Power Corrupts!

When CK Kok, resident guru on DIY Den had an article on a very simple 2A3 based single ended amplifier, I don't have to tell you there's this bloke here grinning ear to ear. Like what "Tok Guru" said, once you listen to some low-power SE magic, your life's changed for good! You won't go back to anything else after that. I know the day when audiophiles appreciate the magic of SE amps and high efficiency speakers is a long long way to fruition.  After all, the very idea of so few watts bringing so much magic is alien to this industry where the likes of mega-power behemoths with electrical consumption higher than your electric kettle is hailed.  So, here let me share with you my journey on an amplifier that consumes less energy than this PC I'm typing on...

Like most Malaysian audiophiles, I look forward to Thursdays as every Thursday is The Star's Audiofile day. That particular fateful day is when Audiofile had an article focusing on DIYers. Hmm... the idea appealed greatly to me. If gears are expensive, why not build one yourself? Sounds good. Also, if I could pull this off, this will be one MASSIVE boost to my ego. Hee hee hee... Also, that particular article led to me this mailing list, Kuala Lumpur Audio NutS. 

A few correspondence on KLANS later got me REALLY serious into considering DIY. Credit goes to that bloke with a tube nickname... You know who I'm talking about! 

Aha! Time to brush up my electronics! But my affinity of falling asleep when holding a telephone-directory-sized-mashed-tree-pulp didn't bring much progress. Fortunately, for my generation, there is the great World Wide Web and off I go! I found a really wonderful site, Nelson Pass' http://www.passlabs.com that explains electronics very beautifully to me. Nelson Pass not only has a gift in electronics, he has also the talent of bringing "life" into the very dry subject of electronics.

Another benefit of Pass' website is the various DIY projects there. Particularly interesting is his 10W Zen amp. Now Nelson Pass is a serious proponent of class A and I can't agree more with him. Class A is most linear with least noise though a lot less efficient, which thankfully, homebuilders can get away with. Anyway, this got me itching towards building my own Zen amp. Hey, with tag lines like "Less is more", can you out-Zen Nelson Pass?

This point in time, I was dead set on Class A and MOSFETs seem to marry the convenience of solid state and sonic quality of tubes. However, one day on the KLANS mailing list this guy, Shamsul Bahrin, was waxing lyrical non-stop about his 0.7W Darling amp. What? 0.7W? Are you kidding? Is this even enough to swat flies? I then realized this guy must be serious when he's putting aside expensive makes like Jolida and Rogers to listen to his Darling. Hmm... the fact that tubes are much sexier to look at is another plus. Hence a few e-mails to Shamsul later and I finally found 'Papa Darling' --- Bob Danielak. 

Legend has it that Bob built an average-sounding amp but stumbled across some cute looking tubes in a surplus store one day. He tried them in this amp and the sound impressed him greatly! After optimizing the circuit, he gave it freely on his website to anyone crazy enough to go a gaga over 0.7W. One of these guys is Rick Francis who's used to building huge mammoth sized amps, so when one day he built the still-unnamed-tiny-amp, Rick's wife took a liking to it and said "what a darling". And there you have it! The Darling!

It's easy to see the popularity of the Darling. First, the choice of output tube, the 1626 which is an unknown in the audio world. It's actually a RF oscillator and the curves don't look good on paper at all but it is Bob's ingenuity to operate this tube at a region where it works best for audio. Kudos to Bob. Secondly, the 1626 is a very cheap tube. Thanks to it's non-audio pedigree, these tubes are available at next to nothing. How about USD3 per tube? (The 1626 is a victim of its own success,  it's hard to get them at USD3 these days.) And this is NOS Sylvania, RCA, Tung-sol, Ken-rad, Hytron... Compare this with a pair of Western Electric 300B that cost 300 times more expensive and it's easy to see why it's popular. Oh yeah, plus Bob utilizes cheap components in the Darling. Any half-baked designer can take some boutique parts and assemble into a good sounding amp but it takes talent and vision of a genius to do some with cheap parts. The output transformer is a Hammond 125SE that puts out a sound that belies its cost. How much to build a Darling? How about less than USD300? Since it's "cheap and good", we got a winner here.

Thirdly, another DIYer, Gary Kaufman, organized mega sales of the 1626. He cut deals with surplus stores and shipped literally hundreds of these "poor man's 300B" to many crazy DIYers.

Which brings to this DIYer-wannabe. After visiting Bob's website, I longed to listen to the Darling in action but Shamsul stays too far away in Kota Kinabalu. Well? What choice do I have? Build one!

I began to acquire all the parts I need. As a total greenhorn, I really paid more than I had to on lots of components. Next came the most laborious part - planning. My dad always tell me "when you fail to plan, you plan to fail". Plus the fact that I'm going to deal with 260VDC here makes the above words more pertinent... After consulting some tube gurus on the layout, I began to build.

Utilizing some bench drills at the workplace, I had a steel plate cut and drilled but it was really more work than necessary. Stupid me chose stainless steel and this thing is really tough! I got some help along the way but only realized how hard stainless steel is when I had to do some filing myself. You see, octal sockets to fit the 1626 is 27mm in diameter while the biggest drill bit available to me was a 26mm. Filing off this 1mm took me one whole hour! (I wonder how tough is "buns of steel"?)

A couple of late nights later, I finally got it assembled. The thought of while the rest of the population drifts off to Dreamland, and I'm creating magic, makes me feel good... After powering up (and running away lest it explodes and bring down the whole neighborhood), all voltages measured okay and I was itching to play music already! But you are not going to try on your expensive speakers right? Where to find cheap speakers? I had an idea but I still feel bad over this... anyway, I went ahead and ripped off my car speakers...

Pressed 'play' and... hooray! I have music! It's singing! Another Darling is born! The Gods must be smiling on me! I still remember the exact date, 10 March 2001, that's how momentous this has been. (to tell the truth, a buddy had a durian bet with me to complete this amp by this date after hearing me talk about it for 2 agonizing years.)  But something is not right. It hums, badly but its character is there and I could swap tubes! I put in the RCA 1626 and it sounded sweet. Hey, you folks listening to sand amps, try to do this!

A few consultations on the Net later, I began my mission with vengeance: to eradicate hum from mankind, once and for all. Okay, it's not that grandiose but the action plan is this:

  1. twist tightly filament heating wires. At least 3 knots in an inch. This cancels out, to some degree, stray magnetic flux from each wire.
  2. grounding heater center taps or elevating it to some higher potential.
  3. grounding the chassis.

I tried all 3 and hum is gone. I'm happy! I have my music and it's hum free!

So I thought... Then I hear hum again. This time it's more menacing. Sometimes you hear it, sometimes you don't. Talking about The Phantom Menance...

This bugged me for quite a while until one day when music was playing and hum was singing, I accidentally touched the RCA shield of my interconnect and... DEAD SILENCE. No hum at all! Huh? I found out I haven't grounded the chassis after all! Oh well, a simple wire and that's it! No more hum!

[As an aside, please be reminded that this "one finger poke here and there" tweak is no solution to audio problems. I had the learning experience of electrolytic capacitors discharging its contents on my fingers not once, but TWICE. Whoever said "once bitten twice shy" obviously haven't met me yet.]

There you have it! My journey to ecstasy! SE magic! 


Part 2. Romancing the Darling...