Baltimore Hackerspace Member Designs Modern Tube Hi-Fi System

A member of ours has been hard at work designing a really sweet modern/retro hybrid audio amplifier with a built in media center.  It’s open source, hackable, and sounds awesome.  He’s currently running a kickstarter to kick off getting them produced.  You can check out the kickstarter here.  I asked Jason to do a little writeup on his experience building the amplifier, and tell us more of the details inside.  He shares his experience below;

My name is Jason Perkins. I am co-founder of Tubecore and joined Baltimore Hackerspace in May 2013. I joined wanting to learn more about CNC machining and needed a home to prototype a project I had designed. The project started out as a modern tube amplifier built into a bluetooth speaker, but what I ended up with was a bit more.

A month after I joined I had completed the first prototype for my modern Hi-Fi audio system. Unfortunately, a week later it was destroyed by a rogue CNC at a friends house. The machine is called Kronos, is DIY and is the fastest robot I have ever seen up close. Kronos has a jog speed of 14” a second and that’s how quickly Kronos killed Duo v1.0. I highly recommend Kronos CNC to anyone looking for a Pro Level CNC that can machine billet aluminum and is advertised as being accurate down to .001” (1 mil.), while free jogging @ 14” a sec. I also highly recommend kill switches, since topping out the -z axis is what caused it to scare the crap out of me.

After we extinguished Duo v1.0, I used the opportunity to redesign and was able to make some huge improvements to the Cabinet’s engineering, the system’s design and peak performance.

The cabinets are solid hardwood. In this case African Sapele. The cabinet’s 7/8” thick main body is four pieces cut and mitered from a single board with horizontal grain that is matched all the way around. The face of the box is a burl mahogany and requires 38 precise machining operations to complete and features safe zones where additional sensors and optical hardware can be added.

The drivers are 4” full-range, composite cone drivers with machined aluminum horns and santoprene surrounds. They live in their own sealed enclosures, which are hand tuned for L-R balance and peak performance. I find these little reference-class drivers produce a big sound; warm mids and screaming highs. They reproduce clear audio from around 125Hz to well over 20Khz and are crossed at 120.

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Wrestling with Filament on your 3D Printer?

My Solidoodle 3 printer finally came in last week and I was able to pretty much plug it in and start printing. I immediately noticed that something needed to be done about the filament spool. With it being a new spool, the filament was just falling off  at the slightest turn on the PVC holder which was really annoying because that meant I had to babysit it. So with a small filament holder I found on thingiverse and some old folders, I was able to come up with a solution that allows me to hit ‘print’ and then just walk away until my print is done.

Laser Cut Jewelry Box


A few weeks ago one of our members (Mike) picked up the RedSaid X700 Laser Engraver from ebay.  Ordering and shipping of the engraver turned out to be a lot of trouble and very expensive.

Mike spent a few days soldering wires to the laser tube, aligning the mirrors and doing a few test cuts on various materials we had laying around the shop. Then he turned the machine loose for the rest of us to play with.

I decided that I wanted to make a gift for my daughter so I used SolidWorks to draw a Jewelry Box and then exported the files as DXF 2D Drawings. These were then imported into LaserMate  which is software that came with the laser engraver.

I designed the Jewelry Box to use 1/4″ Material. It turns out that the Birch wood and Acrylic from Home Depot says 1/4″ (5.2mm) but if you do the math a 1/4″ is not 5.2mm. So that material we had laying around the shop was not going to work for me.

Luckily, another member of ours had left over scraps of 1/4″ Baltic Birch which he purchases locally from Woodcraft.  I attempted cutting this wood but even at 100% Power, 2mm/s speed, and 4 passes I was unable to cut consistently all the way through the wood. Also, this wood is rather expensive. So I decided to look for other materials which I thought would cut easier but was still 1/4″ thick.

I learned about a place called Total Plastics, Inc. located on Pulaski Highway through Terry Kilby.  I stopped by their showroom and the nice man behind the counter gave me a piece of 1.4″ Cast Acrylic which was painted red on one side. I cut test patterns on this acrylic and I was surprised to find that was not cutting much better than the Baltic Birch. After roughly 10 hours of cutting pass after pass I was eventually able to make a Jewelry Box from the Acrylic.

I have come to the conclusion that the laser cutter needs some tweaking. It seems that the top left corner cuts okay but as you move down and to the right of the cutting area the laser is not as powerful.  My guess is that it has to do with the alignment of the mirrors but I have not looked into the problem yet.

After many hours of work I present to you my Jewelry Box.