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+--- Thread: Khadas Tone Board (/showthread.php?tid=649)
RE: Khadas Tone Board - williamlawson - 05-14-2021
Thanks for the input regarding volume control guys!
So it seems the KTB is not actually doing hardware VC even though it says it should or am I getting something wrong here? I am actually not concerned about DSD.
Since I want to use it without a preamp I would probably steer clear of it then. Maybe I should just go for a dac with a regular old volume control knob on it.
RE: Khadas Tone Board - TheOldPresbyope - 05-14-2021
(05-14-2021, 07:19 PM)williamlawson Wrote: Thanks for the input regarding volume control guys!
So it seems the KTB is not actually doing hardware VC even though it says it should or am I getting something wrong here? I am actually not concerned about DSD.
No, all the VC wonkiness we are talking about involves playback of DSD tracks.
As I said, with PCM-encoded tracks (e.g., the usual .wav, ,aac, .mp3, .flac, .ogg, etc) hardware VC seems to be working just fine.
As for the 100 percent volume issue, it is a characteristic of DSD that the bitstream cannot be modified upstream of the DAC. This means no software control and the output will be at 100 percent unless the DAC has some sort of volume control mechanism built into it. The ESS chip supposedly does but AFAICT it's not exercised through the XMOS interface.
Quote:Since I want to use it without a preamp I would probably steer clear of it then. Maybe I should just go for a dac with a regular old volume control knob on it.
I'm always nervous about directly driving a power amp but that's just me.
Regards,
Kent
RE: Khadas Tone Board - Tim Curtis - 05-14-2021
If the volume controller in ESS chip is not being used it a vendor implementation issue. I thought Khadas released a f/w update that enabled the ESS controller to be used??
RE: Khadas Tone Board - williamlawson - 05-14-2021
Alright, probably just a misunderstanding on my part! Totally agree about the being nervous directly driving a power amp. I'm looking into the Soncoz LA-QXD1 now, at least that gives me a mute button if something goes terribly wrong
RE: Khadas Tone Board - TheOldPresbyope - 05-14-2021
(05-14-2021, 08:34 PM)Tim Curtis Wrote: If the volume controller in ESS chip is not being used it a vendor implementation issue. I thought Khadas released a f/w update that enabled the ESS controller to be used??
I just discovered I was incorrect in my previous post. I've gone back and edited it. In fact, software volume control of DSD playback with the KTB works as you describe for the Allo Rev. I don't know why I thought otherwise?!?
Hardware volume control of DSD streams, however, works as I described and contrary to what you describe for the Allo Rev. IIRC I updated the Khadas to firmware v2.00. This appears to be the latest but I'll check it later if I can find the time.
Hardware volume control of PCM streams worked already with firmware v1.04.
Maybe I'm missing something in the scattered documentation (or worse, their forum). I can't imagine I've borked the configuration but anything is possible.
Do any other USB DACs incorporate the ESS9038Q2M? Do they properly support hardware volume control for DSD?
Regards,
Kent
RE: Khadas Tone Board - Tim Curtis - 05-15-2021
Sure lots of ESS based devices implement the hardware interface to ESS chip volume controller and other chip options. Prolly Topping, Gustard and others. I2S devices include Audiophoinics 9028/9038 and Allo Katana.
IIRC to do DSD volume the ESS chip like other sigma/delta chips converts it to a PCM-like format as part of its internal processing and does volume attenuation on that format before shipping to out to the analog stage of the device.