Sunday 22 March 2015

Building a BK Monolith+ clone, a 500w RMS subwoofer

The BK subwoofers have a wonderful reputation:

  • Excellent components
  • BK is the OEM manufacturer for REL subwoofers
  • Attractively priced ; you are buying them directly from the OEM and they make virtually no marketing (except the word of mouth on the Internet)
  • They're UK built

Although everyone knows they're very well manufactured and excellent purchases... they come with a major issue: they forgot the wife acceptance factor. And the name "Monolith" certainly does not help. Which wife would want a huge wooden monolith sitting in her living room?

This was exactly the problem a friend of mine was facing: he quickly realised his wife would never agree with him spending the cash for a big block of wood sitting in the living room. This is the very reason why he asked me whether we could build one ourselves. He figured if he came back with a beautifully built subwoofer that he made himself, his wife would never dare to say no. And the story proved he was right.

Thursday 19 February 2015

Bose QC15 make an adaptator from a damaged cable and use standard 3.5mm cables

The connector can be easily opened
by sliding a thin blade on the side
The Bose QC-15 are wonderful headphones, no doubt about it. One of the things that bothers me is the silly connector: if the switch is useful to some people, its shape renders the headset useless unless you have and use the Bose's original cable. A 3.5mm female socket on the headset would have made the it compatible with any 3.5mm male/male cable and this is something I did not want to accept: for this reason I decided to hack an old broken cable to recover the connector and add a standard a 3.5 female jack where the cable originally was.

Sunday 4 January 2015

Repair burnt tweeters on B&W DM602 S3 speakers

The second hand market is filled with great audio gear. For example, last week I bought a high end Yamaha amplifier (DSP-A1, 5x 115W RMS) for only 18€ on eBay and just had to clean the volume potentiometer (I used this technique)!

This time I purchased the exceptional B&W DM-602 S3 speakers (on eBay as well) for 91€ with two defective tweeters. In good condition, these speakers sell for 200 to 300€ and replacement tweeters cost 75€ plus shipping so I guessed 91€ was a regular deal at worse.

First thing I did when I got my hands on them was to detach the tweeters: remove the woofer, the tweeter can be removed from the inside by twisting it. As expected, both tweeters were burnt and read 'open circuit' when measuring the resistance at the terminals.

Sunday 16 November 2014

Configure your WR703n with a switch (or two)

The TP-Link TL-WR703n is a versatile piece of hardware and very handy to have with you when you need WIFI connectivity... The problem is that you need to configure it to fit your needs every time.

This mod aims to re-configure it by the flip of a switch (or two):

  • Choose between WIFI Access point or client.
  • Choose between bridged or NAT/DHCP for WIFI & wired networks.

Wednesday 22 October 2014

Make your Raspberry pi b more power efficient with a cheap dc step down

Modified RasPi B with a buck converter

The raspberry pi b (the original one, not the b+) uses a linear regulator to bring the 5V down to 3.3V. That's a lot of waste: 33% of the power consumed by the pi is dissipated as heat here! A DC step down (buck converter) would definitely do better than 66% of efficiency. This would certainly improve the stability when running on a weak power supply and make it run much longer if on batteries. Without making any precise calculations, using a buck converter would make the raspberry pi consume somewhere between 20 and 30% less power (efficiency of about 90% vs 66%). Here is how I did it in 10mins for 1.29 USD:

Saturday 28 June 2014

Building a Wooden Ghettoblaster: Painting faux rust on the speakers (part 4)

This is the final post on how I built my wooden ghettoblaster.

While my previous my three previous building the front face, the enclosure and wiring it all), this post will describe the final touches I brought to this project: painting faux rust and quieting the fan of the cheap Chinese power supply.

Tuesday 29 April 2014

DUMMYRESEND scam on eBay: You will never receive a replacement for the item that arrived broken

Ten to fifteen years ago people were scared to buy on-line and on on-line auction websites such as eBay, thinking chances of never receiving the ordered items was high without any way to ever see the item or money back.

The web has now evolved and thanks to on-line communities any rip-off is now immediately documented (through direct feedback, blogs and forums). This means that and you usually get something for what you paid for. This does not mean that there are any loopholes and weaknesses in processes that unscrupulous sellers exploit. This article will go through what I call the 'DUMMYRESEND' scam which usually happens when you get a broken item eBay.