Audio cabinet refit with modern equipment

Hard at work on making this 1960′s Fleetwood audio console usable again, [Travis] packed a lot of power into the retro case. Both the radio and turn table had stopped working but the cabinet looks great and the speakers still work. In the lower center cavity you’ll now find a full computer motherboard and replacement amplifier. A new turntable has been added with an interesting vibration-dampening shelf to support it. [Travis] built the shelf with a void in between two layers of wood which he filled with sand to help with isolation. The remote control for the amp also needed some work as the receiver is pointed to the back of the unit. To fix that a second IR receiver found a home behind the fabric for one of the speaker grates. That receiver is monitored by an ATmega168 microcontroller and signals are repeated back to an IR LED mounted near the amplifier.

Comments

  1. Nomad says:

    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

  2. lwatcdr says:

    Pretty and kind of cool but.
    If you are going to use a full PC in this I have a few suggestions.
    1. Add an FM USB stick. You can also get an AM/FM USB device but I am not sure they have Linux drivers for it.
    2. Run the Turn table through the PC. The better to rip your records plus you could stream the turn table to other devices.
    3. There is IR blaster software available for Linux so you could use the PC to handle the IR duties that you are using the ATMega for.
    The sound dampening is going to be the hard one. Good luck with that.

  3. js says:

    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).”

  4. Abbott says:

    Nice looking rebuild. I like the fact that he has the (new) turntable in there and that he kept the old speakers. No need to fix what’s not broken. To solve the feedback problem, I would probably attempt to suspend the turntable shelf with some springs. Though I’m not an expert by any sense of the imagination with acoustic dampening.

    Great job!

  5. Travis says:

    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.

  6. Fallen says:

    +1 for neoprene as damping.
    Might want to check the DIYaudio.com forums. Those guys are always looking for ways to isolate turntables from vibration

  7. jim says:

    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?

  8. SelfSilent says:

    Surely it would have been easier, cheaper and quicker to run a short length of fibre optic cable from the amp IR receiver and channel it to the front of the cabinet.

  9. lwatcdr says:

    @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.

  10. Travis says:

    lwatcdr:
    I still plan to have a preamp and mixer controlled by the remote, so I’d still need something to interface between the computer and the digital potentiometers’ SPI.

    Having the remote parsing on the uc also allows the computer to be an optional part of the system, so it can be shut down by remote via the uc, drawing orders of magnitude less power while not in use. I don’t believe you can wake my computer with a USB remote, but I should be able to wake it by connecting the power button to the uc.

  11. lwatcdr says:

    @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.

  12. echodelta says:

    I hope the amp is no more than 10w per channel. Modern bass production and a 50w amp will kill the vintage high efficiency spkrs. Most modern replacements will not work in the open back mode either. Put a real tuner in it and use a real antenna, no webstream can do justice to a good analogue station. We lost a venerable hifi AM station to “hd”. A good car radio is the cheapest and best way to go. It will mount where the original was, and have the right power. Some even have remote.

  13. Travis says:

    @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.

  14. Masta Squidge says:

    @ Travis. That last bit is exactly why I have so much fun arguing with people who think they know car stereos. You can always tell someone who has never actually looked into anything they hear because they think capacitors are the solution to voltage drops.

    Then when you ask them how many alternators they burned up they give you a number and blame the “high powered Pyle amplifier” that they are using. Usually followed by claims that they are running like 3 thousand watts.

    When presented with a multi-PAGE article on why caps are worthless, with solid math and everything, they claim real world experience makes proven math incorrect.

    I have a severe dislike for (most) people with many years of experience in the “hobbyist” category of most technical things. Usually no amount of proof will make them shut up.

  15. Bill says:

    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.

  16. lwatcdr says:

    Hey if you want to add FM..
    http://hackaday.com/2010/09/21/small-and-simple-fm-radio/
    It uses I2C or SPI so you could use the AVR to control this as well.
    I want one of these that supports HD Radio as well as standard FM but this might work for you.
    You could run this right into the audio in of the amp or you could run it into the audio in of the M1000.
    Using the audio in of the M1000 would give you the option of creating a radio TVIO type deal. You could have it record audio at specific times or allow you to rewind and or skip commercials.
    Of course then you would have to have the ITX running to hear the radio. The other option would be to switch inputs using the micro but the user interface for that might get to complicated for it to be of any real use.

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