Topic: Levels on the 722/744 question

[boojum]

What he said.   

[prof_peabody]

I thought I would revive this.  I've had my fair share of "learning experiences" with the 7XX series boxes.  I just ran a 744t last night for Black Mountain.  I ran 24/48 - with peaks at 3 db on the 744t (average was probably -6 to -9).  I am amazed by the high levels of distortion.  Last night when I listened to it in playback, I thought it might be the compression/limiting of the venue PA (running a small PA too loud in a small concrete box).

What's up with the distortion?  Is this normal for a 744t.  I guess I've learned that the hottest I want is a -6 peak, but more likely -9 or -12.  I haven't had a chance to open the files in wavelab yet and take a look.  I'm kind of frustrated by this to say the least.

Any thoughts or insight appreciated.

I just thought I'd add some details:

I ran DPA4021 > 744t (mic in).  I'm pretty sure they use a lot of compression in the PA at the small cruddy Meridian Red Room in Houston.  There was not a lot of variance in the meters during songs, so I'm assuming it was compressed to hell.  Still I think it may have been the recorder, because I don't remember the show sounding as bad as the recording.

[it-goes-to-eleven]

Everyone talks about peak levels but I suspect avg rms levels are every bit or more important in finding the 'sweet spot'.

For example... I recorded a no-PA jazz show recently, mk4 > 722.  Recorder gain was 35dB and the highest peak (drums or horn) was -3.60dB.  Avg rms was -30.49.  It sounds nice. Given a do-over I might have run 28-30dB of gain instead.. But I'm not certain that would have improved the result.

[prof_peabody]

Any idea whether the distortion is caused by the PA or recorder with the levels I ran at?

PS - that's pretty low RMS level - but I guess you'd definitely have a huge dynamic range for that.  I bet the RMS level on these ones is -12. 

[it-goes-to-eleven]

Not sure.... Was there a quiet song where you could compare?

[fobstl]

I run 4021 > 722 and my levels sometimes peak at 0 at some point during a show. I have never had any distortion. Do you have the mic gain range set to normal or low? You need to be on low gain range or you may get  distortion regardless of your peaks.

[it-goes-to-eleven]

Do you have the mic gain range set to normal or low? You need to be on low gain range or you may get  distortion regardless of your peaks.

I have read that SD says high and low are exactly the same with the only difference being the range available from the knob.

[prof_peabody]

I run 4021 > 722 and my levels sometimes peak at 0 at some point during a show. I have never had any distortion. Do you have the mic gain range set to normal or low? You need to be on low gain range or you may get  distortion regardless of your peaks.

The choices are low and normal.  I had it set to low.

It sounds like this might be a PA (too much compression/limiter issue).  Thanks for the input people.  There's nothing I hate worse than making a cruddy recording.

[Kyle]

I think this link has been posted before but it seemed applicable to this thread.

http://messageboard.tapeop.com/viewtopic.php?t=38430

[prof_peabody]

Ladies and gentlemen - after re-reading the manual.  I discovered this:

Page 15:

When limiters are engaged, audio on channels 1 and 2 is limited to -6 dBFS.

This advice on page 8 is also helpful:

27) Microphone Input Limiter LEDs

Illuminates orange when limiting is occurring on the microphone input.  If constantly lit, the microphone input is being hit with too "hot" a signal.  Reduce the input sensitivity until limiting occurs infrequently.

http://www.sounddevices.com/download/guides/744t_en.pdf

The limiter was definitely on - and I remember watching those orange lights flicker on and off constantly.  Problem solved - too bad I lost a night worth of solid music.   

[nedstruzz]

Why run the limiter at all?

[MattD]

The limiter is great for being on stage at a jazz show. It helps keep those drum solos or horn attacks from clipping, especially when the music is hovering around -18.

[prof_peabody]

Why run the limiter at all?

It was on when I borrowed the box.  Good call though - I'll probably turn it off in the future.

[nedstruzz]

The limiter is great for being on stage at a jazz show. It helps keep those drum solos or horn attacks from clipping, especially when the music is hovering around -18.

Cool, I know a lot of people used to run the limiter on their Mini Me units with good results but I have not seen to many people run it on the 7xx series boxes. 

Seems like a good reason to run it for those jazz situations. 

[terrapinj]

at least you figured out the problem 

ive run the limiter when stealthing before but prefer to just run more conservative now and not bother