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Thread: Vox DA5 lineout modification - speaker bypass

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    Vox DA5 lineout modification - speaker bypass

    Hi. I've been searching to try to find out how to bypass the internal speaker cut off when using the lineout jack on the Vox DA5. It seems thata member on the forum has found the answer! Could someone please advise me on the detail of how to do this. am I right in assuming that the jack just breaks one of the lines (pos or neg) going to the internal speaker, If so, which contact in the socket? the one nearest the opening ie the first contact??
    I would really appreciate guidance on this as I need to use the DA5 as monitor close to my playing position.
    Many thanks in advance and regards and best wishes.
    Martin

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    Old Timer olddawg's Avatar
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    Difficult to say without a schematic or looking at it. It may simply require you to run a wire from some point on the board or Jack to one of the terminals (probably the negative) on the speaker. I would suggest putting a small toggle switch in series with it so you could take the mod in or out of the circuit. The speaker will be in parallel with the voltage divider for the line out/ headphone jack. One thing for sure. You don't want to accidentally short output amp.

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    Stray Cap DrGonz78's Avatar
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    There is a link to the schematic right here on MEF.
    http://music-electronics-forum.com/a...a5_amp_sch.pdf

    Edit: Also note I think this is the post that the OP is referring to about the line out mod. However, the member that posted has only 3 posts and very little activity here in general. Someone will know though how to make this mod.
    http://music-electronics-forum.com/t19187/

    Double Edit: I did find one link on youtube about someone who did this mod. You can always try to email him and find out what he did. Then bring the ideas back here and see if they are good ones.
    https://www.youtube.com/watch?v=SV4Kam9gJuY

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    Last edited by DrGonz78; 03-24-2016 at 10:50 PM.
    When the going gets weird... The weird turn pro!

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    i also found the youtube link but got nowhere withy it. Its a shame he didn't show where the attached wires went to! . I don't want to damage the circuit by using trial and error methods!!!

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    Yup - your last sentence worries me! How can I make sure I dont short the output amp (my electronics knowledge is minimal! I can solder connections but don't understand the technicalities!!!

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    Supporting Member Jazz P Bass's Avatar
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    I would strongly advise that you take the amp to a competent tech.

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    I'm sure you are right! Having looked at the schematic, It clearly is not a case of just making a by-pass switch!

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    Hi olddawg Looking at the schematic - it would appear to be complex . toggle switch may not do the job?? see schematic here DA5_amp_sch.pdf

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    Supporting Member Jazz P Bass's Avatar
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    What is confusing things IS that schematic.

    It is not complete.

    That said: the Line Out jack as shown is a "break" type switching circuit.
    When nothing is inserted into the jack, the signal passes on through to the power amp.
    When you insert the headphones, the signal no longer passes on.
    Hense, the amp speaker is muted.

    So what needs to be done is a switch needs to complete the 'broken' signal path.

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    Right, thanks . I'll see if I can locate the remainder of the schematic

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    Supporting Member Jazz P Bass's Avatar
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    Here is a crop from a VT80+.

    It shows the basic switching of the jack.

    Vox_Line Out_Phone.pdf

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    Old Timer oc disorder's Avatar
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    Here's some grabs from the movie .. I think the quickest way is to bridge all 3 contacts on the jack socket as shown in my Ben Hur diagram !
    Not sure on the contact arrangement with tip and ring so would advise a special lead for line out with tip and ring joined.
    On the printed circuit board the tip and ring switch contacts are joined.
    All this would mean would be that the speaker would always stay on even if you plugged in headphones!
    A triple pole double throw switch could be used to return the amp to stock.
    You would have to make sure of what switch contact was what !
    My numbering on diagram.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Old Timer olddawg's Avatar
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    How about this... Leave everything as it is and simply parallel a different/separate line out jack off of the speaker? A jack and a couple of resistors. Then you would have a headphone jack and a line out jack.

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    hi people :-) i'm new, just sign up just for this thread
    i have a second hand da5 and i love it! i'm using it with a dulcimer, playing french and italian dancing folk music mostly outside. i've already modded the amp (a new handle, a new strap, a 12v/10ah lead battery (ops-like) with his own switch.
    next step should be the reboxing next week or the next-next (so the thing will fit my backpack), but a line out without muting the speaker is a plus for me
    since the dulcimer is a very quiet instrument when i'm playing right next the accordion i'll be so happy to hear myself too, not only to be heard by the people in front of the amp (sorry for my poor english)

    question:
    can i go to a stage mixer with the line-out modded as oc disorder says (bridging the contacts)?
    next saturday my friends and i will have a gig with a real stage, a real mixer and so on, a very serious thing
    i wonder if with that mod i will be able to use the da5 like a monitor, since the speaker works, AND send to the mixer the signal already processed (the guy i play with told me i have to go straight to the mixer with the dulcimer's pickup cable, while i usually use the da5 to add a little bit of chorus and reverb)
    the other question is: when i play our "standard" gigs and the da5 is my only voice :-), i'd plug a headphone right in the same output, or in a 3,5mm socket (that i will add by myself) without impedance issues?

    thanks a LOT! and sorry again for my little english:-)

    matteo from italy

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    Last edited by tzenobite; 03-29-2016 at 10:06 PM. Reason: BAD english :D

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    Thanks for your help on this

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    Hi I just signed up!!! I have the same issue different critter. I have a line 6 spider 3 75w... Lol it is my first attempt at a modeling amp. I dropped an EVM 12L in it and it sounds pretty good.
    I need to have a preamp out to my Acoustic 150 and my Peavey board or it's not happening.
    I'm 64 years old, retired banking equipment tech but my knowledge of audio circuits on a board level is seriously lacking.
    I have found the schematic but am not sure if the same jumper configuration will work..Click image for larger version. 

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