JVC RC-M70

Built in 1980, the RC-M70 sits just under the RC-M90 within JVC's boombox range. It is quite possibly the single best mid-sized boombox ever, in terms of the whole package deal. The others don't offer the same combination of power, performance, features, looks, build quality, and availability. It was a very successful model for JVC, so even today it's very easy to find one for sale. Although HiFi enthusiasts would probably never say JVC was one of the best home hi-fi manufacturers, it's a different story with boomboxes. JVC was clearly one of the best in that product category. The M70 is a perfect example of what one seeking a quality boombox would ask for. Great looks, great performance, portability, auxillary inputs and outputs for flexibility, power to spare for external speakers, sensitive tuner, very reliable tape mechanism, and sturdy construction.

Specifications:

• 6.5 inch (16cm) woofers
• 2 inch (5cm) tweeters
• Two AN7145K(H) amplifier chips (made by Matsushita/Panasonic)
• Output: 2x7 watts minimum from 100 to 15,000 Hz into 8 Ohms, at no more than 10% THD. The "maximum" output is a claimed 2x15W.
• The tape deck's wow & flutter is 0.065%.

Optional accessories included the JVC MU-103E electret condenser microphones (impedance 1 kOhm +/-30%) which require two to get stereo, or the M-201/T/U, a 600 ohm microphone that only needs one for stereo.

Service Manual

The service manual can be purchased here: AnalogAlley.com

Model Variants:

There are several model variations of this boombox. The first one isn't rare at all. You can find at least 10 of them on Ebay every single week. But the other ones are less common.

1. JVC RC-M70 C, L, LB, or JW, depending on which country it was sold in.
2. JVC RC-M71 (This has gold tint and slightly different trim).
3. JVC RC-M75 (This also has gold tint like the M71, but it's got 3 extra knobs under the tape door).
4. Victor RC-M70 and RC-M70GX (These are badged "Victor" instead of JVC because they were sold only in Japan. The voltage is 100 volts. They've got the extra knobs under the tape door. The GX version has gold grills).

Here's a photograph of the Victor RC-M70's tuner dial. It has 2 bands instead of 4 or 6.

As mentioned, the Victor models have extra knobs under the tape door. These control tape pitch and speed. The example shown below was modified by its owner, changing the 76-90 MHz Japanese FM tuner to an international-spec 6-band tuner:

Label and top panels showing the Japanese writing:

Common Issues:

The RC-M70 line has turned out to be a very robust and reliable design. There are however a few idiosyncratic issues known to affect this model:

• Worn slide controls. JVC employed Alps branded sliders for the slide controls and over time, the internal feelers break off and/or the internal resistor board has fractures on the traces. These controls are now obsolete but enthusiasts have found ways to repair these.
• Power Switch. The power switch is a brass leaf design that sometimes fail. Filing, bending the contacts or leafs are sometimes the only way to repair them. These parts are obsolete.
• Muting Circuit. A failed muting circuit can sometimes result in extremely attentuated output at the speakers.
• Failed voltage regulator: The M70 employs several internal voltage regulators and failure will affect only the circuits powered by that particular regulator. The most common regulator to fail is the X505 regulator which also powers the tuner dial lamp and parts of the cassette deck.

Modifications:

This model just may be the most modded boombox model.

• LED tuner mod:
  • Several years ago, an enthusiast performed an LED upgrade of the tuner dial. This mod was so well received that the mod was packaged and offered as a kit (which is available HERE. It remains an extremely popular mod today. And no wonder, because the difference is night and day compared to the original design. Additionally, this mod includes a modification of the switching circuit so that the lamp can remain on. The original design required you to push the switch to illuminate the lamp.
• Refinishing the cabinet:
  • In 2009, member Superduper of Boomboxery.com refinished an M70C in a maroon color. That same boombox is part of Wikiboombox and Boomboxery member Superduper's avatar here. Since then, M70's have been repainted in many many colors. One enthusiast in California has a collection of several M70's, all painted a different color, and another collector in SoCal painted his and called it the Van Halen edition . The M70 may be the most repainted boombox we know of.

A Victor RC-M70 with blue LED dial lamps:

Superduper's Maroon RC-M70:

Community Member (Lasonic TRC-920)'s 'Van Halen' edition

Click HERE to return to the JVC page, or HERE to see the list of all manufacturers.