Nakamichi ST-7 Vintage AM/FM Tuner - Super Clean

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General:

More from Nakamichi:
"The Nakamichi ST-7 is a digital synthesis tuner with the latest Schotz Noise Reduction technology.

This revolutionary system improves effective stereo sensitivity by about 9db and lets you enjoy clean stereo on broadcasts that previously could only be received in mono.

Other features include seek and manual tuning as well as 16 FM/AM presets that can be programmed at random, thus combining convenience with top-level capability."

Super clean unit with little to no signs of use.

Great match to a CA-5 or CA-7 Nak preamp.

Brand Background:

Nakamichi was founded in 1948 by Mr. Etsuro Nakamichi, starting from a small research institute in Tokyo, Japan that provided R&D for major brands, government entities, universities and organizations.

Since then, it has established itself as a trusted creator of high-quality audio products, such as the Nakamichi 1000, the world's first 3-Head cassette deck.

Nakamichi's product lines are driven by an intense scientific curiosity, the passion for audio, and commitment to uncompromising quality and performance.  

Ownership:

Single Owner

Amplifier Recommendation:

Nakamichi PA-5AII

Connections:

RCA analog outputs, Coax antenna input, standard power plug for US market. 

General Sound:

Neutral sound with little to no coloration 

Cosmetic Condition:

8 - Very Slight Signs of Use

https://skyfiaudio.com/pages/our-rating-scale

Working Condition:

Working perfectly and tested in our lab.

Included:

Tuner, captive power cord, and owner's manual.

Packing:

Will be packed using our highly developed in-house process and custom packing materials.

Dimensions:

17.13" x 2.48" x 11.38"
(435 x 63 x 289mm)

Weight:

10 lbs.

Age:

1989

Link to Manual:

https://cdn.shopify.com/s/files/1/0003/3275/9084/files/Nakamichi-ST-7-Tuner-Manual.pdf?v=1671206743

Recommended Cables:

Kimber Kable - RCA Interconnects - Good

Kimber Kable - RCA Interconnects - Better

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. 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.

Specs:

Tuning Reception:
AM, FM

Tuning Scale:
Digital

Sensitivity:
1.7uV (FM)

Signal to Noise Ratio:
76dB (FM), 48dB (AM)

Distortion:
0.08% (FM), 0.4% (AM)

Selectivity:
60dB (FM), 20dB (AM)

Frequency Response:
20Hz to 15kHz (FM)

Output:
500mV (FM), 200mV (AM)