1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. Things you need to know about the new ‘Conversations’ PM system:

    a) DO NOT REPLY TO THE NOTIFICATION EMAIL! I get them, not the intended recipient. I get a lot of them and I do not want them! It is just a notification, log into the site and reply from there.

    b) To delete old conversations use the ‘Leave conversation’ option. This is just delete by another name.
    Dismiss Notice

QUDOS - the brilliant new amplifier boards from Avondale

Discussion in 'd.i.y.' started by misterc6, Jul 10, 2017.

  1. Nic Robinson

    Nic Robinson Moderator

    I want! Can I trade in my NCC200s, Les?
  2. LesW

    LesW Making electronics make music

    I can think of no reason why not. The stability of the amp
    lies in the preceding stages.
  3. LesW

    LesW Making electronics make music

    You've perhaps hit the nail with this Malcolm and highlighted the source
    of the characteristic 'rip' in NAPA circuits. The use of the Baxendall diode
    to simulate a complimentary device may result in a non-linear transfer
    of signal into the output pair but there will be more technically able
    members than I who may care to comment.

    An amplifier I once designed for Sugden, used a diode chain to achieve
    output bias but produced the same kind of 'rip' I outlined above. Only
    when I modified the circuit to a more conventional resistor network,
    did the rip disappear.
  4. molee

    molee pfm Member

    I have no idea what you gents are talking about. It's a bit like the Japanese poetry we were taught at school- inherently beautiful but way beyond my faculties of understanding. I am embarrassed to ask such a trog question amidst such elevated discussion but are/will these boards be 'fittable' to a NAP180?
  5. misterc6

    misterc6 Wasted and wounded, it ain’t what the moon did

    Yes, they can.
  6. misterc6

    misterc6 Wasted and wounded, it ain’t what the moon did

    Yes, they can. They are the same size as the NAPA boards fitted in NAPs 110, 140, 160 (CB), 180 and 250. You can see one fitted in the same place as the original NAPA board in the photo in the OP.

    YNWOAN 100% Analogue

    Les, will this new board be part of your Nap135 upgrade?
  8. LesW

    LesW Making electronics make music

    Could be but we'll see how it pans out

    YNWOAN 100% Analogue

    Actually, after I posted the above, I was thinking; you already do your own reservoir cap board (very highly regarded), your own amp boards (similarly popular) and you have just started doing the 500VA transformers and you either already make or are working on regulator boards (sorry, I'm out of date and not sure which) - as such, one could easily build ones own Avondale 135's from scratch.
  10. 337alant

    337alant Negatively Biased

    You sure could Mark :)
    I built a pair of Voyager's a couple of years back and I am very happy with them they are excellent IMO

    [​IMG]Voy 5 by Alan Towell, on Flickr
    [​IMG]Voy 3 by Alan Towell, on Flickr
  11. YNWOAN

    YNWOAN 100% Analogue

    Very nicely done Alan :).
  12. matthias

    matthias pfm Member

    I thought this board is a replacement for the NCC200 and the replacement for the NAP135 boards is the NCC300.

  13. 337alant

    337alant Negatively Biased

    That is what Les has written on the Avondale web site and I believe that design is in the final stages.
    However right now you could still use the NCC-200 Amplifier with the HCR-200 Reg.
    The Voyager Amplifier uses the NCC-200 with the VBE filter to the front end supply only.
  14. LesW

    LesW Making electronics make music

    There are several levels of 135 system in use today beginning with a standard
    duo of 135s driving a pair of Briks, next a foursome driving for example a pair
    of SBLs in either passive or active form and then, the ultimate, a six pack used
    actively with Briks.

    Active systems:

    Sharing advice with a specialist in active Briks, it seems that the way forward is to
    produce different configurations of converted 135s with the NCC300s looking after
    bass driving duties where the B139s present a current-hungry load. Then, either
    the NCC300s or Qudos conversion to the 135s on midrange duty (yet to be finalised
    after listening tests) finally, treble driving may be looked after by HCR200 regulated
    supplies feeding Qudos modules biased heavily into Class A mode to complete the
    six-pack lineup.

    Passive systems:

    Using a simple duo of 135s, the NCC300s appear to hold the key to current delivery
    so this will be the staple diet for passively driven Briks etc.

    We're still working on this project and will be for some time but after the initial reports,
    I'm beginning to alter my cold attitude towards Briks - it seems that there has been a
    deficit in the amplifier department for many years and it's this I'm looking to address for
    135 owners.

    More later......
  15. flashgo

    flashgo DIY Practitioner

    I have several times extolled the wonders of 'briks on this august forum. ;)

    Having been through many configurations, I agree with Les and his friend that, when it comes to 'briks, the more power the better. After that, an active configuration allows for tuning the amps to the drivers. Interestingly, I've come to much the same configuration:
    • Bass – NAP135 x 2 (better than NAP250 x 2 with separate channels for each of the four B139s)
    • Mid – NAP180 converted to almost dual mono with a CAP-6 on each NAPA board
    • HF – NAP250
    I will be working towards the NCC300 + Qudos configuration.

    For my part, I've played with different feedback caps for the different drivers. While the mil-spec tants are excellent everywhere, here are some options:
    • Bass – MMK 47uF x 2
    • Mid – mil-spec tant 47+uF
    • HF – AVX polypro 47-68uF

    Cheers to Les for advancing the state of the art!
  16. YNWOAN

    YNWOAN 100% Analogue

    Personally my 135's only drive the mid and tweeters in my Yammies with the bass handled actively by another amp (with much more power), so the Qudos may be the way to go - let's see how Les' thoughts pan out.
  17. Pine Marten

    Pine Marten pfm Member

    There will be another pair of 110 monos with "qudos" boards soon. Had a quick chat with Les today, and ordered the amp boards and 2x psu boards. Lovely chap, cant wait. Now lets see how the ES14's like them!
  18. DuncanF

    DuncanF pfm Member

    Anecdotally, when I had a 135 4-pack hooked up to my Epos ES30s, I found the best result for me was a pair of 135s for the tweeters, and the other pair for the mids and woofers. I tried both ways round, dedicated woofer amp vs dedicated tweeter amp, and preferred the latter.
  19. YNWOAN

    YNWOAN 100% Analogue

    In my case the dedicated bass amp also applies some DSP to overcome the predominant room modes and, being active as opposed to bi-amped, is connected directly to the drivers without a passive crossover.
  20. matthias

    matthias pfm Member

    OK, let us wait for the NCC300s:)


Share This Page