Thursday, December 24, 2009

Christmas eve "presents"

Three packages for me today. My used copy of Freak Power's Drive-thru Booty CD. A copy of Andy McNab's book "Brute Force" and the JAN6418 tube preamp kit from Australia. Woohoo!

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

Stupid record labels

Have cash, will spend it on CD. Hello? Anybody out there? Nope!

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

PSU PCB's

A large USPS envelope in my mailbox today. In it two power supply PCB's from chipamp.com. Brian, the man behind chipamp.com, sells top notch quality PCB's for chipamps, Aleph amps and PSU's. My mini Aleph is built using his PCB's, and I have built a dual mono chipamp with his PCB's too. So when I wanted to order a PSU PCB for my still work-in-progress F5 amp the PCB's from Brian are my first choice. I ordered two so I have a spare PCB for a future amplifier project... The PCB measures 20.3 x 8.9 cm. It has room for six big capacitors upto 40mm in diameter.

Tube pre kit on its way

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

Tube pre

Ever since I started making my own Hi-Fi amps I wanted to make a tube preamp. All those tube lovers can't be wrong, right? I do have one condition, a decent quality PCB must be available for it since I can't make PCB's myself. Enter the K272 Stereo Tube Preamplifier from Oatley Electronics, Australia. It's a complete kit with two sub-miniature JAN6418 tubes. I ordered a diy tube preamp kit after reading the review @ DIY Audio Projects.

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

Sinterklaas

Sinterklaas had some gifts delivered to our home yesterday evening. I was given a Marcus Miller DVD, a new Ersa Multi-Pro soldering iron, a K1823 PSU kit, a digital multimeter with spare leads and a chocolate "B" of course.

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

LT317 and 21DQ06's

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.

Thursday, December 3, 2009

Tomato

I'm a big fan of the Tomato open source router software. Recently version 1.27 was released. I upgraded my 1.25 installation just now. Again, everything works as it should. So what's the big deal? Well, that it actually works really well once you've set it up to your wishes and needs. Having a stable router is a good thing to have.

Google DNS

Found this at Lifehacker.com. Google now offers a free DNS service to all. I already had OpenDNS' primary and secondary DNS servers entered into my Tomato powered WRT54GL router. I replaced Open DNS' secondary DNS server with Google's DNS server. Check it out, it might give your connection a boost.