R1200CL Posted February 4, 2021 Share Posted February 4, 2021 15 hours ago, SwissBear said: Just be careful if you follow this path to chose a clock which has a 50 Ohm impedance output, as this is what the SU-2 is expecting, Can you confirm clock impedance input for the DAC ? If I got the Chinese correct translated, Singxer says the DAC will perform better with an external clock. I was not able to create a user there, as they require a Chinese cell number. (Witch I actually could fix, but it’s not that important to join). Link to comment
R1200CL Posted February 4, 2021 Share Posted February 4, 2021 On 1/29/2021 at 8:21 AM, SwissBear said: We had an interesting discussion the other day with @Miska on the subject of 10 MHz clocks. I was trying to make the point that 10 MHz clocks had an interest in music reproduction which Jussi refuted, explaining that the conversion of 10 MHz signal to frequencies usable by DAC oscillators (multiples of 44.1 kHz and 48 kHz) added jitter and was therefore not useful. This was related to the SU-2 or the SDA-6, or both ? Would in any case be interesting to see measurements (if it make sense) with external clocks. Even the $92 cheap one. As an SU-1 modified owner, I may be interest in SU-2 due to clock input. I will only use AES out. Did you own a SU-1, so some sort of compares is possible? Can external 5V be applied? Would you know main difference between SU-1/2 ? (Except clk in) Do you know if square wave would be preferable? (If you’re in contact with Singxer). Link to comment
R1200CL Posted March 6, 2021 Share Posted March 6, 2021 On 1/29/2021 at 8:21 AM, SwissBear said: Hi everyone, We had an interesting discussion the other day with @Miska on the subject of 10 MHz clocks. I was trying to make the point that 10 MHz clocks had an interest in music reproduction which Jussi refuted, explaining that the conversion of 10 MHz signal to frequencies usable by DAC oscillators (multiples of 44.1 kHz and 48 kHz) added jitter and was therefore not useful. At the end of the discussion, Jussi shared some measurements of his Holo Spring 2 DAC, which were in fact not comparable to the ones I had published, essentially because he was measuring multiples of 44.1 kHz to show how powerful his technology of HQPlayer was in reducing jitter, when increasing sampling frequency to PCM 1.4 MHz or DSD 256. Measurement published by Jussi and mine were not comparable because the upsampling drastically reduces jitter, at least on his DAC and also because we had no idea of the number of samples used to make the FFT in either measurements, which has a direct impact on the noise floor. To come back to my point, and to the comparison of things which are comparable, here is a graph of the jitter measured at the output of an R2R DAC, in connection with an interface SU-2. Please note that you cannot compare the noise floor with Jussi's measurement as we do not know how many samples were used to produce this FFT. Also, the impulse is at 12 kHz as the sampling frequency is 48 kHz. Please also note that the x-axis has been very much enlarged. In red, measurement of the jitter induced by the oscillators of the SU-2 (Accusilicon AS-318B). In blue, measurement of the jitter when the SU-2 is connected to an external 10 MHz clock which is cold. In green, measurement of the jitter when the SU-2 is connected to an external 10 MHz clock which is hot (after 12 hours of warming). I am tempted to infer from this graph that Yes, definitely, 10 MHz clock can have a beneficial influence on the J-test measurements of jitter, made at a DAC. I am also tempted to infer that Singxer has a good knowledge on how to implement these technologies. Hope this helps :-) Reference: http://www.erji.net/forum.php?mod=viewthread&tid=2216213&page=1#pid33553664 [EDIT] Measurements have been made by l7audiolab.com (https://hv6mkka65l5nbcgw64taospppe--www-l7audiolab-com.translate.goog/f/tmmt再出发/). The 10 MHz clock was Gustard C-18. This is a very helpful post. Text beneath is from here. Quote SDA-6 supports external clock input, among which USB supports 10M clock input, and other interfaces support WCK input. In USB mode, it also supports 50 and 75-ohm switchable input impedance. I’m considering upgrading my Modified SU-1 with an SU-2 which also has 10 MHz clock input. Since external OCXO clocks has such an positive impact on the EtherRegen, I would expect same on a USB to SPDIF Converter. I would expect the USB and clock interface and circuits is shared between the SDA-6 and SU-2. SU-6 isn’t an option for me, as lack of external 10 MHz clock. Denafrips could be an option, but also lacking 10 MHz clock input. So far I haven’t found any converters that’s offering 10 MHz clock input. EDIT: (I forgot posting almost same in this tread). Thanks again for great answers. Link to comment
R1200CL Posted March 21, 2021 Share Posted March 21, 2021 Got an SU-2. Not connected yet. Just on power. Should equal burn in. One guy told me an USB to SPDIF converter can’t use or benefit from an external 10Mhz clock. Makes me wonder where this external clock is used in the SU-2. Link to comment
R1200CL Posted March 22, 2021 Share Posted March 22, 2021 14 hours ago, SwissBear said: In case your DAC follows the clock signal included in the SPDIF or I2S flow, you will benefit from this high precision clock signal. Can’t say how my old Theta Generation VIII deal with AES/EBU. I taught it could only be one way ? Link to comment
R1200CL Posted March 22, 2021 Share Posted March 22, 2021 Yes, of cause. I probably didn’t understand your first answer. Quote In case your DAC follows the clock signal included in the SPDIF or I2S flow As there are DAC’s that don’t benefit from the clock signal included in the SPDIF. Link to comment
R1200CL Posted March 22, 2021 Share Posted March 22, 2021 2 hours ago, Miska said: You need a PLL when you need to recover an external clock into usable local clock. IOW, when you are a clock slave. Like in case of S/PDIF or AES/EBU (or I2S for that matter although implementations vary). When you have a local clock oscillator, you don't need a PLL. IOW, when you own the master clock. Like in case you are using USB or network interface like NAA. So in other words, the theory is that a converter like the SU-2 will benefit from a good clock ? Clocks matters and play a role in USB to SPDIF conversion ? Link to comment
R1200CL Posted March 23, 2021 Share Posted March 23, 2021 1 hour ago, Miska said: But why would you use something like SU-2 with SDA-6? Maybe I should start a SU-2 tread. I don’t have a SDA-6. My idea is to upgrade my SU-1. I’m totally dependent on a converter after the opticalRendu. I’m just trying to understand if the Idea with an better clock was somewhat meaningless. As I have been told that a converter don’t use a 10 MHz clock. The diagram is under developed. It won’t be clocking this way. Link to comment
R1200CL Posted March 23, 2021 Share Posted March 23, 2021 1 hour ago, Miska said: Of course someone may have an old DAC that doesn't have USB input or such. Exactly 😀 Theta Generation VIII S3 And it’s still a very good DAC. Link to comment
R1200CL Posted March 23, 2021 Share Posted March 23, 2021 @Miska or anyone else. It's not totally clear to me what the clock, internally or externally is doing in a USB to an SPDIF converter. And what frequency is needed. I probably didn’t understand the answers given so far. Some explanation would be very helpful. @JohnSwenson or @Superdad I think you guys know a lot about USB to SPDIF converters, and how they ought to be designed. A short explanation from you would be very helpful. I do understand that some sort of isolation between USB and the rest of circuits is good. Is more about how a a good clock (with low phase noise) used in converters, should matter or not. I’m not asking for any technical evaluation of the SU-2. (It’s only on power now. Not connected yet). It’s more about understanding the possible (technical) value of adding a better clock. I also think it’s widely accepted that the best solution is to have the DAC do any clocking. But I can’t understand how that could be part of a discussion when I’m only using AES/EBU. if this statement is correct “The AES/EBU and S/PDIF formats both have word clock in the digital audio stream”, then it seems to me the quality of the clock may matter. I was trying to read “GUIDELINES THE EBU/AES DIGITAL AUDIO INTERFACE” there they talk about clock recovery. But I don’t understand if that matters or not as the DAC has its own clock. (I assume). Link to comment
R1200CL Posted March 23, 2021 Share Posted March 23, 2021 Thanks Miska. My understanding of this answer is that it’s totally meaningless to have a 10 MHz clock in a USB to SPDIF converter. (General speaking). http://www.singxer.com/pd.jsp?id=80 (Auto translate using chrome). On the other hand, it may seems that the 10 MHz input is used to convert up to the needed frequencies in a converter, and then maybe the quality of external clock matter. Maybe Singxer has done something very clever. To reframe the question, does the quality if the 44.1k-base rate family 22.5792 MHz or 45.1584 MHz clock and the 48k-base rate familiy 24.576 MHz or 49.152 MHz clock matter ? 44 minutes ago, Miska said: But when using S/PDIF or AES/EBU, typically you don't have a DAC side clocking other than a clock recovered using PLL from the S/PDIF or AES/EBU signal. So one could assume better input to this PLL, may affect further what’s happening in a DAC ? Link to comment
R1200CL Posted March 23, 2021 Share Posted March 23, 2021 20 hours ago, Miska said: Yes, if you have a better clock at the source (USB to S/PDIF converter), then the PLL at receiver side has better chances or recovering a clean clock from the S/PDIF signal. Aha. Very good 😀 Sorry for not getting this point before. This qualifies for testing using a better external clock. Thanks Miska Link to comment
R1200CL Posted March 23, 2021 Share Posted March 23, 2021 Product introduction: SU-2 digital interface is a new high-performance USB digital audio interface developed by our team. It adopts a microprocessor with the latest ARM Cortex-M4 as the main control of the USB data part. SU-2 adopts the self-developed ultra-low jitter clock system (ACCUSILICON's AS-318B series, ultra-low jitter up to the femtosecond level), and the large-capacity FPGA as the processing core of Digital audio data, with standard USB2.0 input. Interface, rich output interface, including XLR balanced output AES, coaxial RCA and BNC, I2S interface with HDMI socket output, perfect main clock and word clock (WCLK) output. SU-2 supports external 10Mhz clock input and adopts the common 50 ohm input impedance design. SU-2 is not only a USB interface, but also can be used as a stand-alone main clock product. 1. When used as a stand-alone master clock, you can output 44.1K-384K word clocks, or 22.5792Mhz-49.152Mhz master clock. ( When not connected to USB, it will be used as the main clock device by default) 2. It can also be used as a frequency converter when using an external 10Mhz clock input; it supports 10Mhz conversion to 44.1K-384K word clock, or output 22.5792Mhz-49.152Mhz master clock. SU-2 is the new architecture USB interface we have developed to replace the original SU-1; PCM sampling rate up to PCM 768K and DSD up to DSD1024. Using large-scale FPGA as the core of operation processing, we decentralize some of the FPGA algorithm technology of the flagship interface SU-6 to SU-2; it is positioned in the middle and high-end interface, mainly using the following three unique technologies: 1. Full isolation technology (ground isolation), using 150Mbps full isolation chip, can completely isolate interference from PCs; 2. Source synchronization technology and FPGA shaping technology reshape the isolated I2S signal; thus eliminating the additive jitter brought by the isolation chip; 3. The independently developed clock system adopts ACCUSILICON's high-performance crystal oscillation, low phase noise and low jitter. You can also choose an external 10Mhz clock to support various atomic clocks, constant temperature crystal oscillation, and GPDSO input. Technical indicators: The sampling rate supported by each output interface: PCM: 44.1KHz, 48KHz, 88.2KHz, 96KHz, 176.4KHz, 192KHz, 352.8KHz, 384KHz, 705.6KHz, 768KHz [of which I2S out supports total sampling rate, S/PDIF supports up to 384KHz, DOP128] 2.8 MHz (DSD64) - DOP, native 5.6 MHz (DSD128) - DOP, native 11.2 MHz (DSD256) - DOP, native 22.5792 MHz (DSD512) - DOP,Native 45.1584 MHz (DSD1024) - native [where I2S out supports all DSD formats, S/PDIF and AES/EBU support DSD128 DOP mode] Bit width: up to 32 bits over I2S output Up to 24 bits over S/PDIF Electrical standards for each interface: 1. The USB input socket is a standard USB-B-type parent seat, and the USB power supply range is 4.5V-5.1V; 2. The RCA interface outputs the standard S/PDIF signal, with a level of 550mV (connected to the standard load) and the output impedance of 75 ohms; 3. The power input is 115V/230V AC, and the internal power supply is powered by TALEMA imported transformer. Design details: 1. Implement the design concept of electricity as the mother of sound, attach importance to the design of power circuits, and adopt high-performance, low-noise and fast-response LDO as the main power supply. The whole board adopts multiple independent LDO power supply, and the clock part even adopts ADI's ultra-low noise LDO, laying a solid foundation for ensuring the ultimate output performance. 2. The PCB motherboard adopts a 4-layer circuit board design to ensure that it has a complete ground level and power layer, and adopts a high-speed digital design method to ensure the signal integrity and power supply integrity of the whole board. Special processing of clock signals adopts inclusive design and accurate impedance control, thus ensuring the signal quality of the clock and improving its anti-interference ability. The input and output signals follow the standard design, especially the USB high-speed signal adopts 90 ohm differential impedance control. System compatibility: 1, Windows 7, Windows 8, Windows 10; 32/64 bit, requires a dedicated driver 2, Native MacOS 10.6 and later, using the system's own driver 3, Native Linux with UAC2 compliant kernel, using the system's own driver, (tested on Ubuntu and Daphile systems, based on the INTEL X86 platform) 4. Android OS 4.2 and above require devices to support OTG functions. Generally speaking, Android 9.0 and above systems are supported by default, and it is recommended to use below 9.0 with special players. The I2S interface adopts HDMI socket output: 1. LVDS differential signal with a level of 3.3V; 2. DSD ON signal, 5V power supply (small current), MUTE signal internal CPLD has been processed, and there will be no need to output MUTE signal; 3. The DSD ON signal can be defined by itself. The DSD ON signal can be output arbitrarily to the pins of the socket's PIN 13, 14, 15, 16. Link to comment
R1200CL Posted March 23, 2021 Share Posted March 23, 2021 I think I’m getting closer to some understanding. The clocks in SU-2 doesn’t look bad either I guess. http://www.accusilicon.com/docs/AS318BM.pdf 2 different versions in use. I suppose in order to each facilitate 44.1 and 48 base rate families. From SDA-6 specifications: “The standard version of the crystal oscillation is AS-318B, and the high-configuration version is CCHD-957.” (Edit. As stated by @Miska) Obviously is CCHD-957 is a better option and not offered for the SU-2. OK, that may be a possible future DIY upgrade 😀 (Not even Kitsune has that on the list). So then there is some FPGA that takes the correct multiple from the clocks based on type of audio resolution is feed to the converter (or DAC). And an external 10 MHz is bypassing the internal clock, and somehow is able to be create same needed frequencies. That’s the part of something that’s a very mysterious thing. How a single 10 MHz can replace the function of those two internal clocks ? Maybe there still is a chance I haven’t understood how this 10 MHz external input actual is working and it’s real mission. The external 10 MHz clock input on SDA-6 is described as this: “SDA-6 supports external clock input, of which USB supports 10M clock input, and other interfaces support WCK input.“ So if it’s 10 MHz only USB, then shouldn’t that be same for the SU-2 ? There must something very fundamental I’m missing. Maybe this will also be covered by @JohnSwenson clock paper too ? In what application is a 10 MHz good to use and why ? When do we use a Word clock ? (WCL) Will circuits that produce multiple frequencies degrade output from the clock. Link to comment
R1200CL Posted March 24, 2021 Share Posted March 24, 2021 23 minutes ago, Miska said: Through a programmable fractional PLL. A bit like a sample rate converter that can convert between rate families. OK. That’s the secret 😀 Then maybe a very good 10 MHz clock can replace the dual internal ones. Both SU-2 and the SDA-6. So worth testing 😀 Just why wouldn’t designers then use programmable fractional PLL and a 10 MHz clock in general instead of dual clocks of different frequencies ? Not remember what was said before in this tread about those two available SDA-6 options, one may benefit of purchasing the standard one, and use the “saved” money on a good external clock. I guess only listen will tell. So first step for me is to compare SU-1 to SU-1 during next days. Then test with external clock. Thanks for clarification again Miska. Link to comment
R1200CL Posted March 24, 2021 Share Posted March 24, 2021 1 hour ago, fmzip said: If you want to do the mod, I used the RHEA Adapter board from Twisted Pair Audio, scroll all the way to the bottom of this link: This one: So the clocks not exchangeable on the PCB. Holes doesn’t fit ? Or is there an option to purchase the correct boards including the right versions of the Crystek CCHD-957 Did you actually notice a difference ? What regulators did you add ? Any other tweak ? Link to comment
R1200CL Posted March 24, 2021 Share Posted March 24, 2021 Just ordered. Now must find the clocks. Link to comment
R1200CL Posted March 25, 2021 Share Posted March 25, 2021 11 hours ago, Superdad said: I suppose a clock synth could be on the bottom of the board, but would need to see pics of the underside to know. Here you go. I think you just saved me an external clock for this one. However question then remains what that external 10 MHz actually does. Or how. Well you already said Spartan 6..... Link to comment
R1200CL Posted March 26, 2021 Share Posted March 26, 2021 On 3/24/2021 at 8:02 PM, etane said: Singxer SU2 is an indispensable upgrade to my D90 MQA. That is all. On 3/24/2021 at 8:43 PM, fmzip said: I agree. There's not much talk of the SU-2. I really lucked out with my Kitsune SU-2, found it used for $350. Upsampling to DSD512 with HQPlayer/Roon never sounded so good :) Did any of you had the SU-1 before upgrading to SU-2 ? Link to comment
R1200CL Posted March 26, 2021 Share Posted March 26, 2021 Let’s hope John has an idea how this works. Link to comment
R1200CL Posted March 26, 2021 Share Posted March 26, 2021 2 hours ago, ambre said: Why do you not ask the manufacturer at first place? That seems me more appropriate. Because Singer doesn’t answer emails. Link to comment
R1200CL Posted March 26, 2021 Share Posted March 26, 2021 @SwissBear It seems the USB input isn’t equal to SU-2. Agree ? Link to comment
R1200CL Posted March 30, 2021 Share Posted March 30, 2021 Seems the SU-2 is on sale. https://shenzhenaudio.com/products/singxer-su-2-dsd1024-usb-digital-interface-femtosecond-clock-interface?variant=31512938348676 Link to comment
R1200CL Posted April 15, 2021 Share Posted April 15, 2021 26 minutes ago, DomiJi said: Does anyone tested some other clocks as well? I will soon (in a week I hope) test my SU-2 with AfterDark King version clock. I need also to figure out if I have to tell the SU-2 if it shall switch from internal to external clock. I tried with a BG7TBL clock. I couldn’t hear any difference. As it’s a mystery how this external clock input is working, I doubt it will help much. DomiJi 1 Link to comment
R1200CL Posted May 2, 2021 Share Posted May 2, 2021 How do I tell my SU-2 it should use the external 10 MHz clock ? Does it change automatically ? Edit: Found the answer. No wonder I couldn’t hear a difference before 😂 9. If you need to use an external clock, you must first set switch 5 at the bottom of the chassis. When switch 5 is turned ON, use an external clock. If the external clock is not input or the lock is abnormal at this time, the PLAY LED will flash red (the clock is in the unlocked state, and the sound can still be played, but it is not recommended), the lock is normal and the red is always on; when it is OFF, the internal clock is used. When the clock is switched, it is recommended to restart the device. Link to comment
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