Digitally Remastered User & Technical Manual
The RCA BK-6B, factory designation MI-11017, was part of RCA’s BK-series broadcast ribbon microphones developed for dependable studio and institutional service in the post-war era.
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-11017 identifies the complete microphone assembly as sold through RCA Broadcast Sales channels.
About the BK-6 Series
The BK-6B was designed as a professional-grade ribbon microphone offering the classic RCA bidirectional response in a compact, practical housing.
Passive ribbon (velocity) microphone
Bidirectional (figure-8) pickup pattern
Balanced low-impedance output
Optimized for voice and general program material
Durable metal construction for long-term installation
The BK-6B continued RCA’s emphasis on:
Smooth, natural midrange reproduction
Controlled proximity effect
Excellent side rejection typical of figure-8 ribbons
Consistent tonal performance for broadcast speech
Compared to the larger 44-series microphones, the BK-6B offered a more streamlined form factor while retaining traditional ribbon tonal character.
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 BK-series manuals from the late 1940s–1950s period are often: Lightly printed on thin stock; Faded or yellowed; Difficult to read in schematic sections; Incomplete when found today.
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.
We combine shipping to save you money. Our preferred method is USPS Priority Flat Rate Padded Envelope. Our international sales are handled through eBAY and they instruct us where to ship the merchandise for processing to your country. If you wish another method of shipping or want to make sure the shipping price is accurate, please contact us. Our standard policy will be to refund any excess shipping that eBay's calculator may charge over a modest handling fee for your entire purchase.
REVIEWS: "Absolutely gorgeous item." "Super Professional Work." "America Needs More Like You!":
Please see our store for other items you may want. We have produced:
Protective Covers: For both a desk stand and boom mic. Models 74, 77, 44 + Western Electric 639A/B
Manuals (digitally restored) ** see list below**
Supplements (remastered articles & info for the avid RCA fan)
Artwork - digitally restored advertisements AND a unique commissioned 44/77 microphone print
T-Shirts - unique graphic artist design onto high quality 100% cotton material that lasts for years
Other logo'd special items.
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.