Audio-GD R1 R2R ladder converter

R2R ladder converters are gaining popularity rapidly and nowadays offer oversampling and native playback of DSD. In February 2020 I reviewed the Audio-GD R7 HE Magna version, costing less than € 4000. This time I look at the R1 that is priced just below € 1000. Audio-GD DAC’s are easily recognised by their design: relatively large housing with rounded corners and a numerical display with blue characters on the front. But let’s first see where it fits into your stereo.

The analog outputs are connected to your amplifier 00:50 - or receiver that drives the loudspeakers. If you want to use a computer as a source, it preferably is to be connected to the DAC over USB, although SPDIF or TOSlink are possible too. If you have an audiophile computer that has an I²S output on HDMI, even that can be used by hooking up the HDMI cable to the I²S input on the DAC. If you use a NAS or a computer placed in another room, you need a streamer or network bridge that is connected over the router to the NAS or computer and over SPDIF, TOSlink or I²S to the DAC. In most cases you control the music playback over a smartphone or tablet.

You could also 01:33 - connect other digital sources as for instance the TOSlink output of your TV to the DAC. But there is no HDMI audio return channel input. The black anodised aluminium housing of the R1 is deeper than wide, measuring 240 by 320 by 80 mm. It weighs 6 kilos. The front holds a standby button, a button to change settings and two selector keys that are used for input choice and changing settings. On the rear we see the IEC mains socket. New on the 2020 version is the update port; there no longer is a need to open de DAC for updates but you do need a special cable.

There are four digital 02:21 - inputs, one SPDIF that has an RCA and BNC connector in parallel, a TOSlink optical input, an I²S input on HDMI and a USB B connector according to USB Audio Class 2. There are three types of analog outputs per channel: balanced outputs on XLR, single ended outputs on RCA and ACSS outputs on mini XLRs. ACSS is what Audio-GD calls the current signal system. It functions the same as Krell’s CAST system and the in Japan popular SATRI system. In stead of a voltage transporting the audio it is the current, more or less like the old balanced lines used in telecom systems.

But in stead of matched impedances 03:10 - on both ends of the line, here a very high output impedance drives a low input impedance. This way very long interlinks can be used while the influence of cables is drastically reduced. But you can only use the ACSS outputs if your amp has ACSS, CAST or SATRI inputs. Here we see the R1 with the lid taken off. The front is on the left side and the circuit board indicated here holds the display and three buttons below it. Then we see a hefty linear power supply, especially for this price category. It uses a low radiation R-core transformer with on the secondary side three windings, one for the digital electronics and one for each analog audio channel. Then we see two DA-8 ladder DAC modules. When we look from another angle you see there are two more below them. So per channel there are two DA-8 boards, one for the positive and one for the negative signal, together forming a balanced signal. Let’s look at the top left DA-8 board to see what’s happing on these boards.

A bank 04:24 - of resistors - forming the ladder - are switched in and out the circuit by the switches around them, depending on the data on each and every sample. This all is controlled by this Xylink processor. The review sample is a deluxe version that has these lovely Accusilicon 318B series clock crystals installed. These are very high quality types, specified at 198 femto second peak precision between 10 Hz and 1 MHz. It also has the Anamero USB Combo 384 interface, in this case with the high spec Crystek crystals update, making this R1 the highest spec version.

05:07 - The Altera Cyclone 4 does the rest of the interfacing thought Audio- GS’s proprietary code. It enables 384 kHz 24 bit resolution and reduces jitter on SPDIF and TOSlink inputs by buffering. Then we get to the analog output stages that are built fully discrete using matched transistors and ending in normal balanced and single ended voltage sources plus the Audio-GD Current Signal System, ACSS. The user interface is simple and somewhat abstract. Inputs are chosen by pressing one of the two selector buttons while the right digit in the display shows the number that corresponds with the chosen input.

After pressing the settings button once, the first character 05:55 - in the display starts flashing and you can select N for non oversampling and O for oversampling. Press the Setting button again and you can set the oversampling factor at 2, 4 or 8 times. There are setting for the I²S input and the PLL, settings for the techies. One last setting enables dimming the display after 10 seconds save one small element. There is no volume control and no remote control. In day to day use you only select the input, which is really easy. Lows are powerful, fast and have a fine texture. Using the USB input the mids have good resolution while sibilance is fairly good controlled. The stereo image is wide and moderately deep while pace and rhythm are good. All while taking the price into account, of course.

06:52 - And, using the 8 times oversampling mode, which to me is the cleanest option. Using the SPDIF input, even when coming from the Auralic Aries G2, offers somewhat less resolution in the mid range while sibilance is clearly less controlled. Switching to non oversampling makes that worse. Having said that it is a DAC that would fit in my setup 2, somewhere halfway, when using the USB input and set to 8 times oversampling. At least to my ears. The build quality is rather good and it’s easy to use once you understand the basic user interface, which will take only little time.

At almost € 1000 the R1 is an R2R 07:39 - ladder converter that offers not only 384 kHz but also DSD and offers a number of settings to play with. Things that the audio enthusiast will really enjoy. Furthermore it has an I²S input, something not to many DAC’s in this price range offer. Which brings us to the end of this video. There will be a new video, as always at Fridays at 5 PM central European time. If you don’t want to miss that, subscribe to this channel or follow me on the social media so you’ll be informed when new videos are out. If you liked this video, give it a thumbs up. Many thanks to those viewers that support this channel financially, it keeps me independent and thus trustworthy. If that makes you feel like supporting my work too, the links are in the comments below this video on Youtube. I am Hans Beekhuyzen, thank you for watching and see you in the next show or on theHBproject.com. And whatever you do, as always, enjoy the music. .