wave wrote:Hello,
I've put one of these together for a client and I'm trying to calibrate. Is there a procedure for calibration using a standard function generator?
Preferably one that I can count LEDs to align with as I don't have the purpose made JLM meter scale.
Also, I'm not understanding how to jumper the unit so the LEDs are in full brightness mode all the time. I can apply a jumper to position 1 and get the 2.5V dimming or I can remove it and I get the dim then brighter with level behavior.
Thanks!
Dave
For full brightness fit jumper in header which will link pin to 0v for full brightness.
Put in 1khz tone and turn input trimpot RV1 up until you have just lit the 40th red led. Then turn up VUPPM balance trimpot RV2 until the 40th green led just lights. Cal between VU and PPM is not done. Adjust input trimpot to maximum input level for your system.
Hi Joe,
Thanks for the reply. I'm still confused. Which pin(s) do I jump? Also, I'm assuming I feed 1.228VAC from the generator and I have done that but it seems that normal program just slams the meters full. There are 4 banks of 10 leds so the 40th is the very last LED on the unit, correct? Some pics would aid tremendously.
Pondering on using this in a mastering console I'm planning. I would have use of monitoring loud signals and would need a scale that's shifted upwards. My main converters are calibrated to the same as my monitoring DA ('+22dBu), but I also use a H8000 for final master 2track AD conversion that has +26dBu headroom on it's inputs. So as to both monitor my various converters but also the analog gear inserted into the mastering switcher it's going to be housed in, I'd like to monitor levels in that area, preferably a little above (the 8K sounds great clipping it's ad). How high can it go?
Pondering on using this in a mastering console I'm planning. I would have use of monitoring loud signals and would need a scale that's shifted upwards. My main converters are calibrated to the same as my monitoring DA ('+22dBu), but I also use a H8000 for final master 2track AD conversion that has +26dBu headroom on it's inputs. So as to both monitor my various converters but also the analog gear inserted into the mastering switcher it's going to be housed in, I'd like to monitor levels in that area, preferably a little above (the 8K sounds great clipping it's ad). How high can it go?
The input trim is passive in front of the active circuit so can handle any level from high powered amp outputs etc. I have setup pairs for mastering as high as +32dBu but they can handle more and adding series resistors with the inputs can help keep the input trim in its fine adjustment zone. I would look at using the more modern stereo VUPPM compact or VUPPM500 on our website as it can do several metering options and we could run some custom scales if needed for a few dollars more.
Just built two of these and they are working and looking great!
One question: what brand/style of connectors are you using for the audio and power inputs? (the 2-, 3- and 4-pin ones).
I'd like to clean up the wiring of my device a bit and will need to purchase the right crimp contacts for these.
Many thanks and a happy new year!
Matthias
Happy New Year Matthias!
The connectors are JST XH 2.54mm type. They come in 2-20 pin and can be bought pre wired with up to 30cm of cable and pcb socket.
I have assemble 7 of the VUPPM GR40 meters, the first three worked with no problems. The next 4 all have issues. Two i think will be okay. The most frustrating one has power to the input, but no power on the other side of the pins. One has only red LEDs, no green. Any thoughts? Thanks, dave.
Also the other two skip LEDs in sequence, like the 1st LED in each block.
Let me know the fault you are seeing on each pcb. Clean the bottom of the pcb with alcohol and old toothbrush and send me clear in focus top and bottom photos of the pcb to check for you either on here or to my email.
