Classe Audio DR-5 All Analog Solid State Preamp with Phono - Serviced

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General:
Great all analog no-nonsense preamp from Classe. Designed and made during the best era of Classe, when David Reich was responsible for the design. You can see his signature etched with pride into the PC board.

Best of all it has a very capable phono stage switchable in the back between moving coil and moving magnet.

Notice the amazing parts selection, high quality PC board, and metal partition isolating the beefy toroidal transformer from the rest. 

Condition is very presentable and very industrial looking with the beefy handles and clean design.

Cosmetic Notes:
Light scratching on handles.
Misc marks on faceplate near rack mounting points.
Scratching on top cover.

Technical Notes:
We replaced a bunch of axial caps in the phono stage to get it working as it should.

Ownership:
Single Owner

Connections:
RCA on all inputs, XLR on single input and outputs. Removable IEC power cord, 2 convenience outlets.

Cosmetic Condition:
7/10 = Good. One or two minor scratches. Well Maintained. See our detailed rating description here.

Working Condition:
Working perfectly and tested in our lab and listening room.

Included:
Just the unit and power cord.

Packing:
Will be packed using our highly developed in-house process and custom packing materials.Specs:
Frequency response: 20Hz to 20kHz

Gain: 24dB (MC), 35dB (MM), 25dB (line)

Input sensitivity: 0.3mV (MC), 3mV (MM), 120mV (line)

Signal to noise ratio: 80dB (MC), 80dB (MM), 90dB (line)

Approximate Age:
1995

Recommended Cables:

Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

Kimber Kable - Phono Interconnects - Better

Kimber Kable - Flagship Phono Interconnects - Best

Testing Process:

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.