I reported a while back that I had noticed that setting the track volumes too high in a midi file caused my PSR2000 output waveform to show significant signs of clipping.

Well I've just bought a PSR3000 (and I haven't stopped smiling since...) It is not a shock to find that that this situation is still the case but interestingly I can now actually hear the distortion when the midi file is played on the 3000. Maybe I'm listening harder, or the output from the 3k is a bit cleaner to start with (so I hear the distortion more acutely)

So to modify my previous statement - don't take track volumes in a midi file above 100, and if you are using high note velocities and lots of tracks then maybe max track volume of 80 is a good rule.

But after the tweaking - my midi files don't half sound good.... and thats before I've edited to suit the megavoices!

For the Auto Volume function on my MidiPlayer program I looked at a lot of Yamaha midis including the demo files on Tyros.

I found that Yamaha itself sets 70-80 as a typical average volume (note specific tracks will be +- this, often by 20%).

I do not know what exactly is causing your sound quality to degrade at higher volumes. Functions such as DSP and EQ are implemented in code and hence need some headroom, but I would not have thought 40% would be required.

Interesting.

I sure the degradation is due to the fact that the sound is created totally digitally and at some point in the chain the sums add up to more than 16 bits worth of signal. I have met the same behaviour when working with aircraft autopilots!

I don't consider this behaviour to be a fault, just something to be aware of.

I too find this interesting.

What kind of distortions do you hear? I've read before that analog clipping and digital clipping are two totally different beasts. When you hear the cracking sound of digital clipping, you know it, it's unmistakable.

I've also read that, technically speaking, digital audio has no headroom because there is no margin for overshoot. 16-bit audio has a ceiling, there are no more bits to designate going past that ceiling. The engineers are suppose to design the electronics so that the entire dynamic range of the signals being reproduced fits within the limits of those electronics.

I can't help but think of all those midi files out there that have track volumes set higher than 100. Trycho midi files are notorious for setting all track volumes at 127 (at least their first generations did). That's a lot of editing.

-mike

" a lot of editing..." was true...

The MidiPlayer program has an batch mode that can revoice and/or rescale (keeps the same relative mix between instruments) the midi volumes of many midis at once and running unattended (2-3 midis per second).

It is available for free at: http://www.svpworld.com/util_midiplayer.htm

Regards,

Michael

What a Star - MidiPlayer here I come!

The distortion I get is always associated with loud bass / drums and so I don't hear a high frequency crack, more like, the bass loses definition and turns into a sort of suishy thud.

If you look at the sound with an audio level meter (e.g. the monitor window in SoundForge) it is quite easy to interpret the display and realise that clipping is occuring. You have to set the recording levels so that the peak is at about -6db (so you know that the clipping is not happening on the PC) and then playback a midi file. If the level hits that peak before the part of the midi file that you consider to be loud, and stays there, then you can be sure you have clipping. Once the levels are adjusted correctly then the audio hits the peak very rarely throughout the entire song.

I've been thinking further about the issue. The problem Yamaha (and everyone else) will have working in the digital domain is indeed headroom. If you design your sound generation system around the possibility that someone is going to come along with a dense midi file with 16 channels of max velocity notes and high channel then, unless you internally limit or compress these high volume events, the amount of headroom you have to build in to cope with the peak means that "normal" sounds are going to come out really quietly and quiet solo notes will be inaudible. Therefore the generation system is designed with sufficient headroom so as not to distort in normal situations. And as a consequence really loud midi files will distort and need to be mixed down somewhat. C'est la vie!

Well it's a Great British Thankyou to Michael on this one.

His MidiPlayer program has done the trick nicely. The reduction in track levels performed by his program has reduced the audible distortion to the extent that I cannot actually hear it any more!

Nevertherless on my more aggressive mixes I have still had to drop the volumes by about a further 10%. You can only see the last occasional clipping by looking at the waveform.

Excellent job, Michael!

I am happy that it did the job for you.

Please note that you can set the levels used for the auto volume settings; depress the manual volume button on the main screen.

Regards,

Michael

Further Thankyou's to Michael. Letting Midiplayer loose once again on my files, with "Midi Average Volume" set to 60 and "Midi Rhythm Volume" set to 65 sets my files consistently to just under the clipping threshold. Fabulous!