Kenwood SP-120

A small, gray-box ham radio speaker that existed for one reason: to match the TS-120S sitting next to it.

Overview

The Kenwood SP-120 is an external speaker for amateur radio gear. It is not a bookshelf speaker or a monitor, and nobody wires it to a stereo amp for fun. It's a communications speaker, sold to sit under or beside a transceiver and make voice intelligible. Kenwood built it, Trio sold it in Japan, and Radiomuseum catalogs it as "SP-120 Speaker-P Kenwood, Trio-Kenwood Inc." Listings show the brand as Kenwood, Trio, and Trio-Kenwood depending on which market the unit originally shipped to.

It's a small speaker. Sources consistently describe it as a 2.9-inch, 8-ohm driver with a frequency response of 300 to 5,000 Hz. That bandwidth tells you what it is - a voice-band speaker. There's no attempt at bass and none at air, just the range where human speech and CW tones live. For SSB and FM voice on the ham bands, that's the right compromise. For anything else, it isn't.

Kenwood's own documentation matches the SP-120 to the TS-120S and TS-130S transceivers. Radiomuseum's listing extends that to the TS-120S, TS-120V, TS-130S, TS-130V, and TS-130SE. It's an accessory, not a standalone product. It existed to complete a station built around one of those rigs, in looks and in wiring.

Key Features

2.9-Inch, 8-Ohm Driver

The driver is small. Sources repeatedly give it as a 2.9-inch, 8-ohm speaker. A 2.9-inch cone in a small enclosure is a compromise by any hi-fi standard, but for communications it's a deliberate choice: small drivers are efficient in the midrange, and the midrange is where SSB intelligibility lives. Eight ohms is the standard load for the transceivers it was designed to pair with, so there's no matching transformer inside and no impedance switch. It's a driver and terminals.

One caveat: a listing at speakepar.com describes the SP-120 as a "12-inch box speaker" and part of an "S-Series lineup, specifically the S-120 model." That contradicts every other source on the SP-120 and almost certainly describes a different product. Treat the 2.9-inch figure as the reliable one.

300 Hz to 5,000 Hz Response

The rated frequency response is 300 to 5,000 Hz. Universal-radio.com, eham.net, hamradio-shop.co.uk, and radioworld.co.uk all confirm it, and Radiomuseum echoes it as "Response: 300 - 5.000 Hz." That's a narrow window. It cuts everything below 300 Hz, so no rumble and no thump, and it tops out at 5 kHz, well short of the 20 kHz a hi-fi speaker would aim for. What it does reproduce sits in the range where a human voice carries its information. For CW operators and SSB ragchewers, that's fine. For music playback, it will sound thin.

Screw Terminal Inputs

Connection is by screw terminals. There are no binding posts, no 3.5 mm jack, no plug of any kind. That fits ham gear of the period: strip a bit of wire, twist it, tighten the screw. It also means the SP-120 has no cable of its own, so you supply the wire and decide how to terminate the transceiver end. One eham.net seller noted that a 1/8-inch cable wasn't included but that they're "easy to find," which suggests some buyers wire the speaker to a 3.5 mm mono plug to match a rig's output. A Yahoo Japan listing mentions a unit with a 3.5 mm plug cord already attached. That's a user modification, not a factory feature.

Plastic Enclosure with Grey Finish

Radiomuseum notes the cabinet is plastics - specifically, no bakelite and no catalin. That puts the SP-120 in the molded-plastic era of ham accessories. One German eBay listing describes the finish as "silbernes Zifferblatt mit grauem Gehäuse" - silver dial face with gray housing - which suggests a silver-toned front grille or trim on a gray body. A Japanese listing calls it a "slim body," which fits a small driver in a small box. Beyond that, the fact sheet has no dimensions, no weight, and no cabinet material specifics. Expect a compact, lightweight plastic box.

PHITS Acoustic Upgrade Compatibility

Phonema sells a PHITS acoustic material kit, part number PNE-K23A, listed as a "Speaker Sound Quality Upgrade for Kenwood SP-120, SP-430 & SP-23." The kit is designed to fit all three models, which is the only explicit product-family grouping in the research. It's an aftermarket product, not original design. It does suggest the SP-120's enclosure is close enough in size to the SP-430 and SP-23 that the same damping material fits. If you want to tame the plastic-box resonance, that kit is the documented path.

Historical Context

The SP-120 was sold in Japan under the Trio brand, and the Trio-Kenwood dual branding shows up across Japanese and Indonesian listings - yahoo.aleado.com, auctions.yahoo.co.jp, vintage-hamradio.blogspot.com, medan-radio.blogspot.com. In the export markets it was Kenwood. Same speaker, different badge.

Its documented purpose was to match specific transceivers. Universal-radio.com, eham.net, hamradio-shop.co.uk, and radioworld.co.uk all state that "the Kenwood SP-120 matches the TS-120S and TS-130S." Radiomuseum extends the list to the TS-120S, TS-120V, TS-130S, TS-130V, and TS-130SE. A vintage-hamradio.blogspot.com listing describes it as "kelengkapan lain untuk TR9000/G dan TR-9130" - an accessory for the TR9000/G and TR-9130 - and a medan-radio.blogspot.com listing calls it "Extra speaker Trio SP-120, untuk kelengkapan setline Kenwood TR-9130." So the speaker turns up paired with more than the TS-120/130 family, but the factory documentation ties it most tightly to those two transceiver lines.

One eham.net seller describes the SP-120 as the "older version of the SP-23, same size enclosure." That's a seller claim, not a manufacturer statement, but it's consistent with the Phonema kit fitting both models. No production years appear anywhere in the research, and no original price survives. The history is thin. It was a supporting accessory, not a flagship, and it left few traces beyond the transceivers it was sold alongside.

Collectibility & Value

The SP-120 trades as an accessory, not as a collectible in its own right. Prices are modest. One eham.net classified seller listed a unit at "$95 w/free shipping," describing it as looking and sounding great. Hamradio-shop.co.uk sold used units with a 90-day warranty. Universal-radio.com lists it as "Discontinued!" and points buyers to a used list. Weca.site shows "Sold out. Only 1 left!", which is the language of a small remaining stock, not a hot market.

Most SP-120s change hands as part of a package with a TS-120S or TS-130S, or as a cheap add-on for someone who just bought one of those rigs and wants the matching speaker. Indonesian and Japanese resale listings show it as a collectible accessory, and most of those are marked SOLD or terjual, but the prices aren't dramatic.

Support is better than you'd expect for a discontinued accessory. Manualslib hosts five Kenwood SP-120 manuals for free PDF download, including a service manual. JSE Repair sells a dust cover under SKU KW-sp120-cvr. Phonema's PHITS K23 kit is available as an aftermarket upgrade. The fact sheet lists no common failures, no repair procedures, and no spare parts availability beyond those aftermarket items. There's no documented failure pattern to check against, so inspect the driver and terminals carefully.