Topic: Countryman B3 modification question

[one8ung]

There was recently offered me two separate Countryman B3 Omni Lavalier Mics (B3W5FF05LNC) with a Lemo1 plug.

I want to make a stereo pair out of them and terminates into a 1/8" jack and power them with a ca-ugly battery box.

Question: do i need to make a 4.7k modification and if yes, how can i do that myself?

Think they are "Low Sens" microphones...

Thanks for any help!

[Gutbucket]

Plenty of folks use them wired directly to a 3.5mm (1/8") stereo plug.  However, Richard stated the following in an older TS thread about them-

You need a source resistor - between black wire and ground, one for each channel.

I use a 2.2k sometimes, for moderately loud stuff.  This works with both plug-in-power and a battery box.  For absolute certainly, use a 4.7k resistor, but in that case, you'll probably want a 9v battery box (or preamp) instead of plug-in-power.

  Richard

[snip..] I'm definitely planning to record some really loud shows in the future. There isn't really any benefit to powering the B3s with 9v without the resistors, is there?

OK, you should have 4.7k in there at all times.  For quiet shows (or ambient stuff) use Plug-in-power.  For loud shows use a regular (2-wire) battery box.

  Richard

[one8ung]

Thanks...

Which Resistors can i best use, a Carbon Film or Metal Film Resistors.

And what about the tolerance?

[Gutbucket]

I'm not sure the answer to either. But I don't expect tight tolerance to be critical.

[commongrounder]

Thanks...

Which Resistors can i best use, a Carbon Film or Metal Film Resistors.

And what about the tolerance?

Metal film resistors have the lowest self thermal noise, and are preferred for audio signal paths. The tolerance doesn’t matter in this application. Metal film has inherently tight tolerances anyway.

[kuba e]

I think two resistors that have the same value should be used. I read somewhere that you should buy multiple resistors and then choose the pair that is the closest to each other. But I could be wrong,  I have no experience with this.

[illconditioned]

Plenty of folks use them wired directly to a 3.5mm (1/8") stereo plug.  However, Richard stated the following in an older TS thread about them-

You need a source resistor - between black wire and ground, one for each channel.

I use a 2.2k sometimes, for moderately loud stuff.  This works with both plug-in-power and a battery box.  For absolute certainly, use a 4.7k resistor, but in that case, you'll probably want a 9v battery box (or preamp) instead of plug-in-power.

  Richard

[snip..] I'm definitely planning to record some really loud shows in the future. There isn't really any benefit to powering the B3s with 9v without the resistors, is there?

OK, you should have 4.7k in there at all times.  For quiet shows (or ambient stuff) use Plug-in-power.  For loud shows use a regular (2-wire) battery box.

  Richard

Have you got a multimeter?  Measure resistance from both wires to ground (shield).  I think one is already grounded and mods are not needed.

[illconditioned]

Plenty of folks use them wired directly to a 3.5mm (1/8") stereo plug.  However, Richard stated the following in an older TS thread about them-

You need a source resistor - between black wire and ground, one for each channel.

I use a 2.2k sometimes, for moderately loud stuff.  This works with both plug-in-power and a battery box.  For absolute certainly, use a 4.7k resistor, but in that case, you'll probably want a 9v battery box (or preamp) instead of plug-in-power.

  Richard

[snip..] I'm definitely planning to record some really loud shows in the future. There isn't really any benefit to powering the B3s with 9v without the resistors, is there?

OK, you should have 4.7k in there at all times.  For quiet shows (or ambient stuff) use Plug-in-power.  For loud shows use a regular (2-wire) battery box.

  Richard

Have you got a multimeter?  Measure resistance from both wires to ground (shield).  I think one is already grounded and mods are not needed.

[one8ung]

Have you got a multimeter?  Measure resistance from both wires to ground (shield).  I think one is already grounded and mods are not needed.

Will try it after removing the Lemo connector.

But for now it seems that I am not measuring resistance.

[one8ung]

I removed the connector and have a red and white wire and a shield.
I have a connection between the shield and white wire.
Between the red and white wire I measure 11 KΩ

[commongrounder]

I think two resistors that have the same value should be used. I read somewhere that you should buy multiple resistors and then choose the pair that is the closest to each other. But I could be wrong,  I have no experience with this.

The resistor value should definitely be the same for both mics. Hand matching those resistors with a multimeter isn’t necessary for this application. Most metal film resistors have a tighter tolerance than the reading uncertainty of a DYI-grade multimeter anyway.

[kuba e]

commongrounder, thank you for the addition.