Just to be sure: We are talking the discrete shield here, not the dac board already shipped, right?
Sonny,
After many listening sessions and some opamp swap, I have to admit that I've fallen in love with that DAC. I'm using RPi 2 with Volumio 1.55 and the ADA4898-1YRDZ Opamps along with the PCM Short Delay Slow Rolloff firmware.
I've also tried the BB OPA1611, BB OPA1641 and the included ADA4627 and although they're all good, the 4898 has yet to be beaten. It is a very well balanced opamp. The 1611 has a bit more bass but lacks in the upper range, the opposite with the 1641 although it does not really lack bass and the 4627 is outstanding but is a bit more in your face, focus more on the midrange.
Last Sunday I had a friend over (Fab @ DIYaudio) to listen to his new amplifier design and he listened to your DAC and was REALLY impressed by it. You can go see the thread here, last post.
http://www.quebecdiy.net/t646p30-mirand-audio-ak4490-dac-dsd
Ciao!
Do
After many listening sessions and some opamp swap, I have to admit that I've fallen in love with that DAC. I'm using RPi 2 with Volumio 1.55 and the ADA4898-1YRDZ Opamps along with the PCM Short Delay Slow Rolloff firmware.
I've also tried the BB OPA1611, BB OPA1641 and the included ADA4627 and although they're all good, the 4898 has yet to be beaten. It is a very well balanced opamp. The 1611 has a bit more bass but lacks in the upper range, the opposite with the 1641 although it does not really lack bass and the 4627 is outstanding but is a bit more in your face, focus more on the midrange.
Last Sunday I had a friend over (Fab @ DIYaudio) to listen to his new amplifier design and he listened to your DAC and was REALLY impressed by it. You can go see the thread here, last post.
http://www.quebecdiy.net/t646p30-mirand-audio-ak4490-dac-dsd
Ciao!
Do
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OUTPUT Shield DIFF/SE V1.0 Discrete
Hi all.
We have assembled the outputshield seen on the picture...
What!?? is there anything missing!??? resistors and capacitors!!?? I forgot to order the filter resistors and capacitors
The filterparts will arrive Tomorrow, which means we can ship Monday.
Display units can also ship Monday. Encoder is not used for the DAC, only for the preamp.
BR
Sonny
Hi all.
We have assembled the outputshield seen on the picture...
What!?? is there anything missing!??? resistors and capacitors!!?? I forgot to order the filter resistors and capacitors
The filterparts will arrive Tomorrow, which means we can ship Monday.
Display units can also ship Monday. Encoder is not used for the DAC, only for the preamp.
BR
Sonny
Attachments
Yes it is Mister Rogers.
The first pdf is ADA4898-1, and second is the discrete output stage.
It is run using short delay, slow roll off both of them.
There is some external noise source in the measurement, but you can clearly see that with the discrete outputstage 2., 3., 4. and 5. harmonics is nearly gone.
The first pdf is ADA4898-1, and second is the discrete output stage.
It is run using short delay, slow roll off both of them.
There is some external noise source in the measurement, but you can clearly see that with the discrete outputstage 2., 3., 4. and 5. harmonics is nearly gone.
Sound of Discrete output stage.
Some of you have asked me about what the discrete output stage sounds like.
The comparison is a bit difficult to do because the discrete output stage is fully balanced (DIFF) all the way to just before the single-ended (SE) output.
This actually mean that we get +3dB more signal. So for comparing with the single-ended opamp based output stage we have to turn the volume 3dB down.
Some features above the previous output stage:
One could think that the DAC would emit an high noise floor with this output stage. But with the ear 1cm from the tweeter we can barely hear some white noise. With any noise source in the room you will not be able to detect it.
When playing music
On to the comparison:
Media: Apple MAC mini running Tidal app in HIFI mode.
Output shield with ADA4627-1:
Compared to the ADA4898-1 the ADA4627-1 has a more in your face presentation. There is plenty of details but it tents to focus on the midrange, so voices are more in front. The side effect of this is that bass moves in background and does not sound as detailed as it could be. This also fits the highs. It seems like the bass and highs drowns in the focus made on the midrange.
Not that the ADA4627-1 is not good. Compared to the OPA1611 and OPA1641 this opamp is a lot better in my opinion.
But in this comparison we will focus on the ADA4627,ADA4898 and the discrete output stage.
Output shield with ADA4898-1, PPS capacitor 2%, same filter components as the discrete output stage:
ADA4898 is more balanced in its representation. So midrange is pulled back a bit and makes room for the bass and highs to shine more. It sounds like the ADA4627 plays louder but that is not the case. Drums gets more texture and more attack. The air around the musicians gets filled with more details.
If someone would like to upgrade the output shield i would suggest to buy the ADA4898-1YRDZ. It will drop in where the ADA4627-1 without any changes.
Output board DIFF/SE V1.0 (Discrete):
This discrete design gives you more of everything of the ADA4898. The attach in the bass. how the sound stage is balanced. Nothing is off scale. But also we get more details. Not by a huge amount more than the ADA4898 but it is noticeable. Voices sound a bit more clearer, On Roger Waters "Amused to death" album it is easier to differentiate the hear the dogs, the voices from the television, how the axe hits the wood and how the thunder rolls into the scene.
If someone cannot afford the Discrete output stage i would suggest that they upgrade the output shield with ADA4898 and PPS capacitor in 0805. It is possible to solder the 0805 components onto the places of the 0603 capacitors.
Some of you have asked me about what the discrete output stage sounds like.
The comparison is a bit difficult to do because the discrete output stage is fully balanced (DIFF) all the way to just before the single-ended (SE) output.
This actually mean that we get +3dB more signal. So for comparing with the single-ended opamp based output stage we have to turn the volume 3dB down.
Some features above the previous output stage:
- PPS film capacitor instead of Ceramic NP0/C0G
- Resistors are 0.1% thin film in 0805 casing instead of 0603
- Fully discrete amplifier sections all running in class A. Even with 1K load
- Relay is replaced by discrete SSR relays with state of art mosfets
- both SE and DIFF outputs
- 6 amp sections with a total of 48 bjts and 12 jfets
One could think that the DAC would emit an high noise floor with this output stage. But with the ear 1cm from the tweeter we can barely hear some white noise. With any noise source in the room you will not be able to detect it.
When playing music
On to the comparison:
Media: Apple MAC mini running Tidal app in HIFI mode.
Output shield with ADA4627-1:
Compared to the ADA4898-1 the ADA4627-1 has a more in your face presentation. There is plenty of details but it tents to focus on the midrange, so voices are more in front. The side effect of this is that bass moves in background and does not sound as detailed as it could be. This also fits the highs. It seems like the bass and highs drowns in the focus made on the midrange.
Not that the ADA4627-1 is not good. Compared to the OPA1611 and OPA1641 this opamp is a lot better in my opinion.
But in this comparison we will focus on the ADA4627,ADA4898 and the discrete output stage.
Output shield with ADA4898-1, PPS capacitor 2%, same filter components as the discrete output stage:
ADA4898 is more balanced in its representation. So midrange is pulled back a bit and makes room for the bass and highs to shine more. It sounds like the ADA4627 plays louder but that is not the case. Drums gets more texture and more attack. The air around the musicians gets filled with more details.
If someone would like to upgrade the output shield i would suggest to buy the ADA4898-1YRDZ. It will drop in where the ADA4627-1 without any changes.
Output board DIFF/SE V1.0 (Discrete):
This discrete design gives you more of everything of the ADA4898. The attach in the bass. how the sound stage is balanced. Nothing is off scale. But also we get more details. Not by a huge amount more than the ADA4898 but it is noticeable. Voices sound a bit more clearer, On Roger Waters "Amused to death" album it is easier to differentiate the hear the dogs, the voices from the television, how the axe hits the wood and how the thunder rolls into the scene.
If someone cannot afford the Discrete output stage i would suggest that they upgrade the output shield with ADA4898 and PPS capacitor in 0805. It is possible to solder the 0805 components onto the places of the 0603 capacitors.
Attachments
I use the PCM right now. DSD filter is good for the DSD but 99.5% of my music is PCM. The DSD filter gives softer highs for DSD but at the same time it mask a bit of the high on PCM material.
The DSD filter also has an high phase shift in the audible range. The PCM filter only makes an phase shift of 13 degrees at 20KHz. for the DSD you will need to add at least 10 degrees more.
The DSD filter also has an high phase shift in the audible range. The PCM filter only makes an phase shift of 13 degrees at 20KHz. for the DSD you will need to add at least 10 degrees more.