DIY soundbar for TV?

Discussion in 'The Projects Forum' started by MikeML, Nov 15, 2015.

  1. MikeML

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    I fished a dead Polk PSW100 subwoofer out of the dumpster. Enclosure, speaker, and power supply are ok, but the amp is toast. Since the schematic for the amp is made of unobtainium, I'm thinking of just replacing the amplifier with one of many available Chinese amplifier kits available on EBay, like this one

    Anybody have any experience with these? How about the Class D version like this one?

    I can handle the active lp filter for the subwoofer. I'm thinking of adding two more amps for Right and Left Channels. I have the speakers.
     
    Last edited: Nov 15, 2015
  2. joeyd999

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    Get an amp board with built-in bluetooth in addition to standard audio. You'll be happy you did.
     
  3. MikeML

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    What would I do with BT? I have never used it for anything.
     
  4. joeyd999

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    Neither did I. Until I did.

    I've got a cheap Chinese 100W BT amp I use to run a set of patio speakers. The convenience of being able to run audio from my phone or laptop without the need to plug in is awesome.
     
  5. GopherT

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    Just buy a little belkin BT adapter (or Chinese knock-off). Plug into Aux input and done.
     
  6. crutschow

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    I've had no direct experience with the Chinese units but the Class D unit looks like it should work well for a subwoofer.
    For the right and left channels I would select a linear amp since they likely have less distortion (although not necessarily) than the Class D units.
    What would you use power them?

    Although more expensive you might want to consider a plate amplifier such as one of these, which includes the LP filter, phase shift circuit, and power supply.
     
  7. wayneh

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    Give that some thought. A proper home theater setup should send mostly the LFE channel to the subwoofer. Some additional bass from any channel might also be sent to the subwoofer, but spatial localization is not much of an issue with low frequency. It seems to come from everywhere, more or less regardless of where the speakers are located. I guess what I'm saying is that I might be more interested in a single, more powerful amp than in worrying about maintaining stereo information with multiple amps.
     
    Last edited: Nov 16, 2015
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  8. GopherT

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    I was wondering if a strong class D amp could be made from an ATX power supply. Drive several speakers in parallel to get the most of a 12 v rail. Anyhow, I was wondering if the voltage reference (commonly a small shunt regulator) could be replaced with a bias voltage and a capacitively coupled audio signal. Or, better, keep the voltage reference but cut the reference in half - add a resistor between the reference and the Pwm chip and then feed the audio into the node between PWM chip and resistor that connects to the reference voltage.

    The class D output would be filtered by the array of voice coils in the speakers. I'll have to look into this - or first read your comments.
     
  9. wayneh

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    BTW, I saw the movie "San Andreas" recently and (spoiler alert) the scene where the Hoover Dam fails is perhaps the best demo sequence for a subwoofer I've ever seen. One of my other favorites is the scene in 3:10 to Yuma (Russell Crowe's remake) when the train pulls into town and the ensuing gun battle. Awesome home theater goodness! :)
     
  10. GopherT

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    I hated that scene. The bad guys shot a thousand bullets and couldn't hit anything. The two good guys hit everything they looked at.
     
  11. joeyd999

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    'Bad' shooters are 'bad' guys. Sine qua non.
     
  12. R!f@@

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    It's not a the shooters fault. It's the Script's fault.
     
  13. wayneh

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    That pretty much defines most of TV and Hollywood. Think Stormtrooper versus Jedi.
     
  14. nsaspook

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    One of my fav bass demo is Master & Commander (DVD) : The Far Side of the World

    The ships in fog cannon blast sequence is unreal but I'm a movie bass junkie with lots of power, LFE parametric equalizer, 4 12'inch subs and subsonic transducers so my ideas about a soundbar might be a little warped.:D


    Transducer platform. (flipped up)
    [​IMG]
    [​IMG]
     
    Last edited: Nov 16, 2015
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  15. R!f@@

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    Hey Jedi uses the force..!
     
  16. MikeML

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    Ok, back to my project...

    I appreciate the link to the plate amp; I can easily just restore the existing sub-woofer with one of those...

    I looked at the TV (Samsung) , and it has just two audio output connections: one is an 1/8" stereo jack and the other is an Optical Digital Audio output.

    I presently use the 1/8"analog audio output jack to feed wireless headphones, and that is line-level L/R stereo, but it is not muted, nor is its volume controlled by the normal TV remote. If I turn down the TV's speaker volume, the headset volume is not affected. If I push the mute button, the headset volume is not muted.

    If I use the 1/8"analog audio output jack to feed a DIY soundbar, I would have to put an IR remote detector/decoder in it just to intercept the remote's volume Up/Down and Mute signals. Sigh... What I don't want to wind up with is YAFR; (yet another #$&^% remote)!

    I know nothing about the Optical Output, particularly if is volume-controlled, and mute-controlled, or if I would still require the IR receiver...

    It looks like I may have to buy a complete soundbar that includes the optical link, and hack it to connect my own speakers???

    I was hoping to avoid buying a five channel AV receiver, because all I need is L and R, and the subwoofer..., and I dont want its heat, cost, size, and YAFR.
     
  17. wayneh

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    The optical digital output is unlikely to be controlled by the TV volume control. Mute could go either way.

    Is it possible that the analog output may be set to follow the TV's control? It's surprising to me that it's not controlled.
     
  18. crutschow

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    Some TV's have an option in their setup menu where the analog stereo output can be either fixed level or controlled by the volume control.

    Edit: Alternately one of these might work.
    You might be able to use a Universal Programmable Remote to eliminate YAFR.
     
    Last edited: Nov 17, 2015
  19. eetech00

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    Just to give you idea..
    I have a PA system with a substantial speaker system. It has a mixing console with tape input/output jacks. I bought a BT device that connects to the tape input jacks.
    Now I can send audio from any device that can transmit BT stereo audio (like my IPhone) to the PA. You could do the same with your optical output. Adapt to BT and send audio wirelessly to a BT stereo audio device (like a subwoofer with BT reciever capability)
     
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