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Help me finish my polystyrene cab build

#241
Spectroid has a hold max capability. I swept 20-20,000hz on it at roughly half of full volume.on the Pyle. the red line is that sweep. The yellow was a note on the bass at far lower volume. This was just the beta 12a. I have no baseline for comparing this graph to anything. There are different EQ settings on the Spectrum app, but I used the default. You can download it and look at the options and decide which one I should use to rerecord the sweep.
 
#247
Downunderwonder said:
there be a clue.
Click to expand...

Agreed, this acts as a compressor (actually almost a limiter) when transferred into the "frequency domain" (I'm using this term inaccurately on purpose).

It serves to compress the differences between the different frequencies by holding the highest peak per frequency. Since pink noise has random varying dynamics that make up its crest factor, if you take enough "highest samples" of each frequency, it will appear compressed by the ratio of the dynamics to the average crest factor (very much like a peak to average ratio function).

The raw, unsmoothed data in a room with significant boundaries should show variations of at least +/- 10dB, otherwise the data is suspect right from the start.
 
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#248
So you'd have me run the test again at a considerably lower volume to see if I get a similarly shaped curve. I would be happy to do it at many volumes on the same graph, however the app doesn't output the actual data in a format I can import into excel to plot in such a fashion. I will definitely run it at lower output volume and try using each of the channels of my Pyle PA amp to see if I can get anymore visual information. I have a gauss 3161dsx 2*10 cab I can test with, but nothing 'standard.' Same issue as before with no "known quantity" amps/cabs.
 
#249
neal sanger said:
So you'd have me run the test again at a considerably lower volume to see if I get a similarly shaped curve. I would be happy to do it at many volumes on the same graph, however the app doesn't output the actual data in a format I can import into excel to plot in such a fashion. I will definitely run it at lower output volume and try using each of the channels of my Pyle PA amp to see if I can get anymore visual information. I have a gauss 3161dsx 2*10 cab I can test with, but nothing 'standard.' Same issue as before with no "known quantity" amps/cabs.
Click to expand...
Turn off the "Hold Max" feature or you will only get the same result at lower level.
 
#250
ehhh ...definitely a hard no on that one. If I turn off the hold max, how will I record the frequency sweep?

The yellow output line of the graph is an instantaneous output. It measures only the sound in the room at the moment I screenshot the app. If I don't use the hold feature, the graph will only be be able to represent one instant of sound and not the output of freq sweep as a whole.
 
#251
To illustrate my point, this is the max hold for playing all notes on my bass individually (as opposed to a traditional frequency sweep). Only look at the red line. The yellow line (again) was the instantaneous background sound when the image was screen-shotted.
 
#252
This one
 

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#253
neal sanger said:
ehhh ...definitely a hard no on that one. If I turn off the hold max, how will I record the frequency sweep?

The yellow output line of the graph is an instantaneous output. It measures only the sound in the room at the moment I screenshot the app. If I don't use the hold feature, the graph will only be be able to represent one instant of sound and not the output of freq sweep as a whole.
Click to expand...
I don't know. It sounds like you need to read the manual. If you indeed cannot do a true sweep or pink noise RTA you may have to, shock horror, put pen to paper to plot single frequency shots.
 
#258
Is there a hold average function?

You can see why guys who do this all the time typically have more comprehensive tools at their disposal. There is nothing worse than thinking bad data is good data. Leads to all kinds of embarrassing situations.
 
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#259
There is no hold average function. There are several options for the audio. I encourage you to download the app and try generating a curve of your own with a frequency sweep and also to look into the settings pane. Spectroid is incredibly easy to use and I would be able to make more meaningful statements about the validity of the data if I could see someone else's attempt to apply it to the same task. I will try fdeck's software, too.
 

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