Custom Adapter
- Thread starteravkid
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The resistive summing network does several things.
1. It mixes the left and right channel signals to generate a mono signal to go int one XLR channel.
2. It properly matches both the headphone-out impedance of the boom box and the microphone-in impedance of the board.
3. It attenuates the headphone-level signal down to something that won't overdrive the mic-level input.
4. It gets rid of the phantom power, so it doesn't blow up the output circuits of the boombox.
I've got a home-brew version in my cable bag - I occasionally work with a performer who brings most of his backing tracks on minidisc... and wants the disc player on-stage with him. It's a very useful item.
$30 may seem like a lot - there's less than $8 in parts. But building custom cables is labor-intensive: you're paying someone to put it together for you.
John
1. It mixes the left and right channel signals to generate a mono signal to go int one XLR channel.
2. It properly matches both the headphone-out impedance of the boom box and the microphone-in impedance of the board.
3. It attenuates the headphone-level signal down to something that won't overdrive the mic-level input.
4. It gets rid of the phantom power, so it doesn't blow up the output circuits of the boombox.
I've got a home-brew version in my cable bag - I occasionally work with a performer who brings most of his backing tracks on minidisc... and wants the disc player on-stage with him. It's a very useful item.
$30 may seem like a lot - there's less than $8 in parts. But building custom cables is labor-intensive: you're paying someone to put it together for you.
John
I've noticed a tendency to put down Peavey, Behringer and Mackie gear, and to sometimes ridicule the people who use it. What makes a good audio engineer is not the pricetag of the gear you or your organization has, but what you can do with that gear. A friend of mine, Steve Albini, has a beautiful recording studio, Electric Audio, in Chicago. He's got a Neve console, a pair of Studer-Revox 24-track 2" tape machines, a collection of microphones to die for and some of the most acoustically-perfect rooms in the world. That doesn't make him a great recording engineer. What makes him great is that he could get a better recording in a garage, with a Tascam Portastudio and a pair of SM-58's, than most engineers could get if they had his fancy gear and perfect rooms. It's less about the gear than about how well you use it.
John
John
no, it is a consumer stereo system that looks like this : http://www.jvc.com/product.jsp?productId=PRD3602000&pathId=36
As I mentioned, the specially-made cable matches impedances and levels, mixes the stereo output of the player to a single mono input on the board and isolates the player from the board's phantom power. On a small board with a mono PA, you might not have channels to burn and only wish to use a single input for the player.
Although my PA is capable of stereo operation, I generally run it mono. It's a choice between giving a few people in the center of the room the position information of a good stereo image or giving everybody in the room the sound of all the instruments/performers on the stage, sans position information.
John
Although my PA is capable of stereo operation, I generally run it mono. It's a choice between giving a few people in the center of the room the position information of a good stereo image or giving everybody in the room the sound of all the instruments/performers on the stage, sans position information.
John
DMXtools - just a quick question for you.
I am assuming that from your description, the summing of the stereo signal into a mono one is done by a passive resister network. If so, how exactly is this done?
I built a summing amplifier to do this using a TL072 op amp and several resistors and caps. It works well but the only drawback is it requires a + and – 15V DC power supply.
If the same result can be achieved through a resistor network I would be interested in learning more about it. Especially if (as it would appear) this could be housed in the plug.
I am assuming that from your description, the summing of the stereo signal into a mono one is done by a passive resister network. If so, how exactly is this done?
I built a summing amplifier to do this using a TL072 op amp and several resistors and caps. It works well but the only drawback is it requires a + and – 15V DC power supply.
If the same result can be achieved through a resistor network I would be interested in learning more about it. Especially if (as it would appear) this could be housed in the plug.
A purely resistive summing network is easy. The only drawback is that it has negative gain (in other words, loss). In this case (high-level headphone out to low-level mic. in) it's a good thing - it cuts the signal level down to something that won't overdrive the mic. preamps.
The particular network used would depend on the impedances and signal levels involved. I'll try to make time to draw up a couple examples and post a link to them here later today.
John
The particular network used would depend on the impedances and signal levels involved. I'll try to make time to draw up a couple examples and post a link to them here later today.
John
i paid ten bucks for a hosa stereo mini plug to two 1/4" plugs that i use for my laptop and my iPod. it's just like a insert cable but it has a mini jack instead of a quater. i then put it into two channels on my board. but if your presssed for space you could put it through a di and have one mic line. lot cheaper. espesially if you have a di already.
pearsonally, i make all my adaptors in the schools head end room. (i do all the soldering in the boiler room though cuz theres no fire sensors there. i made good friends with the custodians. i get lots of keys too) just look up what wires connect to what on the internet.
pearsonally, i make all my adaptors in the schools head end room. (i do all the soldering in the boiler room though cuz theres no fire sensors there. i made good friends with the custodians. i get lots of keys too) just look up what wires connect to what on the internet.
I suggest that $30 for that cable seems high. Next time, try http://www.entsyscorp.com They make custom cables, and usually for less, and they come with a lifetime guarantee. They use whirlwind connectors. I get all my dmx line from them. Never once had to replace one and I tend to beat on things.
I don't know why the link doesn't work, but I suspect it has something to do with this site. If you type it into your address line on your browser manually it works fine.
BTW, I don't get commissions from them, but they do provide a quality product. And the owner, Bill, knows a lot of really bad jokes.
http://www.party-chicago.com
to see if it's all links or just that one.
BTW, I don't get commissions from them, but they do provide a quality product. And the owner, Bill, knows a lot of really bad jokes.
http://www.party-chicago.com
to see if it's all links or just that one.
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