I Made Some Bread! (Sausage Bread and Focaccia)

Hello! This is Jooyoung Kim, an audio engineer and music producer.

While resting at home, I made some bread just as a hobby! I like bread and sweets, so I studied baking a little and even earned a Craftsman Confectionery Making certificate issued by the South Korean government.

In Korea, dry yeast is quite expensive, so I substituted it with raw Makgeolli, which contains live yeast that converts sugar into alcohol and carbon dioxide.

Also, I made the dough using a focaccia recipe because I thought it would add more flavor than making sausage bread with a simple dough. The dough recipe is shown below.

  • Flour: 300 g
  • Raw Makgeolli: 250 g
  • Salt: 4 g
  • Sugar: 6 g
  • Olive oil: 10 g
  • Some dried herbs (basil, rosemary, and parsley)

There are very few ingredients in the dough, so I refrigerated it for a day to absorb the aroma of the dried herbs.

The two pictures at the bottom show a large focaccia that I made before making the sausage bread and the small focaccia. Both of the breads use the exact same dough recipe.

I used a sausage, frozen mozzarella cheese, chopped onion, and ketchup for the sausage bread! Since I didn’t use an oven, and an air fryer has trouble heating the bottom of the dough, I pan-fried it as well.

As I expected, it was great! I’ll make it again if time permits.

Today was just a story about my hobby. Knowing that I don’t need to take the TOEFL brings me such peace of mind.. Well, I’ll wrap up my post here for today. See you in the next post!

My Research Paper Was Published in the Audio Engineering Society (Which Relates to HDMI Cables for Analog Audio)

Hello! This is Jooyoung Kim, an audio engineer and music producer.

Last week, my recent research was published in the Journal of the Audio Engineering Society, which is regarded as one of the best research journals in this field.

The title of the paper is “High-Definition Multimedia Interface 2.1b Cables for Analog Multichannel Audio: Objective and Subjective Analysis.”

When I started this research, I wondered if it was feasible to publish in the prestigious journals I wanted to target. It stemmed from a surprisingly simple idea – ‘People use LAN cables for analog audio these days, but why don’t they use HDMI cables instead? With the emergence of Wi-Fi and wireless internet transmission systems, HDMI cables have become much more common nowadays.’ – making it quite unexpected that such a simple concept would end up in a top-tier journal.

Therefore, I wired an HDMI female connector to a TRS connector… 🙂

Something like this weird creation, featuring one HDMI cable for every six TRS connectors!

So, following this, I wrote a Python program to measure THD+N and crosstalk in compliance with the AES17-2020 standard, as well as the frequency response. (Note: Measuring the frequency response is not related to this standard.)

You can check out the program via this Github link (https://github.com/JYKlabs/Audio-Measurement-Tools).

I ran the main audio tests using the program I shared on GitHub, which included comparing pure TRS cables. Separately, I used a quick, simple Python script I wrote to perform a phase-cancellation test, and I also conducted a listening test using the MUSHRA standard via webMUSHRA.

I tested nine different HDMI 2.1b cables across three different brands, covering 1-meter, 3-meter, and 5-meter lengths for each (3 lengths × 3 brands = 9 cables). As a reference, the comparison cable was a Canare L-2T2S, and the TRS connectors were Rean NYS228BG.

The result was simple! In the listening test, people couldn’t tell the difference between the cables, and the objective measurements also showed that using HDMI 2.1b cables for analog audio works surprisingly well.

You can read the full paper via this link: https://doi.org/10.17743/jaes.2026.0287.

Additionally, all supplementary materials can be found here: https://zenodo.org/records/19621854.

The paper exceeded the page limit by two pages, so I had to pay an extra $200. Honestly, I paid it gladly just to be published in such a great journal—I’m really excited!

However, I cannot share the full paper here due to the journal’s copyright policy – sorry about that!

Also, another piece of research related to a Korean traditional instrument was accepted by the Journal of the Acoustical Society of Korea last Monday! I’ll share more about the subject once it’s officially released.

That’s for all today. See you in the next post!

I Finally Met TOEFL Test Score Requirement!

Hello! This is Jooyoung Kim, an audio engineer and music producer.

It’s been a long time since I wrote my last article. During this time, I concentrated on studying English to get a good score to apply for Ph.D. degree programs in the Audio Engineering field. I knew that my English skills were not good at all, so I began to study in earnest in May 2025.

Last year, I tried my best and took four tests, but they were not good enough to qualify me. Because the test format changed after January 2026, I had a hard time adapting to these types of questions.

The upper photo shows my first trial score. It was really horrible. I got a huge shock, so I studied intensively after receiving it. The second trial is shown below.

As you can see, every score drastically rose, except for the speaking part. There were two more trials last year; however, they were not as good as the second test I took. Although, my speaking score was in the 13–15 score range during the 4th test.

I truly felt that speaking using templates, which many people do, did not fit me. Thus, I decided to attend a private academy taught by native English-speaking teachers to improve my speaking skills. Although it was operated by a church (the Seventh-day Adventist Church) and I am not a Christian, it wasn’t a TOEFL prep academy, and it was reasonably priced.

I went there every Monday to Thursday at 7 AM, and it really did help me overcome my fear of speaking in English. However, I felt extremely nervous during the first and second tests this year, so I got disappointing scores when I took those two tests.

But eventually I hit every threshold (audio engineer joke… :))! However, I’m so bummed that those seven tests (four tests last year and three tests this year) cost about 2,100,000 KRW (around $1,300–$1,400)—an amount that could buy me pretty good used audio hardware in Korea.

Not all of these books are related to TOEFL, but most of them are. I was just throwing them away 🙂

For Koreans who are struggling with the TOEFL test, I really recommend memorizing vocabulary and practicing grammar with an app named ‘Malhaboca’ (or ‘Sayvoca’), which significantly helped me improve my English skills.

Because of concentrating on the test, I couldn’t take care of this blog, publish my own compositions, or continue my own audio hardware DIY project. I am also planning to post some plugin reviews, which is one of the things I haven’t been able to do. I believe that I can keep going with those things starting today!

That’s all for today. Stay tuned for my next post!

DIY Audio Project #1 | Tube Saturator with Baxandall EQ (Part 4): Fix, Tune, and Refine

Hello, this is Jooyoung Kim, a mixing engineer and music producer.

Lately, I’ve been struggling with a few things like studying English for the TOEFL, preparing class materials, and conducting research. Among all these things, troubleshooting my tube saturator is the most convoluted work.

I wanted to post my article when I finished my build. However, since this continuous refinement makes it hard for me to write it, I’ve decided to document my progress step by step from now on.

Let’s start!

Main Problems

While fixing this machine, too many problems kept popping up. I’ve listed them below in the order they occurred:

  1. The unit wouldn’t power on, even though I flipped the power switch. -> resolved
  2. As soon as I powered it on, the toroidal transformer got so hot that it could fry an egg. -> resolved
  3. No output signals. -> resolved
  4. I found some issues with the meters. -> resolved
  5. One channel was muted, and a persistent white noise appeared. -> unresolved
  6. To fix the problem 5, adding capacitors made things worse. -> unresolved

So far, those are the steps I’ve taken. Therefore, I’ll explain each step chronologically.

The unit wouldn’t power on

It turned out to be just a cold solder joint. However, it was a real struggle to track down. While re-soldering everything, the problem still wasn’t solved. Then, I realized I hadn’t checked the solder joints on the power cord! Once I reflowed them, the power finally came on!

The toroidal transformer got so hot

This problem stemmed from a design mistake. Specifically, the connection between the 0V line and GND caused the transformer to overheat. To fix this, I disconnected the line and insulated it with heat shrink tubing.

No output signals

I figured that if I mounted the THAT1646 (SOP-16) onto an SOP-16 to DIP-8 breakout board, it would work. However, it turned out to be a completely wrong assumption. So, I ended up replacing all of them with DIP-8 standard devices.

Meter problems

Once I finished soldering the entire circuit, I ran into three major issues with the meters:

  • The right meter channel wasn’t working at all.
  • Even though the meter circuit followed VU RMS standards, the ballistic response was way too fast.
  • The audio signals were too hot, causing the needles to peg.

I found that the first problem was just a wiring mistake on my part.

With a little help from Gemini and ChatGPT, I sorted out the second and third issues by feeding them the circuit text. It turns out the meter circuit was designed for -10 dBV (consumer audio level). To fix this, I swapped out a couple of resistors to pad down the input levels for both channels. As for the meter ballistics being too fast, I replaced the damping capacitors with higher-value ones to slow the needles down.

One channel was muted, and a persistent white noise appeared

Yes… and this is the exact problem I’m still trying to sort out. Following ChatGPT’s advice, I added several decoupling capacitors to stabilize the power supply for the THAT1646 and OPA1612 chips.

At first, I misunderstood the advice and connected the capacitors in series with the supply voltage line and the chip pins. However, drawing on my background in physics, I realized that since it’s a DC power rail, connecting a capacitor in series didn’t make any sense. So, I double-checked the circuit configuration and finally realized it was a mistake.

To make matters worse, I totally messed up.

Honestly, I just needed to solder a few capacitors in parallel to the power rails. But instead, cluelessly overcomplicating things, I ended up desoldering all the chips and trying to install sockets.

Since cleanly desoldering an 8-pin chip is an absolute pain, I just lost my patience and clipped the pins with nippers. Then I tried using square-pin headers, which didn’t fit into the sockets at all. So I had to order brand-new OPA chips, re-solder the pins, and wire up the capacitors in series again.

After going through all that self-inflicted hell, I finally tracked down some round-pin headers, re-soldered the chips properly, and got them plugged into the sockets.

But guess what? Now, instead of music with some background noise like before, I’m getting pure, signal-driven noise blasting through. Ugh… hahahahahaha…haha…

hahahahahahahahahahahahahahahah……ahaha..aaaaaa!!!!!!!

So yeah, this is the story of my troubleshooting journey so far.

While writing this post, I tried fixing a few more things last night. However, it turned out that my efforts were completely ineffective.

Juggling multiple things at once makes this feel like it’s dragging on forever, and I just want to wrap it up already. If all else fails, my last resort will be to rip everything out and wire it up on a fresh PCB… ugh. Trying to finish this all during break was definitely too ambitious.

See you in the next post!