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
Re. the components link (part of the "in progress" caveat), I put some effort into putting together what I'd learned... here.
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
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.
Except this comparison falls down as Sidious payed less heed to H&S considerations than you clearly did in this case...
http://audiosciencereview.com/forum/index.php?threads/now-hands-up-who-want-to-try-a-40w-seca-version.938/#post-25842
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.
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. :-)
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.
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.
The "C4 upgrade" as I understand it is not so much an upgrade as hacking out the little bugger.
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.
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?
Cheers in advance for any pointers
Anyone else with answers?
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.
Anyway, let me know if the pics would be helpful and re-post / retake some for you here.
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!
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.