2022年12月27日 · I picked up some original transformers for a RCA BA21 preamp. I'll post some pictures along the way. This is a 40 dB fixed gain preamp with 20dB of negative feedback, fed from a tertiary winding on the output transformer, using two 12AY7 tubes.

2009年10月29日 · While out in LA a few months ago, we did a casual (not too scientific) RCA preamp shootout. I was most interested in hearing the BA-21a. We had (what I think was) an RCA OP6 and a pair of Vintage NEVE 1073. Our test was pretty simple, and like I said, not too scientific. Source: Acoustic guitar with vocalist Mic: Vintage Neumann U67

Rare 2x RCA BA-11 & 2x BA-21 tube Microphone preamplifiers in rack w PS serviced. These have been fully serviced by my tech, recapped and wired up with xlr in and outs and are in beautiful preserved condition. Includes original rare RCA BX power supply, RCA rack, a pair of BA-21 and a pair of BA-11 preamplifiers.

2022年12月27日 · You can see a little low end boost at the low end but it is minimal with the 220uF, actually flattens the response like the C4+R14 compensation. Could do a switched R+C for each position to match the C to the R for frequency compensation through the whole gain range. At high gain, C would drop to about 0.047uF.

For sale is a pair of RCA BA21A Microphone pre-amps in GREAT working condition, comes with a rack and an external PSU. Main components like tubes and Xformers seem to be all original. Sounds so nice especially with RCA ribbon microphones like 44, 77, or BK5! I’ll sell modules only (without a rack and a PSU) upon a request.

This is a pair of vintage RCA BA-21A tube mic preamplifiers that have been re-capped and tested . There are connectors included with the modules .The BA21A has a gain of about 40-45db. These require a input attenuator ( or pad) as well as an output attenuator . The full manual and schematics are on line at a couple of places ,

2009年2月2日 · The BA21 has about 40db of gain and is rated flat +/- 0.5db from 50-15Kcycles OK, now here is some mods I would like to try with this. Once done, it probably won't be an RCA BA21, so I decided to call it a Blue_Luke BL-21a. Here is the schematic I came up with. For the time being I am concentrating on the output section.

2018年3月11日 · He did a lot of Rca, Quad Eight, Wardbeck, Api and others high end preamps and he's doing nice wood and metal racking. I'm looking to rack some Rca Ba71, Ba31 and BA73 pre in a near futur from him. Good luck with your project

2024年6月18日 · With these transformers you can build a DIY RCA BA-21 or tube mixer with the correct, original, input transformers. Sold as-is for parts

2023年9月1日 · Excellent shipment packaging, item as described, and in perfect working order. Just installed it as a replacement to a damaged input transformer on my 4 track Scully recorder and the preamp now operates as good as the others, making the 4 preamps fully operational. Thanks a lot! I definitely recommend this seller.