 8.6" (21.8 cm) D. Rear chassis fittings
Link to Manual:
Kimber Kable - RCA Interconnects - Better
Kimber Kable - Phono Interconnects - Better
We start with a visual inspection of all internal components to make sure that there are no signs of heat stress or damage. Capacitors are checked for telltale signs of predictive failure including bulging, shrunken wrappers, or physical leakage. We also inspect the PCB’s for discoloration from resistors or transistors that may have been running hot. On vintage units we often spot check select capacitors for value and ESR.
When we first power on a preamplifier we connect its RCA output to a Sencore PA81 Power Analyzer which simulates real world loading conditions and gives us an oscilloscope interface. The first order of business is checking that the volume control works smoothly throughout its entire range with acceptable channel balance. This is accomplished by feeding a 1KHz sine wave into one of the preamp’s line level inputs while monitoring the preamp’s output on an oscilloscope. We then switch to a 1KHz square wave to test the tone controls, loudness function, and filters where applicable. During this step we are watching for equal alteration of the test signal by both channels. This also helps us identify dirty controls that will need treatment. Once the basic line stage functions are verified, we test each input individually. This is especially important for devices that use relays to select their sources. If the preamp is equipped with a phono stage we test that as well. We use an inverse RIAA filter which allows us to feed a reference test signal into the phono input with the proper RIAA equalization and level. A square wave or sine sweep is used to verify that the device’s phono stage is faithfully reproducing the RIAA curve. If the preamp under test has balanced inputs and/or outputs these are tested as well.
We finish up our bench testing with a listening test with our bench amplifier and reference speakers. During this test we check for hum or hiss that may not have shown up in earlier testing. We also check that all of the tone controls and filters perform as expected. If the preamplifier has remote control functions these are also tested. Preamps with tube circuits or complicated power supply topologies are connected at our long term test rig for extended stress testing under real world conditions.