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Author Topic: 3 wire battery box build .......please help  (Read 1476 times)

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Offline joekar

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3 wire battery box build .......please help
« on: July 25, 2006, 11:30:09 PM »
Hello,
    While sitting here  playing with my toys I came up with an idea to build a new toy with some of the toys I already own.....(well most)....kind of like LEGO...but with a Dremel and a hot glue gun....I already have a SP PREAMP ...that little one with the adjustable gain...It sounds nice but it only has one 1/8 input instead of two... I was interested in making a true 3 wire bat box to help with the higher spl's using some AT 853 boxes and mics I have.......I purchased a set of AT853's from a fellow forum member ( thanks again Todd) and he provided me with small custom made heatshrinked together adapter box so I could connect the 853's directly to phantom power..therefore providing their required voltage (9V I believe not 48V) and a signal path (I/O)....The guts of these boxes came out of the stock boxes that AT provides to connect their mics to 48V phantom power.The inputs are 2 1/8 mini connectors (female) and the outputs are two XLR's connectors.......Since I recently purchased another pair of AT853's from SP I obtained the Sampson phantom power adapters I thought I would convert this "box" into a 3 wire battery box for "Jedi Council business".....
  My main question is how to power this thing with a 9V bat........The outputs are already laid out but I'm have some difficulty understanding how to provide power to it a get a signal out......I drew a little picture to show my delima....Any advise would be greatly appreciated....I would PM the person I bought them from but I think I already bothered him enough......
  I would like to output the signal to my R-09 with hard wired 1/8 connector and provide power from a 9V battery to feed the mics.......From looking at it I believe the bare/shield is negative.....the red positive and the yellow signal...please correct me if I am wrong....I looked at the thread for the 3 wire box for the 943's and found it very helpful......I have "heard" that the circuitry in the AT boxes sounds better than a regular battery box so I thougt I would give this a try.....The original reason I took apart the heat shrink box in the first place was because of intermittent static from the right channel....I found a bit of a bad connection...so since I didn't have any large heatshrink laying around I came up with this idea.....Thanks....I took a few pic to show what I was talking about.....
  One more question......how should I wire the 1/8 trs connector for the output signal....and sorry about all of the simple questions....but I just don't want to "smoke test" anything..........

Peace,
jk

Instead of using up TS space and bandwith... here is a link to my photobucket album

http://s96.photobucket.com/albums/l168/joekar/?sc=3?sc=3?sc=3?sc=3


edit:: I found the TRS wiring on Wikipedia...Sleeve ground.....Ring right and Tip left.....please correct me if I'm wrong

« Last Edit: July 26, 2006, 06:02:02 AM by joekar »
Roman Moroni: I would like to direct this to the distinguished members of the panel: You lousy corksuckers. You have violated my farging rights. Dis somanumbatching country was founded so that the liberties of common patriotic citizens like me could not be taken away by a bunch of fargin iceholes... like yourselves.

Offline poorlyconditioned

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Re: 3 wire battery box build .......please help
« Reply #1 on: July 25, 2006, 11:42:24 PM »
Hello,
    While sitting here  playing with my toys I came up with an idea to build a new toy with some of the toys I already own.....(well most)....kind of like LEGO...but with a Dremel and a hot glue gun....I already have a SP PREAMP ...that little one with the adjustable gain...It sounds nice but it only has one 1/8 input instead of two... I was interested in making a true 3 wire bat box to help with the higher spl's using some AT 853 boxes and mics I have.......I purchased a set of AT853's from a fellow forum member ( thanks again Todd) and he provided me with small custom made heatshrinked together adapter box so I could connect the 853's directly to phantom power..therefore providing their required voltage (9V I believe not 48V) and a signal path (I/O)....The guts of these boxes came out of the stock boxes that AT provides to connect their mics to 48V phantom power.The inputs are 2 1/8 mini connectors (female) and the outputs are two XLR's connectors.......Since I recently purchased another pair of AT853's from SP I obtained the Sampson phantom power adapters I thought I would convert this "box" into a 3 wire battery box for "Jedi Council business".....
  My main question is how to power this thing with a 9V bat........The outputs are already laid out but I'm have some difficulty understanding how to provide power to it a get a signal out......I drew a little picture to show my delima....Any advise would be greatly appreciated....I would PM the person I bought them from but I think I already bothered him enough......
  I would like to output the signal to my R-09 with hard wired 1/8 connector and provide power from a 9V battery to feed the mics.......From looking at it I believe the bare/shield is negative.....the red positive and the yellow signal...please correct me if I am wrong....I looked at the thread for the 3 wire box for the 943's and found it very helpful......I have "heard" that the circuitry in the AT boxes sounds better than a regular battery box so I thougt I would give this a try.....The original reason I took apart the heat shrink box in the first place was because of intermittent static from the right channel....I found a bit of a bad connection...so since I didn't have any large heatshrink laying around I came up with this idea.....Thanks....I took a few pic to show what I was talking about.....
  One more question......how should I wire the 1/8 trs connector for the output signal....and sorry about all of the simple questions....but I just don't want to "smoke test" anything..........

Peace,
jk

Instead of using up TS space and bandwith... here is a link to my photobucket album

http://s96.photobucket.com/albums/l168/joekar/?sc=3?sc=3?sc=3?sc=3


edit:: I found the TRS wiring on Wikipedia...Sleeve ground.....Ring right and Tip left.....please correct me if I'm wrong



There are two ways to power your mics:

1. AT853x adapters.  These convert phantom (48V) down to ~9V to power the mics.  They also isolate and strenghten the signal, and provide a balanced output with the transformer.

2. Battery box.  Supply 9V (or so) to the mics, typcially unbalanced outputs.

*do not* mix the two.  There is no sensible way to power your adapter boards from 9V.  They are designed to run on phantom power only.  So, you can do either 1 above (build the power modues into a box and power with a phantom supply or preamp with XLR connectors), or 2 above (build a *new* batterh box.

Now, for 2 (battery box), you can build either: a) two wire (standard) type, b) three wire type, c) two wire type, with added 4.7k resistor.

The simplest is probably case (c).  Connect a 4.7k resistor between yellow (audio) and shield (ground) on each mic.  Then supply power from a standard 2-wire battery box on red of each mic.  That's it!!!

  Richard
Mics: Sennheiser MKE2002 (dummy head), Studio Projects C4, AT825 (unmodded), AT822 franken mic (x2), AT853(hc,c,sc,o), Senn. MKE2, Senn MKE40, Shure MX183/5, CA Cards, homebrew Panasonic and Transsound capsules.
Pre/ADC: Presonus Firepod & Firebox, DMIC20(x2), UA5(poorly-modded, AD8620+AD8512opamps), VX440
Recorders: Edirol R4, R09, IBM X24 laptop, NJB3(x2), HiMD(x2), MD(1).
** This individual has moved to user "illconditioned" **

Offline joekar

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Re: 3 wire battery box build .......please help
« Reply #2 on: July 26, 2006, 12:56:30 AM »
Bummer man, I guess my idea was not such a good one after all.....thanks for the advise....as soon as my new soldering iron arrives I'll make a 3 wire box...and see what other damage I can do.....

Peace,
jk

Roman Moroni: I would like to direct this to the distinguished members of the panel: You lousy corksuckers. You have violated my farging rights. Dis somanumbatching country was founded so that the liberties of common patriotic citizens like me could not be taken away by a bunch of fargin iceholes... like yourselves.

Offline Church-Audio

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Re: 3 wire battery box build .......please help
« Reply #3 on: July 26, 2006, 01:39:35 AM »
You can mod that preamp to run three wire, but you would have to put it in a new box in order to do it because there is not much space left over once it is all built. You could use the  existing preamp power supply that runs the preamp to power up the mics, using a 10k resistor between the power supply + and the bias connection on the mic. It's very hard to do but it would work. The next question would be the saturation point of the preamp in question. Your AT mics have a huge output on them, as Richard mentioned one of the methods I have developed is using a 4.7k resistor between ground and the Yellow connections of the AT mics to reduce output / distortion. The trade off is reduced bias voltage feeding the mics, but that is not a huge deal since your reducing the output / distortion anyway. Good luck with your mod.


Chris Church



Bummer man, I guess my idea was not such a good one after all.....thanks for the advise....as soon as my new soldering iron arrives I'll make a 3 wire box...and see what other damage I can do.....

Peace,
jk


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