The RCA 77-DX is one of the most iconic broadcast microphones ever produced by RCA, representing the peak of RCA’s variable-pattern ribbon microphone design.
Introduced: approximately 1954
Primary production period: mid-1950s through 1960s
Continued use: well into the 1970s and beyond in broadcast and recording studios
MI-4046-F → earlier production configuration
MI-11006-C → later production / updated catalog designation
These MI numbers reflect RCA’s evolving internal catalog system rather than major redesigns of the microphone itself.
The 77-DX represents the refinement of the earlier 77 series (77-A, 77-B, 77-D), combining versatility with broadcast-grade reliability. Variable Polar Pattern Control was one of its defining features because of the selectable pickup patterns of Omnidirectional, Cardioid, Bidirectional (figure-8), Intermediate patterns being controlled via the Rear acoustic shutter system and/or Front pattern selector switch.
This made it one of the most flexible microphones of its time. The “DX” version introduced additional features that allowed the engineer to tailor the microphone for things like close up speech, music pickup and more. These microphones were highly regarded in the broadcasting, voice-over and studio vocals.
Please see our store for the speciality supplements that contain reproductions (remastered also) of industry articles and fun regarding this era of microphones. It was a pleasure to create these for my fellow RCA microphone aficionados. If you own one of these microphones this manual is essential for it's use or resale value. Consider picking up one of our cover bags for ease of protecting this sensitive ribbon microphone.
A professionally remastered edition provides:
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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Please see our store for other items you may want. We have produced:
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.