Cayin C9: Dual Nutube, Fully Balanced Class A/AB Portable HeadAmp
May 7, 2021 at 6:19 AM Post #3,931 of 6,212
May 7, 2021 at 6:28 AM Post #3,932 of 6,212
From what I found this one is N8 LE (only 30 units according to PSA)
See: https://weibo.com/3578602913/KedEexiW2
Cayin’s general manager made a teaser in C9’s user group yesterday that Cayin will have a new product release event in May (not an April fool’s announcement lol). It is very likely to be a new player as it begins with “N”.

Edit: If you are a C9 user and wish to join the C9 user WeChat group, shoot me a PM. :)
Maybe @bluestorm1992 can ask the insider contact, if there is more "N" coming :smiley:
 
May 7, 2021 at 6:32 AM Post #3,933 of 6,212
Phew. Not another amp! Because I just bought the C9. Just waiting on it to arrive
 
May 7, 2021 at 6:42 AM Post #3,934 of 6,212
May 7, 2021 at 8:31 AM Post #3,935 of 6,212
Has anyone driven the HD800S out of the Cayin C9 to comment? I've seen a few posts to suggest it is 'okay'. At the moment, my portable setup is the WA11 Topaz which works well enough.
 
May 7, 2021 at 8:33 AM Post #3,936 of 6,212
Has anyone driven the HD800S out of the Cayin C9 to comment? I've seen a few posts to suggest it is 'okay'. At the moment, my portable setup is the WA11 Topaz which works well enough.
Driving HD800 was the intention of our first user here @Whitigir, and he reported very favorable results.
 
May 7, 2021 at 8:49 AM Post #3,937 of 6,212
Driving HD800 was the intention of our first user here @Whitigir, and he reported very favorable results.

Fabulous.

I have a feeling Hugo2/2Go or SP2000 -> C9 with my Utopia, Empyrean, HD800S and Trailli will be a very fine time indeed. I can't wait for it to arrive.
 
May 7, 2021 at 8:52 AM Post #3,938 of 6,212
Fabulous.

I have a feeling Hugo2/2Go or SP2000 -> C9 with my Utopia, Empyrean, HD800S and Trailli will be a very fine time indeed. I can't wait for it to arrive.
I am confident that this pairing should work great with your CANS based on what other people said.

BTW, make sure to try your Traillii with C9. Could be an even bigger surprise. :wink:
 
May 7, 2021 at 9:06 AM Post #3,939 of 6,212
Has anyone driven the HD800S out of the Cayin C9 to comment? I've seen a few posts to suggest it is 'okay'. At the moment, my portable setup is the WA11 Topaz which works well enough.
When I get home later this month, I will try to pair up my HD800S with my Hugo 2 + C9. Right now, I am using this set up for driving my ZMF Verite Closed headphones and it is fantastic. I use R6 2020 + C9 for driving IEMs. Hugo 2 + C9 is better for driving my VC. Need to test it with my other full sized headphones, but I expect these optimal pairings to hold.
 
May 7, 2021 at 1:27 PM Post #3,940 of 6,212
I got my battery charger from Amazon and the replacement Sony batteries. Charging them up was easy and there is a good display on the charger monitoring data such as percentage charged of each battery. I listened to my C9 until it got to 1 bar and I opened up the C9 case with the tool provided and swapped the batteries. Very easy to do. The only issue I encountered is that it took a while for the C9 to recognize the new batteries. Not sure what I did, but it did eventually occur. I am thinking that it might be okay to leave the screws out and stored in a safe place if lots of battery swapping is required to prevent unintentional loss of screw or stripping of the head. Anyway, since I have since decided to pair my C9 primarily with my R6 2020, there is less of a need for battery swapping.
 
May 7, 2021 at 1:30 PM Post #3,941 of 6,212
I got my battery charger from Amazon and the replacement Sony batteries. Charging them up was easy and there is a good display on the charger monitoring data such as percentage charged of each battery. I listened to my C9 until it got to 1 bar and I opened up the C9 case with the tool provided and swapped the batteries. Very easy to do. The only issue I encountered is that it took a while for the C9 to recognize the new batteries. Not sure what I did, but it did eventually occur. I am thinking that it might be okay to leave the screws out and stored in a safe place if lots of battery swapping is required to prevent unintentional loss of screw or stripping of the head. Anyway, since I have since decided to pair my C9 primarily with my R6 2020, there is less of a need for battery swapping.
Every time you pull out and replace batteries, C9 automatically enters into the protection mode. You need to charge it for a sec after you put things back.
 
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May 7, 2021 at 1:31 PM Post #3,942 of 6,212
Every time you pull out and replace batteries, C9 automatically enters into the protection mode. You need need to charge it for a sec after you put things back.
Thanks. That's actually what I did and must be what engaged it.
 
May 7, 2021 at 1:44 PM Post #3,943 of 6,212
I tried several options, but now I think the c9 is best suited for neutral dap / dac with high sound resolution and great detail possibilities. Warm and smooth DAPs / DACs fits poorly, imo. I use P6 pro + C9 with both UM Mest and Empyrean. After a while I finally found the perfect combination for myself.
 

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May 7, 2021 at 4:07 PM Post #3,944 of 6,212
I have explained the Charging and Protection Circuit of C9 previously, given the latest experience and concern, I would like to spend some time to explain the C9 protection mechanism in more detail, but please read through the previous explanation before you move on.

First of all, let me restate the two typical conditions that will result in shorting the ground circuit and triggered the C9 protection mechanism:
  1. When C9 is connected to a source device (e.g., DAP) with interconnect, and both devices are charged through USB charger at the same time.
  2. When C9 is connected to your computer with interconnect, and using the USB from the computer to charge up C9.

The C9 battery module has two independent grounding system, the reference ground for audio power supply (aka Audio Ground) and reference ground for USB Charger (aka Charger Ground). Since the C9 power amplification circuit requires positive and negative voltage concurrently, we have designed the battery module to connect four pieces of 18650 lithium battery in series. The design will deliver a high quality ±8.4V power supply without needing a complicated DC/DC power regulation circuit, one of the critical success factor to maintain excellent transient current in C9 power supply. However, to achieve +8.4V and -8.4V power supply, we need a 0 reference point, and that is the audio ground.

In C9 implementation, the Audio Ground is connected to the chassis in order to shield the circuit from external interference. The Charger Ground is connected to the chassis of USB-C connector, and they are independent from each other. Their absolute voltage should always different from each other by two pieces of 18650 battery in the C9 battery module (i.e, somewhere between 6V to 8.4V)

When condition (1) or (2) exist, the Audio Ground of C9 will connect to the Audio Ground of the source (DAP or computer) through the 3.5mm or 4.4mm interconnect. If the Audio Ground and Charger Ground of the source equipment are common ground instead of independent from each other (which is very likely), when you charge up C9 and Source equipment at the same time, The Audio Ground of your source equipment will connected to the C9 Charging Ground directly, via the charging ground of the source equipment. This is why we end up with a shorted ground circuit in the system.

C9 Audio Ground => Interconnect => Source Audio Ground = Source Charger Ground => C9 Charging Ground

When the Audio Ground and Charger Ground of C9 is shorted, the current will go up instantly and trigger the protection mechanism of C9, and put C9 into protection mode immediately.

Base on these explanation, we can now examine the questions (and observations) from C9 users:

Well, there is another way to charge your C9 while listening.

1/ Only use Balanced IC cables *without Ground*

2/ Abide the 1 husband/1 wife policy. That means, charge your Source by one charger, and C9 by it own charger. Both can be plugged into 1 Wall AC outlet
There is a note that when the 4th Led is blinking, you stop the charger. But I don’t usually do this though, and when I do, I make sure to monitor it lol

Yes, we have tested the C9 with N6ii as source, connecting with the C9 stock 4.4mm interconnect. When we connect both N6ii and C9 to the same USB charger, it won't trigger the protection mechanism. We can check this video for reference (sorry for the quality of the video, it was taken by an engineer in our R&D lab as internal discussion material, I'll remove the video by end of May)

On the other hand, in contrast to our previous understanding, even when using dedicated USB charger for C9 and DAP separately, there is still a chance that C9 Audio Ground and Charger Ground can linked up if you look at the signal path carefully, so for safety sake, do not charge C9 and source equipment at the same time.

My recommendation is to stick with ONE USB CHARGER for C9 and DAP stack. With this practise, you can charge the DAP or C9 but not both. For example, even when both device are in relatively low battery reading, you can charge the DAP for 20 minutes and then unplug it and charge the C9 for an hour. Since Lithium battery prefer swallow charging cycle and there is no memory effect, you can charge them anytime instead of waiting till the last 10% battery (or when the last C9 battery LED is blinking).

Damn. Might've damaged either my c9 or my sp2000 -- or both -- because I charged them while connected after all. Odd behaviour from both units. My SP2000 somehow outputs volume levels 20% higher than before, like it's stuck on high gain (I don't have LO on and even did a full system reset). Hard to say if something is wrong with the sound -- in addition to the volume issue -- but it feels there might be. And the C9 just doesn't sound good any more. Congested and blurry, soundstage feels smaller and details are missing. Like it was in single ended or something... Tried with new batteries too, doesn't seem to make much of a difference.

Damn, I'm the guy in the celebration thread with the gloomy technical difficulties ain't I? I hate that guy, hogging up the conversation! :D Worst thing is, I can't tell if it's the amp or DAP malfunctioning. Or if I'm just losing my mind. Might be that too. You know how illusive it is when hifi is malfunctions? You can't trust your ears (or maybe head) any more.

Maybe I'm just imagining it...

Feels like I should get out of the hobby. maybe. Bring out my old Fiio x3, hook up my Shure 535s and "just listen to the music" like "normal people do". What a precipitous dall! Just three days ago I was Hifigod, now I'm going asleep on 6000 pounds of audio gear malfunctioning.

Any suggestions on the inevitable gloomy morning?

Marat's case is still a mystery to us. He used a 4.4mm to 2.5mm adapter cable as interconnect between C9 and SP2000, the interconnect is not grounded, so based on our experiment, even charging them together with the same charger won't trigger protective mechanism. Unfortunately, Marat triggered the C9 protection mechanism and to the level that the USB-C port of his C9 battery module is damaged. We need to examine the damaged C9 before we can arrive at any conclusion so we are waiting for the unit to fly back to Zhuhai from his dealer. We do not exclude the possibility that this particular C9 is having some circuitry problem and we apology for all inconvenience caused.

On the other hand, even when the short circuit was more severe than we expect, the SP2000 resume normal operation after the EQ setting is resumed.

@Andykong to test out my laptop audio, I connected the 3.5 aux out from a relatively new ThinkPad laptop to the 3.5 input of the C9. The C9 was charging from a usb c port from the same laptop. The moment I plugged in the 3.5 to the C9, heard a high pitched sound from the laptop follows by an instant shut down. Upon restart the laptop audio is fried including internal microphone and speakers. Is this a grounding issue of the C9 or a phantom power that fried the laptop audio.
The C9 seems to have escaped unscathed from this incident.

Theoretically when condition (1) or (2) existed, the C9 protection mechanism will kick in and power off immediately. We have conduct numerous protection mechanism tests with our DAPs during the R&D and QC process, and the protection mechanism will always responds very quickly and our DAPs were not damaged. So far this is the only instance that the source equipment was damaged when the C9 Protection Mechanism was triggered. We suspect that the grounding system of a computer is more complicated and fragile than the grounding system of a DAP because the common ground of a computer is designed to share by many internal devices and external peripherals. We don't pretend to know the reason for sure based on the short description of the instance, but we want to remind our users who plan to connect their computer headphone output to C9, please proceed with extra care.

Agree. Maybe there can be another version of C9 WITHOUT the replaceable batteries but with a Li battery power supply and allows for simultaneous charging.

As I understand it, the power shorting thing is unavoidable with a 18650 battery design. But for me, for example, I don’t remove the batteries at all, so it could work for me to purchase a version that allows for simultaneous charging.

The protection mechanism is not related to the replaceable battery design. We need to have the protection mechanism in place because the four pieces of 18650 batteries are connected as a +8.4V and -8.4V power supply for the amplification circuit and introduced an Audio Ground that is independent from the Charger Ground.

I hope this will help us to understand the protection mechanism and preferred charging practise of C9. I'll add more explanation if there are new issues arise related these topics.
 
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