[Whitigir]

Well I picked my current solution because the Z1 has no streaming. If not I might already have the Z1 hahaha.

Also 1kg is better than 2.5 kg(!)

Edit: I did briefly consider a transport to the Z1 but the cost and weight.. Urgh.

Edit 2: what I kinda want now are some "open" customs...

Understandable, but since you are using Utopia , that is a little different.

 

[Andykong]

How about a conventional way by charging with 18650 dedicated charger, then pull out the batteries and replace for more hours ?

This is what I am doing when I have four sets of 18650 but only 1 battery module. Pick a 18650 charger that can regulate the charging current of four battery slot independently.

 

[xand]

Understandable, but since you are using Utopia , that is a little different.

Andy's view might be that the Utopia isn't properly driven too.. Note it has a 300ohm + spike...

 

[Whitigir]

This is what I am doing when I have four sets of 18650 but only 1 battery module. Pick a 18650 charger that can regulate the charging current of four battery slot independently.

Yepe, already have everything ready, I just don’t know if I made the right call jumping into C9 for my needs

 

[xand]

don’t know if I made the right call jumping into C9 for my needs

What's the cancellation/return policy you are subject to?

 

[Whitigir]

What's the cancellation/return policy you are subject to?

Idk, restocking fees and so on ? But as long as I have not received it, I should have no problem in cancelation

 

[ahossam]

Since we have several C9 users showed up in the thread, I'll start to explain more operational side of C9. Someone has asked whether you can charge while you are listening, so let me started here.

Charging and Protection Circuit

The 18650 is very different from the 3.7V Lithium battery that are commonly find in mobile phone. Overcharge and discharge of lithium-ion batteries will cause permanent damage to the positive and negative electrodes. Excessive discharge leads to the collapse of the negative carbon layer structure, and the collapse will cause the insertion of lithium ions in the charging process; overcharging will cause too much lithium ions to be inserted into the negative carbon structure, causing some of the lithium ions to no longer be released. (Extracted from HERE)

A fully charged 18650 is around 4.2V and a discharged battery should stay at around 3.0V. A deeply discharged cell has fallen below 2.75V, it goes into a sleep mode and the battery is essentially useless.

1. The Battery module and the C9 audio circuit did not share a common ground, so it is likely that there will be potential different between the two grounds. Therefore it is very important to charge the battery with a separate USB charger. Using the USB from connected audio source equipment (such as computer or media player) to charge up the C9 batteries will trigger the short circuit protection, and might even damage the device and/or connected source equipment.
2. In case your C9 (or the battery module) entered protection mode, you need to remove everything and connect C9 or the battery module to a charger, charge it for at least 10 seconds and the device or battery module will revoke from protection mode and resume normal operation.
3. After replacing or dismounting the battery, the battery module enters protective mode, you need to connect the battery module to a charger, charge it for at least 10 seconds, and the battery module will then revoke from protection mode and resume normal operation.
4. Do not charge and playback both C9 and the connected source (let’s assume that is a DAP) at the same time. The four pieces of 18650 batteries are connected as a +8.4V and -8.4V power supply for the amplification circuit, and there is a set of ground line in between and that is connected to the C9 chassis. The charging circuit via USB-C has its own reference Ground connected to the USB socket. Be reminded that these two Ground are completely independent. If C9 and the DAP are charge and play at the same time, the power supply Ground (C9 Chassis) and charging Ground (USB socket) will short circuit by the charging cable and interconnect between C9 and DAP. C9 will enter protected mode. You can revoke C9 from protection mode by disconnecting everything and charge it for 10 second.
5. You can charge and playback C9 at the same time before the batteries is fully charged. 18650 Lithium battery charge control is divided into two phases. The first phase is constant current charging. When the battery voltage is lower than 4.2 V, the charger will charge with a constant current. The second stage is the constant voltage charging stage, when the battery voltage reaches 4.2 V, due to the characteristics of the lithium battery, if the voltage is high, it will be damaged, the charger will fix the voltage at 4.2 V, and the charging current will gradually decrease. Therefore, if you charge and playback at the same time and your charging rate is faster than discharge rate, the 18650 batteries will reach 4.2V eventually. The problem is, when you continue to charge and playback at this moment, C9 power management cannot enter the constant voltage charge stage, this will put C9 into protection mode. You can revoke C9 from protection mode by disconnecting everything and charge it for 10 second. You are advised to disconnect C9 from charging when the fourth battery LED is flashing in these circumstances.
6. If you charge and playback C9 at the same time and your charging rate is slower than discharge rate, your battery will consume slowly. At certain point, the batteries will drop below 3V and triggered the protection circuit to power off the C9. . You can revoke C9 from protection mode by disconnecting everything and charge it for 10 second and charge up the 18650 batteries. Since deep discharge might damage your battery, you are advised to stop your playback and start to charge up C9 when only 1 charging LED remains flashing.
7. Please do not use USB charger from Huawei mobile device to charge up C9. Huawei has it own quick charge protocol that is not compatible with C9.

So does it mean you can't cooked C9 by plugged it into charger, play on a loop and leave it for days, like everyone does with their new DAP.

 

[bluestorm1992]

A new pic I spotted. The person in the post suggests that C9 has no problem driving HD 800S.

 

[bluestorm1992]

So does it mean you can't cooked C9 by plugged it into charger, play on a loop and leave it for days, like everyone does with their new DAP.

I am actually wondering whether burn-in is at all necessaryy for C9.

 

[Whitigir]

A new pic I spotted. The person in the post suggests that C9 has no problem driving D8000 Pro.

I see I am not the only one with 800S! Thanks for the pictures

 

[twister6]

I am actually wondering whether burn-in is at all necessaryy for C9.

Manufacturers recommend burn in of DAPs. Here you got tube/solid state amp, don't see why not.

 

[Whitigir]

Manufacturers recommend burn in of DAPs. Here you got tube/solid state amp, don't see why not.

Exactly! I would think the same. The best burn in practice is to swap battery set as burn in go ?

 

[twister6]

I see I am not the only one with 800S! Thanks for the pictures

I wish I would have HD800s so I can tell you how it sounds with C9, but the best I can do it with ATH-R70x (470ohm, 99dB sensitivity) which I have no problem driving out of many DAPs. Of course, being able to raise the volume loud enough doesn't mean it is driven properly to its full potential. I know I'm stepping into an unknown territory since I'm mostly into DAP/iems and personally not a fan of being tied up to a heavy-duty desktop setup which molds headphone sound into something different, subjective to user's personal taste. It is a lot easier with IEMs, most could be driven properly from any source, and it is just a matter of pair up synergy and technical limitation of the source.

But while reading the last few pages of the thread, I think it will be hard to draw any conclusion based on reading spec numbers without someone actually trying and comparing it to other portable and desktop sources. Right now it is only a speculation.

 

[twister6]

Exactly! I would think the same. The best burn in practice is to swap battery set as burn in go ?

I'm still trying to figure out the best burn in method. Andy's explanation about battery charging and ckt ground explained a lot. I have seen a few times where C9 was fully charged and I was using N6ii w/E02 LO (on a charger) connected to C9 (on a charger) and its overprotection ckt mechanism kicked in, so I as running off the battery even so C9 was plugged into the charger. Then, my last burn in ran lasted 24+ hours but I started with C9 battery not fully charged and while charging up and being used at the same time it lasted a very long time since it was charging only a little bit faster than discharging. But then, I plugged and unplugged usb-c charging cable and it is back for round 2 now.

But either way, I think what I'm reading and figuring out is that C9 is designed for a portable use, strap it to a dap and carry it around, it is rather small and portable (footprint is a little bit shorter than DX300). If your really want to use it continuously as a desktop amp connected 24-7 to usb-c charger, I don't think it is a good idea, but feasible. Desktop amps come with a powerful supplies and filters to clean up the noise. Here with C9, charging battery base is plug'n'play, and if you don't move around you don't even need to secure screws. I think you can get a spare one and use it as a standalone charger. Keep one spare with 4 additional batteries, use one tray in C9 while charging the other tray and swap it in a matter of a few seconds when battery runs down.

 

[Whitigir]

I would just charge the 18650 on a dedicated charger, pull out the tray, swap the batteries and keep on going