Topic: Homebrew 12V 3 Wire Battery Box for AT853's

[cybermansrev]

I have the AT's powered by a SP's battery box overload at a couple of loud shows so I've finally made my own 3 Wire Battery Box.
 
I decided to try the 12V Battery purely for size. I'm still abit concerned about battery life, Sound Professionals quote 50 hours of use but as the quoted life is 33mAh I think in real life it's going to be a battery a show.
The design is that supplied by poorlyconditioned in http://taperssection.com/index.php?topic=49909.msg647012#msg647012 with a 12V battery and a slide switch on the battery as its not accessible easily.
I thought this project would be incredibly simple but soldering really appears to be an art! I runied 2 expensive 5 pin mini xlr connectors trying to make the mics removeable, oh well you live and learn.
I've yet to tape a show but trials at home seem pretty good, i'll report back how the 12v works and battery life.

[Krispy D]

+T for a nice diy project.  let us know how it sounds

[poorlyconditioned]

I have the AT's powered by a SP's battery box overload at a couple of loud shows so I've finally made my own 3 Wire Battery Box.
 
I decided to try the 12V Battery purely for size. I'm still abit concerned about battery life, Sound Professionals quote 50 hours of use but as the quoted life is 33mAh I think in real life it's going to be a battery a show.
The design is that supplied by poorlyconditioned in http://taperssection.com/index.php?topic=49909.msg647012#msg647012 with a 12V battery and a slide switch on the battery as its not accessible easily.
I thought this project would be incredibly simple but soldering really appears to be an art! I runied 2 expensive 5 pin mini xlr connectors trying to make the mics removeable, oh well you live and learn.
I've yet to tape a show but trials at home seem pretty good, i'll report back how the 12v works and battery life.

+T for the hacking.  As far as connectors go, I agree.  Solder everything together instead.  Easier and more reliable.  I avoided the switch by using a removeable battery (sliding battery tray), but the switch is good too.

  Richard

[Weazel]

cool, i was thinking to do the same with 12v too. so there is a power drain when mics are not plugged in?
i like to hear samples or complete recordings done with 3 wire boxxes.

[cybermansrev]

so there is a power drain when mics are not plugged in?

Well there wouldn't be except that I've soldered the mics directly to the circuit.

[Weazel]

let me know how recordings turn out

[kuba]

Well, sorry for stupid question, but what are advantages of 3-wire box (besides mentioned overload solution) compared to classical one?

[poorlyconditioned]

Well, sorry for stupid question, but what are advantages of 3-wire box (besides mentioned overload solution) compared to classical one?

advanatage: Less distortion, particularly at high sound levels.

disadvantage: slightly lower gain, ie., mics aren't as "hot" into preamp, slightly harder to build and wire, nonstandard wiring

  Richard

[lordbelial]

Mmmm. Just a couple of questions for my self improvement...

What differences in the behaviour of the mic makes the design for a 9V supply better or worst than the 12V supply?

What's the problem with the NJB3 line in and the 3-wire bbox and the volumen dropouts of 6db/12db? Someone could explain it more?

[cybermansrev]

What differences in the behaviour of the mic makes the design for a 9V supply better or worst than the 12V supply?

Not sure I can actually answer this as i haven't built an 9V 3 wire box. I choose the 12V battey purely for size, as then the box (with 12V battery) was the same size as a single 9V battery, not for any difference I was expecting in mic behaviour.
From listening to my recordings over the weekend I don't think the mics sound any "better" than with a 2 wire SP battery box except for the fact that they didn't overload at higher SPL (when obviously the 2 wire version sounds awful).
Of course this is completly subjective, I readily admit to not having "golden ears" and the music I record is bands playing in small clubs, loud with often amateur sound engineers and not the greatest boards / speakers.

As I said in the other post I intend to make another box with is not directly soldered to the mics so i can change between 2 and 3 wire design. Certainly if I'm at a larger venue with no opportunity of getting forward (ie seated) I'd want to go with the 2 wire design as it's more sensitive and i'm unlikely to get above 120db.

[lordbelial]

What differences in the behaviour of the mic makes the design for a 9V supply better or worst than the 12V supply?

Not sure I can actually answer this as i haven't built an 9V 3 wire box. I choose the 12V battey purely for size, as then the box (with 12V battery) was the same size as a single 9V battery, not for any difference I was expecting in mic behaviour.
From listening to my recordings over the weekend I don't think the mics sound any "better" than with a 2 wire SP battery box except for the fact that they didn't overload at higher SPL (when obviously the 2 wire version sounds awful).
Of course this is completly subjective, I readily admit to not having "golden ears" and the music I record is bands playing in small clubs, loud with often amateur sound engineers and not the greatest boards / speakers.

As I said in the other post I intend to make another box with is not directly soldered to the mics so i can change between 2 and 3 wire design. Certainly if I'm at a larger venue with no opportunity of getting forward (ie seated) I'd want to go with the 2 wire design as it's more sensitive and i'm unlikely to get above 120db.

I'll think about the switchable 2-wire and 3-wire version... I think it's a good point thinking about a bbox who could give different Max. SPL's.

In my case, I record always LOUD heavy metal shows at small venues, so, the 3-wire bbox configuration would be the correct one to run under.. What do you think?

I'm running right now CMC-4 (sp miniplug end) - SP-SPSB1 - NJB3 line in.

[cybermansrev]

I record always LOUD heavy metal shows at small venues, so, the 3-wire bbox configuration would be the correct one to run under.. What do you think?

I'm running right now CMC-4 (sp miniplug end) - SP-SPSB1 - NJB3 line in.

Well there's loud and then there's LOUD. Despite using Cardioid elements in the clubs I record I like to get close to the stacks for the best sound, without earplugs i really would have difficulty standing there  (Or at least suffering good going tinitus the next day).
In this case I think 3 wire means I don't overload the mics. So maybe for your requirements 3 wire would be good.

I know nothing about the JB3, but from other comments on 3 wire threads a cold signal to the JB3 may not be ideal. In my case at the minute I'm using an Archos AV4100 line-in this doesn't have a preamp and only allows a little adjustment of the gain so that without a doubt at a less loud gig (and I'm not talking acoustic) I'm sure the 3 wire will mean s/n ratio spoils the recording.

In essence I think if you're happy with your current recordings and aren't getting distortion due to levels >120db, then stick with what you've got. I certainly haven't found the mics tonal qualities to have changed much by using 3 wires BUT i know others say they have and as I say my ears are far from "golden".
If on the other hand you've overloaded your mics then maybe its the way forward.

Looking at your recent shows list Los Lobos don't really seem to fit with exclusively metal?

[lordbelial]

I record always LOUD heavy metal shows at small venues, so, the 3-wire bbox configuration would be the correct one to run under.. What do you think?

I'm running right now CMC-4 (sp miniplug end) - SP-SPSB1 - NJB3 line in.

Well there's loud and then there's LOUD. Despite using Cardioid elements in the clubs I record I like to get close to the stacks for the best sound, without earplugs i really would have difficulty standing there  (Or at least suffering good going tinitus the next day).
In this case I think 3 wire means I don't overload the mics. So maybe for your requirements 3 wire would be good.

I know nothing about the JB3, but from other comments on 3 wire threads a cold signal to the JB3 may not be ideal. In my case at the minute I'm using an Archos AV4100 line-in this doesn't have a preamp and only allows a little adjustment of the gain so that without a doubt at a less loud gig (and I'm not talking acoustic) I'm sure the 3 wire will mean s/n ratio spoils the recording.

In essence I think if you're happy with your current recordings and aren't getting distortion due to levels >120db, then stick with what you've got. I certainly haven't found the mics tonal qualities to have changed much by using 3 wires BUT i know others say they have and as I say my ears are far from "golden".
If on the other hand you've overloaded your mics then maybe its the way forward.

Looking at your recent shows list Los Lobos don't really seem to fit with exclusively metal?

He he... the Los Lobos recording was a request from Dan Gale. So I had the chance of taping them free. And I really enjoyed the show.

This last saturday I taped OPETH. Here's a caption from the waveform. Is this really overloaded?



What I really want is to know if It's really SECURE to mod the CMC-4's for the 3-wire bbox when running into a JB3 line-in, how will affect me those volume dropouts and... of course, what the hell are those volume dropouts??

Also, i don't know the difference between a cold and a hot signal.. please, could you tell me?

[lordbelial]

BUMP!

Looking at the picture I've just figured out that I'm running a kind of X-Y config in the mic.

That may cause this waveform, just because it seems that theres som' kind of "Phase cancel".

I'll change my config into ORTF or similar.

[Weazel]

i was reading the playback forum and found a topic about these capicators http://www.audience-av.com/passive.htm
would they be usable in a batterybox?

[poorlyconditioned]

i was reading the playback forum and found a topic about these capicators http://www.audience-av.com/passive.htm
would they be usable in a batterybox?

I don't believe in all that fancy stuff.  Speaker cables, audiophile caps, etc.  Maybe if you're working at high frequencies (like RF) it would matter, but I challenge anyone to hear a difference between caps, even an electrolytic, in double-blind tests.  In my own battery boxes I've used both polyester and electrolytic caps (proper polarity) and can't tell the difference.  Even Linkwitz, who first suggested this mod, shows electrolytics in his battery box   And this guy should know know audio (he was the inventer of the Linkwitz-Riley crossover circuit if anyone is curious.)

  Richard

[udovdh]

i was reading the playback forum and found a topic about these capicators http://www.audience-av.com/passive.htm
would they be usable in a batterybox?

I see much blabla but no specific info on what they are made of?
Go for polypropylene metal film.