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Messages - dannyboy

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1
SignalScope Pro / Re: Using Oscilloscope
« on: June 13, 2007, 05:19:21 PM »
sorry for that terrible use of the quote button!!!

2
SignalScope Pro / Re: Using Oscilloscope
« on: June 13, 2007, 05:18:09 PM »

The 0 dBFS tone is being generated by what device?

Its a cd run through the head unit that I`m measuring. The cd was recorded @ odbfs according to the liner notes.


So, in SignalScope, you tweaked the user-defined full-scale voltage until the oscilloscope indicated a level of 0.73 Vrms on the appropriate input channel.  What full-scale voltage did you settle on?

I settled on 1.650 volts.

Getting the same reading suggests that you could be clipping on the input channel and that you are reading a peak voltage (Vpk) rather than an rms voltage (and that your full-scale voltage is incorrect).

Yeah the more I think about it the more I`m convinced my full scale voltage is wrong ( I think I read peak to peak as you suggest)which is something that I can fix. What worries me is clipping the inputs of my Mbox2 and if I am I dont know how to prevent that from happening. 

What does the waveform look like in the oscilloscope?

I guess its a bit squared not fully squared though.

3
SignalScope Pro / Re: Using Oscilloscope
« on: June 05, 2007, 05:49:27 PM »
It really didnt take this long to reply I just mainly use Signal Scope for RTA, but have been using more for the o`scope and have been running into a problem hopefully you can help me out Ben.

I`m using it to measure an audio signal to check for clipping. I`ve fed the source a 0dbfs 1kb tone measured the rms voltage w/ a dmm .73 volts and set the full scale voltage according to that number...good so far?

Now,  I`m using an Mbox2 as the audio inputs. Is there any way I could be overdriving the inputs of the Mbox2? In other words could what the o`scope be showing as a  clipped signal not be the actual signal but something in the Mbox2?  I ask this because no matter what signal I measure I always get a reading of .73 volts even after setting the full scale voltage.

Here are some specs on the Mbox2:

Input impedance >1MOhm
Max input level 8volts Rms

Sorry for the long post.....any help is appreciated!

4
SignalScope Pro / Using Oscilloscope
« on: October 03, 2006, 01:03:15 PM »
Can the oscilloscope be used with probes or am I limited to only using it with a mic through a pre amp? 

5
SignalScope Pro / Re: using signalscope in car audio installations?
« on: September 14, 2006, 07:57:46 AM »
I was going to start a new thread but then stumbled across this one and realized that it described my situation perfectly! I do have a couple a of additional questions I was hoping maybe I could get cleared up.

Like acousticatz I too am new to the RTA world and I`m using the signal scope pro, a test disc w/ pink noise from 25 to 20k, a 13" g4, (I plan on getting the behringer mic Ben listed above run thru my Mbox2) but right now I have been using the built in mic.

My questions are what should I have the weighting set @ I know for SPL measurements its usually reccomended to set it at C would it be the same for these types of measurments? Or would flat be the way to go? And I have been having a heck of a time tryng to get the calibration info for my powerbook (full scale voltage for the adc) I have been using the 5.00 setting according to the example in the help menu for a 2003 15" g4 powerbook I dont know if it would be different for a newer model 13".   

The issue I`m having is the high freq readings (6.3k and above) are considerably lower than the rest of the readings and I dont know if thats a problem w/ my internal mic, calibration, settings or all of the above ...lol. 

Thanks in advance

Danny     

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