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Avondale NCC300 Monos Underway

Discussion in 'd.i.y.' started by Mike Hanson, Jul 5, 2021.

  1. Mynamemynaim

    Mynamemynaim 38yrs a Naim owner


    Thanks for the tips...appreciated!

    So, yes... the speaker neg is on the end nearest the transformer (must admit I thought it was supposed to be) but as its literally a straight copper track to the other end I didnt think it would make a lot of odds....But of course I will try it and see (and swop back if not as you suggest)

    All the caps are 10K uF on all the boards so front end has 30K for plus and same for minus
    Its possible this might be a little much for the amp to be "light on its feet" ...do you think i should swop the final Nichicon's for 6.8k ?

    thanks for all the help
     
  2. laverda

    laverda pfm Member

    Yes IMO I think the front end has toooo much F and those inductors between each cap may not help either, others may suggest otherwise. (Its easy to link them out and see) You only need 10,000uF (Max) on the front end PSU. I used, with good result.. 6600uF on each rail (3x2200uF per rail) for the front end PSU without any additional filtering as there's plenty with the on board regs. I believe Les used 6800uf for his voyagers but not absolutely sure. To much F can make an amp sound dull and or slow.

    I'd give the 6.8k a go on their own...
     
    S-Man and Mynamemynaim like this.
  3. Mynamemynaim

    Mynamemynaim 38yrs a Naim owner

    So after some more listening I think I've identified a problem / issue

    My existing layout is with the speakers (kudos S20) being very far apart either side of the fireplace ...about 11 feet apart
    With seating about 8 feet in front

    Now the existing Avondale puts a nice sound stage in the middle and between the speakers

    The ncc300 puts a huge soundstage across the whole room....and so sounds a little thin in the middle ....
    Trouble is I cannot really move the speakers... only maybe angle them in some
     
    geoturbo likes this.
  4. geoturbo

    geoturbo pfm Member

    ..or even try to have them crossing in front of the listening seat?
     
    laverda likes this.
  5. Mike Hanson

    Mike Hanson Lovely!

    Yup, toeing them in a bit more should improve that.
     
    Last edited: Aug 5, 2021
  6. laverda

    laverda pfm Member

    From your listening position:- try right speaker just pointing over your left shoulder, left speaker pointing just over your right shoulder. Looks extreme but works for me. Look at YouTube @ newrecordday he's done a few videos as I recall.
     
  7. Mynamemynaim

    Mynamemynaim 38yrs a Naim owner

    I'll have a little play with position when I get a chance
     
  8. Chops54

    Chops54 pfm Member

    From my listening chair I can just see the inside edge of both IMFs. I’d like them a bit farther apart but the room won’t allow it. I’m not complaining, Tin Pan Alley sounds absolutely blistering :D The NCC300s are performing really well :)
     
  9. Mynamemynaim

    Mynamemynaim 38yrs a Naim owner

    So the 300 monos have been on for a couple of days and seem a lot more focused now... with a much better defined sound stage...and starting to pick up on rhythms I've missed in familiar tracks..

    But still not totally blown away with the sound ...so have ordered new parts to make a pair of new hackercap boards for the front end power supply... with 6 x 2200uF caps each and new diodes etc..
    Will try the suggestion of loosing the inductors as well...they can always be dropped in again as a trial if I like the new boards
     
  10. Mike Hanson

    Mike Hanson Lovely!

    It's worth noting that Avondale often uses their NCM1 power supply module with the NCC300, which has a fuse, soft start module, and separate supplies for input and output stages. On the input supply, there's just a single pair of 3300µF caps. I'm not sure that you'll see much benefit with 3 pairs of 2200µF caps with intervening inductors.
     
  11. Mynamemynaim

    Mynamemynaim 38yrs a Naim owner

    Thanks Mike....but as mentioned I'm not planning to use inductors in this set of boards...and the amp should only "see" the last 2200 caps?
     
  12. Mike Hanson

    Mike Hanson Lovely!

    Ah right... I saw "regulators" and my brain also echoed "inductors". :)

    However, if you're using links instead, then what your input stage will see is 2 x 3x2200, or 2 x 6600µF. (Capacitors in parallel are added.) That's double what's on the NCM1, although might have marginally lower ESR, given each of the three capacitors on each side is smaller than the 3300µF in the NCM1.

    With the regulators in the input stage, though, I would expect this to have no impact.
     
    Mynamemynaim likes this.
  13. Chops54

    Chops54 pfm Member

    My NCC300s have Avondale Cap six boards for the output stage with 6 x 6800uf caps and 4 x 12mH inductors. Front end has Minicaps with 6 x 6800uf and 4 x 4.7 ohm resistors. Caps are Nippon Chemicon.
     
    Mynamemynaim likes this.
  14. Mike Hanson

    Mike Hanson Lovely!

    Ultimately, a power supply with more caps is not going to hurt it. It's just unlikely to help all that much either. At least that's my take on the subject.
     
  15. Mynamemynaim

    Mynamemynaim 38yrs a Naim owner


    Thanks for the clarification Chops!
    At present mine is set a little different with the front end having the bulk of the smoothing (6x10000uF and 4x 10mH chokes) and the back end just having 4 x 10000uH caps

    When the other boards are made in a day or so (6 x 2200uF caps only) for the front end....I might try swoping the current front end supply to the back end...and see how that sounds
     
    Mike Hanson and Mark65 like this.
  16. Mynamemynaim

    Mynamemynaim 38yrs a Naim owner

    Mike Hanson likes this.
  17. mega lord

    mega lord Centre tapped

    Your ears are the final arbiter of good sound. If it sounds good then trust your ears not somebody else's.
     
  18. ramona

    ramona Music lover

    To my reasoning, NCC300 should make big difference for difficult loads.
    With the NCC230 moving away from TO3 output transistors it would be interesting to see that for NCC300.
     
    Mynamemynaim likes this.
  19. Mynamemynaim

    Mynamemynaim 38yrs a Naim owner

    So I'm putting the two new boards in...and before I start I think...I'll just check the bias first.
    They have been on for several days now

    Now I know why one felt hot and the other felt tepid...it's wasn't because one was above the other on the shelves....it was because the bias on one had settled to 110mA and the bias on the other had risen to 160mA
    Why wasn't that my first thought?
    Its so obvious now:oops:

    Perhaps I should put a thermocouple on the heatsinks with a digital readout on the front..
     
  20. Mynamemynaim

    Mynamemynaim 38yrs a Naim owner

    I have an issue that to be honest...I've been trying to ignore...but it keeps coming back to mind to brother me

    When I set the bias...I can set both amps to the same mA settings for current draw
    Or
    I can set both amps to the same voltage across the resistors

    But I cannot set both amps to have similar current draw and voltage??
    One reads approx 120mA and 1.196v
    The other reads 120mA and 1.148v

    Why would that be when the component values and importantly the (regulated) DC input voltage are the same?

    Is this something I should be worried about?
    Should I set the amps for the same draw or the same volts (assuming I cannot correct the problem)
    The amps sound great as is...but that doesn't stop this bothering me

    Any thoughts anyone please?
     

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