DEQ 2496 mods

Discussion in 'DIY Discussion' started by zanash, Sep 11, 2006.

  1. zanash

    zanash

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    So ..just can't resist undoing the screws and taking a peek.

    Having done so and established it has a switch mde psu [not fans of]......

    The opamps are sighted under the board holding the input and output connections.

    So first as the case rings like a bell I've damped with bitumen both case and lid. Effect noticable clarity slightly fuller sound.

    Then swapped the 1000uf supply cap in the switched mode psu for panasonic fc 1200 63v ...effect bass where did that come from ?

    Looked at the processor board and swapped the majority of the 10uf 16v caps for a mix of starget and panasonics ..stargets near the chips and the panas round the regulators. effect more bass ...geez where is it coming from ? extra delicacy in the top and mid.

    But now ....I could attack the caps on the opamp board ...but not certain theres much milage here ?

    any thoughts......?
     
    zanash, Sep 11, 2006
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  2. zanash

    Tenson Moderator

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    The biggest upgrade will come from changing how the circuit works, not just the components in it. Find the wires in the ribbon cable that carry the signal from the DAC chip, cut them. Done :D

    Just kidding! Put in an RC filter to cut high frequency noise and then a pair of the best caps you can find to remove DC. Wire that to some new plugs or clip the old ones and wire it to those. If you have a TVC pre-amp and use balanced you don't need the DC blocking caps as the DC is common mode.

    Another option to the DC caps is to use some miniature transformers as used in mic pre-amps and stuff.

    The PSU will bring some further improvements I'm sure, but I have not got round to finishing that yet. I am making a completely new one.
     
    Last edited by a moderator: Sep 15, 2006
    Tenson, Sep 11, 2006
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  3. zanash

    RobHolt Moderator

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    Pete, the mod Simon recommends works a treat - really does remove a layer of grain and hash.
    Those green PIO caps we've discussed before work superbly in this application to filter the DC on the output.
     
    RobHolt, Sep 11, 2006
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  4. zanash

    Tenson Moderator

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    This is my latest mod to a Behringer DCX2496, the extra space is for the new PSU.

    [​IMG]
     
    Last edited by a moderator: Sep 12, 2006
    Tenson, Sep 11, 2006
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  5. zanash

    zanash

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    Yes....... a new psu will be a must at some stage.

    I've several sets of fat green fellows wait to go !

    very intresting pics ....though its the dcx ....!

    Anyone done much to the src ?
     
    zanash, Sep 11, 2006
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  6. zanash

    Tenson Moderator

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    The DCX and DEQ are basically the same though. Why buy a SRC to mod if you can get a DEQ? ;)
     
    Tenson, Sep 11, 2006
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  7. zanash

    zanash

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    The src is an upsampler plus other bits ...the deq doesn't do this [?]
     
    zanash, Sep 12, 2006
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  8. zanash

    Tenson Moderator

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    I just wonderd what use you had for a sample rate converter in a hi-fi? Its main use is to enable conversion of different digital interfaces.
     
    Tenson, Sep 12, 2006
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  9. zanash

    mr cat Member of the month

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    this will be the first thing i try when I take delivery on mine... :D

    I may hten post this on to you good self at a later stage for you to do some mods if thats ok...:cool:
     
    mr cat, Sep 12, 2006
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  10. zanash

    zanash

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    Setting the src to take the 44.1kh and output a 96kh in analogue gives a more detailed and very much expanded sound stage. The music threads and instraments are more clearly placed and have an air around them that before was missing ......as opposed to the sound of the straight deq which in comparison is distinctly shut in.
     
    zanash, Sep 12, 2006
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  11. zanash

    Tenson Moderator

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    Oops I thought I had posted this already.

    Hmm, I have no experience of the SRC, but on Thorstens new CD player where you can switch between any number of oversampling and upsampling settings they all sounded very much the same to me, apart from the completely non-oversampling or upsampling options with analogue filters, which has slightly less control and precision but had a wider soundstage and were more 'musical'. I believe the DEQ already can be set to dither the bitrate to 24bit so its digital attenuation doesn't have much dynamic loss.

    Just to say, having changed amps I am getting slight trouble, I think, from HF noise on the DACs output, so don't go jumping in head first and put that RC filter on it, I think it may need an LC filter for most amps, we shall see.
     
    Last edited by a moderator: Sep 12, 2006
    Tenson, Sep 12, 2006
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  12. zanash

    zanash

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    Has anyone removed the muting transistors ?
     
    zanash, Sep 15, 2006
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  13. zanash

    Tenson Moderator

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    Hi,

    Just to clarify on my point about the noise earlier...

    The problem with the noise was a grounding issue with my unit because I transplanted the case. I thought I had it sorted, but there were in fact three different layers to the noise in the end!

    So... if you want to do the mods I described then go ahead, as long as you keep the DEQ in its original case and the grounding as it is (can use the hot and cold pins on the output for the new outputs though). It will be fine.

    I found that the RC filter does keep the noise low, but that the LC filter keeps the noise lower. If you replaced the switching-mode PSU for a toroidal type then you can likely go with the RC filter with no worries at all, but while that noisy PSU is still in there I'd go for an LC output filter.

    Zanash, seriously mate, give these mods a go they will do far more than keeping the current output stage and just changing components and muting transistors.

    Here is the output stage, you can see why its not too nice. LC filter, DC blocking caps and out is MUCH better :D

    [​IMG]

    The component numbers wont line up BTW as this is actually the DCX but the output stage is the same.
     
    Tenson, Sep 15, 2006
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  14. zanash

    Tenson Moderator

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    By the way, to anyone interested I am happy to do these mods to make me a little bit of money. I should have a new PSU built for my DCX soon so it is just a matter of a few changes to make it work with the DEQ which I will do soon too.
     
    Tenson, Sep 15, 2006
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  15. zanash

    zanash

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    But have you removed the muting transistors ?.......just that I can easily remove the surface mount component but its not so easy to refit it if the pops and clicks are overwhelming
     
    zanash, Sep 17, 2006
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  16. zanash

    Tenson Moderator

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    I removed the whole section you see there. It does pop a little bit on power up and down but apart from that its fine.
     
    Tenson, Sep 17, 2006
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  17. zanash

    zanash

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    I understand now !

    Mine pops on startup anyway ..........
     
    zanash, Sep 17, 2006
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  18. zanash

    Tenson Moderator

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    Maybe mine did too, I can't remember lol!
     
    Tenson, Sep 17, 2006
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  19. zanash

    zanash

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    just removed the 10k res feeding the muting trans....the image has jumped into focus, not bad for a quick dab with the soldering iron.. Then sprinkled a load of good caps over the processer board ..no huge changes but makes me feel better!
     
    zanash, Sep 18, 2006
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  20. zanash

    bigbrowncow

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    Tenson,

    can you tell us a bit more about the mods you have on your website? How easy are they to fit? How does the sound compare? What other mods might you have lined up for the future?


    Steve
     
    bigbrowncow, Feb 22, 2007
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