McIntosh MI3 Tube Maximum Performance Indicator - Restored in 2023
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 often so when these are set up at our testing bench it is a treat.
They look awesome at night especially!
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 output. This would be a perfect match with a vintage McIntosh tuner such as a MR73.
This will be shipped with care in an original McIntosh box which is an absolute must for units like this with CRT displays.
SkyFi Cosmetic Notes:
This is a super clean example of the MI-3. We cannot find any noticeable imperfections in the glass and the chassis is also in very good shape.
The included manual is a reprint, not an original document.
SkyFi Technical Notes:
This device was restored by Analog Sound Labs in 2023. The restoration included an extensive rebuild of the power supply.
We double checked the performance of the unit with an MR78. The CRT is bright with only light burn in spots to the right of the center mark.
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
General Sound:
Accurate to the recording
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, Box, Manual
Packing:
Original Manufacturers Packing
Specs:
Specifications
- 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
Description
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 often so when these are set up at our testing bench it is a treat.
They look awesome at night especially!
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 output. This would be a perfect match with a vintage McIntosh tuner such as a MR73.
This will be shipped with care in an original McIntosh box which is an absolute must for units like this with CRT displays.
SkyFi Cosmetic Notes:
This is a super clean example of the MI-3. We cannot find any noticeable imperfections in the glass and the chassis is also in very good shape.
The included manual is a reprint, not an original document.
SkyFi Technical Notes:
This device was restored by Analog Sound Labs in 2023. The restoration included an extensive rebuild of the power supply.
We double checked the performance of the unit with an MR78. The CRT is bright with only light burn in spots to the right of the center mark.
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
General Sound:
Accurate to the recording
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, Box, Manual
Packing:
Original Manufacturers Packing
Specs:
Specifications
- 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
