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10 Jan 2012

Denon DCD-620 modificato senza opamp!!!!


Does it needs words to explain?.......it's a simply mod with a great result!
At first I heard a muddy very laid back sound from this device....no detail at all and a strange feeling of a kind of waves sound coming and going difficoult to describe!
Service manual on my hands I started studying the situation....ok let's start from the higly regarder PCM56 by Burr Brown.........mmmmmm.......wow! they've got a V-out that means they has a op-amp build in!!!!!!
Would it be any good???Hope so! all would be simplier!!!! Go for that way c'mon!!!
Guys I'm really lucky : polypropylene bypass everywere nichicon muse output and allen bradley resistor and NO OPAMP at all!!!throwing muting transistors in the trash the sound result is really amazing!!!!!!!
Drum shots in my ear like never before!!!!!!!!!!! guitars cry giving shiver ...piano gives its best!!!!! and voices soooooo sweets and likely detailed .........mmmmmmm!!!!!!
I'll switch to italian in order to make me understand to my friend Orazio!
Questo lettore appartiene ad un accanito audiofilo, ora mio amico Orazio il quale mi rende orgoglioso del mio lavoro con i suoi aprezzamenti!
Grazie Orazio!!! ;-)



Op-amps??!
They're definitively gone with great success

Nichicon Muse filtering and feeding this very good device



Allen Bradley carbon composite resistors and bypolar Nichicon Muse




The Burr Brown Mr PCM61


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14 comments:

  1. orazio1 March 2012 at 08:51

    ..be....effettivamente non cè paragone con il suono di prima...assolutamente non piu riconoscibile ilvecchio suono denon.....piu appertura...piu dettaglio..piu presenza...--senza parole... e bravo maurizio

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  2. Unknown12 October 2012 at 05:44

    Dear MauriAudio, dear Orazio,

    looks like a perfect upgrade! Could you tell the new Parts that you used, especialli the green ones? There was the muting transistors, right?

    Bravo, Best Regards,
    Clemens

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    1. MauriAudio12 October 2012 at 07:02

      Thank you Clemens!!!!

      It's the simplest mod you can do, but with this chip (it has a build in I/V conversion).
      The green caps I used along the signal, are Nichicon muse with mylar by-pass....the resistors are Allen Bradley composite.
      I simply took off and bypassed all muting circuit!

      You can use all kind of low ESR cap you like ( it depende by your taste!)in power supply, increasing their value!
      By-pass with a lot of mylar or MKT caps , schottky diodes (very fast and smooth.....and much more for power supply.
      The result is a more open and detailed sound.......much more analog and pleasant than before!!.......really night and day believe me!!! ;-)
      Greetings!
      Maurizio


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  3. Unknown15 October 2012 at 00:44

    Grazie Maurizio!

    I will try to get the same CAPs as you. What Values are you using for the "Coupling" Caps, I think 470uF? And what value for the bypass CAPs?

    Great Pictures! I see you grab the DAC Output after the R308 and R309 Resistor -> is this resistor the original one or an Allen Bradley?

    Sorry for this lots of questions!


    Grazie Mille
    Clemens

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  4. MauriAudio15 October 2012 at 05:05

    Hi Clemens!

    Don't worry ;-) !.....yes they're Allen Bradley (the best for tonal quality!) ..Caps value is 470uF yes, bypolar but you could even use very good Low ESR electrolitics in "back to back" position, so you need 4 of them with double of value!
    The MKT bypass value should start by 0,1uF....the bigger it is the better is!!!!!
    But i think you could try to measure the Volts value before the output caps and if it's very low ( i mean lower than 1Volt) you could dare to avoid them and go straight to the ampli input with a even cleaner and great phase linearity signal!!!!I guess a great result!!!!!!!!
    When I work for third persons I go for the safest option (i use decoupling!)!!! ;-)

    Ciao!!!!!! Have fun!!!! ;-)

    Maurizio

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  5. Unknown15 October 2012 at 06:35

    Hi Maurizio!

    The Nichicon Muse Series seems a perfect Cap for decoupling. By the way, where do you order those? The completest collection is at "Mouser" I think, rather expensive shipping though...

    What value is your Allen Bradley resistor at R308, R309 I think I read "Brown Blue Brown Gold (Yellow)" 16,1 Ohms?

    Mille Grazie!
    Clemens

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  6. Unknown12 July 2013 at 14:32

    Hello Maurizio ...

    Your tweak seems to be very interesting . Could you make us a small end scheme to see more clearly , please ? I have this drive and it is true that the sound is not terrible. Could you help me?

    Grazie mille .

    DOMCOCO

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    1. MauriAudio12 July 2013 at 20:02

      Hi Dom Coco,
      better says that I found its sound undetailed and very muddy bass character before the mod! I didn't like it a lot differently by other devices with the same chip!
      The mod probably isn't the best you can do , but it's the simplest for sure!!!
      You have to solder two resistors (value 47-200 ohm) by the "pin9" of each PCM56 then you go straight to the output passing throught a pair of bipolar capacitors! Is there anything easier??!!
      Answering to Hans Georg (sorry for my very late response) the Allen Bradley in pic should be 180 ohm but you can use different value...it's your taste!

      Well, I think the next mod on a similar device will be for sure using the I/out of this chip wich is rated to be one of the best achievable!

      Ok, Thanks to you and have a great mod!
      Ciao!

      Maurizio

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    2. Unknown13 July 2013 at 04:51

      Hello Maurizio ,

      Thanks to you for this quick response. I will try this change as soon as I have a little time. After that, if you can provide any additional further improvements, let me know!
      Ciao Maurizio
      Dom

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    3. Unknown25 January 2014 at 02:33

      Hello Maurizio ,

      I made your changes and confirm that the sound is much improved, it is indisputable ... But after measuring V out, I found a channel with a 1mV offset and the other one 8 to 10mV . So I deleted the output capacitor, and connected directly Pin 9 of the DAC through R 68 ohm Allen Bradley (you can experiment with higher values ​​depending on the amp behind) to RCA output... and then ...
      Breathtaking ! ...It is not at all the same player. Everything becomes more airy, transparent, dynamic. Radical transformation. I highly recommend this modification because the result is truly spectacular. .
      Dom

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    4. MauriAudio25 January 2014 at 02:57

      Hi Dom,
      Thanks a lot for all your advices!!!!!
      I will try it for sure!!!!
      Actually I'm quite involved in DAC projects .......
      I've made few usind the great philips TDA1543 and the result is spectacular too .....in these days I'm working to realize TDA1541 DAC for a friend.(take a look at my post)
      I'm gonna do something with PCM56 too for sure........it's a great sounding converter , but one of the Burr Brown best seems to be his brother PCM58 ...it sounds great!
      Thank you again for your precious tips!
      Hope to hear from you soon! Ciao!
      Maurizio

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  7. Unknown28 January 2015 at 11:39

    This comment has been removed by the author.

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    1. Unknown28 January 2015 at 11:45

      This comment has been removed by the author.

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  8. Unknown28 January 2015 at 11:47

    coco dom could send pictures and info of the transformation ?

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