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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: j.mart on January 13, 2006, 12:09:55 PM

Title: 3wire batt bocx for AT943
Post by: j.mart on January 13, 2006, 12:09:55 PM
Ok, i need something to do this upcoming weekend.

Could someone help me to find the schematics to a 3-wire batt. box for a pair of AT943?

Is it the same as the AT853?
Title: Re: 3wire batt bocx for AT943
Post by: graemecogger on January 13, 2006, 03:13:45 PM
Those are the capsules in the SP-CMC-8, I believe?  If so, this should do the trick:

(http://www.gcogger.dsl.pipex.com/stuff/at943_3w_bb.gif)

The ideal value for R1 depends on the caps - on my stereo pair, the ideal values vary by over 20%.  Something around 30k should be fine, though.
The values for C1 and R2 are not critical - as chosen, the capacitor will give no significant bass rolloff into any reasonable load.  R2 simply prevents the output from having a DC voltage on it prior to plugging in.

Obviously this needs to be duplicated for the 2 channels.

HTH
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on January 13, 2006, 03:27:38 PM
Those are the capsules in the SP-CMC-8, I believe?  If so, this should do the trick:

(http://www.gcogger.dsl.pipex.com/stuff/at943_3w_bb.gif)

The ideal value for R1 depends on the caps - on my stereo pair, the ideal values vary by over 20%.  Something around 30k should be fine, though.
The values for C1 and R2 are not critical - as chosen, the capacitor will give no significant bass rolloff into any reasonable load.  R2 simply prevents the output from having a DC voltage on it prior to plugging in.

Obviously this needs to be duplicated for the 2 channels.

HTH

+T Graeme.

That is pretty similar to what I've got at: www.cs.uwaterloo.ca/~mannr/AT853

Comments:
- I generally put a nonpolarized 2.2uF/100V for C1.  In case I plug into phantom power accidently.  (I don't know what happens if I reverse polarize an electrolytic cap C1 with 48V.  Do you know if it will survive?)
- I use a 22K resistor for R1, sometimes down to 10K if I want it to work with other caps (like AKG CK91/2/3).
- Adding and output resistor (R2) is a good idea.  I didn't think of that in my design :)

Keep posting circuits and gear guts folks!

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: j.mart on January 13, 2006, 05:05:39 PM
f'ing sweet! It's a bit more organized and clear than the sketch i've found (by poorlyconditioned, thanks anyway!).

Tomorrow's gonna be a long day 8)

thanks again
Title: Re: 3wire batt bocx for AT943
Post by: j.mart on January 13, 2006, 05:07:19 PM
Ah, i've heard this box could cut down up to 10db to the mic signal. Is this true? Anyone satisfied with the overall performance of these thingy's?

Greame, you don't happen to have a nice schematic for a DIY pre-amp would you?
Title: Re: 3wire batt bocx for AT943
Post by: graemecogger on January 13, 2006, 07:25:57 PM
+T Graeme.

That is pretty similar to what I've got at: www.cs.uwaterloo.ca/~mannr/AT853

Comments:
- I generally put a nonpolarized 2.2uF/100V for C1.  In case I plug into phantom power accidently.  (I don't know what happens if I reverse polarize an electrolytic cap C1 with 48V.  Do you know if it will survive?)
- I use a 22K resistor for R1, sometimes down to 10K if I want it to work with other caps (like AKG CK91/2/3).
- Adding and output resistor (R2) is a good idea.  I didn't think of that in my design :)

Keep posting circuits and gear guts folks!

  Richard


If you reverse polarise an electrolytic by 48V then what happens will depend on how much current the power supply can provide and how big the capacitor is.

I was once testing a large DC converter in which someone had fitted a 470uF/63V cap backwards.  Unfortunately, the supply feeding this thing could provide 50V at 60A (yes Amps, not milliAmps).  The result on switching on the converter was a loud bang, a jet of flame shooting out through the fan and a pool of acid on the workbench :)

On a smaller scale, I've had lower value electrolytics explode with much less than 50V in the reverse direction.  It's not too bad, but the smoke is unpleasant and it makes a bit of a mess inside the case.

For a phantom power supply, it probably can't provide much current so the results would probably be less drastic.  It's still a very bad idea, however, and the cap would be unlikely to survive for more than a few seconds!  I'd definately go for some sort of non-polarised capacitor if there's any risk of significant reverse voltage.

By the way (in case anyone is interested) varying the value of C1 is generally how the 'bass cut' battery box versions work.  The values to use depend entirely on the input impedance of the pre-amp you are driving.
Title: Re: 3wire batt bocx for AT943
Post by: graemecogger on January 13, 2006, 07:38:31 PM
Ah, i've heard this box could cut down up to 10db to the mic signal. Is this true? Anyone satisfied with the overall performance of these thingy's?

Greame, you don't happen to have a nice schematic for a DIY pre-amp would you?

The 3-wire connection should give lower distortion in general, better overload levels and a lower output impedance (better for driving long-ish cables).  It can, however, reduce the gain.  How much it reduces depends on the value of the resistor in the 'normal' battery box and the input impedance of the pre-amp.

My iRiver iHP-120, for example, provides a 2K2 pull-up resistor to allow the mics to be used without a battery box.  This value is so low that a 3-wire 9V battery box might actually give a slightly greater output!

I can post a pre-amp circuit some time soon, with a number of provisos:
- it is designed for my uses and the inevitable compromises may not be the same ones you want to make
- it will be almost the same as Richard's, with my suggested mods, from this thread:
-- http://taperssection.com/index.php?topic=57173.0 (http://taperssection.com/index.php?topic=57173.0)
- it won't have been tested for sound quality at this stage.  Companies producing these for a living have the luxury of building prototypes and tweaking the circuit and components until they sound at their best.
Title: Re: 3wire batt bocx for AT943
Post by: j.mart on January 13, 2006, 07:42:01 PM
Ah, i've heard this box could cut down up to 10db to the mic signal. Is this true? Anyone satisfied with the overall performance of these thingy's?

Greame, you don't happen to have a nice schematic for a DIY pre-amp would you?

The 3-wire connection should give lower distortion in general, better overload levels and a lower output impedance (better for driving long-ish cables).  It can, however, reduce the gain.  How much it reduces depends on the value of the resistor in the 'normal' battery box and the input impedance of the pre-amp.

My iRiver iHP-120, for example, provides a 2K2 pull-up resistor to allow the mics to be used without a battery box.  This value is so low that a 3-wire 9V battery box might actually give a slightly greater output!

I can post a pre-amp circuit some time soon, with a number of provisos:
- it is designed for my uses and the inevitable compromises may not be the same ones you want to make
- it will be almost the same as Richard's, with my suggested mods, from this thread:
-- http://taperssection.com/index.php?topic=57173.0 (http://taperssection.com/index.php?topic=57173.0)
- it won't have been tested for sound quality at this stage.  Companies producing these for a living have the luxury of building prototypes and tweaking the circuit and components until they sound at their best.

Hey, i'm really not demanding any work by you! I tought you found a schem for that batt and posted it here. You've been helpful enough for today ;D
Title: Re: 3wire batt bocx for AT943
Post by: j.mart on January 13, 2006, 07:45:38 PM
Checked that http://taperssection.com/index.php?topic=57173.0 ... Seems hard to do as hell, and it's not a job for me... Guess i'll have to give away some $ for a pre-amp

Thanks
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on January 13, 2006, 07:59:16 PM
Checked that http://taperssection.com/index.php?topic=57173.0 ... Seems hard to do as hell, and it's not a job for me... Guess i'll have to give away some $ for a pre-amp

Thanks

Believe it or not, the hardest part of all this DIY is mechanical.  Fitting all those parts in a very small area, soldering to tiny surface mount packages, getting secure connectors and battery holders, etc.  Most of the time I just kludge stuff, using existing cases, a dremmel tool, hot melt glue and shrink wrap.

At some point I should team up with a mechanical person and it could probably turn out a lot nicer.

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: j.mart on January 13, 2006, 08:06:42 PM
Checked that http://taperssection.com/index.php?topic=57173.0 ... Seems hard to do as hell, and it's not a job for me... Guess i'll have to give away some $ for a pre-amp

Thanks

Believe it or not, the hardest part of all this DIY is mechanical.  Fitting all those parts in a very small area, soldering to tiny surface mount packages, getting secure connectors and battery holders, etc.  Most of the time I just kludge stuff, using existing cases, a dremmel tool, hot melt glue and shrink wrap.

At some point I should team up with a mechanical person and it could probably turn out a lot nicer.

  Richard


I still have to browse the boxes-o-junk that i have in my garage, and i know that i don't have many stuff to complete the pre-amp... But the pics of your pre-amp are REALLY intimidating.

One thing's for sure... I'm gonna need help
Title: Re: 3wire batt bocx for AT943
Post by: lordbelial on January 15, 2006, 03:15:10 PM
ARGH!

So many projects to build up...

I guess in a couple of weeks I'll be able of building all the stuff i want to build, and then, I'll post the results...

Nice jobs and +T for all.
Title: Re: 3wire batt bocx for AT943
Post by: cybermansrev on January 15, 2006, 04:17:55 PM

I can post a pre-amp circuit some time soon, with a number of provisos:
- it is designed for my uses and the inevitable compromises may not be the same ones you want to make
- it will be almost the same as Richard's, with my suggested mods, from this thread:
-- http://taperssection.com/index.php?topic=57173.0 (http://taperssection.com/index.php?topic=57173.0)
- it won't have been tested for sound quality at this stage.  Companies producing these for a living have the luxury of building prototypes and tweaking the circuit and components until they sound at their best.

If you have time please do post your schematic for a preamp, it's always nice to see potential projects.
Title: Re: 3wire batt bocx for AT943
Post by: Zaphod on January 15, 2006, 04:47:54 PM
So what exactly is the benefit of running a three wire battery box, instead of a standard Soundpro type battery box?
Title: Re: 3wire batt bocx for AT943
Post by: j.mart on January 15, 2006, 04:52:34 PM
So what exactly is the benefit of running a three wire battery box, instead of a standard Soundpro type battery box?

Higher SPL handling
Title: Re: 3wire batt bocx for AT943
Post by: Zaphod on January 15, 2006, 04:53:58 PM
So what exactly is the benefit of running a three wire battery box, instead of a standard Soundpro type battery box?

Higher SPL

Gotcha should've figured that, +T
Title: Re: 3wire batt bocx for AT943
Post by: audBall on January 15, 2006, 06:29:12 PM
So what exactly is the benefit of running a three wire battery box, instead of a standard Soundpro type battery box?

Higher SPL

Gotcha should've figured that, +T

Technically speaking (not my native tongue  :P), the sound pros box (12v batt box excluded) only provides ~4.5volts to each mic with the 9v battery.  The 3wire setups provide a full 9v to each mic, correct?  At least, that's how I understood it...    (as always, someone chime in if need be)
Title: Re: 3wire batt bocx for AT943
Post by: graemecogger on January 15, 2006, 07:40:47 PM
Technically speaking (not my native tongue  :P), the sound pros box (12v batt box excluded) only provides ~4.5volts to each mic with the 9v battery.  The 3wire setups provide a full 9v to each mic, correct?  At least, that's how I understood it...    (as always, someone chime in if need be)

I suspect that you're a little mixed up about how the battery boxes work :)
The goal is to have roughly half the supply voltage across the FET in the mic, for best overload levels.
With a 2-wire connection you should end up with the FET drain (output wire) at about 4.5V and the FET source at 0V (it's connected to the ground wire) - that gives 4.5V across the FET.
With a 3-wire connection, the FET drain (red wire) is at 9V and the FET source (yellow wire) is at about 4.5V - again that's 4.5V across the FET.
Of course it's possible that the Sound Professionals box does something weird, but it seems unlikely.
HTH
Title: Re: 3wire batt bocx for AT943
Post by: audBall on January 15, 2006, 08:05:12 PM
Technically speaking (not my native tongue  :P), the sound pros box (12v batt box excluded) only provides ~4.5volts to each mic with the 9v battery.  The 3wire setups provide a full 9v to each mic, correct?  At least, that's how I understood it...    (as always, someone chime in if need be)

I suspect that you're a little mixed up about how the battery boxes work :)
The goal is to have roughly half the supply voltage across the FET in the mic, for best overload levels.
With a 2-wire connection you should end up with the FET drain (output wire) at about 4.5V and the FET source at 0V (it's connected to the ground wire) - that gives 4.5V across the FET.
With a 3-wire connection, the FET drain (red wire) is at 9V and the FET source (yellow wire) is at about 4.5V - again that's 4.5V across the FET.
Of course it's possible that the Sound Professionals box does something weird, but it seems unlikely.
HTH


Yep, I was definitely mixed up....thanks for the clarification.

Your explanation leads me to another question.  (see pic here: http://www.soundprofessionals.com/mas_assets/full/SP-PHANTOM.jpg)
If the SP phantom mod still uses 1/8" plugs to terminate the mics, and then uses the female 1/8 > miniXLR cable, is it rendering a 3wire setup useless and, basically, bringing it back to a 2wire setup?  Does that make sense?
Title: Re: 3wire batt bocx for AT943
Post by: Sanjay on January 15, 2006, 08:13:34 PM
Technically speaking (not my native tongue  :P), the sound pros box (12v batt box excluded) only provides ~4.5volts to each mic with the 9v battery.  The 3wire setups provide a full 9v to each mic, correct?  At least, that's how I understood it...    (as always, someone chime in if need be)

I suspect that you're a little mixed up about how the battery boxes work :)
The goal is to have roughly half the supply voltage across the FET in the mic, for best overload levels.
With a 2-wire connection you should end up with the FET drain (output wire) at about 4.5V and the FET source at 0V (it's connected to the ground wire) - that gives 4.5V across the FET.
With a 3-wire connection, the FET drain (red wire) is at 9V and the FET source (yellow wire) is at about 4.5V - again that's 4.5V across the FET.
Of course it's possible that the Sound Professionals box does something weird, but it seems unlikely.
HTH


Yep, I was definitely mixed up....thanks for the clarification.

Your explanation leads me to another question.  (see pic here: http://www.soundprofessionals.com/mas_assets/full/SP-PHANTOM.jpg)
If the SP phantom mod still uses 1/8" plugs to terminate the mics, and then uses the female 1/8 > miniXLR cable, is it rendering a 3wire setup useless and, basically, bringing it back to a 2wire setup?  Does that make sense?

No, because if its a 1/8" stereo cable, there is still three different sections on it, power, signal and ground.  By using a stereo cable for each mic, it still maintains its three wire capabilities. 

Essentially to break it down, the 3 wire battery box maintains a seperate ground for each mic, wheras the sp battery box keeps a shared ground and shared power.   
Title: Re: 3wire batt bocx for AT943
Post by: audBall on January 15, 2006, 08:23:47 PM
word, thanks Sanjay!
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on January 15, 2006, 08:33:42 PM
Technically speaking (not my native tongue  :P), the sound pros box (12v batt box excluded) only provides ~4.5volts to each mic with the 9v battery.  The 3wire setups provide a full 9v to each mic, correct?  At least, that's how I understood it...    (as always, someone chime in if need be)

I suspect that you're a little mixed up about how the battery boxes work :)
The goal is to have roughly half the supply voltage across the FET in the mic, for best overload levels.
With a 2-wire connection you should end up with the FET drain (output wire) at about 4.5V and the FET source at 0V (it's connected to the ground wire) - that gives 4.5V across the FET.
With a 3-wire connection, the FET drain (red wire) is at 9V and the FET source (yellow wire) is at about 4.5V - again that's 4.5V across the FET.
Of course it's possible that the Sound Professionals box does something weird, but it seems unlikely.
HTH


Yep, I was definitely mixed up....thanks for the clarification.

Your explanation leads me to another question.  (see pic here: http://www.soundprofessionals.com/mas_assets/full/SP-PHANTOM.jpg)
If the SP phantom mod still uses 1/8" plugs to terminate the mics, and then uses the female 1/8 > miniXLR cable, is it rendering a 3wire setup useless and, basically, bringing it back to a 2wire setup?  Does that make sense?

No, because if its a 1/8" stereo cable, there is still three different sections on it, power, signal and ground.  By using a stereo cable for each mic, it still maintains its three wire capabilities. 

Essentially to break it down, the 3 wire battery box maintains a seperate ground for each mic, wheras the sp battery box keeps a shared ground and shared power.   

I agree with Sanjay here.

I would try to avoid those 1/8" plugs, though.  Just put miniXLR plugs on the mics and be done with it.  Then you can either: 1) use the three wire batt. box with miniXLR sockets on it, or 2) use Samson or other adapters with miniXLR jacks on them.  Standardize to miniXLR plugs on everything.  That is what I did, so all my AT853 and AKG CK91, 93 caps.

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: Sanjay on January 15, 2006, 08:37:17 PM
def use the mini xlr's, my gear has gone flying off me during stealthing when a mosh pit started and if it wasn't for those locking connectors i would have been picking up shit all over.
Title: Re: 3wire batt bocx for AT943
Post by: audBall on January 15, 2006, 10:19:49 PM
I definitely hear what you guys are saying.  My current setup with the AT's is like the picture I showed (hence the posted picture and my recent questions). I always preferred the miniXLRs and wished that my bbox used them as well.   It'll be just my luck when those extra cables in the chain go kerplunk on me.  Soldering miniXLRs looks fun  ::) 
Title: Re: 3wire batt bocx for AT943
Post by: whatboutbob on February 24, 2006, 09:33:40 AM
So I just got done building the 3 wire battery box for which Graeme was kind enough to provide the schematic above, and have replaced my sp-cmc-10's 1/8' jack with 2 mini-xlrs.  I'm pleased to report nothing's exploded...yet... :)

Looks like its about 6dB quieter than running into the sp box (sp-sb6).  I'm yet to test in anger, so I'm not sure if the spl handling has improved just yet.  First run will be in a couple of nights, though the best upcoming test for it should be Dinosaur Jr in about 3 weeks.  Wish me luck.

Btw, if I can build this, just about any muppet can.
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on February 24, 2006, 11:01:13 AM
So I just got done building the 3 wire battery box for which Graeme was kind enough to provide the schematic above, and have replaced my sp-cmc-10's 1/8' jack with 2 mini-xlrs.  I'm pleased to report nothing's exploded...yet... :)

Looks like its about 6dB quieter than running into the sp box (sp-sb6).  I'm yet to test in anger, so I'm not sure if the spl handling has improved just yet.  First run will be in a couple of nights, though the best upcoming test for it should be Dinosaur Jr in about 3 weeks.  Wish me luck.

Btw, if I can build this, just about any muppet can.

+T to Adam.  I almost sold him a battery box, but due to me having a bad day and Adam's persistence, he has built his own.  I encourage anyone to do this, using either Graeme's or my circuits.  You'll feel like a hotter and stronger geek when you do :)

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: whatboutbob on February 24, 2006, 06:59:51 PM
...and a +T back Richard...thanks for all your patience with all my newbie solder-geek q's. :)
Title: Re: 3wire batt bocx for AT943
Post by: jeromejello on February 25, 2006, 11:01:57 AM
Technically speaking (not my native tongue  :P), the sound pros box (12v batt box excluded) only provides ~4.5volts to each mic with the 9v battery.  The 3wire setups provide a full 9v to each mic, correct?  At least, that's how I understood it...    (as always, someone chime in if need be)

I suspect that you're a little mixed up about how the battery boxes work :)
The goal is to have roughly half the supply voltage across the FET in the mic, for best overload levels.
With a 2-wire connection you should end up with the FET drain (output wire) at about 4.5V and the FET source at 0V (it's connected to the ground wire) - that gives 4.5V across the FET.
With a 3-wire connection, the FET drain (red wire) is at 9V and the FET source (yellow wire) is at about 4.5V - again that's 4.5V across the FET.
Of course it's possible that the Sound Professionals box does something weird, but it seems unlikely.
HTH


:hmmm:  i am an unfrozen caveman layer and your words and discriptions sometimes frighten me...  however, when i contacted chris at sp when i had a similar idea about only half the power going to the mics.  i told him that i would rather 2 9v in the box so the mics could each have the full 9v or to have a larger cell put in (12v) if it was going to be split.  he told me that the mics would still be recieving 9v each even with one battery.  now i dont know if what he said and you describe in a technical way means the same, but at the end of the day, he had my specific request and an unlimited budget to achieve that and only used one battery.
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on February 25, 2006, 01:28:09 PM
Technically speaking (not my native tongue  :P), the sound pros box (12v batt box excluded) only provides ~4.5volts to each mic with the 9v battery.  The 3wire setups provide a full 9v to each mic, correct?  At least, that's how I understood it...    (as always, someone chime in if need be)

I suspect that you're a little mixed up about how the battery boxes work :)
The goal is to have roughly half the supply voltage across the FET in the mic, for best overload levels.
With a 2-wire connection you should end up with the FET drain (output wire) at about 4.5V and the FET source at 0V (it's connected to the ground wire) - that gives 4.5V across the FET.
With a 3-wire connection, the FET drain (red wire) is at 9V and the FET source (yellow wire) is at about 4.5V - again that's 4.5V across the FET.
Of course it's possible that the Sound Professionals box does something weird, but it seems unlikely.
HTH


:hmmm:  i am an unfrozen caveman layer and your words and discriptions sometimes frighten me...  however, when i contacted chris at sp when i had a similar idea about only half the power going to the mics.  i told him that i would rather 2 9v in the box so the mics could each have the full 9v or to have a larger cell put in (12v) if it was going to be split.  he told me that the mics would still be recieving 9v each even with one battery.  now i dont know if what he said and you describe in a technical way means the same, but at the end of the day, he had my specific request and an unlimited budget to achieve that and only used one battery.


I think Chris did the correct wiring for a 3-wire battery box.  If you get a chance, I'd be interested in seeing a close up photo of the guts, perhaps with board/battery holder removed.

If in fact Chris has wired it correctly, we could just instruct others to ask Chris for your "special order" box.  Or, we could just give Sanjay a ring...

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: audBall on February 25, 2006, 01:30:27 PM
Technically speaking (not my native tongue  :P), the sound pros box (12v batt box excluded) only provides ~4.5volts to each mic with the 9v battery.  The 3wire setups provide a full 9v to each mic, correct?  At least, that's how I understood it...    (as always, someone chime in if need be)

I suspect that you're a little mixed up about how the battery boxes work :)
The goal is to have roughly half the supply voltage across the FET in the mic, for best overload levels.
With a 2-wire connection you should end up with the FET drain (output wire) at about 4.5V and the FET source at 0V (it's connected to the ground wire) - that gives 4.5V across the FET.
With a 3-wire connection, the FET drain (red wire) is at 9V and the FET source (yellow wire) is at about 4.5V - again that's 4.5V across the FET.
Of course it's possible that the Sound Professionals box does something weird, but it seems unlikely.
HTH


:hmmm:  i am an unfrozen caveman layer and your words and discriptions sometimes frighten me...  however, when i contacted chris at sp when i had a similar idea about only half the power going to the mics.  i told him that i would rather 2 9v in the box so the mics could each have the full 9v or to have a larger cell put in (12v) if it was going to be split.  he told me that the mics would still be recieving 9v each even with one battery.  now i dont know if what he said and you describe in a technical way means the same, but at the end of the day, he had my specific request and an unlimited budget to achieve that and only used one battery.


As much as I would like that to be the truth, if it were, then people would be frying their DPAs left and right, right?  :P   :)
Title: Re: 3wire batt bocx for AT943
Post by: whatboutbob on April 22, 2006, 07:15:21 AM
Hey folks,

Since running this box I've had an issue with cell phone interference coming through on my recordings..  Any ideas what I can do to shield against this?

Better cable?

Aluminium box?

Unbalanced? (have i got this right?  think i read somewhere that disconnecting the ground on one end makes some difference...I might just be making it up tho).
Title: Re: 3wire batt bocx for AT943
Post by: jeromejello on April 22, 2006, 10:40:18 AM
Hey folks,

Since running this box I've had an issue with cell phone interference coming through on my recordings..  Any ideas what I can do to shield against this?

Better cable?

Aluminium box?

Unbalanced? (have i got this right?  think i read somewhere that disconnecting the ground on one end makes some difference...I might just be making it up tho).

the box would be where i would first start... the more shielding for rf (whether from the unit [selfnoise] or others cellbies) the better.
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on April 22, 2006, 01:25:53 PM
Hey folks,

Since running this box I've had an issue with cell phone interference coming through on my recordings..  Any ideas what I can do to shield against this?

Better cable?

Aluminium box?

Unbalanced? (have i got this right?  think i read somewhere that disconnecting the ground on one end makes some difference...I might just be making it up tho).

I have never heard any interference (with any mics), so I don't know what this sounds like.

What were you running before?  Do you think the 2-wire would have less interference?  The first thing I would check is the length of the cables.  I don't see how an aluminum case would help (it is all low impedance circuitry), but I guess you could try covering the case in aluminum foil and see.  You can also get alumium "tape", used to fix heating ducts.  Try covering the case in this if it makes a difference

Good luck anyway...

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: whatboutbob on April 22, 2006, 07:26:10 PM
I have never heard any interference (with any mics), so I don't know what this sounds like.

What were you running before?  Do you think the 2-wire would have less interference?  The first thing I would check is the length of the cables.  I don't see how an aluminum case would help (it is all low impedance circuitry), but I guess you could try covering the case in aluminum foil and see.  You can also get alumium "tape", used to fix heating ducts.  Try covering the case in this if it makes a difference

Good luck anyway...

  Richard


If anyone's curious, this is what it sounds like: http://download.yousendit.com/FDA22FC34AFD2ADB

Its not usually quite this prominent - this sample is from me testing by putting my cell right next to my rig (and calling it).  The strength decreases the further the phone gets from the rig (can't isolate exactly which because cables are too short).  Richard, I don't *think* its cable length because the cable out of the batt box is only ~3 feet (and that's the only cable that has changed).  It might be the type of cable I'm using - its not particularly well shielded because its the only cable I could find to fit into a 3.5mm plug.

Previously I ran AT943(h) > SPSB-6 > H120. I'm now running AT853(c) > AT943 bodies > 3wire bb > H120.

Hehe...I was wondering if wrapping it in alfoil would replicate an aluminium box...I'll give that a shot today.  Do I need to ground the alfoil somehow? If so, how?  (i think i read somewhere that if I don't it'll actually act as a conductor...but I might be making that up).
Title: Re: 3wire batt bocx for AT943
Post by: Will_S on April 22, 2006, 09:04:35 PM
My iRiver iHP-120, for example, provides a 2K2 pull-up resistor to allow the mics to be used without a battery box.

Does this mean that there is no advantage to using a two-wire battery box with the iRiver?  Or just that the iRiver can get adequate levels from mics sans battery box, but SPL handling would still be better with even a two-wire box?
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on April 22, 2006, 09:35:35 PM
My iRiver iHP-120, for example, provides a 2K2 pull-up resistor to allow the mics to be used without a battery box.

Does this mean that there is no advantage to using a two-wire battery box with the iRiver?  Or just that the iRiver can get adequate levels from mics sans battery box, but SPL handling would still be better with even a two-wire box?

Like MD, you can use "plug-in-power" without a battery box.  Good for low level recording, but likely to overload for *any* type of amplified music.  Go ahead and try it though.  You might be surpresed.

2-wire battery box uses a higher voltage ((v) so gives you more headroom.  3-wire is the best, though!

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: whatboutbob on April 22, 2006, 10:08:07 PM
wrapping the box in alfoil amplifies the interference by 3db...  ???
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on April 22, 2006, 10:42:19 PM
wrapping the box in alfoil amplifies the interference by 3db...  ???

Interesting.

How about putting some aluminum "tape" over it then?  This is available at hardware stores (I think).  It is probably better than (thin) foil.

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: whatboutbob on April 22, 2006, 11:48:04 PM
Would I need to ground the aluminium foil (or tape) somehow?  If so, how?
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on April 22, 2006, 11:53:49 PM
Would I need to ground the aluminium foil (or tape) somehow?  If so, how?

I don't know.  I would just try it as is.  I guess you could experiment running a wire from ground of the box (eg., shield on the output miniplug) to the metal around the case.

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: whatboutbob on April 23, 2006, 01:56:38 AM
Hrmm...ok...the ground didn't help any, but then I disconnected the ground from the 3.5mm plug and it virtually eliminated the interference.

Any thoughts on why that would've fixed things?

Is there any reason I should reconnect the ground?
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on April 23, 2006, 02:10:59 AM
Hrmm...ok...the ground didn't help any, but then I disconnected the ground from the 3.5mm plug and it virtually eliminated the interference.

Any thoughts on why that would've fixed things?

Is there any reason I should reconnect the ground?

What do you mean "disconnected the ground from the 3.5mm plug"???  Please explain.

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: whatboutbob on April 23, 2006, 03:35:18 AM
Bah...never mind...it loused up the noise-floor anyways. I simply cut the ground so that it wasn't attached to the 3.5mm plug.  Clearly i have no idea what i'm doing...i'm just playing around.
Title: Re: 3wire batt bocx for AT943
Post by: Weazel on April 26, 2006, 07:40:29 AM
i constucted a pcb with this schematic. and made a pdf file. let me know what you think.
http://www.globalxs.nl/home/w/weazel/3wirebox.pdf
Title: Re: 3wire batt bocx for AT943
Post by: kuba on May 04, 2006, 12:17:59 PM
i constucted a pcb with this schematic. and made a pdf file. let me know what you think.
http://www.globalxs.nl/home/w/weazel/3wirebox.pdf

Nice!


Would it be possible to run AT831 with this?? Would it give a "better" sound or just higher SPL handling??
Title: Re: 3wire batt bocx for AT943
Post by: nihilistic0 on May 08, 2006, 12:42:31 AM
Couple of questions here

I have the SP-SPSB-1 battery box and AT853's
How would I go about doing the 3-wire mod on this


Also, I think I have a 12V battery box box from SP layin aruond somewhere...if I used thta with my AT853's would it damage them at all, or would it help rais ethe maximum SPL


thanks
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on May 08, 2006, 12:54:42 AM
Couple of questions here

I have the SP-SPSB-1 battery box and AT853's
How would I go about doing the 3-wire mod on this


Also, I think I have a 12V battery box box from SP layin aruond somewhere...if I used thta with my AT853's would it damage them at all, or would it help rais ethe maximum SPL


thanks

The directions for 3-wire battery box are on my webpage (and in previous messages here):
  www.cs.uwaterloo.ca/~mannr/AT853

You could probably use the 12V box, but I don't think it will improve much.  I suggest ripping the SP miniplug off and building a 3-wire box.  Note: if you always use the same mics, you could just hard-wire the cables and put a switch (or a sliding battery tray) there to turn it on/off. This is much more reliable, and avoids those expensive and fussy "miniXLR" connectors.

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: lordbelial on May 22, 2006, 06:55:28 AM
i constucted a pcb with this schematic. and made a pdf file. let me know what you think.
http://www.globalxs.nl/home/w/weazel/3wirebox.pdf

Hi!

I think you made a mistake with the nodes of the capacitor C1. There should be an empty trace between the "positive" terminal and the "negative" terminal of the capacitor -if electrolytic 10uF are used).

See attached image (draft drawing I've done this morning at work...)

Anyway, your PCB design was great and the components were optimally placed. +T for you.

EDIT: Attachment removed. Bad miniXLR wiring.
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on May 22, 2006, 12:49:23 PM
i constucted a pcb with this schematic. and made a pdf file. let me know what you think.
http://www.globalxs.nl/home/w/weazel/3wirebox.pdf

Hi!

I think you made a mistake with the nodes of the capacitor C1. There should be an empty trace between the "positive" terminal and the "negative" terminal of the capacitor -if electrolytic 10uF are used).

See attached image (draft drawing I've done this morning at work...)

Anyway, your PCB design was great and the components were optimally placed. +T for you.

The miniXLR pins are wrong.  It should be:
1: ground>>>>>>shield of cable
2: audio >>>>>yellow wire
3: battery/bias>>>>red wire

  Richard

Title: Re: 3wire batt bocx for AT943
Post by: lordbelial on May 22, 2006, 03:02:24 PM
i constucted a pcb with this schematic. and made a pdf file. let me know what you think.
http://www.globalxs.nl/home/w/weazel/3wirebox.pdf

Hi!

I think you made a mistake with the nodes of the capacitor C1. There should be an empty trace between the "positive" terminal and the "negative" terminal of the capacitor -if electrolytic 10uF are used).

See attached image (draft drawing I've done this morning at work...)

Anyway, your PCB design was great and the components were optimally placed. +T for you.

The miniXLR pins are wrong.  It should be:
1: ground>>>>>>shield of cable
2: audio >>>>>yellow wire
3: battery/bias>>>>red wire

  Richard



Yes...  ??? I always make the same mistake. But thanks my god my physical wiring is OK. I'll post the correct "draft" tomorrow. I don't want the people to fall into misunderstanding by my fault.

Anyway thanks for this.

I'll post photos later. As soon as I get a camera...
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on May 22, 2006, 03:07:16 PM
i constucted a pcb with this schematic. and made a pdf file. let me know what you think.
http://www.globalxs.nl/home/w/weazel/3wirebox.pdf

Hi!

I think you made a mistake with the nodes of the capacitor C1. There should be an empty trace between the "positive" terminal and the "negative" terminal of the capacitor -if electrolytic 10uF are used).

See attached image (draft drawing I've done this morning at work...)

Anyway, your PCB design was great and the components were optimally placed. +T for you.

The miniXLR pins are wrong.  It should be:
1: ground>>>>>>shield of cable
2: audio >>>>>yellow wire
3: battery/bias>>>>red wire

  Richard



Yes...  ??? I always make the same mistake. But thanks my god my physical wiring is OK. I'll post the correct "draft" tomorrow. I don't want the people to fall into misunderstanding by my fault.

Anyway thanks for this.

I'll post photos later. As soon as I get a camera...

Oh yeah, you don't need a circuit board for this.  Just use "point-to-point" wiring.  Take the caps and glue them in place (epoxy or hot melt glue).  Then just solder all the other parts in between.  Another trick is to wrap the resistors in a very thin tube of heat shrink.  This will insulate the wires and prevent shorts.  Oh yeah, when you're done, smother the whole thing in hot melt glue.  Just to be sure things hold together :)

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: lordbelial on May 22, 2006, 05:48:19 PM
Well. Here are the results...

I hope you enjoy them. This was the second 3-wire battery box I made. First was done with "poorlyconditioned" schematics, and this one you see has got the 220 Kohm resistor at the output, and will go to a friend of mine who requested it.

Thanks god I found the hot melt glue gun at home (well, my father did...)
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on May 22, 2006, 06:32:58 PM
Well. Here are the results...

I hope you enjoy them. This was the second 3-wire battery box I made. First was done with "poorlyconditioned" schematics, and this one you see has got the 220 Kohm resistor at the output, and will go to a friend of mine who requested it.

Thanks god I found the hot melt glue gun at home (well, my father did...)

+T for the glue.  You've got natural talent :)

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: dano420 on May 25, 2006, 02:35:51 AM
This is the first one that I made. It came out OK and sounds great! It's an extra right now so if anyone is looking for one, I have this one available. It has all film caps and resistors, switchcraft mini-xlr connectors, a led power light, a micro on-off switch and a dedicated mini-xlr to 1/8" adaptor. It's also about 2/3rd the size of the SP 2-wire box making it a little smaller for stealthing. I made another one that I'm going to try out this weekend. Fun stuff!!
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on May 25, 2006, 02:42:43 AM
This is the first one that I made. It came out OK and sounds great! It's an extra right now so if anyone is looking for one, I have this one available. It has all film caps and resistors, switchcraft mini-xlr connectors, a led power light, a micro on-off switch and a dedicated mini-xlr to 1/8" adaptor. It's also about 2/3rd the size of the SP 2-wire box making it a little smaller for stealthing. I made another one that I'm going to try out this weekend. Fun stuff!!

Wow, that is nice!  I would remove the LED though.  That will take way too much power (10mA vs about 0.5mA for the mics), and will drain your battery fast.  Hmm.  Ideally, you could put an LED that just flickers when you turn it on, but that is more work.  In fact, don't put a switch at all.  Just turn it on by inserting the mics.

OK, now can you please help me out and tell me the source/part # for that box.  I'm looking for something nice and small like that.  Send by PM if you like...

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: lordbelial on May 25, 2006, 04:12:50 AM
This is the first one that I made. It came out OK and sounds great! It's an extra right now so if anyone is looking for one, I have this one available. It has all film caps and resistors, switchcraft mini-xlr connectors, a led power light, a micro on-off switch and a dedicated mini-xlr to 1/8" adaptor. It's also about 2/3rd the size of the SP 2-wire box making it a little smaller for stealthing. I made another one that I'm going to try out this weekend. Fun stuff!!

Wow, that is nice!  I would remove the LED though.  That will take way too much power (10mA vs about 0.5mA for the mics), and will drain your battery fast.  Hmm.  Ideally, you could put an LED that just flickers when you turn it on, but that is more work.  In fact, don't put a switch at all.  Just turn it on by inserting the mics.

OK, now can you please help me out and tell me the source/part # for that box.  I'm looking for something nice and small like that.  Send by PM if you like...

  Richard


Hi,

Nice work! +T for the lateral concept. I was thinking in that too, changing the miniXLR from the front side of the box to the right/left side as you have done.

Richard wants to know the reference/PN for the box, I think it would be interesting to post the list of materials for every box we have made, so the DYers would have it easier to go ahead in 3-wire battery building.

For example, in my first box I used 10 uF / 63 V electrolitic capacitors and in my second one I've used PANASONIC 2,2 uF / 250 Volt metal film capacitors. I can't note the differences between the two types of capacitors...

ALSO! I'm searching for a 50 KOhm logaritmic Stereo potentiometer for a preamp building, so If anybody knows a PN or reference It will be appreciated  :laugh:
Title: Re: 3wire batt bocx for AT943
Post by: dano420 on May 25, 2006, 11:54:24 AM
This is the first one that I made. It came out OK and sounds great! It's an extra right now so if anyone is looking for one, I have this one available. It has all film caps and resistors, switchcraft mini-xlr connectors, a led power light, a micro on-off switch and a dedicated mini-xlr to 1/8" adaptor. It's also about 2/3rd the size of the SP 2-wire box making it a little smaller for stealthing. I made another one that I'm going to try out this weekend. Fun stuff!!

Wow, that is nice!  I would remove the LED though.  That will take way too much power (10mA vs about 0.5mA for the mics), and will drain your battery fast.  Hmm.  Ideally, you could put an LED that just flickers when you turn it on, but that is more work.  In fact, don't put a switch at all.  Just turn it on by inserting the mics.

OK, now can you please help me out and tell me the source/part # for that box.  I'm looking for something nice and small like that.  Send by PM if you like...

  Richard


Actually, I did a lot of research on the led and this particular one isn't very bright and takes less than 1mA to operate. The switch idea is there to flip it on when you need to even further saving battery power. I know when I go stealthing, sometimes I have my gear on me and running for up to 30mins before the show. It would be nice to just save the power and then reach in my pocket and flip a switch. =)

Oddly enough, the project box is available at your local rat shack! The part number is 270-1801. I even went out to my local electronics superstore and they didn't have anything small enough!

Here's the second one I made with all the controls on the front.

Edit: Both of these boxes use 2.2uF 100v film caps and all 1% film resistors. The input resistor is set at 10k for use with other caps such as the ck9x, which I plan to use someday soon. A big +T to Richard for the great research into this, and anbody else behind the scene!
Title: Re: 3wire batt bocx for AT943
Post by: lordbelial on May 25, 2006, 12:23:57 PM

Actually, I did a lot of research on the led and this particular one isn't very bright and takes less than 1mA to operate. The switch idea is there to flip it on when you need to even further saving battery power. I know when I go stealthing, sometimes I have my gear on me and running for up to 30mins before the show. It would be nice to just save the power and then reach in my pocket and flip a switch. =)

Oddly enough, the project box is available at your local rat shack! The part number is 270-1801. I even went out to my local electronics superstore and they didn't have anything small enough!

Here's the second one I made with all the controls on the front.

Edit: Both of these boxes use 2.2uF 100v film caps and all 1% film resistors. The input resistor is set at 10k for use with other caps such as the ck9x, which I plan to use someday soon. A big +T to Richard for the great research into this, and anbody else behind the scene!

It looks really nice.

I'll try to make my next box with this concept. I have a small box like these at home and I could not find it a use...  ;D

But I really don't want to worry about the led and the switch, most of the times I change the battery when it is not still drained up...

Next DIY project I'm going to build is a 3-wire battery box with a 10db boost gain (preamp stage), to see how it works in the field...
Title: Re: 3wire batt bocx for AT943
Post by: lordbelial on May 25, 2006, 12:26:16 PM
i constucted a pcb with this schematic. and made a pdf file. let me know what you think.
http://www.globalxs.nl/home/w/weazel/3wirebox.pdf

Nice!


Would it be possible to run AT831 with this?? Would it give a "better" sound or just higher SPL handling??

I think YES.

AT831/853/943 are wired the same way, so the same 3-wire battery box would work

Correct me if I'm wrong!
Title: Re: 3wire batt bocx for AT943
Post by: dano420 on May 25, 2006, 12:32:54 PM
Next DIY project I'm going to build is a 3-wire battery box with a 10db boost gain (preamp stage), to see how it works in the field...

I was even thinking of building a 4-channel bbox with gain/pre on each set of channels. It's wouldn't be for stealthing but would be a nice small box for a 4 mic mix!
Title: Re: 3wire batt bocx for AT943
Post by: fozzy on July 13, 2006, 05:34:00 PM
So I am working up a design for a new 3 wire BB for myself.

Woule it be possible to combine the left and right channels into a 4pin ta4f/b4m plug setup. 
Something like this,

Pin 1: +9v(R)
Pin 2: Yellow(R)
Pin 3: Yellow(L)
Pin 4: +9v(L)
housing: ground

Or am I totally off base here,


Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on July 13, 2006, 05:43:48 PM
Yep.  You can do that.

You could even do it with a 3-pin miniXLR, because you really only need one +9V terminal, not two.

So the four connections needed are:
+9V
ground
L audio
R audio

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: fozzy on July 13, 2006, 06:01:38 PM
Yep.  You can do that.

You could even do it with a 3-pin miniXLR, because you really only need one +9V terminal, not two.

So the four connections needed are:
+9V
ground
L audio
R audio

  Richard


Cool, thats what i was thinking too.  I just talked myself out of it.

My over all plan.

trim 2 AT853 to have ~3" cable length

use a small potting box (.5" X .5" x .35") to wire the mics to a single minature starquad cable, a la the schoeps KCY cable. 

terminate the starquad into a ta3f.

Should be able to get this into a 2.25 x 1.5 x1.375 box. 
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on July 13, 2006, 06:23:33 PM
Yep.  You can do that.

You could even do it with a 3-pin miniXLR, because you really only need one +9V terminal, not two.

So the four connections needed are:
+9V
ground
L audio
R audio

  Richard


Cool, thats what i was thinking too.  I just talked myself out of it.

My over all plan.

trim 2 AT853 to have ~3" cable length

use a small potting box (.5" X .5" x .35") to wire the mics to a single minature starquad cable, a la the schoeps KCY cable. 

terminate the starquad into a ta3f.

Should be able to get this into a 2.25 x 1.5 x1.375 box. 

Hey, if you (or anyone else ...) get any leftover cable I could use it for my various "active" projects.

Thanks (to anyone...)

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: fozzy on July 13, 2006, 06:30:35 PM
Looking at 1% tolerance Metal film resistors.  What chemisrty of capacitor is the best for the BB purpose?
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on July 13, 2006, 07:48:59 PM
Looking at 1% tolerance Metal film resistors.  What chemisrty of capacitor is the best for the BB purpose?

I use metal film or polyester caps.  You can use electrolytic too, just get the polarity right.

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: aberg on July 13, 2006, 09:32:03 PM
Wow, those pics of the 3wire BB that you designed look sweet... 943s into that plus an iRiver would be uber stealthy...

how much are you asking for those dano?
Title: Re: 3wire batt bocx for AT943
Post by: fozzy on July 14, 2006, 07:37:52 PM
got my design mostly figured out, but still need 1 more recomenddation

Looking for a mini toggle switch, threaded w/ nuts (5pc set), All the ones on Digikey are 4-7 dollars which seems high to me
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on July 14, 2006, 08:21:00 PM
got my design mostly figured out, but still need 1 more recomenddation

Looking for a mini toggle switch, threaded w/ nuts (5pc set), All the ones on Digikey are 4-7 dollars which seems high to me

Hey, why don't you build it without a switch.  Ie., it is an open circuit until you plug the mics in.  I would only use a switch if I wanted: 1) a lowcut/highpass filter, 2) to hardware with mics to avoid connectors.

Please post photos once you build it.

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: fozzy on July 14, 2006, 08:25:57 PM
got my design mostly figured out, but still need 1 more recomenddation

Looking for a mini toggle switch, threaded w/ nuts (5pc set), All the ones on Digikey are 4-7 dollars which seems high to me

Hey, why don't you build it without a switch.  Ie., it is an open circuit until you plug the mics in.  I would only use a switch if I wanted: 1) a lowcut/highpass filter, 2) to hardware with mics to avoid connectors.

Please post photos once you build it.

  Richard


makes sense
So with the 3wire pdf posted earlier in the thread i see it is an open circuit, I won't have to worry about it being on till I plug in the mics.  cool
having the output hardwired won't "turn it on"?
Title: Re: 3wire batt bocx for AT943
Post by: poorlyconditioned on July 14, 2006, 08:29:08 PM
got my design mostly figured out, but still need 1 more recomenddation

Looking for a mini toggle switch, threaded w/ nuts (5pc set), All the ones on Digikey are 4-7 dollars which seems high to me

Hey, why don't you build it without a switch.  Ie., it is an open circuit until you plug the mics in.  I would only use a switch if I wanted: 1) a lowcut/highpass filter, 2) to hardware with mics to avoid connectors.

Please post photos once you build it.

  Richard

makes sense
So with the 3wire pdf posted earlier in the thread i see it is an open circuit, I won't have to worry about it being on till I plug in the mics.  cool
That's right.

Quote
having the output hardwired won't "turn it on"?
Right.  The *output* will not turn it on, it is the input (the mics).
I say "hardwired" meaning the mics are soldered instead of connecting with miniXLR or other.  In this case you'll need a way to turn it *off* when not in use.  You can do this with a switch, or my favourite, a sliding battery tray.  Just slide in the battery to use the mics.

  Richard
Title: Re: 3wire batt bocx for AT943
Post by: TideBleach on July 16, 2006, 04:48:02 PM
would i need a preamp to go with a pair of sp-at853's and the 3 wire box going into an iriver h120 line in? or would the at853's and the 3 wire box still make it loud enough? anyone have this combo with out a preamp? how much gain do you use from your h120 at a loud show?

thanks tidebleach
Title: Re: 3wire batt bocx for AT943
Post by: hyperplane on July 16, 2006, 05:59:26 PM
would i need a preamp to go with a pair of sp-at853's and the 3 wire box going into an iriver h120 line in? or would the at853's and the 3 wire box still make it loud enough? anyone have this combo with out a preamp? how much gain do you use from your h120 at a loud show?

thanks tidebleach

Obviously, the term "loud" is subjective. At a local club, with a decently 'loud' PA, I used that exact setup (AT853 > 3wire bbox > iriver LINE In) and had the iriver gain set at between +13 to +17 dB of gain, and my peaks were hitting at -3dB on the latter setting (of +17dB of gain). If I were running the two wire version at that same show, I would estimate only using maybe +5 dB to +8 dB of gain on the iriver.

Also, with my AT831s, it seems like the mic output diminished by a solid 12 dB or so (during the pre-3wire modification time period).
Title: Re: 3wire batt bocx for AT943
Post by: TideBleach on July 16, 2006, 06:19:40 PM
thanks thats exactly what i wanted to know  :) i just wanted to make sure it wasn't going to make me add so much gain that it would use digital gain. when i said loud i meant to say was, would the signal still be hot enough to just use analog gain on the irver h120.

thanks for your help

tidebleach   :)
Title: Re: 3wire batt bocx for AT943
Post by: whatboutbob on July 16, 2006, 06:27:25 PM
Obviously, the term "loud" is subjective. At a local club, with a decently 'loud' PA, I used that exact setup (AT853 > 3wire bbox > iriver LINE In) and had the iriver gain set at between +13 to +17 dB of gain, and my peaks were hitting at -3dB on the latter setting (of +17dB of gain). If I were running the two wire version at that same show, I would estimate only using maybe +5 dB to +8 dB of gain on the iriver.

I use about the same settings.  Acoustic sets would require ~+30 gain...which is when the iriver pre starts to get a bit sketchy to my ears.
Title: Re: 3wire batt bocx for AT943
Post by: Chaosu on April 17, 2009, 04:09:55 PM
I finally found someone who can build a bb for me for reasonable amount of money, out of presented schemes he picked this one
(http://www.elektroda.pl/rtvforum/files-rtvforum/aaacii_1939.gif)
I would like to ask if all those values seems ok for AT853 type of mics (SP-CMC-4). I am basically not going to use bass cut but maybe in future... I am also satisfied with these mics so not planning any upgrade (especially if I'll finally have higher SPL handling). Any corrections/ideas welcome. This is meant to be 3 wire bb I hope.
Title: Re: 3wire batt bocx for AT943
Post by: Chaosu on April 17, 2009, 06:13:06 PM
Fuck! Luckily I made that question.... how about this one then?
http://www.gcogger.dsl.pipex.com/stuff/at943_3w_bb.gif
No bass cut but I don't need that anyway.
Title: Re: 3wire batt bocx for AT943
Post by: Sunday Driver on April 18, 2009, 01:39:12 PM
Fuck! Luckily I made that question.... how about this one then?
http://www.gcogger.dsl.pipex.com/stuff/at943_3w_bb.gif
No bass cut but I don't need that anyway.

Yes, that is the proper schematic to use for your application.
Title: Re: 3wire batt bocx for AT943
Post by: Chaosu on May 05, 2009, 07:39:38 PM
Fuck! Luckily I made that question.... how about this one then?
http://www.gcogger.dsl.pipex.com/stuff/at943_3w_bb.gif
No bass cut but I don't need that anyway.

Yes, that is the proper schematic to use for your application.
I just picked up my battery box. Output is mono. I didn't noticed that earlier and it was made according to schematic.
Title: Re: 3wire batt bocx for AT943
Post by: Chaosu on May 15, 2009, 06:44:11 AM
I was just told that no 3 wire battery box can be made for single stereo input. Is this true?
Title: Re: 3wire batt bocx for AT943
Post by: Neilyboy on May 18, 2009, 05:16:06 PM
the schematic you posted was only single channel. you just need to 'double' the schematic.
http://www.gcogger.dsl.pipex.com/stuff/at943_3w_bb.gif

just my $0.02 may be wrong but from all other bb plans I have seen its just a matter of mirroring the schematic.

/edit.. see "graemecogger" first post.. 'Obviously this needs to be duplicated for the 2 channels.'

so if whoever built this for you just built it exactly the the schematic then yes all you will have is mono. you will need to mirror it to get your second channel.

Neil