Digitally Remastered User & Technical Manual
The RCA 88A is one of RCA’s early broadcast ribbon microphones, developed during the formative years of professional studio recording. Designed for natural voice capture and orchestral balance, the 88A reflects the foundational ribbon engineering principles that shaped decades of broadcast sound. The RCA 88A was introduced in the early 1930s, with production generally placed circa 1933 through the late 1930s.
It was part of RCA’s early ribbon (velocity) microphone development period, following the commercial success of the 44A (introduced 1931–1932). The 88A represents one of RCA’s formative broadcast ribbon designs before the later refinements seen in the 44BX and 77 series. During this period:
RCA was rapidly expanding its broadcast equipment division.
Ribbon microphone technology was still relatively new.
The 88A helped establish RCA’s reputation for smooth, natural voice reproduction in radio studios.
By the late 1930s, RCA shifted emphasis toward newer refinements in the 44 and emerging 77 series, and the 88A gradually disappeared from active catalogs.
As with all RCA broadcast equipment, the MI (Master Index) number identifies the complete factory assembly as sold through RCA Broadcast Sales to radio stations, schools, churches, and commercial facilities.
The “MI” prefix stands for Master Index — RCA’s internal product numbering system used for broadcast equipment sold to stations and institutional clients. MI-4048 identifies the complete microphone assemblies sold through RCA Broadcast Sales channels. This manual covers versions -A, -C and -D.
About the 88A Series
Original operating instructions
Technical specifications
Polar response characteristics
Internal construction and transformer data
Wiring diagrams and schematics
Service and care procedures
As with all passive ribbon microphones, proper impedance matching, gain staging, and careful handling are critical. Accurate schematics and wiring diagrams help protect ribbon and transformer integrity while ensuring optimal performance.
This enhanced digital edition restores readability to aging original documents, delivering crisp diagrams and legible technical detail without altering original content.
Ideal for vintage microphone collectors, recording engineers, restoration technicians, and historians preserving classic RCA broadcast equipment.
If you own or are contemplating purchasing one of these microphones for use or restoration this manual is INVALUABLE for that process. Each technical drawing has been painstakingly restored so the schematics are clear.
Original RCA manuals from the late 1930s period are often: Lightly printed on thin stock; Faded or yellowed; Difficult to read in schematic sections; Incomplete when found today having been printed nearly 100 years ago.
A professionally remastered edition provides:
Clear, high-resolution page restoration
Legible wiring diagrams and connection information
Accurate technical specifications
Preserved original layout and formatting
Reliable reference material for servicing and integration
For engineers, proper documentation matters. Ribbon microphones demand correct loading, gain staging, and handling practices — especially when pairing with modern preamps and patch bays. Clear schematics and accurate impedance data are essential for safe operation and optimal performance.
Protect your investment. Preserve the performance. Operate with confidence. Professional documentation for a classic piece of RCA broadcast engineering history.
The time-consuming remastering process involves carefully scanning the original manual and spending hours processing each page to produce a manual that looks better-than-new. All photos are stripped out and processed separately. All tears, marks, stains, etc. are removed from the original manual, even printing defects were corrected. The text is brought back to original sharpness and detail, as are all of the illustrations.
We use heavy stock matte or premium glossy photo paper for the front and back covers, and heavy paper for the inside pages. The outside covers are protected by 10 mil thick, clear plastic sheets. It is then bound with plastic ring comb binding so the manual will open flat and be very durable.
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Protective Covers: For both a desk stand and boom mic. Models 74, 77, 44 + Western Electric 639A/B
Manuals (digitally restored) ** see list below**
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Artwork - digitally restored advertisements AND a unique commissioned 44/77 microphone print
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RCAmic.com Digitally Remastered Manuals: BK-1A; BK-4A; BK-5A; BK-5B; BK-6B; BK-11 (BOTH VERSIONS); SK-46; SK-50; PB-144; AEROPRESSURE; VARACOUSTIC (6204, 6204); 1933 JR VELOCITY; 44-A; 44-B; 44BX-(-B, -D); 44BX-G, 44BX-(-H, -J, -K, -L); 50A; 74-A JR VELOCITY; 74-B 1937 jr VELOCITY) ; 77-B1; 77-D; 77-DX; 88A. We also have digitally remastered the manual for the Western Electric / Altec the 618 and a separate manual for the 639A/639B.