A Nicely Designed Stereo Tube Amp

tube amp

Most of the work that [Ron] has done in the past with vacuum tubes and solid state electronics has been repair. At 59 years old, he finally put together his own stereo tube amplifier and we have to admit it definitely has an awesome look.

The platform is built around the well-known 6V6 beam-power tetrodes which are mostly used by major audio brands for their guitar amplifiers nowadays. The Dynaco 6V6 circuit based PCB was bought from China and minor changes were made to it. The amplifier uses one transformer to convert the US 120VAC into 240VAC and 9VAC, the first being rectified by a glassware PS-14 power supply while the later is converted regulated at 6.3V for the tube heaters. The output stage consists of two Edcor audio transformers (one for each channel) that converts the high voltage for its 8 ohms speakers. The home-made chassis provides proper grounding and as a result you can’t hear any background noise.

We are very curious to know if some our readers have been experimenting with glass tubes for audio applications. Please let us know your experience in the comments section below.

Raspberry Pi Bluetooth Receiver for your Car Stereo

RasPi Car Audio

The ability to play music in your car over a Bluetooth connection is very handy. You can typically just leave your phone’s Bluetooth module turned on and it will automatically pair to your car. Then all you have to do is load up a music player app and press play. You don’t have to worry about physically tethering your phone to the car every time you get in and out of the vehicle. Unfortunately Bluetooth is not a standard option in many cars, and it can be expensive to buy an aftermarket adapter.

[parkerlreed] built his own solution to this problem using a Raspberry Pi. He first installed arch Linux on his Pi. He also had to install pulseaudio and bluez, which is trivial if you use a package manager. He then modified some of the Linux configuration files to automatically bring the Pi’s Bluetooth adapter online once it is initialized by the kernel.

At the end of the boot sequence, the Pi is configured to automatically log in to a virtual console as [parkerlreed’s] user. The user’s bashrc file is then altered to start pulseaudio in daemon mode at the end of the login sequence. This allows the Pi to actually play the audio via the Pi’s sound card. The Pi’s stereo output jack is then plugged into the vehicle’s auxiliary input jack using a standard audio cable.

The Reddit post has all of the configuration details you would need to duplicate this setup. [parkerlreed] also includes some commands you will need to setup the initial pairing of the Raspberry Pi to your smart phone. Be sure to watch the video demonstration below. Continue reading “Raspberry Pi Bluetooth Receiver for your Car Stereo”

Stealth Bluetooth Stereo: It’s a Jeep Thing


[Feueru] wanted to update the sound system in his 1998 Jeep Wrangler. The problem is that soft top Jeeps are notorious for radio theft. His solution was to build his own stealth bluetooth stereo. The music comes from his Nexus 5 via bluetooth. A Fusion MS-BT 100 waterproof bluetooth receiver picks up the tunes. From there the signal is passed through the one external control, a line level volume knob. A “BMWx-43 300 Watt” amplifier provides the power to drive the Jeep’s speakers. We’re a bit dubious about the 300 Watt rating, as well as the “Only from the mind of a German” catch phrase. Hey, at least the real BMW didn’t have the amplifiers destroyed at the US port due to trademark issues. 

[Feueru] used a standard DIN radio install kit for his Jeep. In place of a headunit, he glued an ABS plastic sheet. The ABS provided a good place to mount his volume control. That volume knob was a bit lonely, so [Feueru] added “Plan B”, his winch controls. The final result looks… well, it looks like a single knob, which is exactly what [Feueru] was going for. Any would-be car radio thief would pass this right by. The only thing missing is an actual FM receiver. Sure, there is a bit of loss when using a bluetooth audio path. However, this is a soft top Jeep with stock speakers, so it’s really not noticeable to [Feueru].

[via reddit]

SoundCube: A Companion Cube that can Talk


The Enrichment Center likely disapproves of the SoundCube: a portal music box in the form of a Portal Companion Cube. [Andreas] finished this project a couple of years ago, but we’re glad he’s finally had time to give a rundown on the details at his blog.

The build is primarily a modified speaker box cube—constructed out of what appears to be MDF—with four Alpine SXE-1725S speakers placed at the center of the middle faces. The faces were routed out to resembled the Companion Cube, while the electronics mount and the speaker grills were 3d printed. Inside is a homemade amplifier built around an Arduino Mega, with a TDA7560 quad bridge amplifier, a TDA7318 audio processor, a Belkin bluetooth receiver, and a 3.5″ touchscreen for volume control and for input selections.

Two 12v 7.2Ah lead-acid batteries keep the cube functional for an entire weekend of partying, but probably add a few pounds to the already hefty MDF construction. Check out [Andreas’s] blog for more pictures and his GitHub for all the necessary code.

A Retro, Not Steampunk, Media Center

[toddfx] wanted to put his Raspberry Pi to work and set about creating one of the best stereos we’ve ever seen: It’s called the Audio Infuser 4700, and turns a conglomeration of old disused stereo equipment into a functional piece of art.

[toddfx] used a Raspberry Pi to stream music over WiFi, but also wanted to play some classic vinyl. He took apart an old Yamaha YP-D4 turntable. stripped it to the bone, and created a fantastic oak enclosure around it. To this, he added a seven-band graphic EQ, aux jacks (both in and out), and a tiny 5″ CRT from an old portable TV.

Where this build really gets great is the fabrication. The front panels have all their graphics and lettering engraved via a toner-transfer like method using copper sulphate and salt. [todd] got the idea from this thread and we have to say the results are unbelievable.

Even though this awesome device only used for music, [toddfx] used the tiny color CRT to its fullest. Flick one switch, and it’s an oscilloscope-like display. Flick another switch, and it’s the output of the Raspberry Pi loaded up with a few MAME games including Pacman, Asteroids, and Space Invaders.

[toddfx] put up a build page for his Audio Infuser and an awesome video for his project, available below.

Continue reading “A Retro, Not Steampunk, Media Center”

Adding stereo to monophonic audio


A lot of awesome stuff happened up in [Bruce Land]’s lab at Cornell this last semester. Three students – [Pat], [Ed], and [Hanna] put in hours of work to come up with a few algorithms that are able to simulate stereo audio with monophonic sound. It’s enough work for three semesters of [Dr. Land]’s ECE 5030 class, and while it’s impossible to truly appreciate this project with a YouTube video, we’re assuming it’s an awesome piece of work.

The first part of the team’s project was to gather data about how the human ear hears in 3D space. To do this, they mounted microphones in a team member’s ear, sat them down on a rotating stool, and played a series of clicks. Tons of MATLAB later, the team had an average of how their team member’s heads heard sound. Basically, they created an algorithm of how binarual recording works.

To prove their algorithm worked, the team took a piece of music, squashed it down to mono, and played it through an MSP430 microcontroller. With a good pair of headphones, they’re able to virtually place the music in a stereo space.

The video below covers the basics of their build but because of the limitations of [Bruce]’s camera and YouTube you won’t be able to experience the team’s virtual stereo for yourself. You can, however, put on a pair of headphones and listen to this, a good example of what can be done with this sort of setup.

Continue reading “Adding stereo to monophonic audio”

SqueezeBerry: a Raspberri Pi powered Squeezebox appliance


We like the look which [Emmanuel] achieved with his Raspberry Pi based Squeezebox client. It’s got that minimalist slant that makes it seem like a commercial product at first glance. But one more look at the speakers without grates, the character LCD, and the utilitarian buttons, knobs, and switches tips us off that it’s filled with the hardware we know and love.

Since Logitech announced that it was terminating the Squeezebox line we’ve seen several projects which take up the torch. We’ve seen the RPi used as a Squeezebox server and several embedded Linux systems used as clients. This follows in the footsteps of the latter. The RPi is running Raspbian with the squeezelite package handling the bits necessary to talk to his server. The controls on the front include a power switch, rotary encoder and button for navigating the menus, and a potentiometer to adjust the HD44780 LCD screen’s contrast. The speakers are a set of amplified PC speakers that were liberated from their cases and mounted inside of the wooden box that makes up the enclosure. The in-progress shots of that case look pretty rough, but some sanding and painting really pulled everything together. As you would expect, we’ve embedded the demo video after the jump.

Continue reading “SqueezeBerry: a Raspberri Pi powered Squeezebox appliance”