Ipod Line Out Dock (Turbodock)

Discussion in 'Headphones, Earphones & Portable Music' started by kevH, Mar 16, 2006.

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  1. kevH

    kevH
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    Just thinking aloud here...

    Browsing the Apple store i noticed that they sell the radio remote which connects to the bottom of the Ipod Video and Nano. Its been reported that the SQ thro this connect is better than thro the headphone out. Is this maybe as reported that the remote has its own codec and amplifier??
    Anyone any experience of its use linked with "decent" phones and not the stock buds its supplied with.

    Also thinking aloud here ... why cant you buy something like the "turbodock" or others now folks are making and linking with the volume adaptor as supplied with the likes of the Shure E4's and using that way thus possibly getting better SQ. I mention this as i seem to be able to control the Ipod's volume from the scroll wheel when its actually docked in the Universal Ipod dock so why not thro what would then be just a headphone line out adaptor.
    This would then free me up from "lugging" a headphone amp about, i know the sound will not be as good as Ipod>Amp>phones but maybe an in between house.

    In essence is it the amp etc in the remote that apple supply that gives it the "improved" sound over straight headphone out to phones ???

    Any thoughts reasoning??
     
  2. extremelydodgy

    extremelydodgy
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    The Turbodock simply taps the analog Line Out (and a Sendstation Pocketdock USB is a better product in any case). The 5G also has pin-outs for tapping the digital signal for interfacing to a codec. The remote taps this.


    Example of a codec and what it does: http://www.wolfsonmicro.com/products/digital_audio/codecs/WM8750/


    The remote's codec is the same one used for the headphone out. There could however be a change in the circuitry surrounding the codec. It could be placebo, could be something else. I haven't done proper comparisons yet. Will post when I do.
     
  3. mattals

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    what is a turbodock !!
     
  4. kevH

    kevH
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    Its an adaptor that utilises the line out (the bottom connection) of the Ipod with a headphone out that you can connect to a headphone amp and then to phones. Supposedly gives better SQ when hooked up this way.

    For info of the guy who makes them look at fixup.net , there are others who make these type of connections try browsing the head-fi.org forums where its well documented and discussed.:smashin:
     
  5. kevH

    kevH
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    This seems, in my view, to throw the cat among the pigeons regarding the line out / headphone out which is better in terms of SQ debate quote...

    "To those who hear the SQ difference, it will be helpful to look into how Apple designed the line-out and headphone out in the 5G.

    Below is part of the DAC WM8983 signal path diagram referenced by the Rockbox developers. It has appeared to be identical to the speicifc CODEC used in 5G. You will see both the line-out (LOUT2/ROUT2) and the headphone out (LOUT1/ROUT1) are all branched out from the same signal paths out of the CODEC.
    All D/A conversion and amplication are handled by the CODEC. The output signals are then shared by the headphone and the line-out. Apple simply fixes the line-out at 0dB, and EQ remains functional in both.

    This fact confirms my experience with no SQ difference in the headphone out and the line-out. I would imagine for those who can hear the difference, they must have very sensitive ears or perhaps due to other reasons.

    Here is the datasheet if you want more details about the CODEC."

    http://www.wolfsonmicro.com/uploads/.../en/WM8983.pdf


    Raises the question are there other reasons why most people find the line out better in terms of SQ or is this a placebo effect, not that im doubting peoples ears of course. Would be just interested to know.

    I was myself tinking of buying a turbodock or even the Apple remote to enhance the sound now im thinking twice.
     

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  6. extremelydodgy

    extremelydodgy
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    The analog line out presented with the likes of the Turbodock or the Sik Din, Sendstation Pocketdock US, etc is simply a volume-fixed clone of the headphone out. Comments for the Pocketdock (handy as it is) / Turbodock being better on the 5G than amping the volume-fixed (it's not quite maximum volume) headphone out, or one being better than other is placebo.


    What you get out of the Universal Dock and the Radio Remote is different because they take the digital (once again, non-SPDIF, don't get too excited) feed from the iPod and then use a built-in codec on the accessory to translate that into analog. Simply put, the codec is basically used as an integrated DAC / amp / volume control.


    And as far as I'm aware, the codec used on the iPod headphone/analog line out, and the codec used on the remote and the universal dock are identical. So if they do sound different, the sound would depend on what is around the codec as well as the codec itself. There's all sorts of potential parameters for a difference in sound: e.g. Codecs work at a variety of voltages and they could be being fed differing amounts of power.


    Once other thing I have noticed is that many people interpret some differences as better, simply because it's different. Is it placebo? We'll see, it's something I don't suffer from these days. I'll probably get around to a comparison this weekend.
     
  7. kevH

    kevH
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    Thanks Dodgy looks like from what youve ascertained there will be no difference in amping my Ipod thro the headphone out or thro the line out. To be honest ive tried both and i cant hear any difference at all. Maybe thats my ears who knows ? it just seems the placebo im taking isnt the same strength as some others !! :D

    For portability tho it maybe better, instead of lugging the amp around, just to buy the remote which as you say has a built in codec and maybe some form of amp ? is the way to go ? Maybe ill give that a go and see what the results are.

    Sounds to me like , for those who use headphone amps, that the sendstation/turbodock et al are surplus to requirement as the sound from the headphone out is no different. Is that right in my way of thinking ?

    I do , however, notice a very considerable difference in headphone out to phones against my little amp in the middle.:smashin:

    I do also notice a very noticable difference in my bank balance after listening to you both here and at head-fi LOL
     
  8. extremelydodgy

    extremelydodgy
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    Well not exactly. In order to get the same signal as the Line Out, you have to set the volume of the headphone out to just-below-full volume. It's not possible without practice to get the exact level even if you do know it (the iPod's volume control is as you know unnumbered). From just a practical point of view something like a Pocketdock is handy to have (not only a line out, but also a standard USB socket to boot). A Turbodock... less so IMO.


    Now whether the remote headphone socket is better to amp than the regular headphone socket is a question I can't answer yet. It's not something I thought about testing but I might as well anyway since I'm testing the dock.
     

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