OK, so...I think I'm understanding this a lot better now. There are a couple things I could still use clarification on.
Is it correct that:
A true 3 wire mics has three distinct (ie, never shorted together) "wires" coming out of the capsules.
One wire (usually red) carries the + DC bias.
One wire (let's call it blue) carries the audio signal.
One "wire", which is usually a conductive jacket around the other two wires for the bulk of the cable, is the shield, and also serves as the ground or return for both the bias and signal voltage.
Is it also correct that:
Such a 3 wire mic can be converted to 2 wire (possibly making it more susceptible to distortion at high SPL) by shorting one of the wires to the shield. This can be done at the output end, like Sound Professionals does in their stock AT853 version. Or, it can be done at the capsule end like is done in at least some MKE2s.
Does it matter which wire is shorted to the shield?
Depending on your answers to the above, I may have a further question which I think will illustrate that the MKE-2-5 is indeed 3 wire.
All of the Sennheiser mics I have repaired some 100+ microphones were all two wire capsules with an output/bias and a ground pad. A three wire capsule has an output + a bias input + ground.
I know they were two wire capsules because I hacked off the bodies on all of these mics and soldered brand new cable to all of the capsules.. They did use three conductor cable but it was not because they were using a three wire capsule.
Thanks for your patience and explanation. Sorry if what follows is a dumb question, but now I'm a little confused:
I'm a little confused about what wires I should check the resistance between. Before, you suggested that there would be continuity between either the red or blue wire and the shield. But if the capsule has a ground pad and a combined output/bias pad, shouldn't it actually be the red and blue wires that have continuity? I.e., the shield should connect to the shield pad and the signal and bias wires should both connect to the output/bias pad. Can you explain why this is not the case?
Ok here goes. The MKE2 IS A TWO WIRE CAPSULE with a separate ground wire for the case. One wire should be bias/output one wire should be ground.. So you should connect the ground wire and the ground terminal together...If you look at the PDF you will see that's what they are doing in the diagram. On some of the MKE2 Mics I have seen they used one conductor wire + a shield.
You should contact Sennheiser they will tell you the same thing.. I am in direct contact with them all the time.
Sorry but I still don't follow. It seems you are implying the blue wire is the case ground, since it is the one that is shorted to the shield IN METHOD 2. Right?
Then the wiring scheme diagrammed works because the red (bias+signal) wire is connected to both the bias (pin 2) and audio (pins 3 and 4). So far, so good.
But then going back to METHOD 1, the red wire is connected only to pin 2 (bias). How is signal getting to pins 3 and 4 through the blue wire if it is the case ground, and signal is on the red wire?
Grasshopper your confusing 3 pin mini xlr wiring with wiring for a wireless beltpack.. They are not the same thing... Shure uses a TA4F connector they have a separate ground line and you have to short out the line input to ground hence the reason why the blue wire is on the other terminal pin configurations are NOT standard like they are for THREE WIRE MINI XLR connectors where you have pin 1 ground pin 2 output pin 3 bias.... this is a whole new ball game when your talking wireless belt packs. Keep up the questions its the only way to learn I drove all my sound engineer friends nuts they eventually showed me how to do sound lol....
Chris
OK, here's what still has me confused. The pdf gives the pin assignments as:
TA4M
Transmitter View
PIN 1 = cable shield/ audio return/ bias return
PIN 2 = +5V DC Bias
PIN 3 = audio input for dynamic mics or instruments
PIN 4 = 20kΩ resistor to ground jumpered to pin 3 for condenser mics
So it's ok that in Method 1 the audio+bias cable is not connected to pins 3 or 4? These are only connected to audio if you have a balanced signal? But then why is the audio+bias cable connected to these same pins in Method 2?
Also, it says:
"Note: This circuit [Method 2] may not work if the MKE 2 is supplied with a connector by Sennheiser. MKE 2 units with
factory supplied connectors may be wired differently within the capsule." If all MKE2s are 2 wire capsules, why would the method work with some and not others?
Just hypothetically speaking, what if:
All MKE2s started their lives as 3 wire capsules. Red>bias pad, blue>audio pad, shield > ground pad. In some/most (but not all) versions, the red and blue wires (or their respective pads) are shorted together, so that in effect you have red+blue = audio+bias and shield = ground.
Then, Method 1 works with either 3 wire or shorted to 2 wire capsules. Red>bias, blue>audio, shield>ground for the 3 wire version or red+blue>bias+audio, shield>ground for the two wire version.
Method 2 works as long as red and blue aren't shorted together. (If red and blue were shorted together at the capsule, there's no circuit since blue and shield are shorted at the TA4F). It takes a 3 wire mic and converts it to 2 wire, just like when Sound Professionals shorts yellow to shield in the AT853s. Thus it also provides a boost of 10-14dB like the pdf says.
And of course it doesn't work if red and blue are shorted at the capsule. In other words, it doesn't work if the capsules have been converted to two wire. Instead, it only works (like the pdf says) with mics that have pigtailed cables. Like the MKE-2-5. The version Richard and I have been saying is 3 wire.
I guess I'm confused what the reason why Method 2 would work with some MKE2s but not others if they were all 2 wire capsules? How else would "MKE 2 units with factory supplied connectors be wired differently within the capsule"?
and you have to short out the line input to ground
Is that different from what you are accomplishing by shorting pins 3 and 4 together? Both wiring schemes do that, but only one connects the pins to the signal wire as I understand it.
Topic: mics directly into recorder question (at943 4.7k/853/ssdsm6; r-1;r09;iriverh120 (Read 32839 times)