RCA 70-C1 (1945)
A broadcast turntable built for NBC's transcription racks, with a switchable NAB equalizer.
Overview
The RCA 70-C1 is a transcription turntable. That means a record player built for radio stations, not living rooms, designed to spin the large-diameter transcription discs that carried prerecorded programming in the 1940s. RCA Victor built it in the United States, and the model is generally dated to 1945. Radiomuseum.org lists the build year as "1945 ??" with its own question mark, and microgroove.jp cites 1945 flatly. So the year is close to confirmed but not nailed down.
The 70-C1 exists for its playback equalization. It carries switchable playback equalizers offering the NAB lateral curve, with the response flat above 500 Hz. Before the RIAA curve standardized playback in the 1950s, a broadcast turntable had to be told what curve it was reading, and the 70-C1's switching let an engineer match the disc in hand. That is the only concrete technical specification that survives in accessible documentation. There are no published figures for speed, motor, platter, dimensions, weight, or power requirements that can be confidently attributed to this model. Anyone claiming otherwise is likely repeating a listing or a misfiled spec from a different product.
Where the 70-C1 sat in service is well documented. RCA's own technical papers from 1947 reference "The RCA 70-C1 'Transcription Turntable', NBC Eng. Division, Princeton, N. J.," and the same paper trail cites an NBC Engineering Notice (Recording) No. 37 issued from National Broadcasting Co. in New York in January. One sales listing states the turntable was originally used for broadcasting by the NBC network. RCA Broadcast News coverage of broadcast facilities shows "RCA 70-C Turntables" installed alongside RCA 76-B2 Consolettes and RCA 44-BX microphones. Be careful there, since that source says 70-C, not 70-C1, and the two should not be conflated.
Key Features
Switchable NAB Lateral Equalization
The 70-C1's defining feature is its bank of switchable playback equalizers, which microgroove.jp documents as offering the NAB lateral curve with flat response above 500 Hz. In practice an operator could select the correct playback characteristic for a given transcription disc instead of living with a single fixed curve. It looks fussy today. Depending on which disc was on the platter, the wrong curve would sound thin or boomy.
Transcription-Duty Build
RCA catalogued the 70-C1 as a transcription turntable, a category distinct from consumer record players of the period. The designation reflects its role in broadcast facilities, not any published mechanical specification, because none has survived in the accessible record. The model appears in RCA's own broadcast-facility documentation alongside consolettes and microphones, which places it in professional installations rather than home hi-fi.
NBC Engineering Pedigree
The 70-C1 is tied directly to NBC's engineering division in Princeton, New Jersey, per the title of RCA's 1947 technical paper on the unit. That is the clearest evidence of how the turntable was developed and who it was developed for: a network engineering group specifying a playback machine for its own transcription needs.
Historical Context
The 70-C1 belongs to the pre-RIAA era of record equalization, when playback curves were a per-label, per-disc negotiation rather than a standard. Microgroove.jp cites the 70-C1 as an example of a professional transcription turntable equipped with switchable equalizers in that context, and mentions it alongside the RCA 70-D of 1948, the later model that followed it into the same equalizer discussion. RCA's technical papers from 1947 preserve the model's documentation trail, including the NBC Engineering Notice from January of that year. Beyond that paper record, little about the 70-C1's production run, quantity, or service life has surfaced in accessible sources.
Collectibility & Value
Surviving 70-C1s turn up occasionally, usually attached to period tonearms and cartridges. A listing described as "Vintage RCA 70-C1 16" Transcription Turntable +MI-4875 Tonearm +Cartridge -Lathe" was noted on the HiFi Haven forum as having been in deep storage for decades, and the MI-4875 tonearm and cartridge are the accessories most often seen bundled with the turntable. The "16-inch" figure comes from that listing title alone. Treat it as single-source and listing-derived, not a confirmed platter specification.
Pricing is murky. A shopozz.ru listing showed 294,090₽ for what appears to be a bundled lot - an RCA 70 transcription turntable with a Rek-O-Kut 160 tonearm, a Fisher 6BQ5 amplifier, and other pieces - so that figure cannot be read as the turntable's standalone value. No confirmed current market price for a 70-C1 by itself has been established. Sales listings describe the model in the usual breathless terms ("a beautifully preserved relic of a bygone era," "a piece of audio history"), which is marketing copy, not an assessment. There is no documented failure pattern or repair guidance specific to the 70-C1 in the available record, so buyers should inspect mechanical condition on their own terms. Operation footage exists online for those who want to see one running before committing.
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