Here are where I will place my witterings on matters geekiness. 

 

Restoration of a Kennedy Model 20B Console Radio

image  I stumbled upon this beautiful project whilst browsing the web today.  This restoration by Greg Charvat takes a very ornamental and indeed ancient Console Radio and sympathetically brings it back to life.

The temptation with projects like this is to replace on a wide scale components with new parts.  However Greg has kept some of the original capacitors, all of the original resistors and more. 

The description of the wiring as crumbling gives a very good reason not to power up a device of this vintage until you have an opportunity to inspect the internals, these valve devices have some mighty voltages inside and electrical safety (i.e. grounding) can not be assumed to be up to Today’s standards…

I have to admit that I am looking for a restoration project for myself… It seems though that so is everyone else.  E-bay auctions seem to go skywards for any interesting vintage tube amps…  Ahhh one day!

Restoration of a Kennedy Model 20B Console Radio

SparkFun Electronics Hits Legal Problems with Bully SPARC International Over Trademarks.

imageI don’t like bullies, no-one does I hope.  I was disappointed to read today that the good folks over at Sparkfun Electronics, a company that produces and sells open source hardware popular with electronics hobbyists.

SPARC International originally formed by Sun Microsystems has launched a legal shot over the bows of Sparkfun with a Cease and Desist letter from their solicitors.  The demand is that they stop using their Sparkfun trademark (which they have traded under now since 2003) and hand over their website to SPARC.

The argument is that Sparkfun sounds and looks too similar to SPARC.

SPARC Industries position I think is bizarre.  Their solicitor states that Sparkfun is selling computer hardware, they don’t in the conventional sense.  Apparently their is not a legal distinction between a servers architecture and that of an integrated circuit board.

If you too feel that Sparkfun are being hard done to here, please feel free to mail SPARC International at This email address is being protected from spambots. You need JavaScript enabled to view it. to voice your displeasure.  Sun Microsystems (for their brand is synonymous with SPARC, and indeed they are part of the group) and SPARC International  should take a look at the bad feeling that Monster Cables has generated web wide with their bullying legal tactics.  Ill advised and bullying behaviour on their part has no doubt lost them millions of pounds worth of sales globally.  In a competitive industry can SPARC International really risk their reputation on a frivolous legal action?

Read more at the following link…

SparkFun Electronics - News - 2009.10.23

DIY ProAc Response 2.5

mvc-004s This is a do-it-yourself (DIY) version of the ProAc Response 2.5 which was one of the most famous speakers in its class made from around 1996 to 2003. This model was replaced by a new model around 2003 called the Response D25, which uses different driver units but still in a similar two-way floostanding concept.

The Response 2.5 is considered to be one of ProAc's most successful and famous designs and is a modern testament to the skill and voicing of it's designer Stewart Tyler of ProAc. It is perhaps among the most full range 2-way floorstanding conventional cone loudspeakers in it's class and is still an excellent sounding speaker even by current standards.

Read more: DIY ProAc Response 2.5

Poddwatt Class-A Stereo EL84 (6BQ5) Vacuum Tube Amplifier

image Over at DiyAudioProjects, Bruce Heran of OddWatt Audio has shared another one of his Tube Amplifier designs.  The project is based heavily on a previous design, but Bruce has worked to reduce the need for expensive large transformers in this design.

This should make it a little more accessible to a hobbyist looking to add a great sounding tube amplifier to their system.

Outputting 5-7W of clean power this design should suit nicely a set of sensitive speakers. Bruce has improved on several circuits over his previous design. 

The amp construction is a mixture of point to point wiring and vero-board mounted components, click the link below to see more of the construction as well as schematics…

Poddwatt Class-A Stereo EL84 (6BQ5) Vacuum Tube Amplifier

Sonik Sound Dock

 image Jarek Lupinski created an active loudspeaker for use with his I-pod in this little project.  He purchased a cheap centre speaker from a Goodwill store and adapted it for passive use.  Using a LM4950 - 7.5W Mono-BTL or 3.1W Stereo Audio Power Amplifier chip from National Semiconductor running in DC mode as his source, this powered speaker is capable of being powered by batteries. 

The plastic speaker case and low power means I can’t imagine this project as reaching the higher echelons of High Fidelity music, but it is probably as capable of any of the standard commercial offerings.  Jarek built this with loose change scale funding and gets the satisfaction of building his first chip amp!

Read more at Jarek’s site…

Sonik Sound Dock

Simple Passive Load With Measurement Points

image Over at his site Krzysztof Marcinek has a simple little project that should be of interest to anyone who is thinking about amplifier construction.   He has built an elegant and useful little tool.

A passive load is pretty much just a pair of resistors that emulate the impedance of a set of speakers.  They give you the benefit of being able to test an amplifier without fear of destroying or damaging your precious speakers. 

Because these passive loads are designed to take amplifier output sized voltages and current, the resistors have to be pretty hardy to avoid burning up.  Personally I use resistors with large aluminium clad resistors to load test my projects. 

My analogue scope is able to withstand large voltages, but Krzysztof is using a computer soundcard to conduct measurements.  In his design he includes a low voltage output by using a stereo variable resistor to divide the voltage from his test amplifier. 

What’s very impressive is the construction that Krzysztof has applied to what is for most a common tool. (my passive load is simply a CPU heat-sink with the resistors tie wrapped to it!).  Check out his site for more information…

DIY, audio, electronics...

25 Microchips That Shook the World – What About the Audio Contenders?

image  Over at IEEE spectrum Brian Santo has an article about the silicon that has a massive impact on the electronics world.  Its an interesting article that I am afraid makes me feel old.  Born in the 70’s, I am very much a child of the digital generation. 

It’s fair to say that the innovation that I have experienced in my relatively short life has been dramatic.  I can think back to a time before push button telephones, answer-machines, mobile phones, portable music players, the boombox, streamed audio, internet access and a whole host of other “Tomorrows World never warned us about that” inventions

On the Audio front, Brian identifies several IC’s as being important:

  • Fairchild Semiconductor μA741 Op-Amp (1968)
  • Micronas Semiconductor MAS3507 MP3 Decoder (1997)
  • Tripath Technology TA2020 Audio Amplifier (1998)

I think that the list has a major omission.  Whilst an MP3 decoder makes it into the 25, I think a more key invention is the Digital to analogue converter.  MP3 is one thing, but would we have ever got to this point in the history of digital media without the humble CD.  Should a Wolfson, AKM or Philips Dac chip not be in this list?

I think if we were to compile an audio only list I can think of a few more classic Microchips that would would be vying for space in the top 25.  Which would you put in there?

IEEE Spectrum: 25 Microchips That Shook the World

20% Discount on Kits at Chipamp.com

imageBrian over at Chipamp.com left this message on his site,

“ I have put up a new special, 20% off all kits. I will keep this special up until the end of the month.”

Chip amps are fairly simple circuits and can be made without a PCB with little to no experience of electronics building, however some prefer to stick to a kit for their first build.  Advantages are that you get to hear a tried and tested design.  This can serve as a benchmark for your next project

If you are thinking about dabbling in creating your own Gainclone type amplifier, a kit certainly makes things a little easier.

Brian has kits based on the lm3886 and lm1875 amplifier chips made by the daddy of integrated amplifier chips, National Semiconductor.  Now all you need is a good power transformer and a couple of reduced price kits….

DIY Chip Amplifier Kits, PCB's, Components and Information.