Colin Wonfor's SECA amp build

[Marra]

Winter is approaching so I thought that I would build a class A amp /room heater to compare with my Voyager type monoblocks(thanks Les)

My build will be slightly different from those in the links as I will be reusing the case and power supply from a previous build so my amp will have a common dual rail supply.

I will post pics as I go.

A couple of links

http://theartofsound.net/forum/showthread.php?38912-SECA-KITS-Diy

http://www.audiochews.com/discussion/1608/building-colin-s-seca-kit#latest

 

[shoom]

Hi Keith

Thanks for setting this up.

What size heatsinks are you thinking of using.

I have a spare 4u 360 and would add another for mono blocks to save a little cash. Or strip the heatsinks and build another case.

I'll be interested to hear what you think of the sound

 

[Marra]

Hi Shaun;

I am using the PS385 in a 165mm length per channel from these guys which currently cool my Aleph J.

http://www.gdrectifiers.co.uk/uploads/Heatsinks_for_large_isolated_modules.pdf

How will it sound? Curious about that my self.

The p/s is a 500VA from Toroidypl with 2x18V secondaries which gives +-23vdc so slightly higher than Col recommends but the sinks should cope. This feeds discrete rectifiers followed by a CRC supply consisting of 2x33000uf 0.2R 2x33000uf per rail.Some might say overkill The SECA needs to dissipate 100W per channel which is pretty much the same as the Aleph and the sinks sit comfortably at 44C all day.

 

[quickie]

Sounds good.

I've got a pair of the same sinks here in 175mm length.

Was going to use them for a TOCA build, but might have a play around wih the new stuff.

 

[Marra]

@ Quickie I really like the look of your builds.How does the amp with the power supply board compare to the standard amp?

This is the chassis and p/s that I will be using.

 

[quickie]

Thanks Marra

That looks ideal.

 

[shoom]

Hi Keith

Nice work on the Aleph.

Never tried a solid state SE before so could be interesting. The official PSU looks like it's using a basic 3 pin reg with a power transistor doing most of the heavy lifting.

The regulated supply looks good and can make a big difference.

But you can always add those latter.

keep us posted.

 

[cj66]

I was tempted by the larger 40w jobby with uprated components. I'm currently trying to find time to make an integrated version of an Aclass pre/power I built a wee while ago. Hoping I won't have too many challenges with noise by shoving them together in one box.

I fancy a big brute amp!

 

[Yank]

I'm sure the SECA is a nice amp, but why would you gut an Aleph J to build one? Are you disappointed by the Pass amp?

 

[Marra]

I'm sure the SECA is a nice amp, but why would you gut an Aleph J to build one? Are you disappointed by the Pass amp?

No not at all. I've built Nelson Pass designs on and off for a long time and have never been disappointed.

I thought that I would try something from a different amp designer as it's a simple enough job to swap out the pcb's and if I don't like the SECA the Aleph will go back in.

I'm just addicted to building stuff

 

[shoom]

I'm just addicted to building stuff

Well said Keith

No need to be unhappy to be curious about other things

The Voyagers are sounding superb and even better now the R cores are in but it's still fun to build other things.

I have a spare case and errr if you got em, smoke em.

oh and if you do tire of the Papa's work the you can always send it to a good home

Where did those nice looking rectifier boards come from?

 

[Marra]

Where did those nice looking rectifier boards come from?

Hi Shaun; there was a group buy on diyaudio some years back for Aleph X pcb's.
I never completed the amp but the rectifier boards came in handy. A good number of boards were sold but I don't remember any being built the thread just dried up.

I'm addicted to building stuff.

And apparently there's no known cure.

The SECA boards

 

[CJ14]

Neat work.

 

[Marra]

Thank you Col

 

[shoom]

Great work Keith.

Up to your usual high standards.

Nice board also.

''And apparently there's no known cure''.

 

[Marra]

Thank you Shaun.

I have to agree the additional p/s board does look interesting; it's certainly something to think about for the future.

Quickie has I believe built monoblocks with the extra supply or is in the process of doing so. It would certainly be interesting to hear his thoughts on this.

 

[quickie]

P/S mono's are still work in progress i'm afraid..........

 

[CJ14]

This is one I made for Justin.

PCB mounts on PCB to heatsink

 

[shoom]

Nice work Colin

What's the little vero board item mounted on the heat sink?

The red board in the middle looks like a switched relay on/off?

I have such a device in my Voyager build but I've not seen the red one before.

Any chance of a link and/or some details?

 

[Marra]

Nice one Col.

I like the inclusion of the thermal switches on the heatsinks just in case.

Spacious those Modushop cases aren't they.