McIntosh C2500 Tube Preamplifier - Complete W/ Remote

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General:
The C2500 is one of my favorite preamps McIntosh ever made.

I used this exact listed preamp in my main system for many years until I replaced it with the flagship two-piece C1100.

While the C1100 is a formidable tube preamp and probably the best measuring unit we've tested, the C2500 comes pretty close. I do miss the convenience of the built-in DAC for streaming which the C1100 eliminated. 

The C2500 is also a gorgeous unit with its visible glass tube window on top and the highly polished stainless chassis.

It also has a fully tubed phono section for hooking up even the most demanding of MC (Moving-Coil) phono cartridges. This particular preamp sounded great in testing.

If you're considering the new C2800 and want to save on its $10,500 retail price, then this might be your best option with very little compromise.

Included will be its originial remote control, Manual, and shipping box.

Note: This unit has felt pads on rear feet for protection (completely removable if wanted).

From McIntosh:
• Electromagnetic Input Switching with Level Trim Adjustment
Digital Logic integrated circuits drive Electromag- netic Switches on all Inputs and operating functions for reliable, noiseless, distortion free switching. All eight Inputs on the C2500 can be matched in level, so there are no abrupt changes in volume levels between the different Inputs.

• Moving Coil and Moving Magnet Phono Inputs
The C2500 contains two different precision Phono Preamplifier Circuits. One for low output Moving Coil Phono Cartridges with selectable resistance loading, the other is for Moving Magnet Cartridges with select- able capacitive loading. Both circuits use the latest designs to provide the lowest possible noise and dis- tortion. The RIAA Correction Equalization Circuitry utilizes close tolerance resistors and capacitors for an extremely flat frequency response.

• Digital Audio Inputs
The C2500 has Coaxial, Optical and USB Digital In- puts to Decode PCM Signals from an external source. The C2500 Up Samples the Digital Signal to 192kHz with 32Bit resolution before the Digital to Analog process begins.

• Balanced Inputs
The Balanced Inputs allow the connection of a source component using long cable lengths without a loss in sound quality.

• Precision Tracking Volume Control
Volume levels are controlled by a new Multi-Stage Precision Digitally Controlled Attenuator System with superb tracking accuracy.

• Variable Rate Volume and Balance Controls
The C2500 Tube Preamplifier’s Volume and Balance Control Circuitry provides an ideal rate of change with control rotation.

• Remote Control with External Sensor Input
The Remote Control provides control of the C2500 operating functions and McIntosh Source Components connected to it. Enjoy your McIntosh System from another room in your home by connecting an external sensor.

• Special Power Supply
Fully regulated Power Supplies and a special R-Core Power Transformer ensure stable noise free operation even though the power line varies.

SkyFi Cosmetic Notes:
Has felt pads on rear feet (completely removable if wanted). Has slightly cloudy glass, visible mostly around the center screen. Overall condition is good.

Brand Background:
McIntosh Laboratory is an American manufacturer of handcrafted high-end audio equipment based in Binghamton, New York. The company was founded in 1949 by Frank McIntosh. The company designs and produces audio amplifiers, stereo tuners and other consumer electronics products.

Ownership:
Single Owner

Connections:
XLR, RCA, Power Control, Optical Digital

General Sound:
Smooth, uncolored, undistorted natural and clean

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:
Unit, remote, manual, box, and power cord.

Packing:
Original Manufacturers Packing

Original MSRP:
$6,500.00

Specs:
Frequency Response
+0, -0.5dB from 20Hz to 20,000Hz 
+0, -3dB from 10Hz to 100,000Hz
Total Harmonic Distortion
0.08% from 20Hz to 20,000Hz
Rated Output (Main)
2.5V Unbalanced, 5V Balanced
Maximum Output
8V RMS Unbalanced, 16V RMS Balanced
Sensitivity (for rated output)
High Level, 450mV unbalanced, 900mV balanced 
Phono MM, 4.5mV
Phono MC, 0.45mV
Signal To Noise Ratio (A-Weighted)
High Level, 100dB below rated output 
Phono MM, 75dB below 5mV input Phono MC, 75dB below 0.5mV input
Input Impedance
High Level, 22K ohms unbalanced, 44k ohms balanced
Phono MM, 47K ohms; 50 to 750pF, in 50pF steps 
Phono MC, 25, 50, 100, 200, 400 or 1,000 ohms; 100pF
Maximum Input Signal
High Level, 8V Unbalanced, 16V Balanced 
Phono MM, 80mV
Phono MC, 8mV
Voltage Gain
High Level to Record Output: 0dB 
High Level to Main Output: 15dB 
Phono MM to Record Output: 40dB 
Phono MC to Record Output: 60dB
Output Impedance
220 ohms
Headphone Impedance
20 ohms to 600 ohms
Digital Input Sample Rates
Optical: 16Bit, 24Bit - 32kHz to 96kHz 
Coaxial: 16Bit, 24Bit - 32kHz to 96kHz
USB: 16Bit, 24Bit, 32Bit - 32kHz to 192kHz
Power Control and Trigger Output
12VDC, 25mA

Dimensions:
Width is 17-1/2 inches (44.45cm) Height is 7-5/8 inches (19.37cm) including feet Depth is 18 inches (45.72cm) including the Front Panel, Knobs and Cables

Weight:
30 lbs.

Link to Manual:
Click Here

Recommended Cables:
Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

Kimber Kable - Phono Interconnects

Kimber Kable - BALANCED XLR Connectors - Better

Kimber Kable - BALANCED XLR Connectors - Best

Kimber Kable - Power Cords - Better

Kimber Kable - Power Cords - 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 PCBs 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 1 KHz 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 1 KHz 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.