Valve Amplifier Study 010: Vacuum Tube Microphone Pre-Amplifier RCA 5AR4 (12AY7)

Here we have our audio service technician taking you through a voltage amplifier. The RCA 5AR4 circuit employs two 12AY7 double triode valves which have the military equivalent 6072A.
Our next video will be another vintage valve amplifier, the British AC/SP3A Microphone Pre-Amplifier.
We have many more videos to upload covering a wide variety of vintage British & International audio circuits for hi-fi and recording studios.
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[@dhelton40]

I know this console and relocated one in the 1980's. I will point out that in typical RCA fashion, all of the 1R and 1C numbers relate back to a parts list that will be more specific about the values. Also keep in mind that these consoles were mostly used in AM radio broadcast (sometimes FM) and not recording, so while they wanted it rugged and well built, the fi didn't need to be too high, just reasonable. They were really just for announcers and news broadcast. This is a preamp, that would work for years without any need for attention. Many of these ran non stop for 40 years, and mostly needed output tubes changed from time to time. Preamp tube ran a lot longer.

[@vintageaudioworkshop]

@@dhelton40 thanks for the info...we will video doc a lot more on consoles in the near future!

[@Mr39036ce]

the input wasn't only a potentiometer. Sometimes they used a step attenuator. These were preceeded by the mic input transformer which connets to 3&4.That's where all those Daven attenuators you see on ebay come from. To us they were just service parts.

[@vintageaudioworkshop]

Good point, Thanks!

[@FateGathersStudios]

This is some amazing video right here..... how do you not have a larger subscriber base??? Thank you.

[@vintageaudioworkshop]

We are making many more tutorial videos for this year and plan to continue strong in this direction, it'll pick up. Thanks!