Another RCA BA-2 Build

[dmp]

great, thanks.
I was thinking the LS10 may be great for a higher gain pre as well, since the hum I was seeing in the BA2 was appearing in the input tx. Other than that hum the noise floor was really low.
So a LS10 - no nfb - LS50 design...  the SA-70 design looks compatible with the LS50 on the output. It would be nice to use a cheap common tube like a 12ax7 or 6sn7.
Ideally I would like to go up to 75 dB of gain to use this with low output mics on quiet acoustic instruments. I generally like to record straight in (without a compressor for adding gain). Not having enough gain is just inconvenient.

 

[Purplenoise]

The iron is the biggest part of the sound. I had a BA-2 once that had EF86's in it, no other parts changes at all, just new sockets dropped in. I can't split hairs on the sound differences other than to say it wasn't the biggest part of the picture by any stretch.

No NFB design is a big part of it, after the iron sound.

The 2 versions of Gates SA-70 / SA-70A, difference is transformer types, sound is clearly different. The Gates/WE mashup I did sounded even different, predominately in lacking the output transformer.

LS10/LS50 is a great platform for doing a no feedback build. You can try the LS10 easily with clip leads in the BA-2 build for comparison.

Hi emrr…reviving an old thread here. Do you have any recommendations for output transformers for ba-2c build? Dc coupling in the transformer, original schematic. Thanks in advance.

 

[emrr]

Hi emrr…reviving an old thread here. Do you have any recommendations for output transformers for ba-2c build? Dc coupling in the transformer, original schematic. Thanks in advance.

the main ba-2 thread mentions some Cinemag. I have no personal report. Most common vintage is utc a-25.

 

[Purplenoise]

the main ba-2 thread mentions some Cinemag. I have no personal report. Most common vintage is utc a-25.

Great, thank you so much.

 

[mattrad]

Cinemag can gap their CM-27101 for you upon request, which works good for the BA-2. I actually have a brand new one lying around not in use, ended up going with an Edcor OT w/ an anode choke for the DC. Message me If youre interested!

 

[Purplenoise]

As I am still waiting for a Sowter input I tried a bogen tm-200 ( 200/50k). I know those are not very respectable but…it sounds great in this build. Very different than the Jensen 115 I was using. Of course the specs are more “correct” with the bogen.
Darkish and very thick sound but with great definition…really nice low mids.