McIntoshMI-3usedMcIntosh MI-3 Maximum Performance Indicator - RARE and ServicedThis is a 2nd and last unit that we have. Its cleaner than the first and the faceplate, lettering and metal trim are near perfect. No scratches or dings on the face or trim at all. There is a sl...2500.00

McIntosh MI-3 Maximum Performance Indicator - RARE and Serviced [Expired]

no longer for sale

This is a 2nd and last unit that we have.  Its cleaner than the first and the faceplate, lettering and metal trim are near perfect.  No scratches or dings on the face or trim at all.  There is a slight bit of tarnish, but we know you vintage guys know how to polish that up.  The top and sides have a few scratches but nothing serious.  Slide this into a wooden case and it will look new!

If you're a McIntosh lover or a collector you won't want to miss this.  These are pretty rare and super cool.  The McIntosh Ml-3 is five laboratory instruments combined into one compact instrument. It is a professional oscilloscope, relative signal strength indicator, calibrated FM deviation meter, calibrated balance meter, and phase indicator.

These instruments are used by FM stations to determine the best possible performance for your listening enjoyment.  We simply hooked it up to a tape output to monitor the right and left channel signals.

The McIntosh Ml-3 Maximum Performance Indicator makes it easy for you to attain professional broadcasting quality FM listening.

The McIntosh Ml-3 shows you what you need to do to improve your system's overall performance. It is designed to be used with an FM tuner and stereo preamplifier.

When the Ml-3 is used with an FM tuner it will detect and display multipath reception. Multipath reception is the result of a reflected signal arriving at the tuner antenna slightly later than the direct signal. By rotating or repositioning your FM antenna it is possible to reduce the multipath reception. The Ml 3 Maximum Performance Indicator makes it easy to know when the FM antenna is oriented for the best reception of any station.

To show multipath reception the Ml 3 displays instantaneous signal strength versus frequency deviation. Signal strength is shown as vertical deflection of the indicator display beam. Frequency deviation is shown as horizontal deflection. Multipath reception appears as a peak or valley in the Ml 3 picture tube display.

The Ml-3 is a very effective tuning indicator:

1. Signal strength is shown by the vertical position of the display trace. The higher the position of the trace the greater the signal strength.

2. Correct tuning occurs when the display trace is centered horizontally on the screen. Since the display trace effectively follows the tuner I.F. response curve, centering the trace tunes the detector to the center of the I.F. curve.

The Ml 3 Maximum Performance Indicator is a versatile instrument.

When used with either a stereo preamplifier, or power amplifier the Ml 3 when switched to the L+R AUDIO position will show you the character of the audio signals present. The Ml 3 will:

1.  Display a trace along the L+R line when a monaural program is playing.
2.  Will display along the L—R line when a monaural program source has one channel out of phase.
3.  Display a vertical trace if only the left channel is being de- livered.
4.  Display a horizontal trace when only the right channel is being delivered.
5.  Helps you set the precise balance of your system. With the balance control you can change the angle of the L+R or L — R display.
6.  A stereo program will be a complex and varying circular or elliptical display of irregular outline that depends on channel separation or on the phase amplitude relation of the left and right channel.


  • Audio display level

  • L/R Audio, Multipath and Test setting

  • Scope position, focus and intensity controls

  • RCA inputs and outputs

  • Real glass face


  • SENSITIVITY - Signal Strength  (vertical) Input: — 700 MV, Left Audio (vertical) Input: 20 MV, Deviation (horizontal) Input: ±350 MV, Right Audio (horizontal) Input: 20 MV

  • DIMENSIONS - 16" W x 5-7/16" H x 13" D 

    1— 3RP1, 3 inch cathode ray tube
    4— 6EA8, horizontal and vertical deflection amplifiers
    1— 6EA8, electronic voltage regulator
    2— OB2, voltage regulators
    1— Selenium rectifier, high voltage rectifier
    6— Selenium rectifiers, low-voltage supply
    4— Silicon planar transistors


CONDITION -  This unit was used in a non-smoking, private home studio.  The front glass and trim are free of scratches and there is no separation.  There are some scratches and scuffs on the top and sides.  We are an authorized McIntosh Service Center and It's been fully tested in our service department and guaranteed to work perfectly. 

SHIPPING - We ship worldwide with UPS, Fed-Ex and various truck freight lines.  All items are packed and padded with care if the original packaging is deemed insufficient.  We know how exciting it is to anticipate the arrival of new gear and we want your item to arrive in the same condition it left our facility.

TAX - 6.5% if picked up in our store or shipped to a FL address. 0% if shipped outside Florida.

 ABOUT US -  Salon One Audio is a small town, hi-end audio store dedicated to a great customer experience.  We've been selling new, pre-owned and demo audio gear since 1986.  We'll treat you right whether its a new purchase, trade-in, upgrade or you just need some expert advice.  We offer excellent trade-in values and package discounts.  We are also authorized distributors for most lines we carry.

Great audio is a journey not just a purchase.  We'll guide you to the best gear within your budget and are always available for after the sale support.


(407) 953-9596

[email protected]



member since August 2004

Salon One Audio  Verified Dealer

Last 12 months
Items from this seller