Topic: AT8531 RCA mod (completed w/ pics)

[kinglerxst]

>I completed both boxes and tested. They work fine.

They look good and they are what you were looking for connection wise. For some of the less intense stealth situations I would be comfortable using that set-up.

[kinglerxst]

>It just occurred to me, if people are pumping 48V into this module, then 9V is totally OK.
>All you have to do is take the bottom off, remove the battery sled for the AA and solder on a 9V clip.
>Then the 9v battery sits in the space, and you just use gaffer's tape to hold it in place.
>9V battery box, no problem. No extra anything needed.

That kind of goes with my powering question as the 8532 version runs on a 9V battery.

Just wondering what the powering difference is between the boxes running a single 1.5V AA and a 9V? Is the 8531 stepping up the 1.5V upto 9V internally?

You mentioned you measured 9V at the mini-xlr output to the mic, was that for both boxes, the AA one and the 9V one?

[igene]

 the traces all connect from the components to each pin except ground.

[igene]

>It just occurred to me, if people are pumping 48V into this module, then 9V is totally OK.
>All you have to do is take the bottom off, remove the battery sled for the AA and solder on a 9V clip.
>Then the 9v battery sits in the space, and you just use gaffer's tape to hold it in place.
>9V battery box, no problem. No extra anything needed.

That kind of goes with my powering question as the 8532 version runs on a 9V battery.

Just wondering what the powering difference is between the boxes running a single 1.5V AA and a 9V? Is the 8531 stepping up the 1.5V upto 9V internally?

You mentioned you measured 9V at the mini-xlr output to the mic, was that for both boxes, the AA one and the 9V one?

No, the output of the battery was the same at the output of the miniXLR.

AA output was 1.5-ish  and the 9V was around 9V.
I tested a tiny 12v, and I was getting That output.

[kinglerxst]

>AA output was 1.5-ish  and the 9V was around 9V

Interesting......

I have run the 8532's and 8531's at the same time using 2 rigs and they both powered the mics fine. Would be interesting to run one of each as a stereo pair and see how the signals differ with one mic running the 1.5V in one channel and the other running the 9V in the other.......

[kinglerxst]

>to act as an RF filter


Would this aid in protecting from "outside" interference, like from other electronic gadgets?

[igene]

I'm wondering now if that's something I should add to the mod (as I have removed it)

What should I add, and what value ?

although it may just be redundant and unneeded>

Posted by: mshilarious
The bits on the XLR are ceramic capacitors, they would be a small value to act as an RF filter.  Probably a bit belt & suspenders given the output transformer.

[Chuck]

The bits on the XLR are ceramic capacitors, they would be a small value to act as an RF filter.  Probably a bit belt & suspenders given the output transformer.

That's what I suspected too, as they don't look like the resistors I see on the SMT boards I've seen.

[kinglerxst]

>before audio band interference becomes objectionable.  The RF caps will do nothing about that.

Thanks for the info.

Too bad we can't solder in something to create an ACN (Assclown Crowd Noise) filter 

[illconditioned]

Igene: Why are you doing this???  If you're looking to power AT853 mics from battery, why not just build a battery box.  To reduce distortion, either build a three-wire battery box or do a 4.7k mod on the AT853 mic and then use a standard battery box (or plug-in power for lower sound levels).

  Richard

[Chuck]

I was just pointing out that the best use for that device is to turn 48v phantom power into ~9v for electret condenser microphones.
If he needs a battery box, he should buy or build a simple battery box. From my way of thinking if you're going to buy or build a battery box, you may as well get one that's a pre-amp too. For example the pre-amps that Chris Church makes. I believe it was Chris that pointed out that the AT boxes have a low cut filter built into them, which I don't think is a good thing necessarily.

[igene]

Igene: Why are you doing this???  If you're looking to power AT853 mics from battery, why not just build a battery box.  To reduce distortion, either build a three-wire battery box or do a 4.7k mod on the AT853 mic and then use a standard battery box (or plug-in power for lower sound levels).

  Richard

Because I could. I didn't need to really.
I envisioned it, and wanted to see what it would look like.
Also, I figured it would be a logical mod to improve connections, cables and limit space used.
Basically an experiment to see what works.
I think it came out nice.

I actually am in the process of building a battery box. (2 different ones)

This was just a fun diversion.
(also a learning process)

------------------------------------------------------------------------------------------------
I'm nowhere near done. I wasn't going to post this till I was done.
I just finished finding cases and started installing jacks and laying out the circuit on paper
(from designs I got links to here)

It's just bare bones right now...
2 wire >




3 wire >

[Church-Audio]

I don't know.
I can guess though.
Perhaps it has something to do with amps.

It just occurred to me, if people are pumping 48V into this module, then 9V is totally OK.
All you have to do is take the bottom off, remove the battery sled for the AA and solder on a 9V clip.
Then the 9v battery sits in the space, and you just use gaffer's tape to hold it in place.
9V battery box, no problem. No extra anything needed.


You must terminate pin 3 to ground. If you want to do this because if you dont you will have noise issues.



I'll take a measurement now...of the resistor (?)

[Sunday Driver]

igene, I just noticed this thread. I have two of these boxes collecting dust at home. Mine are the ones that are built to be hard wired to AT831 microphones. The connectors are different, but from memory the internals look the same. These things really are a waste of space, as they are poorly soldered together, and there are other higher quality alternatives for either unbalanced or balanced powering. One possible improvement though may be to use a 12 volt battery instead of the 9 volt. The 12 volt is smaller so it would probably fit in the AA compartment, and usually they can be found cheaper than the 9 volts even though they're not always as readily available.