Colin's SECA Kits

[Colin Wonfor]

From Alan Elsdon

I made an assumption that everyone would know what I was talking about - sorry about that.

There are two versions of Colin's SECA amps available for DIY.

The 10-15 watt version which has been detailed here on AudioChews, there are three boards available for this version, an Amplifier board which has its own power-supply built in, this gives the cheapest and quickest build. A Tracking Power Supply board does as its name suggests it tracks the Amplifier boards requirements and adjusts its output to compensate. A third board allows for a Soft Start avoiding any nasty turn on thumps.

I personally use the Amplifier + Tracking PSU and with my Infinity RS3B speakers there is no problem with switch-on nor any problem driving the speakers to quite loud volumes in my 5 x 3 metre room.

The second version is a 40-45 watt version, only one of these currently exists and was built by Sovereign(James). The single board for this combines the Amplifier and Tracking PSU boards but with more output devices - so it is the 10-15 watt ON STEROIDS. The board has thicker copper tracks to cope with the extra load. James so likes his amplifiers (and having had them on my system I can see why) that he wanted another amplifier to allow him to bi-amp his speakers.

When James asked for more boards Colin and I decided to do a limited run of these boards and so 12 were made, I was going to keep 4 but due to the interest shown by a few people I will keep 2 which Colin is building to ensure that the Bill of Materials we have is correct.

Pricing of the boards has been mentioned and I have also said I would see about getting the SMDs soldered to boards. I have also been ensuring that the parts are available from Farnell and looking at supplying all the parts needed to complete the boards.

I am making a spreadsheet of everything required to build one of the 40-watt amplifiers assuming 2 SMD-populated boards, a pair of transformers, a suitable case from Modushop and sundry bits. James used 4 big heatsinks available from RSComponents and built his own case - obviously we cannot price that but we can give links to the heatsinks.

I will give some ROUGH figures now for a build - but I reserve the right to change them!

2 x 40-watt boards unpopulated £120 including delivery.
Kit of parts to populate two boards £280 including delivery.
2 x Airlink Transformers 225va 22-0-22 £58 plus vat + delivery from Airlink, 300va 22-0-22 £62 plus vat + delivery from Airlink.
1 x Modushop Case Pesante Dissipante 4U or 5U - website currently down but £200 plus for this, more if you want the holes drilling.
Cables / Phono Sockets / Speaker Posts / Mains Inlets / Switch - allow a minimum of £25 - lots more for boutique parts.

So ROUGHLY about £800 for an amplifier plus your time. We would supply the parts and boards only and you would need to get the transformers / cases and sundries at your leisure.

If any interest is shown in the 10-watt Kit then we will look into offering the same sort of deal for the boards and parts.

I will make the finished BOM and spreadsheet available when completed and checked.

[Colin Wonfor]

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.

[Dr Bunsen Honeydew]

Go tell the idiots at AoS who are doing the power supply capacitor bake-off. According to them it is night and day differences arses

[Geoff.R.G]

Go tell the idiots at AoS who are doing the power supply capacitor bake-off. According to them it is night and day differences arses

Perhaps it is, they may have very poor power supplies in the kit they are testing.

[Dr Bunsen Honeydew]

Power supplies are very simple at this level, its regulation and regulators that can complicate it. It is simply a transformer, followed by a rectifier, with smoothing cap(s) what can be bad in that that makes the capacitor crucial (beyond certain well known criteria), nothing!

Sorry to be on your thread Colin but it clarifies your point.

[Colin Wonfor]

Power supplies are very simple at this level, its regulation and regulators that can complicate it. It is simply a transformer, followed by a rectifier, with smoothing cap(s) what can be bad in that that makes the capacitor crucial (beyond certain well known criteria), nothing!

Sorry to be on your thread Colin but it clarifies your point.

That is OK Doc, it in this case increases the ripple volts but when the PSU is used you can't measure any significant problem, none at all.
And lets face it ripple current, ESR (frequency conscious) and MTBF and working Temp and colour is all that really maters. ( and wiring the correct way round)
And a 50-200Hz the ESR is pointless.
All boils done to 0.5CVV = J , or do you buy a Ford , me Citroen every time, better on the piles.

[Colin Wonfor]

This one looks good and in stock.

http://uk.farnell.com/cornell-dubilier/ ... dp/2361782

[Colin Wonfor]

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 so you lots take care best Wonf.

[Colin Wonfor]

Well it is Christmas and another day in the life of most of us, But I will wish you Happy New Years OK and Happy Christmas.

[terrybooth]

Hope Christmas and the New Year treats you kindly. Cheers.