Marantz 10B Vintage Analog Tube Tuner - Top 3 Tuners Ever Made and Highly Collectible

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General:
The Marantz 10B remains one of our all time favorite FM Tuners. This unit was designed and constructed in the mid 1960's and features all vacuum tube circuitry. The 10B consistently ranks high in shootouts among the best tuners of all time, and rivals the performance of more advanced solid state designs for both selectivity and sensitivity. 

The built-in scope and muting features offer an enjoyable user interface while the all tube output section makes listening to FM broadcast a truly enjoyable experience. Pair this unit up with a Marantz 7 preamp and an 8B (or a pair of 9's) for a taste of the best of the best from the Golden Age of American tube audio.

This specific 10B is in very good condition considering its age, showing only minimal wear. Our physical inspection revealed that the "4" digit in the "94" on the dial is fading, a bit of light bleed through the stereo pilot lamp, and a small burn-in spot in the middle of the CRT. We also added a set of reproduction feet to the bottom cover as this unit was pulled from a custom built-in console and had no feet installed.

Our initial bench testing of the tuner revealed surprisingly good performance. The circuitry appears to be all original and all features worked as intended, with only minor issues which we have since corrected with bench alignment. The IF portion of the 10B was actually aligned in an oven during production to minimize drift from temperature variation. We left the IF circuitry untouched but did perform an alignment on the front end to correct some issues with dial tracking. The dial now tracks within 0.1 MHz through the entire band. We also touched up the other adjustment trimmers to optimize scope performance, stereo separation, stereo balance, and muting threshold.

On our long term listening tests this 10B did not disappoint, pulling in stations that many other tuners struggle with in our shop. The scope makes it so easy to tune in stations and adjust antenna placement.

What more could you ask for in an analog FM Tuner?  

Check out our YouTube video from a previous 10B we listed for sale (Not this 10B):

Recommended Cables:

Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best 

The SkyFi Testing Process for Tuners:

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. Vintage analog tuners also have moving parts related to the tuning gang and dial string. These parts are inspected for smooth operation.

If the unit passes visual inspection it is bench tested for a handful of key performance parameters using a Sencore SG80 AM/FM Stereo Analyzer. The SG80 allows us to “simulate” an ideal radio station using precision test signals instead of music. This device, in conjunction with an oscilloscope allows us to properly evaluate the following parameters:

1.  AM Reception (Where Applicable)

2.  FM Mono Reception & Tuning Meter Function

3.  FM MPX Reception (Stereo)

4.  Dial Tracking - How accurately the tuner dial or display indicates the actual frequency of the broadcast being received.

5.  Stereo Separation - A properly working stereo tuner will have minimal crosstalk between the left and right channel.

6.  Sensitivity & Signal Strength Meter Function - By lowering the output of the SG80 we can simulate weak stations and determine how well the tuner will be able to pull in weak distant stations. This adjustment also helps us verify signal strength meter function.

If the tuner has acceptable performance related to the parameters above we connect the unit for listening tests with a simple dipole antenna. We listen for audio reproduction quality of local stations and evaluate how many stations the tuner can receive while we sweep through the dial. We are looking to verify that the tuner can decode stereo on strong local broadcasts and pick up a wide variety of local stations at the bottom, middle, and top of the frequency band. At this point we also test convenience features such as muting, filters, built in oscilloscope function, etc.

We finish up with an extended listening test on our long term test rig. We tune in a strong local station and monitor for drift over a 2-3 hour period.