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Soundboard attenuator DIY?
Nick_Riviera:
I've got a Roland R-07 and an upcoming show I'm considering trying to get a soundboard from. It has a mic in port and you can turn the power off and run powered mics, but from what I've read (on the R07 review threads here) I'd need an attenuator to patch in a SBD.
I'm very much a DIY sort of person, so I'm wondering how exactly I can make one, and how much troubleshooting might be involved - is it plug and play, or would I have to mess with the sensitivity and give the sound guys a reason to dislike me?
Apart from that, I've been really happy with the R07 so far. Very compact and some great features. My only wish might've been an xlr connection over the 3.5mm.
goodcooker:
Here's a pad diagram that can be built into the shell of an XLR connector. I made some years ago. You can fit the necessary resistors inside the shell of the XLR. It's just an Lpad type of voltage divider across pins 2 and 3.
Sebastian:
--- Quote from: goodcooker on March 21, 2024, 09:09:53 PM ---Here's a pad diagram that can be built into the shell of an XLR connector. I made some years ago. You can fit the necessary resistors inside the shell of the XLR. It's just an Lpad type of voltage divider across pins 2 and 3.
--- End quote ---
This method only works with a balanced signal. While this is obviously the case with most SBD feeds these days, there have been occasions in the past in which I have been given an unbalanced signal from the board when all balanced outputs were already taken. Therefore I'd suggest a slightly different approach that also works with a single-ended signal.
A single 4.7kΩ resistor (which is a standard value) in series with the non-inverting signal (pin 2 of the XLR input) will form a simple resistive divider with your R07's input impedence (4.5kΩ). This roughly divides the voltage in half, giving you a -6dB attenuation. Use a 15kΩ resistor instead for -12dB or 47kΩ for -21dB. You can leave pin 3 of the XLR input floating because your R07's input is single-ended anyway. And you'd only need one resistor instead of three.
checht:
--- Quote from: Sebastian on March 22, 2024, 05:56:28 AM ---
--- Quote from: goodcooker on March 21, 2024, 09:09:53 PM ---Here's a pad diagram that can be built into the shell of an XLR connector. I made some years ago. You can fit the necessary resistors inside the shell of the XLR. It's just an Lpad type of voltage divider across pins 2 and 3.
--- End quote ---
This method only works with a balanced signal. While this is obviously the case with most SBD feeds these days, there have been occasions in the past in which I have been given an unbalanced signal from the board when all balanced outputs were already taken. Therefore I'd suggest a slightly different approach that also works with a single-ended signal.
A single 4.7kΩ resistor (which is a standard value) in series with the non-inverting signal (pin 2 of the XLR input) will form a simple resistive divider with your R07's input impedence (4.5kΩ). This roughly divides the voltage in half, giving you a -6dB attenuation. Use a 15kΩ resistor instead for -12dB or 47kΩ for -21dB. You can leave pin 3 of the XLR input floating because your R07's input is single-ended anyway. And you'd only need one resistor instead of three.
--- End quote ---
Great point, in the past, I was given rca outs b/c nothing else was available.
This design also has the virtue of being simple enough to fit into rca connector, which is what I've done.
Nick_Riviera:
Thanks so much to everyone here! I'll investigate these options more. Might have to pick up another Roland or another recorder - I'd hate to put all my eggs in this basket to find out I flubbed this up (I won't get a chance to try it out or troubleshoot much ahead of time).
As far as plugging into the soundboard, which xlr connector should I be looking at? Can't say I've ever spent much time looking at one before. I would probably wire it directly through a 3.5mm to plug into the R07.
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