[KinGensai]

So, I recently had to change my phone (RIP V50 DX ) and got myself a V60 to be hip or whatever. I figure LG has this quad dac thing figured out by now cause the V20 and V50 have been pretty good as DAPs.

Well, the V60 sounded unpleasantly shrill and distorted to all hell when I first set it up, which I was quite unhappy with. On investigation, this is a software problem. LG forgoes the outsourcing they they have been doing since the first V series phone to save money I guess? The result is this hot garbage. Thankfully UAPP exists, so I switch to that from Neutron to bypass the garbage quad DAC digital filter and coloration, and the sound is now fixed.

What the heck happened here? Why did anyone think adding a digital filter to simulate impulse response was a good idea? Is there some merit to this concept I'm not getting? I thought the goal of hi fidelity audio was to remove distortion and unnecessary coloration, not add it.

This incident has been befuddling. My brain needs help understanding the rationale here.

 

[gregorio]

Thankfully UAPP exists, so I switch to that from Neutron to bypass the garbage quad DAC digital filter and coloration, and the sound is now fixed.
What the heck happened here? Why did anyone think adding a digital filter to simulate impulse response was a good idea?

It’s difficult to answer your question because it’s not clear what you’re stating. Firstly, I’m not sure what you mean by “DAC digital filter and colouration”? In almost all cases the digital filters in DACs are inaudible and even with those extreme/pathological filters that are audible, they are relatively minimally audible, they do not apply loads of distortion/shrillness. Secondly, I don’t know what you mean by “a digital filter to simulate impulse response”?

I thought the goal of hi fidelity audio was to remove distortion and unnecessary coloration, not add it.

The goal high fidelity audio reproduction is to remove/reduce the distortion added in the playback chain. Unfortunately despite the definition of the term “audiophile”, that is commonly not the goal of some/many audiophiles. However, it would be very strange for a manufacturer of a mass market product to pander (with default settings) to this tiny niche of consumers.

G

 

[KinGensai]

With the V50, LG introduced some sort of software control for what kind of digital filter you want to apply with diagrams of what those filters do. From the look of it, it adds an artificial simulated impulse response that I would normally expect from a transducer.

The V50 shares this with the V60, but the effect was effectively inaudible to me on the V50. With the V60, the difference with this software enabled is extremely clear as compared to the V50 and my PC playing the same source track.

UAPP bypasses all this software, solving all the problems I had at first. I was just puzzled by what possessed LG to do this in the first place when the hardware is perfectly fine.

 

[gregorio]

With the V50, LG introduced some sort of software control for what kind of digital filter you want to apply with diagrams of what those filters do. From the look of it, it adds an artificial simulated impulse response that I would normally expect from a transducer.

That’s not a “simulated impulse response”, that’s the response to a Dirac Impulse one would expect from a standard linear phase anti-imaging filter. What’s strange is that it’s listed as a “Slow” response filter. This typically means a non-linear phase filter, with a slow/early roll-off that eliminates pre-ringing in favour of an increased amount of post-ringing. However, the diagram shows a fast linear phase filter, with equal pre and post ringing, not a slow filter with only post-ringing. All rather bizarre, including the descriptions of what the filter types are supposed to sound like! There shouldn’t be any audible difference between the filters, unless the “slow” one is exceptionally slow (very early roll-off) but then the impulse response would be entirely different and it would not sound “clearer”!

There certainly should not be any audible distortion.

G

 

[KinGensai]

Ok. The terms and whatever didn't make sense to me either, and as you said here I didn't hear significant distortion & coloration on the previous iteration of the software. On this particular V60 though, I hear it loud and clear, and I remember on the V60 thread someone recorded sine waves and got significant distortion unlike previous devices.

 

[castleofargh]

Those filter settings are available in most modern chips, it's up to the LG to use a particular setting like it's done in most DACs without asking what we want, or make the options available to the consumer through the user interface. Or maybe they even do something on top of that to make the sound clearly different between options?
My personal experience with various gears has been that when it sounds weird and the settings don't allow getting it to sound not so weird, there often is more DSP involved than shown. Like all the crap that is shown as ON or OFF, but OFF turns out not being a bypass by crap by design to convince us that ON is of great benefit. Sometimes it's just quieter, sometimes it's EQed badly, sometimes we just cannot disable some DSP that sucks or might even clip because somehow nobody considered the possibility when added to an already maxed out signal.
Bypassing as much as possible with some rerouting of the audio is often the most effective, sadly it also takes away some other DSPs that might sound nice sometimes.

 

[gregorio]

I didn't hear significant distortion & coloration on the previous iteration of the software.

There should be no distortion/colouration anywhere near audibility, let alone significant distortion.

On this particular V60 though, I hear it loud and clear, and I remember on the V60 thread someone recorded sine waves and got significant distortion unlike previous devices.

Something is very broken then. Most likely as @castleofargh suggests, something else going on that isn’t being bypassed. Even so, that’s a very serious bug/issue, you could maybe forgive something like a bit of additional limiting when mixing different sources together but even that should be barely audible and only under certain circumstances. Consistent “loud and clear” distortion is a serious fault.

G

 

[jagwap]

If I recall correctly on the G8, the Qualcomm DAC is used if you use the built in music player and other APPs if 16bit or less audio is played, to save power. The Quad DAC is enabled when it sees"hi-rez". So I edited my music files to make them 24bit FLAC, adding LSB zeros. This doesn't take up more space as FLAC compresses them to nothing. Your solution of using Neutron does the same thing I believe, by forcing the ESS DAC to be utilised.

 

[KinGensai]

I don't think activating the quad dac was the issue, it was the DSP LG tacked on to the quad dac that was causing those issues. Neutron wasn't bypassing that DSP so my audio was audibly messed up. I'm using UAPP now, it properly ignores all the bloatware, so the signal is very clean now.

 

[jagwap]

I don't think activating the quad dac was the issue, it was the DSP LG tacked on to the quad dac that was causing those issues. Neutron wasn't bypassing that DSP so my audio was audibly messed up. I'm using UAPP now, it properly ignores all the bloatware, so the signal is very clean now.

I guess so. In the past they had B&O and Meridian doing it, where usually there is some expertise (who knows these days), but if it was an LG DIY, maybe they screwed it up. Digital filters are well understood, but without a deep understanding it is easy to make a mess of it.