Friday, November 27, 2009

Filter tweak

Because I had two 10nF MKP1837's still unused in my parts box I thought it would be a good idea to put them to use. According to Tony Gee of Humble Homemade Hifi these MKP1837's are the bee's-knees. So I soldered one parallel to the yellow 4.7µF Bennic caps in my Monitor Audio Bronze 2 speakers. The results: a touch more transparency in the upper frequencies. A simple and cheap tweak but don't expect a miracle.

B1 - slow progress

Progress on the B1 is slow at the moment. Only a few parts are soldered to the PCB at the moment. Still to buy are the more expensive parts: a bunch of 2SK170's, capacitors, source switch and volume pot. The volume pot is gonna be an Alps Blue type, the source switch an Elma 04-1344, caps-wise 10000µF Vishay's and Clarity Caps for the signal path caps. For the 2SK170's I'll have to order more than the four I need; I need two matched pairs for this application. Both transistors in a pair need to have a similar Idss, ideally the same Idss. Problem is nobody can tell you how much you need to buy to end up with two reasonably matched pairs... I'm thinking 20-25 pieces.

For the large electrolytics I have 10000µF Vishay's in mind since I can't find 15000µF caps with a 25mm diameter footprint. To keep the RC timeconstant the same I had to use a 1.5 ohm resistor instead of a 1 ohm. Nelson specified a 1 ohm 3 watt resistor, I've chosen to use the 1.5 ohm with a 4 watt rating, yup it's that big blue one. Should suffice, I hope. 

Wednesday, November 18, 2009

Street View

We can be found at Street View! On a bright and sunny thursday my street was shot. Thursday? Yes, the garbage bins are outside that's how I know it was a thursday. Our car is parked in front and that's about all there's to see. Still it's funny to browse through your street.

Wednesday, November 11, 2009

Sarkozy at The Kitchen Debate

Claims by Nicolas Sarkozy that he was knocking down the Berlin Wall 20 years ago were met with some scepticism. In reality Nicolas Sarkozy took part in or witnessed a lot of historic events. That's right! He can be seen in a lot of photo's from historic events. Here he is at the Kitchen Debate. More photo's of Sarkozy at historic events here.


The original photo was of course made by Elliot Erwitt. 

Saturday, November 7, 2009

Mike Stern - Big Neighborhood

I just ordered Mike Stern's new CD Big Neighborhood at Concord Music Group. I didn't even know he would have his new CD out in August this year. And that's from a big Mike Stern fan... Ah well, at least I did the decent thing and buy his CD instead of downloading it for free. The sample sound clips are promising a lot.

Why did I order the CD online instead of supporting my local record store? It's all about margin. The margin on CD's in the Netherlands is very high. So high that for me as an ordinary customer it's cheaper to buy the CD in the USA and having it shipped here instead of buying locally. Sad but true.

BTW, check out the wear on the neck of his Yamaha guitar!

Photo by Clay Patrick McBride

Friday, November 6, 2009

B1 caps

I've been searching the web for nice yet affordable capacitors for my B1 buffer. I think I've made my choice. I'm planning on using Clarity Caps for the signal capacitors. For the 10µF caps I've settled on the Clarity Cap PX, the 1µF caps are gonna be the Clarity Cap SA type. Both sport a 5% tolerance, much better than the Wima MKP10's I first had in mind. The Wima's I can source have a 20% tolerance. C1 and C2 will be 10000µF Vishay's. C3 is gonna be a Wima MKS4 1µF film cap. C3 isn't in the signal path so a MKS4 will suffice, there's no need for a more expensive and/or better one.

Because it ain't d.i.y. if you don't tweak and tinker I'm gonna add two small bypass caps to the 1µF caps (except C3). I still have two Vishay Roederstein MKP1837's 0.01µF caps in my parts box that I didn't use because the mini Aleph didn't require a low pass RC filter on the inputs. The MKP1837's fit nicely at the bottom of the B1 PCB. Adding these MKP1837's as a bypass cap can bring a nice improvement to the sound.

Tony Gee of Humble Homemade HiFi is very fond of these caps. I am too because I feel they make my LM3886 chipamps sound great too.

B1 PSU

The B1 buffer needs a power supply and for that problem there are a few solutions:
  • two 9 volt batteries
  • a suitable wall wart
  • a generic laptop PSU
  • a DIY solution

Two nine volt batteries can easily power the B1 for a long time since the current drawn by the B1 is very low. According to Nelson Pass it draws less than 0.02 Amps (that's 20 mA). Batteries provide a clean DC but tend to be empty when you need them most... Furthermore batteries are expensive.

A wall wart is a cheap option. Suitable wall warts usually cost only a few euro's, look in the sale bins at your local electronics shop. Wall warts however can suffer from ripple on the DC since cheap wall warts generally aren't regulated.

A generic laptop PSU is an option but they're not exactly cheap. Besides that they're also overkill, since they must be capable of supplying several amps of current. All those amps cost a lot of money.

So that leaves a DIY solution. This is what I'm gonna do. I've bought a Velleman K1823 kit. It's a regulated power supply that uses a LM317 voltage regulator. With the included trim-pot I can dial-in any supply voltage between 1.5 and 35 volts. Maximum current is 1 Amp, plenty for my application. I'm not gonna use all the parts in the kit though... Why not? Because this is DIY, that's why! The capacitors are Jamicon brand and these will be ditched  in favour of Panasonics (1µF and 10µF) and a 2200µF Vishay. The whole PCB is very small and combined with a suitable and small toroid transformer I'll have a nice DIY PSU. And since current draw is so low I might even get away with not using a heatsink for the LM317. The LM317 is supposed to be way better than the 78xx range of regulators. Hopefully this regulated PSU and the RC filter on the B1 itself and a ferrite bead on the supply wiring will result in a clean DC supply for the B1. Other B1 users have succesfully used this kit too BTW.

Wednesday, November 4, 2009

B1 buffer PCB

It's here! Absolutely stunning PCB, great quality too! Can't wait to get started. I'll have to find some nice caps for it first though. 

Sunday, November 1, 2009

RoHS

My 100 grams bobbin of solder which I bought well over 20 years ago was nearing depletion and I didn't want to be without solder during my project. So I recently bought some solder in a local parts shop in the center of town. Aha, lead-free solder. That's good, because lead is nasty stuff. It's  bad for your health and even more so for children. Read the Wikipedia entry. Enter RoHS, which stands for Restriction of Hazardous Substances. Pretty self explanatory really. We probably wouldn't have lead-free solder if the RoHS directive didn't exist.
Today however I went out to buy some solder... What! Again?
In essence lead-free solder is a good thing. There is however a catch. Lead-free solder just doesn't behave like old school solder does. It doesn't flow as good when melted and doesn't stick as quick as the old stuff. I had to grab my 60 Watt soldering iron for jobs that normally calls for my 15 Watt Weller®. Also it doesn't turn shiny as good old solder does when it hardens. I talked about my lead-free solder experiences with the salesman and he totally agreed with me.
So I came home with a 250 grams bobbin of Stannol® 60/40 Sn/Pb solder...