Connecting a Condenser or Dynamic mic to a 1/8" stereo input?

K

Kenny202

Member
I got a little Boss BR Micro recorder and it has a stereo 1/8" input socket for ext mic. I wish to connect my Condenser mic to the unit using a separate 48v phantom power supply. From there I would need an XLR to 1/8" adapter cable with the 1/8" plug to go into the boss..... but the only cable I can find have stereo 1/8" plugs on them. I assume most general Condenser / Dynamic mics are mono so why would you use stereo plugs on one end? Boss does mention it is a stereo input and if you use a mono mic it will simply just record one track instead of stereo and no problem with this...then they vaguely suggests using an XLR to 1/8" stereo cable wont work and show a double headed XLR set going into a single 1/8" stereo plug.

Can anyone put me on the right track here?
 
A 3.5mm stereo input design for dynamic mics can be connected to XLRs quite simply, you just need to unbalance them - if you have two dynamics then the wiring goes as follows.
3.5mm tip, to first XLR, pin 2
3.5mm ring, to second XLR pin 2
3.5mm Sleeve, to BOTH XLRs - connected to pins 1 AND 3 in each one. It will work, assuming the recorder really does have the gain required for a dynamic mic. It's possible it also has +5V on the tip and the ring to hot power a condenser mic. You can buy little stereo condensers with 3.5mm 3 circuit connectors for very little on ebay and amazon.

If it's the BR-80, then it has switchable hot power and a -40dB mic input - so a dynamic should work fine. This probably answers the OP's other topics - about effects, but they're mostly pointing at the track playback facility, and guitar effects. It's a sort of one stop busking shop.
 
rob aylestone said:
A 3.5mm stereo input design for dynamic mics can be connected to XLRs quite simply, you just need to unbalance them - if you have two dynamics then the wiring goes as follows.
3.5mm tip, to first XLR, pin 2
3.5mm ring, to second XLR pin 2
3.5mm Sleeve, to BOTH XLRs - connected to pins 1 AND 3 in each one. It will work, assuming the recorder really does have the gain required for a dynamic mic. It's possible it also has +5V on the tip and the ring to hot power a condenser mic. You can buy little stereo condensers with 3.5mm 3 circuit connectors for very little on ebay and amazon.

If it's the BR-80, then it has switchable hot power and a -40dB mic input - so a dynamic should work fine. This probably answers the OP's other topics - about effects, but they're mostly pointing at the track playback facility, and guitar effects. It's a sort of one stop busking shop.
Click to expand...
Its a micro BR (BR-80 next generation) and does have switchable power (2.5V) for a powered input mic I think they call it. Like a lapel mic used for speaking I think. But you wouldn't use that power for a dynamic mic would you?
 
Well - er, that's a no and a yes. The transformer is an impedance converter. It provides unbalancing and a conversion from the 250-600 Ohm (ash) impedance of a mic to the higher impedance of a line input. There is a bit of voltage gain in the process, but there is no amplification in a conventional way - so if you look at your manual - the specs show two different gain figures. I think it's something like -10 and -40dB - which is an indication the preamp is built to handle mics and line level. The mic close in to voice or instruments has enough gain from the preamp to function well enough. Probably NOT much good for trying to record natural history with the sound of a snail chewing a leaf. (that's a stupid analogy, but makes the point).

The voltage is to power a small condenser. Think of transformers as matching devices, never amplifiers.
 
rob aylestone said:
Well - er, that's a no and a yes. The transformer is an impedance converter. It provides unbalancing and a conversion from the 250-600 Ohm (ash) impedance of a mic to the higher impedance of a line input. There is a bit of voltage gain in the process, but there is no amplification in a conventional way - so if you look at your manual - the specs show two different gain figures. I think it's something like -10 and -40dB - which is an indication the preamp is built to handle mics and line level. The mic close in to voice or instruments has enough gain from the preamp to function well enough. Probably NOT much good for trying to record natural history with the sound of a snail chewing a leaf. (that's a stupid analogy, but makes the point).

The voltage is to power a small condenser. Think of transformers as matching devices, never amplifiers.
Click to expand...
-10 (MIC) and - 40 (LINE) is spot on. Just checked it on the specs, Does that mean it's cutting the input signal by -10db and cutting LINE signal by -40db? So a lot more reduction on the LINE input to compensate for a higher / powered input level?
 
No - this isn't the same as a pad. dB are just ratios, so -40dB is the 'expected' signal level compared against the maximum - so a mic would be a long way down from maximum signal, so -40dB is a lot of gain to introduce. The line input needs less, so it rates -10dB. In sensible specs, real voltages are given - but dB is an alternative way of saying the same thing.
 
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