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I use Stereo Tool plus the TT DR meter VST as effect plug-ins.
I know that the BA peak limiter is always active – independant if the processing is active or bypassed.
But why does Breakaway Live (latest Beta96b bypassed) apply peak reduction though there are already no peaks higher than -1.0 dB ?
❓I would guess because it’s limiting inter-sample peaks. But… I didn’t think Breakaway Live limiter did that. :< Do you also have the high pass and low pass filters disabled?
[quote author=”JesseG”]I would guess because it’s limiting inter-sample peaks. But… I didn’t think Breakaway Live limiter did that. :< Do you also have the high pass and low pass filters disabled?[/quote]The TT DR meter post Stereo Tool shows correctly -1.00 dB peak.
[quote author=”TT DR meter PDF manual”]In the area close to full scale, peak measurement is particularly complex and critical.
First of all, fixed point resolution can only show values up to full scale, since on the
digital level, no overs are possible. However, contiguous full scale words create audible
overs and so called interleaved sample overs. Secondly, floating point calculation makes it
possible to represent values well over 0dB. The measurement and display of peak values in
4x over sampling leads to a display of overs so frequently that we have found a middle of the
road solution. The peak values are measured "normally" and provided numerically.
In the case that two contiguous bit words show full scale (all 16 bits at 1 without any
oversampling) and at the same time a value of over 0 dB is detected via oversampling metering
(run as a parallel process), then the peak display shows "OVER."[/quote]
It is caused by the BA Live high pass filter.
I had not changed this setting since BA Live installation, so it was still activated with the default value (-> HPF: 20 Hz).
Now I have disabled it (HPF: Off) and everything is ok. ❗But I wonder if it is normal that as long as the HPF is active you have to lower the effects output level to -2.5 dB (75 %) to avoid that peak limiter activity ? ❓
It’s normal. Any filtering of any part of the spectrum will cause loss of peak control when there’s signal there getting filtered out.
Jesse is 100% correct. Peak-control is a very finicky thing. It’s hard to achieve, and extremely easy to lose.
The high pass filter in breakaway live isn’t phase linear (as a phase linear high pass filter adds hundreds of milliseconds of delay, like the one in bbp in phase linear mode), and as such causes tilt, so if you start with a clipped waveform (squarewave), there will be overshoots.
If you look at the oscilloscope in breakaway live, you will see what’s going on. I didn’t include it just for shits and giggles, it’s actually an indispensable tool.
The sample rate converter can also reveal inter-sample peaks, but it will not introduce peaks on a TRUE peak and bandwidth-limited signal such as the output of BBP!
///Leif
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