The Audio Chews DIY Knowledge Base - or how to build Colin Wonfor's kits

I've been promising to bring together everything we've learned about building Colin's kits to make them easier to build.

Here's the start. In other words, it's very much a work in progress.

Can you post here if there's anything you disagree with or anything that we should add to the Knowledge Base. If it's discussion you want, please post in the Building... thread.


Comments

  • This is good work, sir.
    Re. the components link (part of the "in progress" caveat), I put some effort into putting together what I'd learned... here.
  • Thanks Ben. I'll have a look at that.
  • sorry to but in but
    colin would you know where i could get the round scokets that are on the rear of isol8 mains conditioner its the mains out lets thank you
  • xtro said:
    sorry to but in but colin would you know where i could get the round scokets that are on the rear of isol8 mains conditioner its the mains out lets thank you
    Try CPC or Medlocks
  • Very Odd I replied to this yesterday before the new kitchen and minor flooding came.

    Right the PCB that James uses biased up and a increase in voltage will give 50W it is in fact the original PCB which I thought I had lost the artwork for, the problem will be in the 40W version the heat sink will rise between 15 - 20C above ambient and with lovely kids about like James darling, I did not want them to get damaged,
    But by increasing the bias and voltage you will get on testing 52W and a heat sink temperature increase above ambient depending on standing and clearance between 18-25C.

    So the PCB we have are the same as James but will do the job so go get them lads.

    But do have fun and any problem do contact me here.
  • Good work. :-)

    image

    Except this comparison falls down as Sidious payed less heed to H&S considerations than you clearly did in this case...
  • It appears that the 33,000uf @ 35V are getting harder to find, you can replace these with 22,000uF/35V or 27,000uf/35V with no change in the sound.
  • Thanks  for the update, Col. 

    I'm reminded that the Chews DIY Knowledgebase needs some TLC. 
  • YEP if do that can I have volunteer to build PCB please. So busy here with the new cables and amps phew need a hols NOW
  • You want someone to build a kit PCB? I'd do it for you, if I knew how not to burn myself with a soldering iron.
  • And I hear on hot ladies he he sorry kettle 
  • Are you talking about the 10-20W seca kit or the 40W seca kit colin ?
  • No Dave going for the big 300W monos.

    image
  • I think you should up them to 500W so you can sell them in America :-)
  • HI all, I have taken the plunge and bought this SECA kit:

    http://theartofsound.net/forum/showthread.php?48678-FS-SECA-10w-kit

    I shall need a bit of hand holding as I dimly understand that there may be a few component revisions; tweaks seem to have been talked about on here (C4?). If anyone can point me in the right direction, point me to a schematic and BOM or anything similar I would be most grateful so I can make a good job of building this intriguing amp to see what the hubbub is all about! Speakers are mostly Audio Note AN-E though a pair of Kef ref 105.1 also get used from time to time.

  • Hi Jaz.
    Sounds like your poised for you journey.
    You're right I think. There's a BOM somewhere and the C4 tweak. I'll search them out for you when I get a mo...
    Also, when building mine, I felt massively supported by people here. I'd never attempted anything like it. It all came together. :-)
  • The Knowledge Base needs updating.

    Perhaps we can have a look at it, Ben. I still haven't built a kit, so I need a bit of handholding in getting it moving again.
  • All good...! :-)
  • edited January 12
    James, the BOM is here. I believe it is the latest one, but if anyone knows differently, please correct me!
    There's a photo of, and some chatter about, the offending C4, and my hamfisted (but effective) removal of it in my build thread here. (I took the easier ready-build boards option.) In the first post of my build thread there's also some links to where I sourced some of the kit (case, toroids, etc.,...) if that's helpful to you.
  • Docfoster said:
    All good...! :-)
    Thank you! I'll have a look at what we have and perhaps we can have a chat.
  • Hi guys,
    Thanks for the encouragement! I am a decent enough solder monkey but building sand amps and testing blind is beyond my pay grade :)
    James's kit has not arrived, he's been most helpful as well. I shall have a look at the heatsinks and ask for advice on casework once I have my paws on them.
    I feel much encouraged, I can't wait to see what Colin's design can achieve in my setup.
  • I believe James has my amp boards. When you chaps talk about the C4 upgrade, is this the same as the bootstrap upgrade?
  • sovereign said:

    When you chaps talk about the C4 upgrade, is this the same as the bootstrap upgrade?

    No idea.
    The "C4 upgrade" as I understand it is not so much an upgrade as hacking out the little bugger.

  • What's the bootstrap that Colin talks about ? Or is he hinting that he needs some new shoes ?
  • edited January 17
    He has soled out :-D
  • Umm, is 'hacking out the little bugger' regarded as a safe improvement or a dodge mod?

  • Jazid said:
    Umm, is 'hacking out the little bugger' regarded as a safe improvement or a dodge mod?
    It was an improvement generally recommended by the amp's designer Colin Wonfor, shortly after I completed my build.
    So yes, I think that it can be assumed that it is safe.
    Removing C4 certainly further improved the sound of the amp to my ears.
    As mentioned above, you can view a the relevant posts about it (including some contributions from Colin) by clicking here.
  • HI guys
    At long last I got some time so settled down to build this amp. It was already part built (mostly the SMD resistors). I have run into a few curious issues as listed below. Can anyone help point me in the right direction so I can get this thing properly built?


    Tracking PSU
    a)  D6, ZD1, D5, Q9, Q8, Q7, R21, R19, R22, R24, R23, C7, C8, D7, C9, R25 and the relay aren't needed. I assume R20 is also surplus??
    b)  On the BOM I have, some of the below are the correct values as some have been changed as at http://seca.freeforums.net/thread/2/seca-kits-wonfor ; ,   others have been pre-installed and I don't know if they are acceptable subs, please advise:
    R4 - spec 3.6k, installed value is 2.7k
    R6 - spec is unclear on my copies, installed 2.7k again.
    R10, R13 - are these now 1k? Installed is 10k
    R11, R12 - are these now 10k? Instaled is 1k in one board, nothing on the other.

    Audio board
    a)  Are any of the four rectifier diodes D5,6,7,8 required and if not should any be replaced with bridge wires?
    b)  Are the smoothing caps still required? I presume so?
    c)  There is a diode marked on the board close to R17 but not on the BOM, is this required and if so what value?
    d) I am using IRFP4410PF Mosfets, is it correct that C7 should be changed from 47pF to 22pF, and are there any other circuit value changes required?

    When setting the current and DC offset are there any tips or tricks to be aware of, and I am not sure where I measure the values, (though I haven't re-read the thread lately)?

    Cheers in advance for any pointers :)
  • @AntiCrap can you help with this, please, Colin?
  • I emailed Colin a week or more back, and no reply. I trust he is on a fantastic holiday :-)
    Anyone else with answers?
  • Jazid,
    I built the amp using pre-built (by Colin) amp and psu boards, so never had to think about these ratings.
    Would it be helpful if I posted up some photos of my boards? Could you see the values you need from that? As I say, Colin built them himself, and they sound fab, so can probably be trusted.
  • In fact, there were probably close-up photos of the boards in my build thread. But I've just looked there and because photobucket has gone to shit, 3rd party hosting isn't working. :-/
    Anyway, let me know if the pics would be helpful and re-post / retake some for you here.
  • edited July 18
    Hi Docfoster,
    thank you for the reply, yes the pics would be very helpful! I am not sure about mods that have occurred since the boards were built but I could always build to your design and futz about afterwards once it was going. A secondary concern is the biasing of the FETs and the variable resistor values. Trying a new Imgur link to see if this can help identify the components..

    image

    image


    Hmm not working, though if I click on the links it takes me to the site. Any ideas?

    [Docfoster edit: images inserted. It's just a case of clicking on the little picture icon (to the left of the "link" icon), and inserting the link in there when you're posting]
  • edited July 18
    Righto.
    Here are photos of the boards in my machine (cat's hairs and general filth are optional during the build)...

    I'm not at all able to function at the individual component level (hence my buying the boards ready built and going from there).
    Give me a shout if you need any close-ups (the photos below are really big, if you can expand and zoom in).

    This is the PSU. I think most of the bits you were after with the red arrows are visible(...?)

    image

    A bit confused by the amp board one, as the part your arrow points to appears to be absent on mine too (is it underneath...?)

    image
  • Thanks for this, Colin's absence of input makes me fidgety about doing anything. You seem to have:
    R4 - BOM spec 3.6k, installed value is 2.7k
    R6 - installed 2.7k. No idea of BOM
    R10, R13 Installed is 10k
    R11, R12 Instaled is 1k
    Are you using the more powerful MOSFET (Mk2 board?) IRFP4410PF or the originals whatever they were?

    I think the diode I arrowed on the PSU is the one that is printed wrong, and should be installed on the underside of the PCB between the IC legs. Nobody has that diode in internet pics, and there's enough paper trail for me to be pretty certain.

    Has anyone here got the tracking PSU and if so do they still use the diodes on the amp board? Please help!
  • Come on Col'...!
  • Jazid said:

    Thanks for this, Colin's absence of input makes me fidgety about doing anything. You seem to have:
    R4 - BOM spec 3.6k, installed value is 2.7k
    R6 - installed 2.7k. No idea of BOM
    R10, R13 Installed is 10k
    R11, R12 Instaled is 1k
    Are you using the more powerful MOSFET (Mk2 board?) IRFP4410PF or the originals whatever they were?

    I think the diode I arrowed on the PSU is the one that is printed wrong, and should be installed on the underside of the PCB between the IC legs. Nobody has that diode in internet pics, and there's enough paper trail for me to be pretty certain.

    Has anyone here got the tracking PSU and if so do they still use the diodes on the amp board? Please help!

    I'm not sure about the mk2 board.
    But I don't think so. I think this is the standard 20 watt jobbie. Tho I ended up getting slightly more powerful trannies, that Colin said would be ok.
    Sorry I can't be more help on the technical front.
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