Understanding and using Spectra Plus

Discussion in 'Archived Threads 2001-2004' started by Sonnie Parker, Jan 2, 2002.

  1. Sonnie Parker

    Sonnie Parker Second Unit

    Joined:
    Dec 11, 2001
    Messages:
    407
    Likes Received:
    0
    Trophy Points:
    0
    I am about as lost as I can possibly be with Spectra Plus. I installed the software and in my "view configuration" my sound card is recognized. I connected the RS spl meter to my sound card line in. Line in recording is at max input. I clicked record in Spectra and played the AVIA sub sweep and stopped recording at the end. I saved the file to .wav.

    Now how do I chart the response? I see bars at the bottom of the spectrum when I play the file but it shows response from 20hz all the way up to 20khz. The AVIA signal only goes up to 200hz. It don't look right. The bars are lower at 20hz than they are at 20khz.

    I've got to be missing something here. Do I have to configure for frequency response? Should I use post processing to view the file? All I can see is the bars moving like crazy while it's playing.

    Please help. Can someone walk me through a step by step procedure in setting up Spectra configuration (or copy and post your "view configuration" here)? And then walk me through a step by step charting? I can't make sense of the help in Spectra.

    If I'm asking too much I understand.

    Thanks,

    SP
     
  2. Rick Radford

    Rick Radford Supporting Actor

    Joined:
    May 12, 2001
    Messages:
    642
    Likes Received:
    0
    Trophy Points:
    0
    Sonnie,
    I subscribed to this thread as I'll be working through this myself before long, I hope. [​IMG]
     
  3. Sonnie Parker

    Sonnie Parker Second Unit

    Joined:
    Dec 11, 2001
    Messages:
    407
    Likes Received:
    0
    Trophy Points:
    0
    Maybe there's an easier program to use to measure frequency response. If so, please let me know.

    Rick, it doesn't look like we are going to get any help. Maybe I posted the question wrong....who knows....seems like someone would let me know. I know there's a host of people who have used this program in the forum and supposedly it worked for them.

    Thanks,

    SP
     
  4. Rick Radford

    Rick Radford Supporting Actor

    Joined:
    May 12, 2001
    Messages:
    642
    Likes Received:
    0
    Trophy Points:
    0
    Don't fret yet Sonnie. It's only been 12 hours since you asked.

    I haven't d/l the program yet since I'm not ready for it.. and don't want my 30 days to begin.

    There are a couple of RTA programs out there. But it's been too long since I read the thread commenting on them to recall the name of the other one.

    Do a search for RTA, maybe that'll get you the name of it.
     
  5. Sonnie Parker

    Sonnie Parker Second Unit

    Joined:
    Dec 11, 2001
    Messages:
    407
    Likes Received:
    0
    Trophy Points:
    0
    Yeah, I'm probably a little antsy. I suppose I should be patient. I just see a lot of post that get kicked way down the list and never answered because they are not seen. Maybe if we keep it up close to the top someone experienced with Spectra will jump in. I keep reading the help menu but it's kinda vague on step by step and there's a lot of terminology that's new to me. Maybe it will eventually sink in.

    SP
     
  6. Sonnie Parker

    Sonnie Parker Second Unit

    Joined:
    Dec 11, 2001
    Messages:
    407
    Likes Received:
    0
    Trophy Points:
    0
    Okay, I've e-mailed Spectra.

    I can't get a recording. I checked about 7 recordings that I've made and I can't even get the *.wav files to play. I'm pretty sure I've got it hooked up correctly. I even tried loading the RTA.cfg defaults only changing the settings to 1/3 octave and c weighting. No luck. Is it suppose to be this dad nabbit complicated. I'm frustrated to say the least. Seems like they could make this a little easier for a general flunky.

    SP
     
  7. Wayne A. Pflughaupt

    Joined:
    Aug 5, 1999
    Messages:
    6,123
    Likes Received:
    40
    Trophy Points:
    6,610
    Location:
    Katy, TX
    Real Name:
    Wayne
    Sonnie,

    There are quite a few Spectra users here; I’m surprised no one has answered your post.

    I don’t have Spectra, but I am familiar with spectrum analyzers, since I own a stand-alone RTA. If I understand, your question, the Spectra can deliver response readings from 20Hz to 20kHz (like all analyzers). However, it should be obvious that if you play a signal source like the AVIA that only goes up to 200Hz, then that’s all the reading you will see on the Spectra’s display. If you’re looking to see the full-range response for you system, you’re going to have to get a signal source that goes all the way up to 20khz.

    Regards,

    Wayne A. Pflughaupt
     
  8. Sonnie Parker

    Sonnie Parker Second Unit

    Joined:
    Dec 11, 2001
    Messages:
    407
    Likes Received:
    0
    Trophy Points:
    0
    Yeah I realize the sweep is only from 200hz down to 20hz on the AVIA DVD. And I've used an RTA in my vehicle before with success. It's just the software is a little intimidating and I'm a lot frustrated about it. I can usually figure things out. This one's getting the best of me. I'm having problems figuring out how the configuration should be set and how to actually get something to record. I've obviously got something set wrong. Things like "plot top" and "plot range", where to set them and what they do, don't make sense to me. I may keep piddling with it but I'm about convinced to just take the manual measurements and go from there. I only tried it because I read where several said it was simple to use. Maybe for them.

    I'll get over it, or I'll figure it out.

    SP
     
  9. ThomasW

    ThomasW Cinematographer

    Joined:
    Nov 6, 1999
    Messages:
    2,282
    Likes Received:
    0
    Trophy Points:
    0
  10. TerryC

    TerryC Stunt Coordinator

    Joined:
    Oct 19, 1999
    Messages:
    218
    Likes Received:
    0
    Trophy Points:
    0
    View-Spectrum

    Mode-Real Time

    Settings-Sampleing Rate-48000, Decimation 1, FFT 8192

    Smoothing Window-Uniform

    Sampling Rate -16bit mono

    Averaging-infinite

    Scaling-Logarithmic, Weighting-Flat, Axis-Logarithmic

    Make sure you have your mic compensation files loaded

    I use display spectrum as a line grapgh but you can use bar depeding what you're doing.

    Make sure to us Peak Hold-Allows you to see the results after you are done.

    Play with the plot top and plot range so you can see the bars or lines

    That should get you working.Sorry for all the spellig mistakes its semi late and I'm going to bed.
     
  11. TerryC

    TerryC Stunt Coordinator

    Joined:
    Oct 19, 1999
    Messages:
    218
    Likes Received:
    0
    Trophy Points:
    0
    "I'm having problems figuring out how the configuration should be set and how to actually get something to record."

    You aren't really recording anyting most of the time. You are seeing it working in real time meaning what you hear is what it shows within a few miliseconds.

    "I've obviously got something set wrong. Things like "plot top" and "plot range", where to set them and what they do, don't make sense to me."

    Think of them as gains to allow you to see the bars or line within the screen you are looking. They really make no difference for basic room measurements.

    BTW, be sure to keep your true line input or mic gain down low. You will notice a little yellow meter in the lower left hand side. You DON'T want that turning red. If it does you are exceeding the measuring input Spectra can use so if you see red lower your input gain witin the sound card mixer "record" settings in the control panel so the yellow bar never exceeds 3/4 full.
     
  12. TerryC

    TerryC Stunt Coordinator

    Joined:
    Oct 19, 1999
    Messages:
    218
    Likes Received:
    0
    Trophy Points:
    0
    The bars you are seeing are likely the noise floor of the computer. When you actually get it to work you will see the actual 200-20hz sweep. I'm guessing you don't have your sound cards recording input selected within the audio mix in windows control panel so spectra isn't getting the signal from the spl meter.

    BTW- An easy way to know if the record function within the control panel isn't selected is if you don't see that yellow bar in the lower left hand corner.
     
  13. Sonnie Parker

    Sonnie Parker Second Unit

    Joined:
    Dec 11, 2001
    Messages:
    407
    Likes Received:
    0
    Trophy Points:
    0
    Thank you, thank you, thank you.....I see a couple of things already that I was doing wrong and not paying attention to. I'll try it again tonight/tomorrow and see what happens.

    Thanks for the link as well....I should have searched that forum also.

    I truly appreciate the information.

    SP
     
  14. Sonnie Parker

    Sonnie Parker Second Unit

    Joined:
    Dec 11, 2001
    Messages:
    407
    Likes Received:
    0
    Trophy Points:
    0
    Terry,

    Thanks for you help here. Have a question for you though. Why is the weighting-"Flat" and Axis-"Logarithmic" instead of weighting-"C" and Axis-"1/3"? The spl meter measures c-weighting. Won't I need to see a c-weighted response at 1/3 octave?

    Thanks,

    SP
     

Share This Page