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KECES DA-131 Dac mini review

post #1 of 31
Thread Starter 
KECES is a well known name for DIYers in Taiwan, they offer kits for tube preamp, power amp, DAC and etc....(Maniac, correct me if I didn't get this part right), and also this already completed DAC.

For specs and RMAA test, please read this thread on Headwize.

The dac now has about 100hr of play time and I'd like to compare it to an unmodded Lite Dac-AH. My amp is Ciaudio VHP-2 and can is HD650.

Sorry for the weird white balance pics









The built quality is so good, especially those wirings







Bass on Dac-ah is fat and more slam, if you system is already warm, it may not be a good choice. Bass on DA-131 goes a bit lower and tighter, bass line and note are easier to follow.

Midrange is smooth on DA-131, and also close to what I'd called laid back. This may due to the use of two OPA604APs. They can be easily rolled with other opamps like OPA627, LME49710....etc, since sockets are installed already.

DA-131 has more details in HF comparing to Dac-ah, but since the amount of treble energy is so right, it sounds "real" and not being harsh.

Soundstage is the most interesting part when comparing these two dacs. Lite Dac-ah has really wide, from left to right soundstage but the middle, front part have less "informations" than I'd like. You'll get the same feeling when you switch from speaker to headphone.
DA-131 has less left to right feeling, but it has more "front" or "depth". Although the soundstage seems small, but imaging is pretty good.

DA-131 is more sensitive when EQ'ing and slightly more revealing than Dac-ah, both of them are not as airy as I'd like (HD650's problem??) but if you mod them, they can.......I dunno! I'll leave that part for DIYers I wish I know how to mod

The Lite dac-ah is known to have warm and lush sound, on the other hand the DA-131 is SMOOTH. It's more neutral, more details but not fatiguing. It's really easy to listen to DA-131 for a long period of time.
post #2 of 31
Thread Starter 
For those of you who are interested in DA-131, this thread may help
post #3 of 31
Just a little note on the OP rolling, OPA 637 is not recommended due to it requires 5x gain or more to be stable, or it could oscillate. You will need DAC that is unity gain stable for this job.
post #4 of 31
Thread Starter 
Just rolled a pair of LME49710, more detail over the spectrum, overall cleaner sound and bass is tighter too
Soundstage is slightly larger than with OPA604 and it's less laid back than before

If I'm not going to merge my Home/Portable rig, I'll be keeping in for sure....and also my VHP-2 and HD650
post #5 of 31
Cool, one interesting thing about LME49710 is that it decrease the overall measured THD by 1dB, increase the dynamic range by 1 db, and so on... Basically almost everything that RMAA presents in dB scale had improved by 1dB.
post #6 of 31

Digital Input Selection by Keces DA-131 DAC

To Maniac,

I understand that the toggle switch on back panel operates as selection switch instead of multiplex switch between optical and coaxial digital inputs. I suppose it set the priority for input selection in receiver chip instead of altering signal path directly to multiplex between optical and coaxial inputs.

When both optical and coaxial inputs are fed with digital audio signals, does it mean that only optical signal will pass through the DAC when the selection switch is set to optical ? When the input selection switch still set to optical but no signal at optical input rather signal is present at coaxial input, what will happen to the output ? In other words, is digital input selection determined by position of input selection switch and presence of digital audio signals at both optical and coaxial inputs ?

I ask this question because I need both optical output from iMac and coaxial output from DAB digital radio to be connected to DAC which will provide proper line output regardless which digital input is active. In other words the DAC must double as digital audio switcher at its input stage as well.
post #7 of 31
The switch is designed to control the CS8416 receiver chip, like you said, we prefer not to pass the signal through the switch. We have experimented before and found that passing SPDIF signal through a mechanical switch like that will degrade the signal badly.

The receiver chip CAN see both signals at the same time and can actually lock onto the channel that is not selected when the selected channel is not getting any signals. However, no matter what it detects, it will ONLY play the signal from the selected channel, which is exactly what it should do.


You should have no trouble using it as you intended, I'm using DA-131 here as well, switching between PS3 and my Sony CDP-X5000. It switches back and forth easily and without any trouble.
post #8 of 31
Quote:
Originally Posted by Maniac View Post
The receiver chip CAN see both signals at the same time and can actually lock onto the channel that is not selected when the selected channel is not getting any signals. However, no matter what it detects, it will ONLY play the signal from the selected channel, which is exactly what it should do.

You should have no trouble using it as you intended, I'm using DA-131 here as well, switching between PS3 and my Sony CDP-X5000. It switches back and forth easily and without any trouble.
In other words, though SPDIF receiver of DA-131 is able to detect any active signals at both optical and coaxial inputs at the same time, the selection switch alone will determine which input signal will appear at the output regardless of presence of input signal.

I have this suggestion for manual selection of input signals:
- The toggle switch will determine priority between the two digital inputs.
- When input signals are present at both digital inputs, the digital input with higher priority (selected by the switch) will be converted into analog output.
- When no signal present at selected digital input (higher priority) but there is signal present at unselected digital input (lower priority), the digital input with lower priority will be converted into analog output.
- Digital input selection is determined by both switch and presence of signals rather than just the switch alone. This way the DAC will select between the two digital inputs automatically without user having to toggle the switch manually and frequently between two digital inputs.
- This is a set-and-forget option for lazy man like me (also a good option when DAC is installed quite a distance away from user).

I used to own Firestone's Splitfire DAC which rely solely on presence of signals to select between optical and coaxial inputs with optical input default to higher priority. So no switch is needed at all for input selection. Perhaps this is another way to eliminate the selection switch all together from back panel of DA-131.
post #9 of 31
Quote:
Originally Posted by littletree76 View Post
In other words, though SPDIF receiver of DA-131 is able to detect any active signals at both optical and coaxial inputs at the same time, the selection switch alone will determine which input signal will appear at the output regardless of presence of input signal.

I have this suggestion for manual selection of input signals:
- The toggle switch will determine priority between the two digital inputs.
- When input signals are present at both digital inputs, the digital input with higher priority (selected by the switch) will be converted into analog output.
- When no signal present at selected digital input (higher priority) but there is signal present at unselected digital input (lower priority), the digital input with lower priority will be converted into analog output.
- Digital input selection is determined by both switch and presence of signals rather than just the switch alone. This way the DAC will select between the two digital inputs automatically without user having to toggle the switch manually and frequently between two digital inputs.
- This is a set-and-forget option for lazy man like me (also a good option when DAC is installed quite a distance away from user).

I used to own Firestone's Splitfire DAC which rely solely on presence of signals to select between optical and coaxial inputs with optical input default to higher priority. So no switch is needed at all for input selection. Perhaps this is another way to eliminate the selection switch all together from back panel of DA-131.
Hello,

We prefer a toggle switch because there are cases where both input may have signal but you want to select one over the other. If you do not have a switch like we have on DA-131, there will be no surefire way to select (or force) one input over the other.

For the moment, I don't believe the receiver chip have the ability to lock onto and decode the unselected input, it can lock, but it does not seem to have the ability to do what you have mentioned.


Thanks

David Wei
post #10 of 31
How does the sound compare from the USB compared to a DAC with optical or coax? I bought and tested quite a few USB type DACs and USB to optical adapters with a variety of music, but the results have been more poor-fi than hi-fi. The biggest problem lies with the dynamic range and signal to noise ratio. Everyone I tested had a woolly bass and a fog like reproduction. Most of them had the PCM27XX or PCM29XX USB chip. Is the poor reproduction from USB down to the chip or something else?
I haven't yet tried the DAC1 USB though.
post #11 of 31
Quote:
Originally Posted by StanleyB1 View Post
How does the sound compare from the USB compared to a DAC with optical or coax? I bought and tested quite a few USB type DACs and USB to optical adapters with a variety of music, but the results have been more poor-fi than hi-fi. The biggest problem lies with the dynamic range and signal to noise ratio. Everyone I tested had a woolly bass and a fog like reproduction. Most of them had the PCM27XX or PCM29XX USB chip. Is the poor reproduction from USB down to the chip or something else?
I haven't yet tried the DAC1 USB though.
Well since you mentioned "adapters", I believe you mean those dongle type products. Those are not the optimal way to do it, as USB 5v is a very bad power source. Using a good power supply to power your USB audio device will dramatically improve the sound quality.

If you check a bit about our product, you should find that problems with dynamic range, S/N ration and resolution are often praised, and never did we get any complaints about those abilities. One exception is a few users had experienced noise with DA-151 due to their notebook charger being the culprit that dumped a lot of noise into their AC power line.

In my own tests with 550W mono block power amplifier and a ghostly quiet pre, the whole system plus DA-151 or DA-131 is still ghostly quiet (with all volume cranked to max), not a thing can be heard.
post #12 of 31
Quote:
Originally Posted by Maniac View Post
Well since you mentioned "adapters", I believe you mean those dongle type products. Those are not the optimal way to do it, as USB 5v is a very bad power source. Using a good power supply to power your USB audio device will dramatically improve the sound quality.
I tried a few different implementations and even disconnected the 5V from the PC and inserted a clean 5V. The main issue was with the attack and decay time. i.e. the slams were mostly more like pats on the back.
Do you do trade prices? I wouldn't mind testing a sample of yours. Is shipping to my Taiwanese office also favourable instead of shipping to my UK office?
post #13 of 31
Quote:
Originally Posted by StanleyB1 View Post
I tried a few different implementations and even disconnected the 5V from the PC and inserted a clean 5V. The main issue was with the attack and decay time. i.e. the slams were mostly more like pats on the back.
If you provide good power, it should at least give you good digital output if you were using that. As for analog, well there's no replacement for good old PCB real estate with good quality components. Which is one of the reason that we ditch the idea for a power adapter and decided to do it all by ourselves.
post #14 of 31
Quote:
Originally Posted by Maniac View Post
Which is one of the reason that we ditch the idea for a power adapter and decided to do it all by ourselves.
There is nothing wrong with an external power adapter, as long as it is a good design and other measures are taken inside the product that uses it to overcome any unexpected defects from the external adapter. I am thinking about additional filtration and power supply regulation.
post #15 of 31
Quote:
Originally Posted by StanleyB1 View Post
There is nothing wrong with an external power adapter, as long as it is a good design and other measures are taken inside the product that uses it to overcome any unexpected defects from the external adapter. I am thinking about additional filtration and power supply regulation.
Indeed, but good power adapter is expensive, not to mention that all the added measures combined would mean that you will have to spend more to get the same level of performance. You could spend about the same or less, and you could get even less performance. IMHO external power adapter is most useful for applications where there is no room inside your equipment that you could use to house the power supply. This would be the main advantage of the power adapter IMHO.

We really hold no grudge against external power adapter, but at our price point and target application, it is more economical and better C/P to integrate it all in our unit.
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