Chapter 1 Why would the FiiO K9 Pro keep you waiting for such a long time?
Perseverance makes who you are. The K9 Pro, FiiO's latest flagship DAC/Amp, finally entered the market!
It took about 20 months from its first appearance to its final release. For FiiO, one of the strong manufacturers in the HiFi industry in China, it seemed absolutely abnormal.
What was the reason for the repeated delay of such a well-planned product? And what kept our users waiting for so long? Today, I, as FiiO's product manager of the DAC/Amp line, would like to give you a brief explanation.
The whole K9 Pro project has taken about 2 years from the start to release. Here is the rough timeline.
--In November 2019, the new desktop DAC/Amp project started, with a tentative model as K7.
--In January 2020, the FiiO forum announced the project information.
--In May 2020, the first draft of the product ID and electronic scheme was completed.
--In June 2020, we decided to re-plan the project as the higher-end K9 Pro with configurations and features upgraded according to user feedback.
--In September 2020, the K9 Pro was first exhibited at the Guangzhou Headphone Exhibition.
--In October 2020, an accidental fire happened to AKM, which resulted in a chip shortage. The whole project went back to the beginning.
--In November 2020, after clearly knowing AKM's inventory and losses, we decided to start an initial K9 Pro version with a single AK4499.
--In December 2020, the wave of chip shortage spread that the supply of the THX 788 amp chip was cut off, so we were forced to select another chip scheme.
--In March 2021, during the reliability test, we found that the balanced output of the THX 788 would be thermally exhausted due to temperature rise. After discussing with THX, we used the alternative scheme.
--In April 2021, we readjusted the parameters after using the alternative scheme.
--In May 2021, the K9 Pro passed the product reliability and function tests.
--In June 2021, the K9 Pro prototype was qualified for trial production.
--In July 2021, we started trial production in a small batch.
--In August 2021, we produced the K9 Pro in a medium batch and started to sell them in China.
From the timeline, we can see how difficult the R&D process of the K9 Pro was. First, it was the plan adjustment, and then three negative changes to the DAC chip, amp chip and amp module. Every success behind these adjustments was quite hard. It was the result of countless experiments and tests by our group members of the K9 Pro project.
For example, it took us nearly 2 months to successfully adjust the THX AAA 788+ headphone amp module.
When our quality test team found that the balanced output of the THX module would be heat exhausted in March, we were quite confused. After all, this was not the first time for us to use the THX 788. Unfortunately, after many experiments, the result was still the same. Some of the K9 Pro would even be thermally protected even after working for about ten minutes. We were so frustrated. Was it the circuit design issue, or the module issue?
We discussed it several times. For one thing, we tried to get a prototype device overseas. For another, we kept communicating with the THX R&D crew (they were basically not in the office at that time because of the COVID-19). In a word, it was very difficult.
Unfortunately, both the communication results and the retest of the purchased prototype were basically the same as our previous experiments. That was: the original scheme did not support long-term stable work in high-power mode. And THX also admitted such shortcomings.
It is true that most people will not select the maximum power for a long time when listening to music. So, should we just ignore this problem, or try to figure it out? To do or not to do, that is a question.
As you know, we finally decided to solve this problem, because the K9 Pro is a flagship!
The project team spent 2 months changing 2 PCB schemes while keeping discussing with the THX R&D team. Eventually, we solved the problem. THX thus gave a new name to our module, THX AAA-788+.
This little "+" was really a condensation of lots of our time and effort!
The whole process was full of challenges. Every change and adjustment required repeated tests and experiments. Fortunately, the K9 Pro is now qualified to enter the market. I believe most of you will like it. After all, it embodies the efforts and pursuits of a group of engineers.
