Graves

Duplex Box

25 posts in this topic

Anyone make their own? I made one using a 5 pin xlr (pin 1 shield, pin 2 +, pin 3 - mic / pin 4 tip, pin 5 ring for headphones) I grounded the shield on the stereo hp 1/4" jack to chassis of the 5 pin xlr. Mic works great, 48v works, but the headphones turn down when I turn up the volume from my SD 702t. Cable is Canare L-4E3-2P. Should I use a 6 pin xlr? I removed the ground from the headphone jack in the box and the same, actually, it works better with the ground removed, but still no volume adjustment, level goes down, not up. What am I missing? All solder joints are solid and resistance is at a minimum..... 000.5 or less on all connections using my multi meter.

Thanks,

John

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Have you tried tying the HP ground to only pin 1 of the xlr-5 and not the chassis ground?

Eric

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Maybe pin 4 tip and ring, pin 5 sleeve? It would be mono, but I don't think you can send a stereo headphone signal without a negative signal. Right?

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Hi Eric,

I think I initially tried it that way, but didn't work, but I'll go back and dbl check.

Thanks for the help.

J

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Maybe pin 4 tip and ring, pin 5 sleeve? It would be mono, but I don't think you can send a stereo headphone signal without a negative signal. Right?

HP signals are unbalanced meaning no negative as in a balanced line.

Eric

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Anyone make their own? I made one using a 5 pin xlr (pin 1 shield, pin 2 +, pin 3 - mic / pin 4 tip, pin 5 ring for headphones) I grounded the shield on the stereo hp 1/4" jack to chassis of the 5 pin xlr. Mic works great, 48v works, but the headphones turn down when I turn up the volume from my SD 702t. Cable is Canare L-4E3-2P. Should I use a 6 pin xlr? I removed the ground from the headphone jack in the box and the same, actually, it works better with the ground removed, but still no volume adjustment, level goes down, not up. What am I missing? All solder joints are solid and resistance is at a minimum..... 000.5 or less on all connections using my multi meter.

Thanks,

John

I'm trying to understand why you used a 5 pin xlr and how it allows you connect a mic & phones to/from your 702. Normal convention would be a 3 pin XLR-F for mic input and a 1/4"TRS jack for head phone feed. Something like this one. There is a belt clip attached to the back of the box. Having seperate connectors eliminates a lot of potential problems.

Eric

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Hi Eric,

I do have a box w/clip. The 5 pin XLR attaches at the bottom, then is wired to a F-XLR and F -1/4" TRS connector(s). The 5 pin XLR cable breaks out to M-XLR and M-1/4" TRS, which connects to the 702t. It looks very much like the PSC duplex box/cable, but I used XLR connectors instead of the multi-pin screw on connectors they use. Right now I'm only using 30' of cable, so not much of a run, but it seems like there's too much resistance in the cable?? I connected my ipod to the cable/box and I can hear the volume change, but I also get some aliasing, like it's a very low quality mp3, very strange...?????

My initial thoughts were (when I was making the cable/box) to drop the shield/ground of the headphones, because it's an unbalanced signal and wasn't needed, but I'm not sure what's going on? I wasn't sure if they (PSC or the like) used a resistor and/or cap in the box's wiring? I have seen them with a volume control built in, but wanted to keep it simple.

Thanks again for your help.

J

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Okay, I've seemed to have fixed the problem. I connected the ground from the 1/4" jack to pin 1 and removed the ground on the M-TRS connector going to the recorder, so there's only one common ground, pin 1 of the XLR input. For some reason, it only wanted a single ground connection??? Volume works with full stereo output.

Thanks Eric and Joshua, I truly love this forum.

J

Now I have to buy more Canare cable to make a longer run, pacific radio, here I come.

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Okay, I've seemed to have fixed the problem. I connected the ground from the 1/4" jack to pin 1 and removed the ground on the M-TRS connector going to the recorder, so there's only one common ground, pin 1 of the XLR input. For some reason, it only wanted a single ground connection??? Volume works with full stereo output.

Thanks Eric and Joshua, I truly love this forum.

J

Now I have to buy more Canare cable to make a longer run, pacific radio, here I come.

Glad I could help to solve your problem. What you've got now is a floating single ended ground. You should be able to reconnect the the ground at the recorder end of the TRS with no issues. What happened was that by connecting the ground to the chassis ground there was no ground as the chassis ground did not connect to the 702t. If you had originally connected the chassis ground to pin one all would have been fine.

Eric

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Hey John,

  I finished making a pair of these recently. The only thing left is to add on belt clips. Does anyone have a recommendation or online supplier for them? Otherwise I have a few lectrosonics spring clips from some UMs thaI changed over to the wire clips. I also put in a 5k potentiometer for the headphones( thank you Wyatt for the help with this!). When I have boomed, I got annoyed with not having control over my own volume.

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Good looking box. I made a few duplex boxes over the years and used Lectro clips just like you suggested. I also made one with a walkie-talkie clip which also worked nicely.

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I like the volume control, I'll have to make another box and add one. I used the smaller hammond box, maybe going with a larger one

will give me the room I need.

As for clips, I think I bought mine at Wilcox Sound in burbank?

You can try this online store?

http://www.theclip.com/store/home.php?cat=275

John

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Having used boxes over the years, I got tired of the screws coming loose or falling out. The nut that holds the phone

jack allways loosens up too. So I went back to an older method and added a cell phone case.

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Kevin,

While maybe not the prettiest, an elegant solution!

Jay

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Does anyone have a recommendation or online supplier for them?

I called up Denecke and asked for a clip (as seen on their phantom PSU boxes). I think it was 8 bucks. Nice, hefty clip.

In other news, could anyone provide a part #/schematic for the headphone pot in the box? I have been looking to add one to my box for a while now...

Travis

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Anyone make their own? I made one using a 5 pin xlr (pin 1 shield, pin 2 +, pin 3 - mic / pin 4 tip, pin 5 ring for headphones) I grounded the shield on the stereo hp 1/4" jack to chassis of the 5 pin xlr. Mic works great, 48v works, but the headphones turn down when I turn up the volume from my SD 702t. Cable is Canare L-4E3-2P. Should I use a 6 pin xlr? I removed the ground from the headphone jack in the box and the same, actually, it works better with the ground removed, but still no volume adjustment, level goes down, not up. What am I missing? All solder joints are solid and resistance is at a minimum..... 000.5 or less on all connections using my multi meter.

Thanks,

John

I also used 5 pin xlr for box input, which means that you have to wire up mic and headphone shields (ground signals) together, obviously, because you only have 5 pins to go to the box. To avoid shared ground signal for mic and headphones, you need 6 pins.

I tested my box on sound device mixer and both signals for mic and headphones were coming from mixer. But the gain of mic was little bit low than usual and when you'd turn up the gain it would have noise. I guess it's because of shared ground signal.

here's my box (headphone wires are disconnected)

rsaicj.jpg

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" both signals for mic and headphones were coming from mixer. "

I'm guessing you mean the signal was going from the mic to the mixer.

I commented in another thread...

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" both signals for mic and headphones were coming from mixer. "

I'm guessing you mean the signal was going from the mic to the mixer.

I commented in another thread...

Sure! I guess I meant phantom power signal. Thanks for reply, I'll check another one.

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Phantom power is not really a signal, it is an industry standard for supplying DC voltage, at pretty low current, over a balanced and shielded audio cable, in a "hidden" (thus phantom) form that does not affect professional balanced dynamic microphones.

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Bringing this post back from the archives..

 

I would like to make a system with a detachable box and mixer end and then make several 5-pin extensions that can be used as needed. I would prefer to keep the wiring of the 5-pin extensions the same as standard stereo-mic wiring so that they could be used for that purpose as well.

 

So I'm wondering how many of you who use a 5-pin XLR for these boxes tie the grounds together for the headphones and microphone input? Is this a potential source for ground loop trouble or the standard method? As someone stated above a 6-pin would be ideal.

 

Thanks,

Derek

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I've made a duplex box myself with a 5 pin and have had no issues. I tied both grounds together on the 5 pin. I've been using it for over a year without fail. Need to sit down at some point and make some more boxes and a few extension cables.

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Derick: " Is this a potential source for ground loop trouble or the standard method? "

yes

" a 6-pin would be ideal. "

a 6-pin would be ideal better

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This is an awesome thread. Thank you gentlemen for sharing your knowledge and pics. I am going to try and build one of these as well. I want to build a passive volume  duplex box if at all possible.

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Do you have any schematics on this?

On 3/1/2011 at 1:47 PM, graham said:

Hey John,

  I finished making a pair of these recently. The only thing left is to add on belt clips. Does anyone have a recommendation or online supplier for them? Otherwise I have a few lectrosonics spring clips from some UMs thaI changed over to the wire clips. I also put in a 5k potentiometer for the headphones( thank you Wyatt for the help with this!). When I have boomed, I got annoyed with not having control over my own volume.

 

 

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Do you have any schematics on this?

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Everything is just straight thru, so you can dope it out with alligator-clip jumpers etc until it works.  This one is a great example of a simple effective and rugged box.  You'll wish for talkback from the boom op but that's a whole diff can of worms, at both ends of the cable.

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