Peak gain and clipping/compression?

[Phil]

Firstly, thanks so much to the creator for this software. It's fantastic. I didn't even think it was possible!

Can any one answer this:
Apart from using the equalisation, I'm trying to use EAPO to increase the output volume of my Realtek jack output.
Even with low impedence ear buds, the volume is not nearly loud enough.

In EAPO I'm setting the preamplification to 2.5dB, and with 6dB of equalisation, the peak gain says 8.5dB.
This gives me a decent volume when the Windows slider is between 80-100%

But what does that mean in terms of sound quality and clipping? Is this likely to create artifacts?
Is there anything in Windows or the Realtek chip that will undesirably apply compression to the boosted signal?

Thanks.

[Peter Verbeek]

If clipping occures you'll notice a distortion in your audio. In Peace you can check the Peak volume meter. For instance a red light will show there's clipping going on. So when your audio is low you can turn up the pre amplification until the point of clipping. In normal cases a positive pre amp can have a negative effect because of clipping. There's even a potential danger of blowing up speakers/headphones when using a large positive pre amp. But I do use positive pre amps for some bad recordings like some YouTube video's. Or get more audio out of my laptop speakers when watching a movie on it.

I'm not aware if Realtek compresses the audio. My Realtek chip doesn't. The audio just gets to it maximum output (and clips and distorts) when dialing up the pre amp.

[Phil]

Thanks. I do get the impression that something somewhere is applying compression, because I can hear the signal 'pumping' when I turn the boosted volume right up. If so, it is a hidden parameter/feature in Windows or in the chip itself.

I guess the proper thing to do would be to buy an external headphone preamp to boost the signal.

[Peter Verbeek]

Yes, pumping is clear sign of compression. My cheap headphones has a good performance but a bad effeciency. Fortunately I'm able to use the pre amp without compression issues. I guess I could buy better headphones but you're right an external pre amp is also a good option.

[Jonas Dahlinger]

I also noticed that some limiter is active that is not part of Equalizer APO. It is either part of the driver or a Windows feature. Recently, there was some problem in Windows 10 that the limiter was not working correctly after resuming after pausing playback so it is more likely a Windows feature.

As Peter said already, if you don't have a reason to, you should try to keep the resulting gain below 0dB for the full frequency range. But if you want to increase output volume, you will of course have to go above 0 dB. Then, it is just a question of your source audio if you get compression/clipping.

[Panayotis Kritidis]

Phil, if your final sound level is too low, try to "violate" a bit the "no positive values" rule in the final EAPO equalization curve, given that the violation will concern frequences above 5 kHz. Due to the much lower signsl levels, which are typically present in this region, this will not result in clipping levels. The degree of violation? Let's say up to 3 dB in 5 kHz and up to 6 dB above 10 kHz. This can be done ONLY if your equalization curve has not higher values in the middle and low frequences!

According to my recent experience, clipping may occur in the final stage of the audio chain, that, controlled by the principal level control of the sound card. To control this, it is good to install and use the free Orban sound level meter, which shows the final signal level(s) and not those in some intermediate stage (e.g. in the media player output).

[Erik Van Hamme]

"I also noticed that some limiter is active that is not part of Equalizer APO. It is either part of the driver or a Windows feature." - Jonas Thedering

I struggle with this thing as well. It is a Windows feature, possibly another APO that is active. I noticed it when I was overdriving the output of a channel due to a mistake in my config.

Further test showed that it will not allow clipping of the signal in the audio driver. Even if I make a tone in audacity at 0dB output (float value of 1.0) and a 6 dB boost in equalizer APO refused to let the output clip.

I had the Equalizer APO installed on the VoiceMeeter virtual soundcard. The control app shows the output level. The VoiceMeeter soundcard was dumping audio out straight into my external DAC via ASIO.

Disabling all audio enhancements on the sound card seems to kill the limiter, although I am not 100% sure of this.