Ask HN: Seeking device to normalize audio output for consistent volume levels

58 points · ghoomketu · 6 days ago

Hello hn. I'm looking for a device that I can insert between the audio output and speaker to normalize the audio.

The goal is to ensure that sudden loud noises don't become overwhelming and quieter parts sound reasonably the same.

My reason for doing this is because it's so hard to watch movies these days because of the inconsistent volume levels (2x harder at night).

Any suggestions or recommendations on specific products or solutions would be greatly appreciated! Any DIY suggestions are also welcome too.

56 comments
shadyfroyo · 3 days ago

Show replies

not_your_vase · 6 days ago
1 - Get an amplifier that has a "Night Mode" function. It has been a basic function on most AV-receivers in the past decade+, assuming you don't buy the most pedestrian model. It compresses the dynamic range of the sound, to avoid the loud parts waking up the neighbors while you can also hear the conversations. Of course here you are looking for an investment of between $350 and $inf. Buying secondhand can save big bucks.

2 - Use a PC for your video needs. Most video players support the same function (VLC, GOM player, Kodi... look for "dynamic range compression" and similar options). A 10 years old mid-tier machine will play everything including UHD, so this solution is fairly cheap. If you get a cheap IR-USB remote, you won't even have to mess with keyboard and mouse.

Show replies

randomfinn · 3 days ago
If your source is Dolby Digital, you may not need anything new - just adjusting your settings. Dynamic range compression is a standard feature, and the bitstream should already include the necessary metadata for the decoder to implement this.

It's been a while since I looked into this in detail, but iirc the decoder must automatically enable dynamic range compression when it's set to two channel output. So avoid configurations where you first convert the audio to 5.1 channel PCM or analog, and then apply downmixing or virtual surround.

If you're using a surround system, most receivers have a night mode as mentioned by others already. Some have also an adaptive system that adjusts the dynamic range based on your volume setting - turn it up and you get the full dynamic range, turn it down and the dynamic range is compressed more as you set the volume lower to try to keep the dialog audible. Many receivers include a microphone for automatic settings, and after calibration know the actual output level. The Dolby Digital bitstream (and I think DTS) include a flag to indicate the overall dialog level, and based on these a receiver can do quite a good job. Some I think go only by the DD metadata, others have a compressor that can be applied to any input.

shermantanktop · 3 days ago
FYI, the place to put such a device is definitely not between the amplifier and the speaker. You want it on the audio input to the amplifier.

Unfortunately modern receivers have preamps that do a ton of digital decoding, input switching and other stuff, making the audio signal between the preamp and the amp impossible to get to. That leaves you with receiver features like night mode, as suggested by others.

marssaxman · 6 days ago
This kind of device is called a "compressor", and they are ubiquitous in recording studios. They can get very expensive and complicated, but for your purpose something like this may suffice:

https://www.amazon.com/rolls-SL33B-Stereo-Program-Limiter/dp...

Specifically what you want is a "stereo compressor" or "compressor/limiter"; if you want something more sophisticated than the device above, there are many 1U rack options available for ~$200 (dbx is a good choice), or used on reverb.com more like $70-$100.

Show replies