Saturday, April 29, 2006

My First 'Tube' Project

I am personally shame when Mr. Bing invites us to test my Amplifier in his home. My Amplifier is only about several dollars, compared with his audiophile gear.
So I then plan to build a more sophisticated amplifier. But my limitation is the high-voltage (usually used in Tube circuit) scarring me. I realize this might be ridiculous for someone with passion in electronic engineering – as I found that is nearly impossible to use low-voltage for Tube Amplifier. A Tube Amplifier at least use 2x320V. AC, which is really, really makes me scare.
As I browsing the www and, coincidentally, I found a hybrid amplifier, using low-voltage tube, i.e. Sovtek 8922, running at 2x35V. Again, Mr. Alex helps me to get the rare 6922 tube, complete with gold-platted ceramic socket.
I assemble the circuit, using ‘air, pin-to-pin wiring’ and test it using my Gainclone amplifier and JBL Pro desktop computer speaker (it is a full-range speaker with waveguide), with off-course audiophile-style ‘Come Away With Me’ of Norah Jones.
To me as the 1st Timer, it is totally different. Deep bass and throat sound is clearly reproduced, even using a small, cheap speaker.
I am now about to make the PCB, inverted version of Gainclone and supporting electronics for my sophisticated amplifier.

My First Audio Blind Test

One day, Kur, my weird friend asked me to test my Gainclone amplifier with his friend, an audiophile person, respected in audiophile equipment industry. His name Alex, from Rich Audio, Jakarta. He did not explain anything regarding the test.
Kur said like this: “We don’t do anything. Just to test your amplifier and ask him to give such opinion about your amplifier. He is an audiophile. Audio specialist...”. Well, I am agree with him and committed to meet his friend on Saturday, March 11 in his place, “The Eye Gallery”, Simprug Permata Hijau.
As we arrived, guess what happened? I see a black, big placard “Audio Blind Test Competition” with few people so busy behind it. Few people sitting in an arranged chair and special chair is provided. To my opinion, that chair is be provided for special people which is act as judges. I tell to myself; this must be a serious event, not as my friend said about the purpose of our visit. It is real event! Then I tell my friend that I am seriously not prepared for this, and it can be a suicide.
Again, later I know competition category: Tube Amplifier or Valve Amplifier. The tube amplifier is a very sophisticated and expensive Audio Amplifier. It really makes me nervous. My amplifier is Gainclone, Solid-State Amplifier. And I came not for this event...
Once the preparation finished, the ‘Landlord’, Mr. Alex warmly welcomes us and please us to take a seat and enjoying song by song, reproduced by each tube amplifier one by one. Every song is played no longer than a few minutes. To me as a young man, it is a weird song. Even though the songs are played by very sophisticated reference-grade audio equipment, such as ‘Consonant’ CD Player and Stirling Tannoy speaker. The judge is then gives appreciation to each amplifier.
Once the competition finished, his friend, Mr. Alex pleases us to test the amplifier. Not all audience including the judges agrees since the category is different. Another opinion said that the Gainclone is very cheap amplifier: only $35, compared with thousand dollars price of tube amplifier. After such preparation, the Mr. Alex play that weird song using similar reference equipment.
Guess what the appreciation: the level is too low... even the input level is maximum! For information, I built the amplifier according to the configuration standard – without pre-amplifier as described in LM1875 datasheet. Few curious audience is then look observe my amplifier, and they gives suggestion to improve my amplifier – things that I did not found in other competing communities.
Next test is my B3S Speaker. Again, not all people agree due to it efficiency: only 89% which can cause the tube amplifier’s output transformer arcing. But one judge, I know his name later as Mr. Bing Isnanto – he told the audience not to underestimate my speaker. Once he said: if the sound is good, I take it home! We test it and the appreciation is: the bass response is low since the 3dB cut-off at 80Hz, but the high-frequency level is good.
After all finished, Mr. Bing then invite us to visit his home around Tulodong to test my amplifier with what he call with ‘Kharma’. I know later the Kharma from Mr. Alex: Hey it is an honor to test your amplifier with Kharma. It is a 600million Rp, very expensive, very sophisticated speaker in the world!
But unfortunately we can not fulfill the invitation, since the time is very short and my ‘driver’ has difficulties when driving in a big road.
Through this page, I would like to the audience and judge, especially to Mr. Alex and Mr. Bing for the time and opportunities given to us.

The B3S Speaker

B3S is a full-range speaker from HiVi Research. I am very impressed with its construction. B3S is a 3” driver, magnetically shielded. The response is relatively flat, across 87 to 20kHz, except at 8kHz, so a proper notch filter needed to reduce it. It can produce 25Watt RMS or 92dB SPL. The flat response may eliminate the need of cross-over circuit.
I adopted the circuit from Zaph Audio, which also provides complete detailed construction. I test it in a Blind Test even, organized by Rich Audio.
Its performance, capability and appreciation make me start thinking to make a near-field audio monitor like this.

It's About Me...

My name Donny Setiawan. I have passion, ideas and thoughts which I dedicate to the electronics and broadcasting industry.

I write the Blog to introduce myself to the world, hope it can bring me to better life. I have 15 years experience in radio communication and broadcasting industry. I also have working experience in Oil & Gas environment, both offshore and onshore. I have almost 10 years worked in local company which later I know can not meet my expectation, and seriously, I can not live with this condition. I can’t marry, I can’t continue my study, I can’t attend any seminar, I can’t buy a vehicle (even lastly the company provides one for me), I can’t buy a home. The only things I can create is ‘owe to my mom’. Not as previously I thought that someday the company may be give me such attention. But this about ten years with ‘flat-rate’ salary. Also, I am not a sales person or marketing, even I can support marketing team through my presentation capability. I am a true engineer. So I don’t understand and sales or marketing things – don’t ask me that. But whenever I try create a project for the company, the company see it as a ‘compromised’ things or ‘business outside the business for personal business.’

That’s why I am feeling weird when the company told me that I have to create such project, otherwise my position is bet. I am now stuck in 'disability-ness' created by working environment.

To fulfill my living cost – instead of creating another debt – I must have extra-work or side-job. Things I never thought before, but I have to realize to. In last few years, I personally support TV station, especially for re-channeling, re-tuning or other R&D work. But I do not prefer this condition. I want to live normally and properly.

Lastly, I am supporting PT. Triwi Putra Jaya (Priyono Lam - 0818-920386) for automatic stereo / dual-mono switchover (TV7, TransTV), building the baseband / program input monitoring (TV7) and sub-audible tone decoder / encoder. And also transmitter re-channel in ANTV, for Lampung few months ago.

Now, I am about looking for another company suitable and appreciate my expertise and my experience. I am waiting for job opportunities, and please contact me on my e-mail: or on my handyphone 0856-91209121. My CV is available upon request.