McIntosh MI-3 Tube Maximum Performance Indicator - Rare and Serviced

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General:
The McIntosh MI-3 is a unique vintage oscilloscope designed to measure multipath distortion from stereo tuners. Using the front controls you can also set the scope mode to L+R audio, where the oscilloscope then reacts to incoming signals.

We do not get these very often, and when one is set up at our test bench it's really a treat. They look awesome at night especially! 

I purchased this from the original owner many years ago along with a gorgeous original C22 that has since sold. As much as I'd like to keep this, there's always gear here that requires testing and someone else should really enjoy this piece of history. 

The MI-3 was only produced from November 1964 to October 1969, with a total run of 1,798 units. Few fully-working serviced examples remain nearly 73 years later.

One of the coolest pieces of 1960's McIntosh equipment, and a perfect addition to any vintage system containing a tuner. Or if you want a super cool light show, it can connect to any system with a a tape or second set of outputs. This would be a perfect match with a period correct vintage McIntosh tuner, such as the MR73.

This particular MI-3 has been serviced where various age affected components were replaced. It is working wonderfully now.

This will be shipped with care in an original McIntosh box which is an absolute must for units like this with delicate vintage CRT displays.

This will ship in a brand new McIntosh double shipping carton that we ordered from the factory, along with it's original owner's manual.

If you're looking for a matching vintage wood cabinet, The L12, L12, L52, and L62 are compatible. We currently have several cabinets listed for sale you view by clicking here.

SkyFi Cosmetic Notes:
We touched up the front faceplate glass as needed, The original Panloc text is no longer present. There is also an extremely small burn-in spot in the middle of the CRT that's barely visible, but we anted to mention. Paint stain as pictured on the top cover from decades ago when someone painted the in-wall cabinet that originally housed this MI-3.

Overall condition is good for a unit this age.

SkyFi Technical Notes:
This unit received a power supply overhaul and routine service here at SkyFi. We replaced the aging electrolytic capacitors, replaced the selenium diodes with silicon parts, replaced a couple of suspect paper capacitors, cleaned all of the controls, and verified proper operation in audio and multi-path modes.

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:
Second Owner

Connections:
RCA inputs and Outputs, Captive Power Cord, Convenience outlet

Cosmetic Condition:
8/10 = Very Good. Excellent front faceplate, one minor flaw on chassis side or top. See our detailed rating description here.

Working Condition:
Working perfectly and tested in our lab.

Included:
Unit, New McIntosh Box, Original Manual, Captive Power Cord

Packing:
McIntosh new replacement double carton.

Specs:
- CRT Type: 3-inch cathode ray tube (3RP1)

Display Modes
- Oscilloscope
- Relative signal strength meter
- FM deviation meter
- Channel balance meter
- Phase indicator

Sensitivity
- Signal Strength (Vertical): 700 mV
- Audio (Vertical): 20 mV
- Audio (Horizontal): 20 mV
- FM Deviation (Horizontal): ±350 mV

Tube & Semiconductor Complement
- 1 × 3RP1 — CRT display tube
- 4 × 6EA8 — Deflection amplifiers
- 1 × 6EA8 — Voltage regulator
- 2 × OB2 — Voltage regulators
- 4 × Silicon planar transistors

Dimensions:
16.00 in x 5.44 in x 13.00

Weight:
23 lbs.

Approximate Age:
1964

Link to Manual:
Click Here