Cayin RU7: 1-Bit Resistor Network Dongle DAC /Amp

[Andykong]

Thank you for the info and clarification! I was actually looking at the HydraVox but its an FPGA implementation, I ended up ordering the Gustard R26 instead. I been really happy with the RU7 honestly I am still astonished at how well this thing performs. The RU7 made me realize that measurements aren't everything, previously I was chasing gear with better and better measurements but to no avail. This little dongle is more enjoyable to listen to than my actual desktop setup so I ended up selling all my delta-sigma gear. I will try R2R for now (external clock + R26 is pretty close to May levels of staging) and maybe step up to 1-bit in the future.

But for now, I have something I can easily recommend to friends and family that doesn't break the bank, is portable, and sounds amazing.

I thought R26 is an R-2R DAC, I didn't aware that it incorporated 1-bit as well, that's a very interesting product.

A HA-3A user plans to purchase the Gustard R26 for his desktop setup (HERE), maybe you can check out his impression later and compare it with your experience.

 

[Andykong]

My opinion being on an iPhone is that come to September we'll be getting usb C on 15 so that's that

Rumor back in February said Apple might want to put an authentication chip in its Type C to limit it function so don't get too excited just yet. Of course EU already express their disapproval as usual so who knows.

I don't think Apple will give up its MFi license program without a fight.

For those who are not affected by the iOS ecosystem, Apple, through its MFi program, charges a fee for companies to be able to produce Apple-compatible accessories. The fees vary depending on the type and volume of products being produced. As of 2015, it was estimated that the MFi program was generating around $2 billion in revenues for Apple. There is no updated information available on the exact revenue generated by the program since then, but given the user base of the iOS ecosystem has doubled/tripled since 2015, the MFi program is too attractive to give up because of EU disapproval.

 

[Andykong]

Connecting a Jewel to a RU6/RU7/M15... gives a much better result than connecting a 250 euro iem to a 5k dap... trust me

Pendulum effect, either ends are extreme, and either end didn't really make sense, IMO.

 

[Andykong]

Another interesting test I just tried with R70x, using RU7 with C9 (solid state output), driving it from PO at volume 100 vs LO. Some people might assume that a shared LO here is just a volume setting at 100. According to Cayin, in LO the volume control is bypassed and the output is set to either 1.2V (3.5mm) or 2.4V (4.4mm).

Under my test conditions, I do hear a noticeable difference. I'm not saying one is better than the other, it will be up to a personal preference, but when switched to LO the sound is more transparent in mids/vocals, while when driving from PO and volume 100, it sounds a bit fuller and colored in tonality, maybe even a bit congested in comparison. I personally don't hear any distortion, and the sound difference could be the artifact of double-amping, which gives more body to the sound. But, you have an option to go either way, with a cleaner more transparent LO or some coloring when driving your external amp from PO.

Also, with either LO or PO at 100, the current draw from my phone was the same.

"Some people might assume that a shared LO here is just a volume setting at 100".
This is correct if they are dealing with a dongle or DAP with digital volume and the amp. the circuit will remain low distortion at full power.
When you deal with amplifying circuits based on analog volume, there are no clear-cut rules, you need to find the sweet spot through measurement or trial and error.

 

[Polky74]

Pendulum effect, either ends are extreme, and either end didn't really make sense, IMO.

Mine was obviously an exaggeration... but I think a RU7 driving a Thieaudio Monarch2 is much better than a $1000 dap driving a $289 iem. And even if the dap were $2000 it wouldn't change that much... because the iem would remain the same... this is just my opinion of course.

 

[DarthVaderKamp]

Is there any processing done on a native DSD256 input by the audio bridge when in DSD256 mode or is it effectively a straight pass through to the 1-bit DAC? I am an HQPlayer user and would like to do all the DSD processing in my PC.

 

[ClieOS]

Is there any processing done on a native DSD256 input by the audio bridge when in DSD256 mode or is it effectively a straight pass through to the 1-bit DAC? I am an HQPlayer user and would like to do all the DSD processing in my PC.

Has been discussed a few times before, RU7 will ALWAYS resample any incoming audio stream because it doesn't have the space inside to implement selective pass-through circuit.

 

[DarthVaderKamp]

Has been discussed a few times before, RU7 will ALWAYS resample any incoming audio stream because it doesn't have the space inside to implement selective pass-through circuit.

Thanks. I’m just wondering if anyone can help me understand what resampling means in this context. Is it actually converting to some intermediate state and then recreating the DSD stream? Is there an audible change made in the digital domain before the final conversion to analog?

 

[ClieOS]

Thanks. I’m just wondering if anyone can help me understand what resampling means in this context. Is it actually converting to some intermediate state and then recreating the DSD stream? Is there an audible change made in the digital domain before the final conversion to analog?

RU7 did this via a chip (Cayin calls it a 'D-to-D Audio Bridge', though I think it is probably a SRC chip of sorts but it can be FPGA as well). It will be something similar to what HQPlayer with DSD conversation does except this is hardware based.

 

[Currawong]

So, I have been focusing lately more on cables and current draw rather than the sound, especially with iPhone where we have a current limitation. ClieOS kindly shared his measurements, and I confirmed that with all the IEMs and Headphones I tried connected to 4.4mm output, in High Gain, I get:

• DSD256: 220 mA
• DSD128: 190 mA
• DSD64: 170 mA

One thing to note, once you are idling, no playback, the current drops to 50mA so you are not draining your phone's battery as much. This is a very good design practice!

For the reference, the volume level under these conditions:

w/UM Mentor Multiverse: v26
w/Elysian Annihilator'23: v39
w/Meze Empyrean: v43
w/ATH-R70x (470ohm, 99dB sensitivity): v65

R70x are my most demanding headphones, and even with iPhone XS and RU7 in high gain and DSD256, I was able to listen to R70x at 65 without any stuttering; could even push the volume higher.

But, I was still trying to force it into a stuttering condition with iPhone, to hit the current draw limit. Was only able to do that with Empyrean in high gain at DSD256 while pushing the volume beyond listening level when I raised it to 63 and current draw hit 230mA. Again, just running the experiment because we use different demanding headphones. Under this condition, once I drop to DSD64, problem goes away since it draws less current.

Another solution where you don't have to compromise switching to a different DSD format is to switch to a different cable. Tried my new @ddHiFi MFi07S and even at high gain, with DSD256, and ear shattering volume with Empyrean, the problem went away once I switched to that cable. I just assume, thicker power wires, less resistance, smaller voltage drop, and just below the threshold of current draw limit which made iPhone happy. Btw, absolutely beautiful cable with high build quality.

So, just in case if someone runs into a problem with their iPhone while listening to RU7 in high gain and DSD256, and you are driving your demanding headphones at a high volume, switching to a different cable is one of the solutions if you don't want to drop it down to DSD64. In my case, ddhifi MFi07S usb-c to lightning OTG cable did the trick!

Nice work! I had the same result but with the Elite and peaks in a classical track at about the same volume level. I didn't realise that there was a cable out there that could override the iPhone's power output.

 

[twister6]

Nice work! I had the same result but with the Elite and peaks in a classical track at about the same volume level. I didn't realise that there was a cable out there that could override the iPhone's power output.

Hi Amos, it did work for me, so curious if you will have the same success? You can ping @ddHiFi (Lily), i'm sure they can provide you with a review sample for testing of MFi07s.

 

[soundblast75]

I don't think Apple will give up its MFi license program without a fight.

For those who are not affected by the iOS ecosystem, Apple, through its MFi program, charges a fee for companies to be able to produce Apple-compatible accessories. The fees vary depending on the type and volume of products being produced. As of 2015, it was estimated that the MFi program was generating around $2 billion in revenues for Apple. There is no updated information available on the exact revenue generated by the program since then, but given the user base of the iOS ecosystem has doubled/tripled since 2015, the MFi program is too attractive to give up because of EU disapproval.

Yeah that's absolutely true, but i thought it would be a case of Apple has no choice, it isade clear by EU theyean To usb C as one standard, no deviations, hope that's the case anyway.
Meanwhile iPhone 14 pro max works well until challenging volumes.
iPad sounds absolutely amazing with RU7

 

[Polky74]

There is only one "very small" problem in using ddHifi TC28 PRO and that is that it interrupts the exchange of information between the battery and the charger, continuing to charge it even beyond 100% with the consequent risk of explosion and fire. Measurement carried out with usb cable/tester, reached 100% charge on the smartphone it continues to charge without any problem.

 

[giuca70]

Hi, i have my RU7 today.
This dac has a unique feature, it allows you to choose the tone you prefer.
AlltoDsd at 64 there is a reproductive scale of the entire sound plane with an analogical similarity to coarser steps, from light to serious.
At 256 the steps become thinner to very fine, it expresses a very fine grain.

With Defa Leppard, rock, we tend to prefer the 256 with a lot of well reproduced details.
With jazz perhaps 64 would be preferred.It depends on the music genre.

My very first impression with the all new out of box small chain:
Uapp Qobuz --> ddHifi TC09S --> RU7 --> KZ ZAX

Pay attention to the TC28Cpro, I paid attention to the parent company due to a battery overload problem that should not be underestimated. Maybe ddHifi will fix it in next releases.

 

[twister6]

There is only one "very small" problem in using ddHifi TC28 PRO and that is that it interrupts the exchange of information between the battery and the charger, continuing to charge it even beyond 100% with the consequent risk of explosion and fire. Measurement carried out with usb cable/tester, reached 100% charge on the smartphone it continues to charge without any problem.

Never seen my android phone go beyond 100% Does yours go to 105% ? As I just mentioned to you in my PM reply, any smartphone on a charger will be "constantly" charging, of course, depending on your smartphone/dap battery management setting, etc. and I think many enter trickle charge mode during fast charging when getting closer to 100%. Just quickly tried it with my Galaxy S22, TC28Cpro, and RU7, using Anker Nano II 30W iq charger. The current dropped as it got closer to 100%.