Author Topic: AT8531 RCA mod (completed w/ pics) (Read 18214 times)

igene · « **on:** March 21, 2011, 07:26:57 PM »

I got a pair of these and I opened them up.

I was thinking I could change the output (XLR) wiring to a Female RCA panel jack.
That way I just need a L/R male RCA to mini jack to a recorder...
instead of a giant XLR/RCA adapter, and then the cable.

How do I wire the RCA jack. There's 3 wires going to 2 wires.
To I tie the common and ground together ?
Or use the common, and ground to the chassis ?

anyone ?

Roger Gustavsson · « **Reply #1 on:** March 22, 2011, 06:20:10 AM »

Hi igene,

How do you power them?

Roger

igene · « **Reply #2 on:** March 22, 2011, 09:45:54 AM »

Hi Roger

I have not changed anything, so with the AA battery.
Do you suggest something different ?
I'm open to all suggestions with these.
I'm basically willing to do whatever needs to be done (if you have some upgrade solution).

Gene

Roger Gustavsson · « **Reply #3 on:** March 22, 2011, 10:10:20 AM »

My mistake, I thought it was a microphone AT853.... So it is a power module like this?
http://www.audio-technica.com/cms/resource_library/product_images/32c9af8fd6582d72/large/at8531.jpg

I am not familiar with it. It seems to have two power options. Balanced while powered from Phantom and single-ended while using the batteries. Are you using two of these? What recording device are you connecting it with? (Not that I am the person to tell what is should be like...)

Roger

kinglerxst · « **Reply #4 on:** March 22, 2011, 10:16:18 AM »

I use a pair of the 8531's on my 2nd rig. I've been curious as to how they function with the AA battery as my main rig uses a pair of 8532's which each use a 9V battery.

Do you have any photos of the inside of the 8531's?

igene · « **Reply #5 on:** March 22, 2011, 10:37:36 AM »

Yes, I'd be using 2, and it's going to a digital recorder w/ a 3.5mm line in.

BONE STOCK >

kinglerxst · « **Reply #6 on:** March 22, 2011, 10:54:18 AM »

Just curious, if you're running from the pair of 8531 XLR's to the recorder via a 3.5mm mini plug, why would the RCA stuff be needed? I run a Y cable from the 2 xlr's on the 8531's to the mini plug on the recorder and I prefer the xlr because they lock.

igene · « **Reply #7 on:** March 22, 2011, 11:04:12 AM »

I'd be replacing the XLR connector with a Female panel RCA.
The RCA connection would be very recessed, eliminates the use of a XLR to RCA adapter barrel
(the extra space needed to accommodate it )and makes for a secure connection because it's out of the way.

Then all you need is a stereo male RCA to mini jack cable.
(smaller footprint, less connections)

kinglerxst · « **Reply #8 on:** March 22, 2011, 11:30:05 AM »

>eliminates the use of a XLR to RCA adapter barrel

Why would you need to go from XLR to RCA and then to mini jack? Is XLR straight to mini jack not what you require?

>(the extra space needed to accommodate it )and makes for a secure connection because it's out of the way.

If the normal XLR's are too big you could always go with stubbies.

>Then all you need is a stereo male RCA to mini jack cable.
>(smaller footprint, less connections)

That's three connections (2 RCA & 1 mini), same as using a Y cable XLR > mini so same number of connections. Maybe slightly smaller footprint, but with stubby XLR's close to the same.

Plus even though it's probably rare, even a reccessed RCA plug can get pulled out, even just little enough to affect the connection, the xlr's locking prevents that. I've used normal XLR > mini Y cables for over 10 years with no problems and in very cramped space.

igene · « **Reply #9 on:** March 22, 2011, 11:50:50 AM »

All that is probably true for the most part, but a recessed RCA connection is also secure.
I don't tape from the mosh pit, the equipment is always in a protected area and the cables and footprint is somewhat smaller.
Besides, I'll have a unique set of modules, the cables are more readily available, and I'd like to do the mod.
I think that it will look great too.

so why not...?

It's a quick and easy mod.

Can someone please tell me where the wires go ?

kinglerxst · « **Reply #10 on:** March 22, 2011, 12:01:22 PM »

>so why not...?

If that's what you want, go for it!

I was just curious as to why since I've never had any issues with them as they are and they already have great connections, but if you're into tinkering that's cool too.

Thanks for the photos of the interior and I hope someone can hook you up with the wiring info.

darktrain · « **Reply #11 on:** March 22, 2011, 01:48:05 PM »

basically you would bridge the 1 and 3 pin on the xlr to the ground of the rca and pin 2 would go to the tip

igene · « **Reply #12 on:** March 22, 2011, 01:51:44 PM »

THANK YOU.

hot to tip is obvious, but I wasn't sure about the grounding.

I just needed the confirmation.

Chuck · « **Reply #13 on:** March 22, 2011, 02:08:37 PM »

igene, check out this thread before you start modifying those boxes.
http://taperssection.com/index.php?topic=32849.0

It looks like the best way to run them is with phantom power.
So, you'll probably want to keep the full sized XLR jacks.

igene · « **Reply #14 on:** March 22, 2011, 02:26:45 PM »

Quote from: Chuck on March 22, 2011, 02:08:37 PM

igene, check out this thread before you start modifying those boxes.
http://taperssection.com/index.php?topic=32849.0

It looks like the best way to run them is with phantom power.
So, you'll probably want to keep the full sized XLR jacks.

I'm just modding the output jack. XLR > RCA
Instead of using an adapter cable, I'm doing it inside the box.

The miniXLR provides the power to the mic.
I'm not touching that !

Does that make sense ?

one thing I'm still not clear on...how much voltage do these modules provide > 1.5V right ?
because the audio-technica specs say 9-48V how can that be true ?

Chuck · « **Reply #15 on:** March 22, 2011, 02:36:34 PM »

If you replace the full sized XLR jack with an RCA jack you will not be able to run them using phantom power from a pre-amp, which according to that thread is the best way to run them.

darktrain · « **Reply #16 on:** March 22, 2011, 02:46:48 PM »

Quote from: Chuck on March 22, 2011, 02:36:34 PM

If you replace the full sized XLR jack with an RCA jack you will not be able to run them using phantom power from a pre-amp, which according to that thread is the best way to run them.

You are correct, he can run em that way but you would be taking them from a 3 wire to 2 wire mic, then you might as well get a 4.7k mod and just use the mic in power or small battery box

Chuck · « **Reply #17 on:** March 22, 2011, 02:47:49 PM »

Quote from: Darktrain on March 22, 2011, 02:46:48 PM

Quote from: Chuck on March 22, 2011, 02:36:34 PM
If you replace the full sized XLR jack with an RCA jack you will not be able to run them using phantom power from a pre-amp, which according to that thread is the best way to run them.

You are correct, he can run em that way but you would be taking them from a 3 wire to 2 wire mic, then you might as well get a 4.7k mod and just use the mic in power or small battery box

Agreed.

igene · « **Reply #18 on:** March 22, 2011, 02:54:41 PM »

so running these after a preamp is kind of like adding a rolloff and a buffer ?

are you saying to leave them as is, and add the 4.7K resistor to the XLR in the box and run these inline w/ a pre or power supply?

not sure.

darktrain · « **Reply #19 on:** March 22, 2011, 03:03:16 PM »

Quote from: igene on March 22, 2011, 02:54:41 PM

so running these after a preamp is kind of like adding a rolloff and a buffer ?

are you saying to leave them as is, and add the 4.7K resistor to the XLR in the box and run these inline w/ a pre or power supply?

not sure.

actually after thinking about that for a second, the output shouldn't matter, whether you run 2 xlr's into a single mini plug or rca's to mini plug, either way they are coming to a single mini plug, i think we got sidetracked but you are only talking about outs right, you are leaving the mini xlrs intact correct

Chuck · « **Reply #20 on:** March 22, 2011, 03:13:20 PM »

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 · « **Reply #21 on:** March 22, 2011, 03:17:31 PM »

correct.

I just want the outputs easier to handle.

miniXLR in > RCA panel out.
recessed nicely, making it more secure.

I have a couple of panel connectors ready to go...
and some rubber isolation too.

I have another question.
What is the max voltage this circuit can handle ?

3V ? 6v ? 9V ? 12v ?

I'd also like to add that as I do this I'm learning as well feeding my creative needs.
I have a CA-9100 and other pre's. That's not what this is about.

igene · « **Reply #22 on:** March 22, 2011, 04:14:45 PM »

couldn't wait.
I'm testing w/ a 9v and everything is cold to the touch, no smell or smoke.
the 9v side is just a bit hotter. running one side AA and 1 side 9v

I also tested the pins w/ a DMM, I'm putting out 9v from the miniXLR output.

igene · « **Reply #23 on:** March 22, 2011, 04:41:54 PM »

what is that circuit on the back of the XLR connector ?

better shot >

igene · « **Reply #24 on:** March 22, 2011, 05:51:37 PM »

first one finished and tested.
Works great.

kinglerxst · « **Reply #25 on:** March 22, 2011, 06:08:36 PM »

What was the difference in powering between the one running the single AA and the one running the 9V?

The 8531 was the "replacement" for the 8532 and the 8532 runs a 9V battery, so curious as to how much the powering difference was, I was figuring the 8531 used the 1.5V and then stepped it up to 9V internally so it ran the same as the 8532. I was never able to locate any spec info for the modules though......

igene · « **Reply #26 on:** March 22, 2011, 06:36:16 PM »

there was maybe 10% more signal and a bit more clarity.
I put it all back the way it was - with the AA sled all soldered back.

I completed both boxes and tested. They work fine.
Actually, they may be a bit louder.
I have a suspicion that the circuit on the output XLR may be some kind of resistor
reducing output...but I'm just guessing.

Here's the completed mod >

kinglerxst · « **Reply #27 on:** March 22, 2011, 06:42:47 PM »

>turn 48v phantom power into ~9v for electret condenser microphones.

That's always had me curious since if the power module by itself was to give 9V to a mic, then why would phantom power of 48V be needed additionally if the module is just going to tone the 48V back down to 9V anyways?

>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.

Some of the AT modules that may be the case, however the 8531 (and 8532 before it) both have switches for off/flat/roll-off, so you don't have to run roll-off. I always run them at flat response.

kinglerxst · « **Reply #28 on:** March 22, 2011, 06:54:23 PM »

>I have a suspicion that the circuit on the output XLR may be some kind of resistor
>reducing output...but I'm just guessing.

Can you measure the resistor values?

Would be curious as to what the difference would be taking out the resistors and running straight across the circuits instead......

igene · « **Reply #29 on:** March 22, 2011, 06:57:10 PM »

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.

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

kinglerxst · « **Reply #30 on:** March 22, 2011, 06:58:55 PM »

>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 · « **Reply #31 on:** March 22, 2011, 07:06:01 PM »

>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 · « **Reply #32 on:** March 22, 2011, 07:10:04 PM »

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

igene · « **Reply #33 on:** March 22, 2011, 07:13:30 PM »

Quote from: kinglerxst on March 22, 2011, 07:06:01 PM

>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 · « **Reply #34 on:** March 22, 2011, 07:32:15 PM »

>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 · « **Reply #35 on:** March 22, 2011, 07:35:13 PM »

>to act as an RF filter

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

igene · « **Reply #36 on:** March 22, 2011, 07:58:15 PM »

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 · « **Reply #37 on:** March 22, 2011, 08:07:15 PM »

Quote from: mshilarious on March 22, 2011, 07:08:59 PM

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 · « **Reply #38 on:** March 22, 2011, 09:15:49 PM »

>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 · « **Reply #39 on:** March 22, 2011, 09:31:11 PM »

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 · « **Reply #40 on:** March 22, 2011, 09:34:59 PM »

Quote from: Chuck on March 22, 2011, 03:13:20 PM

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 · « **Reply #41 on:** March 22, 2011, 09:54:30 PM »

Quote from: illconditioned on March 22, 2011, 09:31:11 PM

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 · « **Reply #42 on:** October 06, 2011, 02:01:57 PM »

Quote from: igene on March 22, 2011, 06:57:10 PM

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 · « **Reply #43 on:** October 07, 2011, 10:03:50 AM »

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.