Optimod 8300 AGC

I have a Hip-Hop/R&B radio station which runs a ton of flatlined/over-compressed material. The last software release of the 8300 made it's handling of this material way better. I was curious if anyone had any suggestions or settings (Mr. Orban, please chime in as well) that can adjust the AGC to be even more kind to such material. 99% of my stuff is flatlined when the .wav data is viewed in an editor, so I know their is only so much that can be done, but I would gladly give up a touch of loudness if I could make the sound a bit better.

Just curious. This will only get worse as I have noticed that CHR and even Country now is being mastered in this way.

All of the other settings are tweaked nicely and on the rare occasion that we play 'older' music that was properly mastered, our sound really shines.

Any suggestions would be appreciated.

Less is more.

You might want to consider slowing down the multiband release along with the AGC ... somewhere around a medium-slow setting might help.

You might also consider a 16khz -or -so brickwall to lop off a lot of info that won't ever be heard, yet still makes any
processor work harder. I frequently modifiy songs with too much hi-frequency info in an audi editor BEFORE the song goes into the database. Especially when they are full-out as you describe.

@Whit... I am already at Medium Slow for the preset. @Tom, I have never thought of doing such a thing, but probably lean against it, because someday, we will probably want the full quality cut for something.

I'm really just looking to see if there were any AGC specific settings that might yield any result.

I suppose that may not be the case. We sound really nice in our market, so I have nothing to really complain about. Just got to thinking the other night...

As the thread linked below discusses, there are software tools available to "de-clip" CD WAV audio, and it actually does help to reduce distortion on poorly mastered CDs. But it's a bit tedious to use and requires low-level access to your music files. So maybe it's only worth using on a case-by-case basis on especially crummy-sounding songs, to see if it can make any improvement.

Also mentioned is using the CD de-emphasis curve to help balance out the sound of excessively bright recordings.

Fixing poorly mastered CDs with declipping & EQ
http://boards.radio-info.com/smf/index.php?topic=166455.0

How about a graphic EQ ahead of the 8300 to brick-wall off the stuff above 15kcs? To me, that would seem the simpliest way to achive that task.

I reduced the threshold on my high frequency compressor. That actually helped quite a bit with the artifacting that was bothering me.

OKCRadioGuy said:

How about a graphic EQ ahead of the 8300 to brick-wall off the stuff above 15kcs? To me, that would seem the simpliest way to achive that task.

Click to expand...

The 8300's base sample rate is 32 kHz. The input sample rate converter and A/D converter operate by sending 64 kHz into the processing. The first thing that the DSP does is to perform very high-quality synchronous sample rate conversion from 64 to 32 kHz. This is to avoid the rolloff at 15 kHz that the commercial SRC and A/D converter chips have when operating at 32 kHz. The 8300's 64->32 kHz SRC provides very tight filtering at 15 kHz before any processing occurs, so external 15 kHz filtering ahead of the box is not needed.

Note that this is not the case with the 8500 and 8600. The base sample rate of these boxes is 64 kHz and the AGC sees full 20 kHz bandwidth, so it can feed the HD processing chain with 20 kHz audio. However, because preemphasis occurs after the AGC and there is very little program energy between 15 and 20 kHz compared to below-15 kHz energy, I don't think that reducing the bandwidth of the signal feeding these processors would have a noticeable effect on the AGC's operation.

Bob Orban

chriscollins said:

I have a Hip-Hop/R&B radio station which runs a ton of flatlined/over-compressed material. The last software release of the 8300 made it's handling of this material way better. I was curious if anyone had any suggestions or settings (Mr. Orban, please chime in as well) that can adjust the AGC to be even more kind to such material. 99% of my stuff is flatlined when the .wav data is viewed in an editor, so I know their is only so much that can be done, but I would gladly give up a touch of loudness if I could make the sound a bit better.

Just curious. This will only get worse as I have noticed that CHR and even Country now is being mastered in this way.

All of the other settings are tweaked nicely and on the rare occasion that we play 'older' music that was properly mastered, our sound really shines.

Any suggestions would be appreciated.

Click to expand...

The AGC can be made more transparent by slowing down the Master AGC Attack, slowing down the AGC Release, and by increasing the Window Size. Doing these things will preserve more of the dynamic range going into the AGC but will also reduce the AGC's ability to respond to level inconsistencies between program segments. So these settings, like everything else in audio processing, is a trade-off. But those are the controls I would work with.

That being said, the AGC normally provides slow, averaging-type control that will not audibly increase short-term program density, which is the fatiguing aspect of a lot of modern mastering. (It never ceases to amaze me that the record companies evidently do absolutely no broadcast-style audience research measurements when making decisions about how tracks are mastered.)

The best way to avoid further increasing density of already densely-master material is to operate the 8300's multiband release at its slowest setting. It is also useful to experiment with the Multiband Limiter Attack controls, which affect the density of the sound in a subtly audible way. The useful range of these controls is 75%-100% for most formats. Reducing the setting of these controls will reduce density, but going too far will cause the multiband compressors to start pumping audibly.

Bob Orban