Why not move the original IR-receiver to the front instead of using a mega168 for such easy task?

Considering you need one pin for the receiver (those things have 3 AFAIK…i’d go for Vcc, Gnd and Data) and another one for the IR-LED, only four of the pins of the 168 are used (Vcc, Gnd, Receiver Data and IR-LED pin). Even if it’s not possible to replace the original IR-receiver, you could’ve used an AtTiny13 or something like that.

Other than that…really cool project

You need to read the article to determine why he used an Atmel:

“There is an IR sensor behind the cloth of the right speaker, which is processed by an ATMEGA168 microcontroller. Signals destined for the amplifier (Master Volume, etc) are repeated on an IR LED temporarily taped to the amplifer’s remote input. Signals that target the digital music player (track forward, etc) will be passed to the computer over USB (this functionality is not done yet).”

Thanks for the comments.

Nomad,
As js said, there are other functions that the microcontroller handles, so in addition to just repeating the IR codes, it will also communicate over USB with the computer, over SPI with the digital pots and PWM some LEDs for feedback. It also filters and reroutes the commands. ATTINY13′s can’t do all that at once. Additionally, there are IR code/decode libraries specifically written for ATMGEA168. The cost difference between chips definitely isn’t worth the development cost for a one-off piece like this

lwatcdr,
Good idea of a FM tuner, but all the stations I listen to stream over the web anyway. I considered streaming the turntable through the computer, but it doesn’t have a digital input, so I’d be adding a pair of A/D-D/A conversions which I’d like to avoid. It would facilitate ripping, though I’d prefer to leave that to the studios.

Abbott,
That’s the idea, I had assumed that the thin wooden rails that support the turntable shelf would have enough springiness but that turned out not to be the case. It’s been suggested that neoprene makes for a spring with some damping.

You could try putting the turntable on spiked feet. Other than that i wouldn’t worry about vibrations.

PS: what’s the impedance of the woofer?

@JS @Travis
http://www.lirc.org/

IR Support for Linux.
You can read IR remotes and transmit IR to devices with this library.
No need to interface the AVR through USB to the PC and you could add a web interface to the amp just as you intend to do. Hey you got a lot more CPU than you need just to play audio so why not use it.
Did you a USB hub near the turntable? You could then allow it to stream from USB drives as well as network shares and or a local drive if you added one.

@Travis you are correct. BTW you may want to use wake on ring or wake on modem if that board supports it.
You could have the remote micro toggle it and have the board wake-up and sleep instead of powering it all the way down.
You should just have to toggle the RI on the ITX boards serial port.
You could also interface it through the RS-232 port and not worry about using USB. Serial tends to be a lot simpler from a programing point of view.

BTW you could control the SPI digital pots from that board without the AVR.
Linux has SPI drivers that work over the printer port.
http://cateee.net/lkddb/web-lkddb/SPI_BITBANG.html

The only thing that is keeping the micro in at this point is the power use which is a valid issue with that mother board. The other option would be an IR detector that would toggle the RI line whenever it saw IR. Not very elegant but could work.
BTW I am not being critical just find the problem solving fun.

@echodelta,
Contrary to Mike’s writeup, the point of this mod wasn’t to pack in a lot of power, so the amplifier won’t be pushing its power rating. That being said, the original amp was rated for 105 W (consumption); I’m sure the speakers can handle more than 10 W. I expect excessive bass will be evident as distortion well before there’s any damage.

The speakers aren’t really open-backed, the back is just removed for pictures. There are some pretty huge vents, though, but they could be blocked if I need to change speakers.

@jim
The woofers are 8 ohm. Regarding mounting the turntable on cones, that would we counterproductive. Those spikes help to couple two surfaces where I want to decouple the turntable from the cabinet. If anything, it might be useful to put spikes between the cabinet and the floor to couple the structure to the mass of the building.

@Fallen
I don’t want to be too hard on the diyaudio guys because there’s a lot of good stuff on there on other topics, but their advice on vibrations has to be taken with a grain of salt. It’s half good engineering and half self-delusional witch-doctory and passions often run too high to easily determine which is which.

This is so weird! I was thinking about this kind of project over the weekend for my grandmother’s old phono. So, what about upgrading/hacking the S/PDIF out section of the turntable? Or maybe getting a better table altogether? I don’t know how much the Stanton weighs and I know Technics doesn’t make S/PDIF out tables (last I checked) but those 1200′s are time tested and HEAVY. Great isolation.