Pro Tools Sine Wave test

Gregg Sartiano · 9th October 2005

Testing...1...2

O.K., so I was running sine waves from PT signal generator through some outboard gear and recording 'em.

At lower frequencies they looked nice & curvy when I zoomed in -- the higher frequency ones started to get jagged & looked more & more like a mountain range as I stepped up the frequency.

I even just snapped together the XLR's so I was recording PT out to PT in analog. I'm gonna test it some more.

What gives?

Gregg Sartiano · 9th October 2005

I just did the same test with internal bussing (digital only) -- same thing. 10k-20k sine waves.

Is it just a zooming/visual feedback thing, or is there an audio artifact happening?

max cooper · 9th October 2005

I really don't think you can go by the way they're drawn on screen, but I could be mistaken.

shaddai · 9th October 2005

Crank the sample rate up & then see what happens.

At 44.1, a single 20khz wave is being sampled twice. It should look like a sawtooth wave on the display when zoomed in. At 96k it's being sampled 4-5 times...a little less sawblade, closer to sine wave. At 192 it's 8-10 times...

The wonders of digital audio..

Todd

Rick Sutton · 9th October 2005

Anybody looked at these waveforms through a 'scope from the outputs of the DA?

krs · 9th October 2005

Actually funny you should post this today - I just zoomed in on waveforms I recorded and it's sawtooth all over place. FRICK! I'm going lightpipe from a Trak2 into Digi001. Why is this happening? PT synced to optical, I think everything is set correctly. To be certain I reset the Trak2 to be sure and sure enough, it's still there. I can hear the distortion.

Any hints? Possible cable problem?

Gregg Sartiano · 9th October 2005

PT Signal Generator -- it's a plug-in that comes with pro tools.

It's in "Other" on PT 6 plug-in categories, I think.

max cooper · 9th October 2005

Quote:

Originally Posted by Gregg Sartiano

PT Signal Generator -- it's a plug-in that comes with pro tools.

It's in "Other" on PT 6 plug-in categories, I think.

Audiosuite only, though, right?

The best way to use the signal gen. in Pro Tools LE is to record a minute or so of audio with no input, then select the entire bit of silence you've just recorded, open the signal generator, select sine/1K (or whatever) and apply.

Then you can loop playback it, etc.

9th October 2005	#1
Gregg Sartiano Lives for gear Joined: May 2004 Location: Lost Angeles Posts: 1,804 Thread Starter	Pro Tools Sine Wave test Testing...1...2 O.K., so I was running sine waves from PT signal generator through some outboard gear and recording 'em. At lower frequencies they looked nice & curvy when I zoomed in -- the higher frequency ones started to get jagged & looked more & more like a mountain range as I stepped up the frequency. I even just snapped together the XLR's so I was recording PT out to PT in analog. I'm gonna test it some more. What gives? __________________ "We need to legitimize peer-to-peer sharing as a business model, because it's already a business. If [the P2P companies] are going to make money on us, we should have a chance to make money along with them." -- Perry Farrell on the failure of national intellectual property policy to keep up with the rapid evolution of online media "Every Internet transmission of a musical work constitutes a public performance of that work. " http://www.ascap.com/weblicense/webfaq.html

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread starter	Forum	Replies	Last Post
10khz square wave + masterlink = sine wave???	carival	Geekslutz forum	23	31st December 2008 08:11 PM
How Do You Export Wave File By Wave File In Pro Tools 7 LE ?	MACHINE	Music computers	2	19th May 2006 04:20 PM
Midiot needs VSTi or RTASi help - sine wave sound	Ruairi	Music computers	6	13th April 2006 02:03 PM
Inexpensive handheld sine wave generator with adjustable output voltage?	NathanEldred	Geekslutz forum	4	2nd March 2006 06:11 AM
Logic Pro and Wave Burnery glitch -- HELP!!!	Tetness	Music computers	0	23rd January 2005 11:38 PM

9th October 2005	#3
max cooper Lives for gear Joined: Aug 2004 Location: tx Posts: 8,802	I really don't think you can go by the way they're drawn on screen, but I could be mistaken.

9th October 2005	#4
shaddai Lives for gear Joined: Aug 2005 Posts: 734	Crank the sample rate up & then see what happens. At 44.1, a single 20khz wave is being sampled twice. It should look like a sawtooth wave on the display when zoomed in. At 96k it's being sampled 4-5 times...a little less sawblade, closer to sine wave. At 192 it's 8-10 times... The wonders of digital audio.. Todd

9th October 2005	#5
Rick Sutton Lives for gear Joined: Feb 2003 Location: Atascadero, CA Posts: 4,058	Anybody looked at these waveforms through a 'scope from the outputs of the DA?

9th October 2005	#6
krs Lives for gear Joined: Jun 2004 Posts: 882	Actually funny you should post this today - I just zoomed in on waveforms I recorded and it's sawtooth all over place. FRICK! I'm going lightpipe from a Trak2 into Digi001. Why is this happening? PT synced to optical, I think everything is set correctly. To be certain I reset the Trak2 to be sure and sure enough, it's still there. I can hear the distortion. Any hints? Possible cable problem?