Stereo Tool

I see your having fun Bojcha. It sounds great! I assume you've been able to back off the compressor clipping further than with earlier versions. I look forward to trying that preset on other tracks in time! Consistency is so hard to nail. No doubt you were inspired by the improvements Hans has made - this latest beta is by some margin, the best yet. I'm not convinced the hole punching has been 100% completely nailed, but its such a vast improvement, I'm happy. Overall it also helps it sound smoother and more consistent. This is indeed inspiring stuff Hans. AJ

@Hans - Can you compile a version here that has the AGC change but leaves out the BS-412 and hole-punching stuff? Beta002 still has BS-412, and has the doubling of memory load.

Edit: Request not needed at present due to latest beta (020).

Wow some of the replies to this seem very very technical, and not something even as an engineer myself (with reasonble golden ears), would want to bother learning about the real nitty gritty to understand the numbers of adjustment.

You should keep everything in terms of simple, ie: in dB not percent and numbers and divisions and stuff.

I noticed on page 1 or 2 someone mentioned inovonics. I think this is here John Burnill started out or a processor that had the MLB software or something in it? I could be mistaken.

I have slow PC's so I can't run stereotool, I still run Sonos and MBL4 (which John made) and would use stereotool if I could.

The AGC has an emergency attack/release setting - real simple to understand for the user - you set the emergency attack threshold in dB, say a sudden 8 to 10dB RMS jump, and an emergency release threshold of say -8 to -10dB RMS jump, and the AGC will act instantly based on those figures in an emergency, such as a one off loud spike of thumping a microphone or the table etc... Remembering, it'll only sound louder if you are acting on average or RMS changes in the audio, not so much transient peaks to the human ear.

If that fails, then it's even easier to implement emergency attack/release, go thump your audio engineer and tell him to learn about sound and levels and voice processors! AGC's should only be for lack of RMS or average level, not take the roll of a peak limiter or voice processor.

I still use VU metering and all audio is set on PC's to the -20dBFS SMPTE recommendations as found in most TV studios as well (a 1KHz sinewave at -20dBFS digital peak = 0VU or +4dBu on a balanced sound card and console). This means peaks can dance anywhere from about -13 to -6dBFS (so the gear peaks output from say about +11dBu to +18dBu with room to the full +24dBu out for live production environments [+24dBu take away 20dB headroom = +4dBu normal operating level or 0VU]. Because I follow this standard, audio stored on PC is amplified not normalised - to 0VU on average (not -0dBFS on a digital peak meter as some incorrectly call VU meters) and no two songs have the same peak level. The PC's full scale peak level (incorrectly called VU sometimes) is just there for clip protection, it shouldn't be what you follow, that's what ears and VU is for. To me, this is how a real broadcast studio library should be stored for consistant mixes and segues and especially, when using various/random hooks from songs in promo's etc.... so they all sound tidy to the ear before processing and fattening up (made louder) by the processor last. This way, heavily compressed audio is stored on average along with really older dynamic stuff... stored to the same average level not peak level. That way, the more dynamic song has higher peaks, and the processor chops them off, as for less dynamic hyper-compressed CD, the peaks are lower yet the RMS is still the same and the processor downstream can then back off it's limiters on an already loud track since it lacks the higher peak output. I think this is basic sound engineering, but most of this has been lost in the digital age of CD's limited to a dB of their life, and there's more domestic not commercial sound engineers around learning by what they buy at the CD store or iTunes, not what they produce and how they manage studio levels in a live broadcast environment. In the studio, production is very different from the final CD or broadcast. Less is more in the studio, much more attention should be paid here than on the final processor.

Yes there is always need for an AGC, but realistically, if you need emergency response in an AGC, you're lacking in studio design... voice processor/limiter, that's about all it takes to solve that live peak based problem. That's the job of limiters, not AGC's full stop.

Cheers,
Gavin.
PS: I have worked hundreds of hours on sound presets and dialing up that 'sweet spot' on broadcast processors, and there's only one way to sound loud and the best on the dial, less is more in the studio, processing is the last thing in the chain, and never should be treated as the first - ie: AGC's acting like limiters.

Hi,

I can agree that music should be at same, like you say, "avarage level", but i would say "avarage RMS Level". Also You did not mention what you use for that, and how.. but now that's not important. However i also think that there is no much need for that, especially when we know that 'time' is needed for that operation and with good/smart AGC it's already solved. AGC might have just more job to do. We are talking about "real-Time" processing, so, broadcast.

AGC and/with Limiter part: This what can you see in current Stereo Tool is more like (protection) compressor which is always better in that part of chain. In just "some" cases it can be called limiter, rare cases when differences in level are huge and there is just no other way to make softer (amplified by agc) level push back when louder part comes un-noticable. This also much depend on AGC designer.
I must admit that i don't like ST's AGC 100% since in some cases does not respond as should, but i hope is some future that will be corrected. Maybe in some other way than it's now.
Also one important thing that is missing in current ST's AGC is 'windowing" feature. With that, many things might act different and this small un-perfections i see might be gone.

Yes I meant RMS average level, the reason I use mechanical VU metering, and I meant real-time/broadcast live use. This is why I have come to like mic pre-amp/voice processors, so there really shouldn't be a reason for a loud sudden spike.

I totally agree with windowing the AGC. The Ariane AGC leveler has a similar feature, where if the RMS of a song is within a defined "window" then the AGC gets gated... basically stops until the RMS level goes outside that window and the AGC starts processing again. This stops unwanted gain riding by the AGC when it's really not needed. They take AGC to a whole new level though, the Ariane can operate in sum and difference, and is a multiband 'windowed' AGC. So you get a really nice live stereo image enhancement at the same time as an AGC.

Cheers,
Gavin.

The current AGC design does not hee a window, but its movements do slow down when differences are small. You just gave me a new idea: not windowing, but a different response shape. Might be possible with 1 (shape) or 2 (window + shape) extra spiders...

Damn android error correction