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Colin Wonfor's SECA amp build

Discussion in 'd.i.y.' started by Marra, Oct 17, 2015.

  1. CJ14

    CJ14 Retired

    You can use with or without but you will find the Bass more lets say dynamic but it more than that the drum comes and the same as the triangle as it did in real life, but the top end peaks are to die for no sign of harshness. I love mine, must build a bigger one for the winter in my cold log cabin.
  2. James Evans

    James Evans Bedroom Bodger

    Bonanza, thanks, will prepare for surgery...
  3. martin clark

    martin clark pinko bodger

    Elegant solution to the unavoidable output device Vgs... and unlikely to affect anything else. Nice thing about bootstraps, even a 'poor' cap is just fine because higher esr/poor HF performance only acts to enhance stability!

    Colin's amp has several dozen fewer parts/ch (and much less 'pointless complication') than the homebrew class-A minibeast project I've been pushing-around on paper. I really ought to just build one!
  4. CJ14

    CJ14 Retired

    Thank you Mr.Clark KISS is how I like things normally less smoke, and mirrors.

    The 1N400X diodes could be a lower Vf but why worry, as you say solves the Vgs problem and now we can use a bigger FET, with a lower RdsOn but why the track has a higher resistance than the FET. Also changing the constant current Darling to a FET to give us another -2V swing and then we can change the sense and source resistors to lets say 10mR not forgeting Ohm's law as the current IQ will have to be reset to read 10mV/A not 100mV/A thus saving another 500 - 750mV now we could get up to a +20v to -20v swing, ie 14VRms about 24W out but the IQ would need to be set to about 3.5A and that now 140W of heat we need to dump.

    So at 2.5A and 14V the nice load look like 10Ohm at about 16W but with much higher peaks. So the only limiting factor is getting rid of the heat, or a rethink on the PSU but then the heat will move to the regulators.
    Now with only 100W to dump as heat. A slow fan maybe?

    Now Alan Brown built one with huge IGBT,s 300A 1200V and monster heatsinks and we got close to 30W nice work Mr.Brown. With if I recall two 100,000uf cap on each rail and Mono Blocks.
    He has a few circuit boards left over so chat him up.
  5. shoom

    shoom open ears and mind

    Ok i'm game for a little more steam.:)

    I've fitted the first boot strap and everything has biased up as normal.

    i'll post some pictures when No two is on the table.

    thanks for the update Col:cool:
  6. Alan Brown

    Alan Brown Registered LUser

    My neighbor (who is quite hard of hearing and very tolerant) came over this week, to ask me to turn it down a bit. She was worried her kitchen cupboards would come off the wall!! So the amps have some puff...

    (By the the way I'm not really antisocial; I was really pushing the system and applying some subtle EQ to tame the room at volume. As a one off, you understand.:D)
  7. Marra

    Marra pfm Member

    It will be interesting to hear your findings Shaun.

    They do go surprisingly loud Alan.
  8. CJ14

    CJ14 Retired

    Just toys compared to the 100W/ch on speakers with a SPL of 86dB at 1M I got with out clipping 120dB+ and the bass rattled the pit. :D
    The 100W measured 140W 8R. 280W 4R 800W 1R , and short 1mS burst s/c current of 200Amps nice now for the 1KW, OK I am mad honest ask Alan :D
  9. CJ14

    CJ14 Retired

  10. CJ14

    CJ14 Retired

    The new pcb are now ready to order with the PSU SECA combined, it has got some SMD parts but I am using 1206 so not so hard to build.
    This helps us all as the cost is reduced yipeee PM please.
  11. CJ14

    CJ14 Retired

    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.

    I have set a page up on the SECA forum, site with all the information in one spot.

  12. CJ14

    CJ14 Retired

  13. CJ14

    CJ14 Retired

    FUN FUN FUN and God loves duck to they make him giggle and with my stick I waddle also he he. Nerves now take over from pain he he.
    The H.A. was due to silly practitioner telling me to stop warfarin whilst I was on Anti Bods, but the Mech Valve (not tube) jammed and bang H.A. so be warned it bloody hurts a lot.
    So the next two days up the hospital for checks and the tame Vampire, (red-headed nurse jummy) .
    Back in mid Novs from honey-moon so you lots take care best Wonf.
  14. Marra

    Marra pfm Member

    Congrats Col. All the best.
  15. PigletsDad

    PigletsDad pfm Member

    Colin, you take care too.
  16. CJ14

    CJ14 Retired

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