DAC/AMP sound issues - Page 1
Forum section: electronics / repair

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: September 23, 2019, 09:16:52 pm
content: I have Questyle CMA400i DAC/AMP/Pre-AMP unit that keep popping stuttering etc. when playing music through the optical connection. The same happens when connected via USB.This happens at random times and I've tried pretty much everything to isolate the issue and so far nothing has worked.I even isolated it with an isolation transformer connected to a pure sine inverter to avoid any ground loops and headphones and the audio still popped randomly and its incredibly annoying!I'm starting to think the unit is defective but I'm not sure where to even start in an attempt to fix it as their customer service is non-existent.What to do?

author: shakalnokturn
author_rank: Super Contributor
timestamp: September 23, 2019, 11:27:25 pm
content: The first thing I'd worry about is the source. Have you tried different digital sources one of which isnotPC based and that you're pretty sure it will be feeding a steady data stream that the DAC is happy with?Once sure you have a decent source start looking at the power rails supplying DAC and Toslink/USB interface. Anything more than 10% low is suspicious.

author: wraper
author_rank: Unknown
timestamp: September 24, 2019, 12:03:26 am
content: Try setting lower bitrate and see what happens. IME not all computer and/or cable combinations can output 192 kHz over Toslink reliably.

author: wraper
author_rank: Unknown
timestamp: September 24, 2019, 12:07:39 am
content: BTWQuote

author: shakalnokturn
author_rank: Super Contributor
timestamp: September 24, 2019, 12:11:33 am
content: Was that a "figure-palm"?

author: wraper
author_rank: Unknown
timestamp: September 24, 2019, 12:15:38 am
content: Quote from: shakalnokturn on September 24, 2019, 12:11:33 amIs it audio amp or radio transmitter? Also it's obvious it can possibly do it from analog input only, of course not mentioned in specs. Not to say human cannot hear it. Nor speakers can convert it into sound.

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: September 24, 2019, 06:11:53 am
content: Quote from: wraper on September 24, 2019, 12:03:26 amYou mean sample rate? I actually switched to 48 KHz 24 bit yesterday to see if the issue would go away. Only time will tell...

author: wraper
author_rank: Unknown
timestamp: September 24, 2019, 10:47:15 am
content: Quote from: drummerdimitri on September 24, 2019, 06:11:53 amYes, sample rate. Bitrate is exactly proportional to it.

author: magic
author_rank: Super Contributor
timestamp: September 24, 2019, 01:51:51 pm
content: Quote from: wraper on September 24, 2019, 12:07:39 amYou know how gain bandwidth product works, right?Even the 600kHz is likely artificial limitation by EMI filter.

author: jogri
author_rank: Frequent Contributor
timestamp: September 24, 2019, 09:01:45 pm
content: What soundcard are you using? If it is one from Asus (i only have cards from them, don't know how other manufacturers handle it), try ramping up the latency in the ASIO control panel. I have tried running my AVR over the onboard Toslink, but it just lagged like hell (same symptoms, it would stutter momentarily).

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: September 24, 2019, 10:02:39 pm
content: Quote from: jogri on September 24, 2019, 09:01:45 pmIsnt my soundcard the Questyle CMA400i?

author: shakalnokturn
author_rank: Super Contributor
timestamp: September 24, 2019, 11:04:29 pm
content: Anyway, how's it doing with a slow enough data rate from a reliable source? Any better?

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: September 24, 2019, 11:06:31 pm
content: Quote from: shakalnokturn on September 24, 2019, 11:04:29 pmToo early to tell with any certainty. Will need to try it for a week at least and see.

author: jogri
author_rank: Frequent Contributor
timestamp: September 25, 2019, 08:39:58 am
content: Quote from: drummerdimitri on September 24, 2019, 10:02:39 pmDepends on your definition... You still need something that generates the digital audio signal from what your PC sends to your soundcard/driver. That chip is most likely something from the Realteak ALC family, and it is in your PC. Your digital output (to your Questyle) comes directly from this chip, it is the digital signal that normally gets send to the internal DACs on your soundcard. I can tell you from personal experience that crappy sound chips (like onboard chips) will produce the problems you mentioned while shielded, high quality soundcards won't have them (in my case said card is a Xonar Essence STX, but that is overkill. Try lending one in the 40-60 bucks range and see if your lag spikes go away).Now for the USB part: Bad idea transmitting audio over that since the USB protocol for audio is the isochronous one: It just sends X amount of data every X seconds. It is a reliable, steady strem of data (just what you want for audio). But: Since the bandwith has to be constant, there are limited options for error correction. Normal CRC works, but no data gets resend if the recieving end (your DAC) detects an error. Combine that with crappy cables and a not really great USB clock on your PC and you get lags every so often.If you want to read more about that issue:https://www.edn.com/design/consumer/4376143/Fundamentals-of-USB-Audio

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: September 25, 2019, 08:48:35 am
content: Quote from: jogri on September 25, 2019, 08:39:58 amI get you. I have an Asus Z170I PRO GAMING motherboard and only use the optical ouput to my Questyle since USB is noisy and creates ground loops.Looked at your sound-card and although it looks fantastic, it doesn't have any optical output which is strange and since my board is ITX, it doesn't have any place for a sound-card.

author: jogri
author_rank: Frequent Contributor
timestamp: September 25, 2019, 10:00:54 am
content: So you most likely have a Realtek ALC1220 with a fancy shield on it... The "SupremeFX" branding is just a different name Asus uses for the 1220. Not the worst out there, but far from good. And manufacturers tend to cheap out when it comes to onboard sound, since everyone who cares about sound quality will choose a different output anyway.But lets talk about solutions for your problem: You forgot that you have a second "soundcard" that is capable of outputting a clear 192kHz stream. It is sitting in your single PCIe slot: your graphics card. You can output audio via hdmi, just use an audio extractor (like this onehttps://www.amazon.co.uk/Extractor-Support-TOSLINK-Optical-1-HDMI-4K/dp/B06XFZXTYW/). Just install the sound drivers for your card and configure it as your audio output in Windows.(And yes, my soundcard has an optical output: The hole in the middle of the digital coax output houses the led for the optical output. You need an adapter that looks like someone glued a 2.5mm banana plug to the end of a toslink port.)

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: September 25, 2019, 04:08:33 pm
content: Quote from: jogri on September 25, 2019, 10:00:54 amI do in fact have a GTX 1080 but why would it be a better "soundcard" then my onboard audio?Also, can I still use my Display port for my monitor and extract audio with the HDMI port?

author: jogri
author_rank: Frequent Contributor
timestamp: September 25, 2019, 04:58:12 pm
content: Because you don't really need a full soundcard, you just need something that has the capability of converting the raw audio stream into another digital format, and since HDMI was designed as a video+audio channel, your graphics card can do that. Plus, you have way more bandwith with hdmi: Toslink (optical) only supports a stereo stream at 192 kHz while HDMI has no problems supporting a 7.1 stream at 192 kHz.Is your 1080 a better "soundcard" then your onboard? Not really, they are both just transmitting a digital signal without altering it. However, i can tell you from my own experience that i never experienced lags with my 1080 as the "soundcard" but had quite a bit of it when i used my onboard Realtek 1150.And yes, you can still use your Display port, Windows just lists another playback device when you connect a hdmi device with an audio output. Since i haven't used one of those audio extractors, i don't know if it'll show (but it should, if it doesn't you can still plug the hdmi cable into your monitor (just to have a communicating device so Windows will show it as a playback device) but use Displayport as your signal source). I have my 1080 as my default audio ouput with monitors on another hdmi and a Displayport output, works like a charm.

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: September 25, 2019, 05:14:38 pm
content: Quote from: jogri on September 25, 2019, 04:58:12 pmGood to know thanks!I bought a cheap one of those from Aliexpress. Hope it will solve my issue thanks!