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K System calibration with Apogee Duet?

Posted: Tue Feb 08, 2011 3:55 am
by yoyodyne
I'm slowly rebuilding my small bedroom studio after losing everything goddam thing I owned in a flood.

So I just got monitors - Event ASP8s - and I want to calibrate my setup for the K System. I have read Mr. Katz book and all the stuff I could find online, downloaded test tones, bought the Radio Shack SPL meter and the NuGen Visualizer au plugin. Now I play the tone and adjust the output on my I/O (Apogee Duet) to read 85dB on the SPL meter and mark that position of the knob as 0dB--

But wait - the knob on the Duet is "endless." So how do I do this again?

I emailed Apogee tech support and all they said was: "Based on the K-14 reference of 0 VU = 85 dB SPL, generate a 1 kHz test tone at -14dBfs from your audio software, adjust Duet's encoder to read 0.7746 volt on a DMM (volt meter)."

Wha? Now I'm getting confused again. So I have to buy another meter, measure 0.7746 volts out of the Duet, and adjust the trim on the back of the Events until they put out 85dBs? But even then how do I recall the knob setting on the Duet later after turning it down?

I hope someone out there is using the Duet and can help me figure this out.

Bonus dumb K System question - Since one should check one's mixes against cds of the same style music, but all my cds are too hot (there's no electronic music on Bob's Honor Roll), I need to back down the mastered material until it reads 0 RMS on the K 14 meter in Visualizer to a/b with my stuff....right?

Re: K System calibration with Apogee Duet?

Posted: Tue Feb 08, 2011 5:53 am
by Khazul
Anything with a non-repeatable volume control is not practical for k-system type calibration unless you also have an additional output level hardware metering system, for eg and presonus central station to enable you to get back to a known level and thus make compensatory adjustments of the level when needed.

There is a way around it - just use the test tone at the start of a session to establish a calibration SPL level, then use the master output level in the DA (ie live) to perform relattive adjustments and leaving the level control on the duet alone once calibrated. Its a bit of a pain - life is so much easier with a monitor controller that actually has a decent built in level meter and vlolume control with end stops (ie not endless). Just make sure you allways have the SPL meter in exactly the same place and that you also standing relative to it in the same place and holding it in the same way (little things like that can significantly impact the reading).

As for the actual K-14 scale, then if your talking about house/trance etc - then most of that tends to be done to about 4-10 db of headroom in high energy bits. Pop is similar, so you will find that you need to back most mastered pop and dance music off by between 4-10dB. The problem with the k-system is it only really works as an absolute reference of peaks for simply recorded and mixed material. In dance music often the highest perceived transients are kicks and snares - however if a limiter has been used on them as an insert, then that will immediately peak to rms differential of the mix - so the peak doesntt really mean a whole lot with the production methods and material we often use. The value fo the k-system come into its own when you own focus on the average levels. You dont need k-system for that, just a means to have a reference level in your DAW being the same SPL from one session to the next and the means to make compensationary volume level adjustments to account for compression, limiting etc (ie if you crank the input to you limiter by 6db, then you need ot drop the output by 6db to retain the same perceived level, and thus be able to properly judge the impact of your limiter, to avoid the louder=better syndrome.

The point of the k-system is to get around the problem of different perceptions of sounds according to its level. If you dont work at exactly the same perceived volume levels, then you cant make repeatable mix/processing descisions - hence the typical experience of switching on the next day, not having levels exactly the same and having the urge to tweak many of the part levels (when you were perfectly happy with them the day before, or even an hour before).

When comparing your work with with other material, then the best mothod for dance music is simply to transition to/from other tracks (ie DJ mix type transitions). Anything wriong tends to stick out like a sore thumb when you do that. If doing a beat matched transition isnt practical/appropriate then still just loading reference tracks into live and crossfading is nnearly as good (just that issues tends to be way more obvious when beat matched).

Two bits of hardware I actually find really useful together after you audio interface.
1. The presonus central station due to it calibratable meter.
2. Behringer DEQ24966 - just because it has a heap of metering modes, including a useful spectrum analyser, peak+rms meter and vu type meter and can be calbrated for repeatable SPL readings via a measuring mix (ECM 8000 for eg). Just dont bother with the audio procesing it can do, but thankfully it has a bypass switch that actually controls a phsyical relay :)

Re: K System calibration with Apogee Duet?

Posted: Wed Feb 09, 2011 3:28 am
by yoyodyne
Thanks for the reply, Khazul.

What about the TC Electronics Level Pilot? The Mackie and PreSonus boxes are all too much for me - both in features and especially price. It's just me, the softsynths, and one set of speakers so I don't need talkbacks and mic pres and multiple ins and outs, that's why I went with the Duet in the first place. It seems stupid to have to get another big volume knob when the Duet is a big volume knob, but it looks like the Level Pilot has the end stops and that's all we need, right?

Re: K System calibration with Apogee Duet?

Posted: Thu Feb 10, 2011 5:45 pm
by yoyodyne

The Duet installs a software bit called Maestro. I hadn't messed with it because you don't need it to run the Duet but if you launch it you can dial in a level setting and save it. There's a check box to revert to that save every time you launch Maestro, and you can also load saved level settings with the Open menu. So I've got a K-14 calibrated level I can return to at any time and still use the Duet knob to back off the volume so my girlfriend won't kill me. At least not over the noise.

I guess I'm the only one with a Duet trying to do this, but there you go!

Re: K System calibration with Apogee Duet?

Posted: Thu Feb 10, 2011 6:04 pm
by yoyodyne
Also I just noticed the the K-14 calibrated volume is at the line out level of "-14" in Maestro (on my speakers which are set at "-5dB input sensitivity"), so that's pretty cool!