RCA BA-6A (Encolsure)

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matriachamplification

Wall Thomas
GDIY Supporter
Joined
Feb 3, 2019
Messages
451
Location
Ontario, Canada
Hello friends of GDIY,

Sometime ago my family and I set the outlandish goal of designing a Tube Compressor Card for Mr. Thompson-Bells ( @ruffrecords ) Custom Tube Console design and, with his encouragement, proceeded to move forward with our research.

Knowing this was no small task we reached out to Mr. Doug Williams (@emrr - one of the worlds foremost experts in vintage audio design) who reccomended the RCA BA-6A as a build that GDIY members might appreciate seeing.

Fortunately we found that Master Audio Blacksmith @DaveP had tackled this build previously and was thoughtful enough to share his build here.
Along with the schematics and manual (that can be found here) we were lucky to find visual aid via images of the BA-6A' guts which we have attached.

Finnally we found an awespiring hard core point-to-point build by @letterbeacon. The rotary switch is especially interesting to learn about.

~~~

Important to our families goals is having our daughter contribute. Western Electric Style Braided Wiring?

A major concern is that controls firmly set during build time need interactive interfacing. We need to integrate these controls into our faceplate design as well as layout our build schemtatics to accomodate these features.

Questions day two

Research Daven Attenuators & Gold Point DIY Builds


Questions day one

What features are set at build time?
How many interactive controls are needed for these features?
Is there a template of the original BA-6A faceplate we can build from?


~~~

We aim to build the BA-6A using new parts or NOS (New Old Stock). With many parts now obsolete, an updated BOM (Bill Of Materials) is needed. For now we will work with what we have ordered pending GDIY approval.

BOM (WIP)

TRANSFORMERS

SOWTER
9835 RCA BA-6A Input Transformer
9770 RCA BA-6A Output Transformer

1195 RCA 86-AL/86-A Compressor Interstage

KNOBS, ATTENUATORS & SWITCHES


GOLD POINT
(Doug Williams) - I'd stick a cheaper Daven 500 or 600 ladder on a BA-6A. Automatic 6dB pad and the loading is built in...

RCA Knobs
Fairchild 660/670 Style Knobs

~~~

Thanks for reading up to this point. More details coming this week.

Wall
 

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matriachamplification

Wall Thomas
GDIY Supporter
Joined
Feb 3, 2019
Messages
451
Location
Ontario, Canada
Will be exciting to see another Ba6a project come to life! In the pics you posted, pics 1 and 3 are of the RCA BA25, an AGC type compressor with a 6386, also a very nice sounding unit.
Hello vitopower,

thank you for catching our mistake. We will adjust the head post now.

Like many other builders were experiencing downtime in between part deliveries giving us the perfect opportunity to start collecting parts for the BA-6A.

Wall
 

matriachamplification

Wall Thomas
GDIY Supporter
Joined
Feb 3, 2019
Messages
451
Location
Ontario, Canada
With Tranformers sorted we can now select our Hammond Chassis.

Hammond - 1441-42BK3 (Black Satin)
17 in x 14 in x 5 in : (432 mm x 356 mm x 127 mm)

Hammond - 1441-33BK3CWW (Black Satin with Walnut Cheeks)
17 in x 10 in x 4 in : (432 mm x 254 mm x 102 mm)
(Decided the large chassis was best)


We've shared the Walnut version in hopes of it being large enough for a BA-6A build.


Which option would you choose?

More soon!


Wall and family
 
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matriachamplification

Wall Thomas
GDIY Supporter
Joined
Feb 3, 2019
Messages
451
Location
Ontario, Canada
Hello friends,

Yes, we are building out a lot of projects. Wilma has decided the RCA shell will become a BA-6A compressor. This was a transistor based product so no need to worry about restoring it to its original set up... or.... no no Tube Compressor it is.

( Should this be moved to the Dynamics section? @JohnRoberts )

She has included the original images and would like to keep the design to represent as much of the original as possible.
Interesting note is this design "could" fit a standard 19" rack into it easily with it being 23 inches wide. (I think)

That said, with the top removed we can add a easily sourced chassis into this encolusre hopefully fastening it with the "rubber feet" screws already drilled into the shell.

She already has 20 Vintage RCA Knobs but we only need 7 for a BA-6A build. There is also 3 meters. In/out and compression meters?

There are also many features we can add given the layout. Any ideas of creating a SUPER BA-6A, we are open to ideas.

Questions? Because at this point I am completely winging it and feel completely full of sh*t.

Wall
 

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letterbeacon

Well-known member
Joined
Jul 12, 2009
Messages
642
Location
London, UK
I'm rarely on this board these days, but thank you very much for calling my build "awe-inspiring". It was fun to build and a huge learning process and I wouldn't have been able to do it without the generous sharing of knowledge from the members of this board.

I currently have the unit out on loan at Toe Rag Studios (The White Stripes, Tame Impala etc.) where it's getting regular use.
 

Rob Flinn

Well-known member
Joined
Jun 3, 2004
Messages
4,723
Location
Sussex, UK
I'm rarely on this board these days, but thank you very much for calling my build "awe-inspiring". It was fun to build and a huge learning process and I wouldn't have been able to do it without the generous sharing of knowledge from the members of this board.

I currently have the unit out on loan at Toe Rag Studios (The White Stripes, Tame Impala etc.) where it's getting regular use.
I thought Toe Rag closed down the other year ?
 
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