RCA 44BX - E

[mrtnasty]

Hi I have RCA 44BX - E and it seems to be more susceptible to hum than my RCA 44BX - K. Also, the E seems to get more noisy with rotating its orientation, where as the K does not. The E is very usable in the right orientation. The E also sounds different than the K, slightly more aggressive (The E got a new ribbon recently (RCA old stock ribbon), the K did not, and I don't know if /when its ribbon was replaced). I replaced the cables in both mics with high quality cables and hooked them up for 250 Ohm output according to their respective schematics (Thanks Emrr for the E diagram). Anyone know why there are differences / how I can reduce the noise on my E? Thanks! David

 

[mrtnasty]

For anyone interested, I took both microphones apart to try to discover a difference in them that would make one more susceptible to noise depending on orientation, I discovered that the K version has a grounding wire that goes all the way around the ribbon as seen in the picture. The E version does not have this, but just has the black wire from the transformer soldered to the metal piece that holds the magnet. I suspect the engineers at RCA implemented this change in order to reduce the noise that is dependent on orientation. I also put a picture of a 44BX-H which is missing the extra grounding surrounding wire just like my E (because I was too lazy to take my E apart again to take a picture because it takes a while to get the grill on right).

Hi I have RCA 44BX - E and it seems to be more susceptible to hum than my RCA 44BX - K. Also, the E seems to get more noisy with rotating its orientation, where as the K does not. The E is very usable in the right orientation. The E also sounds different than the K, slightly more aggressive (The E got a new ribbon recently (RCA old stock ribbon), the K did not, and I don't know if /when its ribbon was replaced). I replaced the cables in both mics with high quality cables and hooked them up for 250 Ohm output according to their respective schematics (Thanks Emmr for the E diagram). Anyone know why there are differences / how I can reduce the noise on my E? Thanks! David

 

[emrr]

Not something I've noticed. Pictures of an AEA and a Warm seem to show the same. There's also whatever the British RCA mod is, something about the way a wire is routed I think.

 

[mrtnasty]

Not something I've noticed. Pictures of an AEA and a Warm seem to show the same. There's also whatever the British RCA mod is, something about the way a wire is routed I think.

Hi Emrr, I noticed the same with AEA and Warm, seems like that change was worth keeping. Interesting about the British 44 mod I'll look into that, thanks! Although my 44 E is very quiet if it is in the right orientation, so for now I'll probably just put it in the right orientation and build the session around it.

 

[emrr]

I own an E as well, haven't noted any orientation problems with it. That's all location based, of course.

I have the Warm, and it seems the same on general noise floor.

 

[a soBer Newt]

I want to say the the British mod was to move the wires closer to the ribbon like the -K you have. I don't think there is a easy modification to re route the wires to tighten up the loop; You could always call AEA and bug my old intern Joey to come up with a solution.

 

[RCAguy]

For anyone interested, I took both microphones apart to try to discover a difference in them that would make one more susceptible to noise depending on orientation, I discovered that the K version has a grounding wire that goes all the way around the ribbon as seen in the picture. The E version does not have this, but just has the black wire from the transformer soldered to the metal piece that holds the magnet. I suspect the engineers at RCA implemented this change in order to reduce the noise that is dependent on orientation. I also put a picture of a 44BX-H which is missing the extra grounding surrounding wire just like my E (because I was too lazy to take my E apart again to take a picture because it takes a while to get the grill on right).

Can one add the ground wire?

 

[emrr]

Can one add the ground wire?

It appears to be through the magnets, those without don’t have the holes

 

[mrtnasty]

I own an E as well, haven't noted any orientation problems with it. That's all location based, of course.

I have the Warm, and it seems the same on general noise floor.

What are your thoughts on the Warm 44?

 

[emrr]

comments and pics here

https://realgearonline.com/post/376128/thread

 

[mrtnasty]

Can one add the ground wire?

In the E version, the ground wire is attached to the metal piece below the magnet. In the K version, the hot and ground wires are twisted, and the ground attaches to a solid rectangular metal piece that goes through the magnet and encircles the ribbon.