I've been recording the audio output from my PSR3000. Whilst I've seen (and reported here) waveform clipping in the past due to excessive mix level in midi files I've now got a much stranger problem and I wonder if anyone else has seen this.

Basically, if you look at the audio waveform it is clearly not symmetrical. The +ve side of the waveform looks fine but the negative side looks compressed and low-pass filtered!

I get this on midi file, styles or live playing. I've used two different power supplies. I've changed the EQ. I've reset the keyboard. No change.

I'm capturing from the Phono sockets, I haven't bother capturing from the jack sockets are these are downstream from the phono so I'd expect the problem to be seen there as well.

It still sounds OK which may just confirm that my hearing is getting worse....

My only thought at present is take the lid off and waggle everything! Are there any
chips in sockets that might have crept a little?

To summarise: HELP!!!

Is there a way we can see what the you a talking about?

How can a level in a MIDI file be excessive?

I'd record just at least a snippet from the main outs, just to make sure...

Quite a lot of real sounds from real instruments exhibit non-symmetrical waveforms, only synths are perfect!

But I would get someone else with a 3k to confirm it for you. You MIGHT have had a component failure on one of the op-amps. I'd also double check your recording signal path. Have you eliminated other sources from the same problem? Your A/D card might be damaged, your mixer's op amps might be faulty, there's a whole signal path to troubleshoot (sorry if you already have)...

Try a recording of just ONE sound, say a synth pure tone recording (sawtooth or square wave) and see if it is those too, or just the result of non symmetrical acoustic waves...

Hpe this helps.

I seem to remember distortion problems with the PSR3000..the culprit was a damaged headphone circuit board..apparently all the sound is routed through this board...

Mac,

Post a small sample of your recording so we can try to analyze the problem.

Gary

You can also record from the headphone out, to see if it happens there too.
DonM

Thanks for that. I don't have any way to post images so Im about to send some of you a small email with a screen shot attached. I was lucky enough to find a recording from December last year of the same midi file so the screenshot shows current waveform to the left and last years waveform to the right.

I agree that real instruments are non-symmetrical but I think I'm well outside that amount of variation!

I'll have a chance to investigate further on Sunday (UK).

Re "How can a level in a MIDI file be excessive" you can get signal clipping caused by the way the channels of a file are mixed digitally within a keyboard.

The digital mixing takes the instantaneous value of each voice waveform, scales it by the mix level for the track, adds up all the resulting values and arrives at a total instantaneous value for the waveform. If this value is larger than the maximum possible value for the summed waveform then the value will effectively get clipped at that maximum.

This is not a fault as such but a consequence of the way the maths is done, in some ways it's the computing equivalent of gain structures.

As a result of this, on my 3k, I rarely set individual track levels above 70, especially drum or bass tracks as these are the ones that are most likely to overload the system.

[This message has been edited by MacAllcock (edited 01-21-2010).]

[This message has been edited by MacAllcock (edited 01-22-2010).]

[This message has been edited by MacAllcock (edited 01-22-2010).]

Hello John,

Got your email with your waveform images.
Definite offset of some kind.
DC offset maybe?
Still you've said it sounds ok.
Normally I work on the premise of; if it sounds ok, then it is ok.

I've never had issues with MIDI files and levels, but I don't use them that much, I've only a few bit's of kit that handle GM.
Have a Yammy XG1000 PCI card lying around somewhere, not currently installed in a PC at the moment.

I wondered about DC offset, but to me the difference in the +ve and -ve cycles looks too pronounced.

I may just have to live with "it sounds OK" until I've saved up for a 910!

I've just noticed a new recent firmware release for the 3K http://music.yamaha.com/products/downloads.html;jsessionid=05DEBA11BCA961B65CC8C75AE41697B8?productId=106898

I don't really see what difference it would make; I don't need the new functionality but is this worth a go just to see?

Sorry, Mac. I replied to your email before I saw this post. If that is the waveform display of the 3k before and afterwards, then of course, yes, you have a problem...

But, for it to pinpoint the 3k as the culprit, you need to make a recording of something else through your soundcard, to eliminate that as the cause.