McIntosh C70 Limited 70th Anniversary Edition Tube Preamplifier - Factory Sealed New Old Stock

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General:
This beautiful limited edition tube preamplifier was manufactured from 2018-2020 to celebrate 70 years of McIntosh.

This is 1 of only 70 made! New Old Stock Condition, factory sealed.

Similar in feature set to the Modern C22, this is an extremely capable preamp. 

This particular C70 is #58. Originally made to be paired with the MC2152 70th Anniversary Edition tube amplifier which was also limited to 70 amplifiers produced.

Perfect for a collector, or for someone who wants a New Old Stock preamp to use right away. 

Standout Features include:
- All analog design
- (5) 12AX7A and (1) 12AT7 vacuum tubes
- Moving Coil and Moving Magnet phono inputs

From McIntosh:
- The C70 70th Anniversary Vacuum Tube Preamplifier harkens back to yesteryear with an all analog design and a retro look.
- The glass front panel is inscribed with special 70th Anniversary lettering.
- Features (1) 12AT7 and (5) 12AX7A vacuum tubes that are visible through a glass panel on the top cover.
- All control operations are done via knobs and rocker switches. Modern LED indicators will denote input selection and volume level.
- Inputs consist of two balanced and three unbalanced inputs, plus one each of Moving Coil and Moving Magnet phono inputs. There are two pairs each of balanced and unbalanced outputs.
- Our High Drive headphone amplifier is included and features our Headphone Crossfeed Director (HXD®) technology.
- Power Control can automatically turn other connected McIntosh components on and off.
- Sits atop a beautiful polished stainless steel chassis and features the timeless McIntosh black glass front panel, illuminated logo, control knobs, and aluminum end caps.
- Pairs perfectly with the MC2152 70th Anniversary Vacuum Tube Amplifier

SkyFi Cosmetic Notes:
Some light wear on box, unit factory sealed brand new.

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.

Connections:
RCA, XLR, IEC Power

Cosmetic Condition:
New = Factory sealed and unopened. See our detailed rating description here.

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

Included:
Complete Kit as it Left the Factory

Packing:
Original Manufacturers Packing

Specs:
Frequency response: 15Hz to 100kHz
Total harmonic distortion: 0.08%
Gain: 60dB (MC), 40dB (MM), 15dB (line)
Input sensitivity: 0.45mV (MC), 4.5mV (MM), 450mV (line)
Signal to noise ratio: 75dB (MC), 75dB (MM), 100dB (line)
Output: 2.5V (Pre out), 8V (Pre out Max)
Valve complement: 1 x 12AT7, 5 x 12AX7A

Dimensions:
17-1/2” (44.45cm) x 6” (15.24cm) x 18” (45.72cm)

Weight:
25 lbs.

Approximate Age:
2018

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.