Sine Waves needed! Send me an LFO... MOTU Volta compat. test

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Kent
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Sine Waves needed! Send me an LFO... MOTU Volta compat. test

Post by Kent » Fri Jan 16, 2009 2:48 pm

Hey guys,

Short version of my request: can someone send me a WAV (or other) file of a couple of LFOs? Please keep them at 10Hz or below or make them change in rate from 20-30 Hz down to 1Hz. No need to be precise about it. Several files or one long one. It don't matter.

I would like to test the output stages of the various audio interfaces that we manufacture. Yup, in in order to see if they are MOTU Volta compatible. I'm gonna do my part in qualifying some interfaces & I'll make it public here.

Oh, and please don't make the entire cycle so long that it takes minutes for a cycle. I've got to test more than few interfaces & I'd like to whip through it rather quickly.

Send me your sines, your saws, your huddled square waves.

Thanks!

zerosum
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Post by zerosum » Fri Jan 16, 2009 2:51 pm

will the signal generator plugin sent straight out of pro tools or logic work?
I can't remember how low in frequency they will go?

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Kent
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Post by Kent » Fri Jan 16, 2009 4:11 pm

I dunno offhand! I was totally avoiding firing up my old PT rig. That's part of what spawned the thread! :hihi:

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criticalmonkey
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Post by criticalmonkey » Fri Jan 16, 2009 10:05 pm

I'll drop one up this weekend - motu 896 will record cv

JohnLRice

Post by JohnLRice » Fri Jan 16, 2009 10:50 pm

hi Kent,

I have WaveLab5 on this computer and it can easily generate simple sine etc files. Look at the images below and let me know what you'd like. Also, 44.1/16 WAV format or???

Image

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Kent
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Post by Kent » Sat Jan 17, 2009 12:32 am

Nice, John. :hail:

If you can be bothered to do so, how about 3 files of 30 seconds each that sweep from 20Hz down to somewhere less than 1 Hz? One Square, one Sine & one Ramp of either direction.

Another Sine Wave file that goes from -5V to +5V would be appreciated as well. I don't see anywhere in the list, that you posted, that allows for negative excursions.

Thanks!

-- CriticalM. If you could get a file or two up as well, that would be great. It would be nice to have some from a known working control sample. We know that your MOTU rig and digest them, so they should work. If you can verify that the same files will play OUT of your MOTU, that would be mighty handy.

JohnLRice

Post by JohnLRice » Sat Jan 17, 2009 3:01 am

Here ya go, I brewed you up a fresh batch! :coffee:

I wasn't sure how to do the +5 / -5 one but I made you a bunch of 30 second sweeps.

The ForKent_SetupTest.wav is the first one I did at a higher range (200hz -> 10Hz) so I could more easily tell what was going on. The rest are 20Hz -> 0.1Hz (except for the 'Brown Noise' one I threw in for fun cuz I was in a 'shitty' mood :mrgreen:) Also, instead of being "instant on/off" volume wise which caused a pop, I put a 0.1 second attack and release at the beginning and end, I hope that was OK. Besides the brown noise I also added a triange and 10% pulse files besides the sine, square and ramp (saw) you asked for.

Enjoy! :hihi:

http://www.imjohn.com/misc/ForKent/ForK ... upTest.wav

http://www.imjohn.com/misc/ForKent/ForKent_Sine.wav
http://www.imjohn.com/misc/ForKent/ForKent_Square.wav
http://www.imjohn.com/misc/ForKent/ForKent_SawUp.wav

http://www.imjohn.com/misc/ForKent/ForKent_Triangle.wav
http://www.imjohn.com/misc/ForKent/ForK ... ercent.wav
http://www.imjohn.com/misc/ForKent/ForK ... nNoise.wav

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Kent
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Post by Kent » Sat Jan 17, 2009 4:42 pm

Preliminary test results are looking good! I've tested 3 interfaces thus far.

The Onyx Satellite appears to slightly slew-limit the very tops (and transitional points) of saw waves and squares. There is one variable that I have to check for tomorrow. I think that it is a gain issue. I've got a friend in from out of town, so I couldn't complete that part of the test in a thorough manner.

The Onyx 400F and 1200F are solid and work well.

John or Monkey, my testing has led me to requesting a short ramp and square wave of .5Hz or lower. 5 seconds long would be fine. I've got to measure exactly where these cut off. It could be that very slow LFOs won't pass. The test files have all passed on these 3 thus far.

Anything slower would be icing on the cake. BTW, the Brown Noise was tonight's winner or pooh-induced fun.

Ever onward!
Last edited by Kent on Sat Jan 17, 2009 4:53 pm, edited 1 time in total.

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Gordon Cole
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Post by Gordon Cole » Sat Jan 17, 2009 4:44 pm

:ghost:
Last edited by Gordon Cole on Tue Jul 20, 2010 6:24 pm, edited 1 time in total.

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Kent
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Post by Kent » Sat Jan 17, 2009 4:54 pm

I think that WE ( the Mufflers ) can bust that out. Apparently, all MOTU are belong to us. The RME units as well... I'm doing my part!


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criticalmonkey
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Post by criticalmonkey » Sat Jan 17, 2009 8:08 pm

here is some more

including something similar to the volta demo using DP and the arpeggio plug

http://www.criticalshit.com/public_download/dc_test/

includes audio, txt file for info and a png of the DP setup ad my plugins

hope they help

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criticalmonkey
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Post by criticalmonkey » Sat Jan 17, 2009 8:08 pm

btw - MOTU 2408 mk 2 is what i used so add that to the success list

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Kent
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Post by Kent » Sat Jan 17, 2009 11:26 pm

Awesome. Thanks to both of you. I'll jump on this once my house-guest leaves later today.

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sydilaxe
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Post by sydilaxe » Mon Jan 19, 2009 10:01 am

I am dying to hear about the Behringer ADA8000 - these supposedly have filters on the outputs (so they probably won't work). But they would be an excellent expansion option..

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Post by widdly » Wed Jan 21, 2009 1:42 am

Here is a quick VSTi I hacked up for doing some tests. It does 1v/Oct output on one side and velocity->CV on the other. You might have to measure the voltage range of you output first so it scales properly. The velocity is gated so you can use it to trigger envelopes.

If people find this interesting I can extend it to do more stuff (LFO's portamento etc.) I think most of volta, aside from the calibration function should be easy enough to copy.
You do not have the required permissions to view the files attached to this post.

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wetterberg
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Post by wetterberg » Wed Jan 21, 2009 2:09 am

ehm, kent, an lfo sweep isnt what you need - you need straight up Dc at fully positive and then at fully negative - otherwise volta wouldnt be able to do pitch cv outs....

or is there something Im missing?

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Kent
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Post by Kent » Wed Jan 21, 2009 10:14 am

Yup, there is... a slow square wave puts out steady DC in both positive and negative energies. :doh: :wink:
If that was unclear to some, just download the posted files and then import them into your DAW. You'll see what I'm talking about.

Thanks to Widdly for the VST. However, I'm MacIntrash OS only over here.

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wetterberg
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Post by wetterberg » Wed Jan 21, 2009 10:50 am

but you're asking for sinewaves, not squarewaves!

What I am saying is: even a slow sine wave does *not* equate DC-compatibility. You'll want to check for droop over perhaps 30 seconds from +v down to 0v.... remember, I did this testing a long time ago? :)

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Kent
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Post by Kent » Wed Jan 21, 2009 10:55 am

Dearest Bong Hit Master,

Please read my 1st & 3rd posts. Then read John's reply to my 3rd post. Then pass that dutchie my way!! :rastanana:

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wetterberg
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Post by wetterberg » Wed Jan 21, 2009 10:59 am

yes, did read, point still stands: You need. DC. Not LFOs. But hey, don't let me stop you.

->

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Post by widdly » Wed Jan 21, 2009 11:28 am

I would have thought the same as wetterberg too.

On the non-DC coupled interface I tested you can output a square wave below 1HZ. However if you output a steady DC voltage it will slowly decay to 0v over a few seconds. The time to decay would be dependent on the size of the output capacitors.

There is a DC wave file here...
http://www.rme-audio.com/english/download/audtest.htm

I'd hook a multimeter up to the output and play the file. If you get a constant value other than 0v then you are half way there.

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Kent
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Post by Kent » Wed Jan 21, 2009 11:54 am

My procedure is as follows:

Play the provided files through output(s) of audio interface.

Interface is connected to Blacet Bar Graph (for visual display) and then to Plan B M15 1st "Freq VC" input (for audible confirmation).

When the test waves get below a certain frequency, it is pretty damn apparent when the output ceases.

And again, it seems like it bears repeating, a square wave is DC at it the extremes of its full swing. Full +5DC and -5DC (or more or less). If no voltage is coming out during these steady states, then we know it can't pass DC. A 1Hz Square Wave is fully positive, & then negative, DC for 1/2 second each.

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wetterberg
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Post by wetterberg » Wed Jan 21, 2009 12:02 pm

Kent wrote:My procedure is as follows:

Play the provided files through output(s) of audio interface.

Interface is connected to Blacet Bar Graph (for visual display) and then to Plan B M15 1st "Freq VC" input (for audible confirmation).

When the test waves get below a certain frequency, it is pretty damn apparent when the output ceases.

And again, it seems like it bears repeating, a square wave is DC at it the extremes of its full swing. Full +5DC and -5DC (or more or less). If no voltage is coming out during these steady states, then we know it can't pass DC.
yes, but as stated this may give false positives for some interfaces that can't actually *HOLD* DC without droop.

Outputting slow LFO != DC capable.

Outputting a 100% steady high or low voltage == DC capable.

I think we must be "talking past each other" here.

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Kent
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Post by Kent » Wed Jan 21, 2009 12:21 pm

I think that I'll just move on as I don't see where our DC voltages are any different from each other. Nor do I understand the line about "false positives for some interfaces that can't actually *HOLD* DC without droop.

If the interface can't hold DC, without waver, for anywhere between .5 to 1 second then it is made of FAIL. There's nothing 'falsely positive' about that even if it momentarily deflects postive/negative. If any interface passes the test @ 1 second (none that I have tested thus far have) then further investigation is warranted. However, not being able to put pass clean squares shows up an interface right away.

It is worthwhile and interesting to find out 'how low can you go?'. At least it is for me.

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