Thursday, December 24, 2009
Boy, those JAN6418's are tiny! Now it's time to gather better quality components for it and lay my hands on some more of those NOS JAN6418 tubes.
Monday, December 21, 2009
I'm at it, again. I wanna buy a CD and am willing to part with some cash for it. Problem is, I can't get the CD because it's no longer being sold. Must be something very old you say. Well not really, it's from 1994. That's how stupid record labels work these days. A lot of music can't be bought because they can't be bothered to make it available. Bunch of tossers. If there ever was a reason to download pirated music this is one.
Oh, I got lucky BTW. I found and bought a cheap used copy for even less than iTunes Store charges me. Yes that does include shipping too!
Friday, December 18, 2009
Received email yesterday that the tube preamp kit is on its way. Now let's see how long it will take, as I've never ordered something from Down Under.
I've been doing some reading on different opamps and I now think that I'll settle for a AD8066 opamp instead of a Burr-Brown OPA2134. One small problem though. The AD8066 doesn't come in DIP-8 but SO-8 only. To overcome this a small adapter is needed. It's gonna be a real challenge to solder the AD8066 to it...
Saturday, December 12, 2009
The review mentions upgrading some of the very basic components to higher spec'd ones. So that's what I'm gonna do too. The op-amp will be a Burr-Brown OPA2134, resistors metal film type 1% tolerance, the 0.1µF polyester coupling caps will be replaced by 0.1µF MKP1837's, for the 10µF 'lytics I have Panasonic FC's in mind, for the large 220µF 'lytics I'd like to use Elna Silmic's if they will physically fit the board. I might even fork out the money for induction-free Vishay-Dale CMF-55-143 resistors since there are so few resistors on the board.
Buying a kit like this with NOS (new old stock) tubes can be a risk since you don't know if you'll be able to find new tubes once it's time to replace them. Before you know it those tubes will cost a small fortune to buy. Luckily I found a cheap source for JAN6418 tubes. Once the kit arrives I'll be stocking up on some replacement tubes for sure.
Sunday, December 6, 2009
The Velleman PSU kit is now assembled. I replaced the electrolytic caps with better quality ones. The bog standard LM317 was replaced with a better spec'd LT317. The equally bog standard 1N4007 diodes were upgraded to 21DQ06's.
A quick check with a 12 volt transformer shows the PSU works. With the trim pot I can set voltages between 1.25 and 17.9 volts. Cool! For the B1 buffer I need 18~24 volts, so with a 15 volts transformer I'm good to go.
Friday, December 4, 2009
I laid my hands on a LT317 this morning. My local electronics shop had them in stock. I had hoped to find one in TO-220 form factor, instead my LT317 is in TO-39 form factor. The LT317 is a better spec'd LM317. It wasn't cheap though...
I also bought four 21DQ06's Schottky rectifier diodes. They're gonna replace the 1N4007's in the Velleman PSU kit. With a current rating of 2 amps instead of 1 amp they offer some margin the 1N4007's don't have.
Still to buy: a TO-39 heatsink.