The SECA Boards

sondale

I am looking after the non-technical side of Colin Wonfor's SECA Kit boards. The boards are SECA 40 (please see Sovereign's build thread) and the three SECA 10 boards - Power Amp, Tracking Power Supply and Soft Start.

A small run of 12 of the SECA 40 was made and 10 of them will be made available at a cost of £120 including delivery; however some of the SMDs on this board are not so easy to solder so I am negotiating to have all the SMDs soldered before delivery which would obviously increase the the price (slightly!).

As far as the SECA 10 is concerned we were not going to make any more boards but interest seems to have picked up, if there are enough people really interested then we would have more boards made.

I am creating a new Bill of Materials for the SECA 40 which I will make available as soon as I have ordered a set of components from Farnell and other suppliers.

The SECA 50 came about because the original artwork was lost and Colin re-drew the board with some minor additions giving a little more power and a more heat to lose! For the time being this will not be released and I will concentrate on the SECA 40.

Docfoster

Alan,
Ooo things are moving forward... :-)
Reading about the serendipitous genesis of the SECA 50 made me chuckle...
I honestly can't remember which board I have in my kit amp (10 or 40...?), but in either case, I do have the tracking power supply and it sounds superb. These boards deserve to do very well. All the best.

uglymusic

That's good news Alan

I might be in the market for a set in a while (awaiting go-ahead on a couple of projects).

AntiCrap

No think of the finger Dave burnt and no more typing Dave NO  

cj66

At this point I'm completely lost!

As my poor little noggin had pictured either a set of 5 boards, i.e. the SECA 10, having 2 x tracking PSU, 2 x amp boards and a soft start board

Orrrrrrrrrr,

SECA 40 (more power?) was a pair of boards with all of the above incorporated along with the boot-strap mod.

How far out am I?


:-$

uglymusic

I'm confused, too. I have to admit.

cj66

I'm contemplating a winter project so it would be nice to know what's what here along with rough costings.
If Alan or Colin could spare some time to explian all, it would be really appreciated and would probably drum up more interest too.

Cheers guys.

AntiCrap

What do you need ?

cj66

Hi Col, see my previous previous post (Sept 28). Confused as to exactly what is what and what is on offer DIY wise.

sovereign

Let me see if I can unpack things a little, Alan and Colin please do step in if I am incorrect. Firstly, there are the 10 what DIY SECA boards that consist of 2 amp bords, that's one for each channel, and if wanted two power supply boards called the tracking powersupply; again one for each channel, and now a soft start bord. So that is the 10w SECA amplifier in its entirety. I must aDD, 10W is the absolute minimum that it will produce I have known people to get about 25 W out of it . Then there are the 40W Seca boards which I have, these consist of two amplifier boards, again one for each channel and possibly a soft start board. However I don't use my soft start board and when I turn my amplifier on each day there is no thump or unusually high power draw at all so as I see it, the soft start boards are not needed however Colin will be able to technically advise further. There was talk of a prototype preamp I don't know how much came of this but there is a preamp going into production at some stage not sure if available for DIY Though. There was also talk of 50W DIY boards but nothing has come of this so far. Hope this goes some way to helping

cj66

Thanks for that, it seems to confirm my understanding. In which case we're just waiting to see Alan's BOM for the SECA 40 and finalised ideas on the SMDs for the boards.

No preamp required for the moment as I already have a nice Aclass one.

I also have a little 15w Aclass but......Scotty, we need more power!

sovereign

That's it mate, when Colin wrote the original BOM last year some of those components aren't at Farnell any more so Allen is checking availability and possible replacements . What pre amp do you use

sondale

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.

James has offered his help (via the forum) to any prospective builders.

sondale

My above post was written over a period of time - so some other posts in the meantime - thanks James for your comments.

sovereign

cj66

sovereign said:

. What pre amp do you use

It's a heavily modified Silicon Chip design and doubles as a very sweet headphone amp too. Single channel below.

AntiCrap

Interesting matched pairs LS352 and LS313 are good but I prefer the sound of the MAT03 and the MAT12.

sovereign

Interesting

cj66

AntiCrap said:

Interesting matched pairs LS352 and LS313 are good but I prefer the sound of the MAT03 and the MAT12.

Looking at the specs there are differences but more interestingly what differences in sound do the "MATS" bring? Plus, do they require a different set up or would they count as drop in replacements? Only out of curiosity.

sondale

Apologies for the lack of news / progress.

Colin has built and tested two of these boards - some minor changes in values were needed.

I am putting these on heatsinks and connecting them up for some listening tests - however other things (EWA for instance) are taking up a lot of my time - so I am not sure when this will be done.

However 4 pairs of boards are available (James already has his and has started building), if anyone is still interested in the plain boards please let me know.