Topic: Where to get a 3-wire battery box?

[su6oxone]

I was curious as to where people are getting their 3-wire battery boxes, for those who use them with AT853s for example.  Seems like people are DIY'ing them but is there any retailer that makes or sells them?  I've read that the 3-wire CA-9100 is not a "true 3-wire."  I wonder if sound pro would make one. 

[nameloc01]

Soundpros is selling the at8532 power modules (phantom power boxes) right now for 57.00 each ( you need two) I just bought a set a couple weeks ago. May be something for you look into,as I'm not sure what it would cost to get a 3wire BB built. Besides that,these are the best way to run the AT mics.

[su6oxone]

Soundpros is selling the at8532 power modules (phantom power boxes) right now for 57.00 each ( you need two) I just bought a set a couple weeks ago. May be something for you look into,as I'm not sure what it would cost to get a 3wire BB built. Besides that,these are the best way to run the AT mics.

Thanks for the info.  I was looking into the AT8532s but wasn't sure if they would be too bulky since I mostly do stealth.  Too bad it's not made as a single, more compact unit.  I would definitely get them then.

[nameloc01]

Each one is a about the size of a pack of cigs, together still smaller than my denecke and adaptors.

[lordbelial]

I was curious as to where people are getting their 3-wire battery boxes, for those who use them with AT853s for example.  Seems like people are DIY'ing them but is there any retailer that makes or sells them?  I've read that the 3-wire CA-9100 is not a "true 3-wire."  I wonder if sound pro would make one. 

As far as it has got a miniXLR connector, then it's 3-wire. CA-9100 it's a "true 3-wire".

[Church-Audio]

I was curious as to where people are getting their 3-wire battery boxes, for those who use them with AT853s for example.  Seems like people are DIY'ing them but is there any retailer that makes or sells them?  I've read that the 3-wire CA-9100 is not a "true 3-wire."  I wonder if sound pro would make one. 

As far as it has got a miniXLR connector, then it's 3-wire. CA-9100 it's a "true 3-wire".

Basically what I did with the 9100 was put a 3 wire connector in and separate the bias voltage to pin 3 pin 1 is ground pin 2 is hot. Now this really is two wire.. for argument sake. Now I have a 4.7k mod that I can do to the preamp what this does is give you the same exact performance as three wire, and the ability in situations where you need the extra 12 db of gain that 3 wire and my mod removes, and get back to you via a switch that simply shorts out the 4.7k resistors. So now in acoustic situations when 32 db of gain is needed you can turn off the 4.7k mod and have it run standard 2 wire. And in situations where you need to run in a loud show you can switch the mod on and get the full performance of three wire in a smaller package then running phantom adaptors + you can get up to 20db of gain to help with your noise floor. IMO its a very good solution. But I am biased pardon the pun lol I crack me up  

I hope that explains it.
Chris

[Church-Audio]

Here's a schemo of an AT capsule (at least the one I opened up, I forget the model).  It had an internal source resistor, which is a good thing, it lowers distortion.  There are three connections; ground (bottom), FET drain (top), and FET source (middle).  There are a number of ways to connect to it:

"2-wire": this would involve wiring bias voltage across a resistor to drain, and not using source.  Signal is taken from the drain wire as well.  In this configuration, there will be gain (within limits) at the FET according to the ratio of bias (drain) resistor to source resistor.  If the resistors match, there is no gain.

There are a few possible ways to do 3-wire; the one I suspect most people here are thinking of is to wire the bias voltage straight to drain, and take signal from the source.  This is a unity gain configuration.

Another way to do it is supply the bias voltage across a matching resistor, and take signal off both drain and source.  This uses the FET as a phase splitter and provides an electrically balanced output.  To take advantage of that, you would need a differential amplifier (or a transformer) somewhere down the line.  That would also be unity gain, but you get a free bump from the balanced signal.

I don't know what AT does in their bits . . . I have a wireless pack on my desk, but I don't feel like opening it up and tracing its circuit.  They do appear to use matching resistors in the capsule and bias supply, so I suppose they might provide a balanced connection, but I don't really know.  I suspect this may be the cause of the claims that AT's adaptors "ideally power" the microphones, but again that is wild speculation.  The adaptors probably also provide a relatively high-impedance input, which helps the capsules out a bit . . .

Funny enough some of the AT mics I have opened up have that resistor some do not.. Its very strange... My preamp has a high impedance input so it works well with these mics.


Chris

[Todd R]

Soundpros is selling the at8532 power modules (phantom power boxes) right now for 57.00 each ( you need two) I just bought a set a couple weeks ago. May be something for you look into,as I'm not sure what it would cost to get a 3wire BB built. Besides that,these are the best way to run the AT mics.

Thanks for the info.  I was looking into the AT8532s but wasn't sure if they would be too bulky since I mostly do stealth.  Too bad it's not made as a single, more compact unit.  I would definitely get them then.

What do you have for a rig?  If you really want phantom power converters and already have gear providing phantom power, I've got some AT8534 phantom adaptors I've modified that I could sell you pretty cheap.

I re-packaged two AT8534 phantom power adaptors into a much smaller shrink wrapped package.  The setup I have is basically like the one in this thread:

http://taperssection.com/index.php/topic,57324.0.html

Instead though, the inputs for the mic side are 3pin mini-XLR male connectors (accepting the typical 3-wire TA3F mini-XLR female connectors used by some AT853's) -- this is instead of the 1/8" connectors on the modded pack in the thread above -- and then standard 3pin male XLRs to connect to the mic input with 48v phantom power on your preamp (this in place of the RA 1/4" TRS connectors on the package in the thread above).

As you can see, the whole modded setup is pretty small, probably less than half the size of two of the standard AT8532 boxes.  Anyway, if you're interested, let me know since I'm not using it much now that I have my Church ST-9100.

[illconditioned]

Here's a schemo of an AT capsule (at least the one I opened up, I forget the model).  It had an internal source resistor, which is a good thing, it lowers distortion.  There are three connections; ground (bottom), FET drain (top), and FET source (middle).  There are a number of ways to connect to it:

"2-wire": this would involve wiring bias voltage across a resistor to drain, and not using source.  Signal is taken from the drain wire as well.  In this configuration, there will be gain (within limits) at the FET according to the ratio of bias (drain) resistor to source resistor.  If the resistors match, there is no gain.

There are a few possible ways to do 3-wire; the one I suspect most people here are thinking of is to wire the bias voltage straight to drain, and take signal from the source.  This is a unity gain configuration.

Another way to do it is supply the bias voltage across a matching resistor, and take signal off both drain and source.  This uses the FET as a phase splitter and provides an electrically balanced output.  To take advantage of that, you would need a differential amplifier (or a transformer) somewhere down the line.  That would also be unity gain, but you get a free bump from the balanced signal.

I don't know what AT does in their bits . . . I have a wireless pack on my desk, but I don't feel like opening it up and tracing its circuit.  They do appear to use matching resistors in the capsule and bias supply, so I suppose they might provide a balanced connection, but I don't really know.  I suspect this may be the cause of the claims that AT's adaptors "ideally power" the microphones, but again that is wild speculation.  The adaptors probably also provide a relatively high-impedance input, which helps the capsules out a bit . . .

Thanks for the info.  What Chris said: some, but not all AT capsules have that source resistor!
I've noticed it in *a very few* AT831 (connects to wireless transmitters, I think).
But most AT853 I've seen don't have this.  The source resistor (5.1k usually) is in the phantom power unit.  That is, the package that is either hardwired to the cable, or connected with a 3 pin miniXLR.

To determine if there is a source resistor *inside* the capsule, take off the connector.  There are three wires: red (positive), yellow (audio), and shield.  Simply measure the resistance between yellow and shield.  Open circuit = no source resistor.

By the way, both Chris and I have done mods where we *add* that source resistor (usually a 4.7k or 2.2k) right inside the capsule.  AT853 caps are easy to disassemble, so this is a nice fix.  Then you can run off a "standard" 9v battery box.  Note: I'm not offering to do this.  Chris might, but I'm not doing mods right now.

  Richard

[Church-Audio]

Here's a schemo of an AT capsule (at least the one I opened up, I forget the model).  It had an internal source resistor, which is a good thing, it lowers distortion.  There are three connections; ground (bottom), FET drain (top), and FET source (middle).  There are a number of ways to connect to it:

"2-wire": this would involve wiring bias voltage across a resistor to drain, and not using source.  Signal is taken from the drain wire as well.  In this configuration, there will be gain (within limits) at the FET according to the ratio of bias (drain) resistor to source resistor.  If the resistors match, there is no gain.

There are a few possible ways to do 3-wire; the one I suspect most people here are thinking of is to wire the bias voltage straight to drain, and take signal from the source.  This is a unity gain configuration.

Another way to do it is supply the bias voltage across a matching resistor, and take signal off both drain and source.  This uses the FET as a phase splitter and provides an electrically balanced output.  To take advantage of that, you would need a differential amplifier (or a transformer) somewhere down the line.  That would also be unity gain, but you get a free bump from the balanced signal.

I don't know what AT does in their bits . . . I have a wireless pack on my desk, but I don't feel like opening it up and tracing its circuit.  They do appear to use matching resistors in the capsule and bias supply, so I suppose they might provide a balanced connection, but I don't really know.  I suspect this may be the cause of the claims that AT's adaptors "ideally power" the microphones, but again that is wild speculation.  The adaptors probably also provide a relatively high-impedance input, which helps the capsules out a bit . . .

Thanks for the info.  What Chris said: some, but not all AT capsules have that source resistor!
I've noticed it in *a very few* AT831 (connects to wireless transmitters, I think).
But most AT853 I've seen don't have this.  The source resistor (5.1k usually) is in the phantom power unit.  That is, the package that is either hardwired to the cable, or connected with a 3 pin miniXLR.

To determine if there is a source resistor *inside* the capsule, take off the connector.  There are three wires: red (positive), yellow (audio), and shield.  Simply measure the resistance between yellow and shield.  Open circuit = no source resistor.

By the way, both Chris and I have done mods where we *add* that source resistor (usually a 4.7k or 2.2k) right inside the capsule.  AT853 caps are easy to disassemble, so this is a nice fix.  Then you can run off a "standard" 9v battery box.  Note: I'm not offering to do this.  Chris might, but I'm not doing mods right now.

  Richard

I still do the mods.. I mostly do them on the inside of the connector though. I find it easier to do. Sometimes you just cant get the nut off the preamp end with out damage so I have done it on the connector side. On the 831 mics I have for sale I did it inside the mic with a metal film surface mount resistor. Because there was room. Its a pita to do sometimes.. But the chip resistors work best. Its not a hard mod to do maybe I will take some pictures so other DIY types can do it them selves.

[Church-Audio]

Thanks for the info.  What Chris said: some, but not all AT capsules have that source resistor!
I've noticed it in *a very few* AT831 (connects to wireless transmitters, I think).
But most AT853 I've seen don't have this.  The source resistor (5.1k usually) is in the phantom power unit.  That is, the package that is either hardwired to the cable, or connected with a 3 pin miniXLR.

I am working the other way around, some people have asked to run my mics off wireless packs.  So I picked up one, but it seems to me all the AT stuff is using a Hirose 4 pin connector.  Do people generally chop that off and replace with the TA4F?  Anyway, I like the good ol' miniplug, it might not lock, but it's $1!

Sennheiser uses an oem version of this connector for there wireless packs.. Its a locking 3.5 mm connector.. Hirose is not used very much but there are still companies that use them. Most Shure and AT, use TA4F. That's only because they have separate inputs for line level and mic level as well as separate ground and bias.

http://www.btx.com/ItemForm.aspx?item=CA-C4407LKA&Category=4348ad2f-1b43-47dc-83b3-5cee8464acbf


There are only two problems with this connector 1- The strain-relief sucks.. And you need to fill it with epoxy because the cable hole is huge!!! you can put in a 8 mm cable into this sucker lol.. And second its expensive around $7 wholesale. You have to use the standard 3.5 mm female connectors that have a knurled nut on them. I will tell you one thing I am thinking about doing an r-09 mod that uses this for a connector no more issues with bad 3.5 mm connectors anymore or connectors coming out or not locking.. This solves that problem big time. They also make a cable mount female for this connector so you can make extension cables with them.

[Church-Audio]

I think tapers are mostly using AT's installed sound stuff which mostly appears to be TA3F.  Unfortunately, I think all their wireless stuff is Hirose, which is like a $7 connector too.  That's more expensive than the capsule! 

$7 For a hirose is a good price.. Digikey? or Mouser? I do like the hirose but its not easy to work with or solder. yep all the AT install stuff 800 900 series is all 3 pin.