GUSTARD DAC-R26 Balanced Decoder R2R+1Bit Dual Native Decoding Music Bridge

[SpursForEver]

Just make a voltage splitter with two resistors.

 

[Jake2]

Depending on the design of the amplifier, it can also go so far that you can always adjust the volume within an audible range without blowing up the headphones or going deaf because it is constantly too loud.

My Hypex Nilai power amp has three gain settings (output signal gain measured in dB) which I think is what you’re referring, a good point you make. The low gain setting minimises attenuation needed in my system (in my case via my preamp rather than a digital volume control) whilst still being loud enough, which to my ear sounds the best and is coincidentally the setting with the highest measured performance on another forum.

 

[Johnybuchar]

I picked up and connected the Gustard R26 today. Since it’s a second-hand device, there’s no need for a break-in period. My first impression is that the 2in1 streamer + DAC performs well, but it feels a bit 'raw' in my setup. Later on, I tried connecting my current digital setup Rpi4 with Volumio (IanCanada upgrade) - Musician Pisces II DDC - G-R26, while simultaneously using the G-R26 as both DAC and streamer. I noticed that the external DAC + DDC combination produced a more refined and detailed sound compared to the 2in1 setup, especially in the bass spectrum, which felt less defined and affected the other frequency ranges in the 2in1 configuration and front/rear scene.

 

[mango lassi]

I can absolutely imagine that — I’m also thinking about trying the Laiv µDDC for exactly that reason. Out of curiosity: what digital output are you using on the Musician Pisces to feed the R26?

 

[Deleeh]

I picked up and connected the Gustard R26 today. Since it’s a second-hand device, there’s no need for a break-in period. My first impression is that the 2in1 streamer + DAC performs well, but it feels a bit 'raw' in my setup. Later on, I tried connecting my current digital setup Rpi4 with Volumio (IanCanada upgrade) - Musician Pisces II DDC - G-R26, while simultaneously using the G-R26 as both DAC and streamer. I noticed that the external DAC + DDC combination produced a more refined and detailed sound compared to the 2in1 setup, especially in the bass spectrum, which felt less defined and affected the other frequency ranges in the 2in1 configuration and front/rear scene.

Hello,
try to use the Pi as a streamer if possible to connect the DDC via I2S to the Gustard, coax would also work.
My personal impression is that the R26 works better with an external streamer.
The internal one is not bad but not necessarily excellent either, so external streamers work better with it.
Apart from that it is a pretty good R2R Dac if such tricks are taken into account.
I2S is my favourite input source.

 

[Johnybuchar]

@Mango: the same setup as Deleeh described ie. Pi4 Volumio -> USB -> Pisces2 -> I2S -> Gustard. Configuration: PCM NOS:ON, DSS NOS:ON, Clock: External. I assume PCM filter is bypassed here (there is FAST). BTW it works flawlessly no changes with I2S pins.

 

[Turbo2288]

Cool, glad to help.

The analogue attenuation is aimed at users with power amps and so no ability to adjust the amp volume in analogue domain (ie as you would via a preamp or integrated amp or headphone amp) so have to do it all via the DAC digital volume. If they find that comfortable listening levels are only with -40dB digital volume set on the R26 that will have a negative effect on sound with reduced dynamic range (DNR)* so better to do 30dB of the cut via the analogue attenuation setting, limiting the digital attenuation needed (to get to the same overall attenuation of -40dB) to 10dB which will sound better, no loss of DNR.

*DNR reduces perceptibly when there’s high attenuation like this due to the design of simple digital volume controls like the one in the R26 due to loss of bits. More sophisticated digital volume controls like those in software like Roon or HQplayer or as implemented in some DACs and streamers do additional processing to ensure there are bits to spare so DNR is not impacted. Google or search HF threads for digital vs analogue volume control for much discussion and debate on this topic!

Excuse for my ignorance, so how do I get into analogue attenuation setting? Or it is automatic? so I don't need to do anything?

The reason I'm asking these questions is because recently I bought a power amp and want to use the R26 as a pre-amp.
I connected the R26 directly to my Nilai power amp with XLR cables, I changed "Attenuation" to "ON" and started off with the lowest setting in the volume control (-90db) ,
I slowly increase the volume to its maximum which is 0 db, then it get into FIXED mode by itself.
The problem is I am getting very low volume even at 0 db, barely enough for late night listening. May I ask how should I increase the volume ? there are no "gain" adjustment in my power amp, my speakers are not low sensitive, Is there something I missed?
BTW "Attenuation" to "Off" position is very loud ! almost blew my speakers!
Thanks again.

 

[Jake2]

@Turbo2288 Here’s what I would do if I wanted to use the R26 remote control as the primary vol control for your system*, having both the R26 and Nilai:
- turn R26 volume right down using the remote to a safe level (eg. -50)
- set R26 Attenuation to OFF in the menu (this is the one step -30dB analogue attenuation I refer), clearly ON is too much attenuation in your system
- with Attenuation OFF find your comfortable R26 listening volume range (values) from quiet - normal - loudest you’d listen
- if normal listening volume is -12 to 0 (ideally -10 or less) in the R26 screen, and you can get a max volume that’s satisfactorily loud enough for you, you’re good
- if still too quiet or if too loud (so needs too much R26 digital attenuation for normal levels which will impact dynamics) then I’d try some alternate gain settings on your Nilai, set via the jumper switches on the circuit board. All Nilai have this. Yours is most likely set to the factory default of medium (22dB gain). As I mentioned mine is set to low gain (12dB) which is the best fit in my system.

Good luck and let us know how you get on!

*alternative and probably better sounding approach is to set R26 to fixed and use a more sophisticated digital volume in a music streaming app like Roon or JPLAY for iOS.

Nilai gain instructions
Three levels of gain (12, 22 and 28 dB) for both the stereo and mono amps.
https://www.diyclassd.com/media/09/22/53/1680596548/User Instructions Nilai500DIY Stereo kit.pdf

 

[Johnybuchar]

Ooops, i probably overlooked displayed status "EXT ERR" with DDC connection yesterday. Does it mean, that external clock cannot be managed by DDC?

 

[Jake2]

It just means the R26 is set to Ext/10Mhz input so is expecting to see a signal there (via the R26 10MHz BNC input) but for whatever reason is not getting one eg. no clock connected, or cable BNC connection issue (sometimes you have to jiggle or reconnect them). The K2 synthesiser just defaults to the internal oscillator sitting beside it on the circuit board in this scenario i.e. the same as if internal clock was selected in the menu.

Edit - you’re probably now wondering what role the R26 internal clock and/or K2 synthesiser (and ext clock if connected, though not in your case I assume) plays when feeding the R26 via I2S as you are. Per Gustard clarification over email it depends…

https://www.head-fi.org/threads/gus...ve-decoding-music-bridge.963630/post-17782097

 

[Turbo2288]

@Turbo2288 Here’s what I would do if I wanted to use the R26 remote control as the primary vol control for your system*, having both the R26 and Nilai:
- turn R26 volume right down using the remote to a safe level (eg. -50)
- set R26 Attenuation to OFF in the menu (this is the one step -30dB analogue attenuation I refer), clearly ON is too much attenuation in your system
- with Attenuation OFF find your comfortable R26 listening volume range (values) from quiet - normal - loudest you’d listen
- if normal listening volume is -12 to 0 (ideally -10 or less) in the R26 screen, and you can get a max volume that’s satisfactorily loud enough for you, you’re good
- if still too quiet or if too loud (so needs too much R26 digital attenuation for normal levels which will impact dynamics) then I’d try some alternate gain settings on your Nilai, set via the jumper switches on the circuit board. All Nilai have this. Yours is most likely set to the factory default of medium (22dB gain). As I mentioned mine is set to low gain (12dB) which is the best fit in my system.

Good luck and let us know how you get on!

*alternative and probably better sounding approach is to set R26 to fixed and use a more sophisticated digital volume in a music streaming app like Roon or JPLAY for iOS.

Nilai gain instructions
Three levels of gain (12, 22 and 28 dB) for both the stereo and mono amps.
https://www.diyclassd.com/media/09/22/53/1680596548/User Instructions Nilai500DIY Stereo kit.pdf

I have been playing with it following your instruction, I still don't know the logic of it, but I managed to raise the volume by a lot, but still it's either too loud or too low. Going to play with it again this weekend and see if I could set the right "range" of attenuation . BTW, here did you find all these information? it's not in the manual for sure. Thank you.

 

[Jake2]

Hi there, the analogue attenuation option is on page 4 of the R26 manual. There’s a Chinese/English language barrier/conversion that makes part of the manual hard to read, but this part is pretty good relatively speaking. Just requires a little understanding of the concepts of digital and analogue attenuation, including the negative impact on dynamic range of having too much digital attenuation which is the reason they provide this option, which I picked up through reading these threads and elsewhere. My posts above are my best attempt to explain it. If you need more assistance to understand this perhaps someone else can jump in with a better explanation.

 

[Deleeh]

Hello,
I would leave this setting as default on the R26 and adjust it with the gain of the amplifier.
This will give you the full dynamic range.
If this does not help, DSD and NOS must be set to off and then you go down with the DB with the remote control until it suits you.

 

[mango lassi]

@Turbo2288 Just to add one small point for context:
When the R26 is in ATTENUATION ON mode, it always applies a fixed -30 dB analog cut, regardless of volume setting — there’s no gradual range. That caught me off guard the first time, too.

And yes — reaching 0 dB on the volume will always show “FIXED” on screen. It's not an error, just an indicator that you're at full-scale output.

In my own setup, I’m using the R26 in ATTENUATION OFF mode and controlling volume via a dedicated preamp. That way, I keep the full output level from the DAC and preserve dynamic range — works great in my chain.

Thanks to @Jake2 and @Deleeh — your explanation really helped clarify how this behaves in real setups with a Nilai Amp.

 

[Deleeh]

Hello,
I will give you a good example of what Attenuator does.
I use my very good rollable tube amplifier.
As a small crash course there are tubes that have a high Mu Factor as well as a low Mu Factor.
The Mu factor is seen as a gain value, which means for drivers and output tubes.
Here you can mix between a low driver tube like 6SN7 which has a mu factor of 20 mu, a 6SL7 has a higher value of 70 mu which is very high.
The same applies to output tubes, typical tubes are EL84, EL3N, EL12 and others, KT66/88, EL34, 6L6 are more in the middle, while a 6AS7G tube has a relatively low u value.

So now I choose a combination of say 6SN7 with KT66/88 Attenuator is OFF, because otherwise I have to extend the potentiometer very far and the overall gain is quite low from the tube amplifier when set to ON.
If it were switched on, I would bring the potentiometer to its maximum limit and the volume would remain predominantly low.
This can be good or bad.
Now I use a combination that is stronger in the Mu factor,6SL7 with EL3N.
Here it makes sense to switch on the attenuator, because you hardly touch the potentiometer and it gets loud directly and you have hardly any control over it.
Furthermore, this can lead to clipping, i.e. crosstalk between the speakers and headphones.
Which is also bad over time.
That's why I switch Attenuator to ON here, to be able to control the whole thing better.
I have just done this with the 6SL7 and EL3N combination and the result is that the amplifier gets half the power, I have more control over the potentiometer when I put my Atrium open on now, I am at about 12 o'clock position rather than 11 o'clock, which is then almost really loud when the attenuator is OFF.
This is also good because the channel imbalance from the potentiometer is out of the window as the potentiometer likes to be turned up from zero.

Since Attenuator is ON, I move the whole thing back a bit and still have the full dynamic range and all these things.

On SS amplifier you have to try something that is better for you.
Either leave the amp at maximum gain and Attenuator OFF and all is well, or just try switching Attenuator on first and see what happens.
If the amplifier has a gain switch, I would work with the latter but set the attenuator to OFF.
But you should only go higher with the gain switch when the potentiometer is at zero on the amplifier.
It is impossible to predict what will happen if the potentiometer is not at zero.
You should pay attention to 2 things when adjusting the gain, the first is that you have enough control over the potentiometer and that it does not clip when you turn it up further.
And secondly, always set the potentiometer to zero when you want to switch.

Listening to and evaluating the sound comes last.
One last thing about what FIXED means.
Here the output voltage to the amplifier always remains the same regardless of whether XLR or RCA.
FIXED always remains active if NOS or DSD is active or both, which means no control.
If you now switch off NOS or DSD or both must be OFF, you can use the remote control to adjust the volume again in minus DB.
However, you may lose dynamics and such things here and have to turn up the potentiometer further on the amplifier to compensate.
That would be the last thing. It would be the last thing I would use if the gainswitch doesn't give a deliverable result.
Then I would work with it, but the price is that there is no DSD neither NOS.