DIY Hicap in a shoebox
Having bid and missed on several Hicaps on Ebay, and due to the fairly ridiculous (IMHO) prices for the said items, I decided to 'have a go' myself. First thing for me was the box since this is typically the hardest thing to find. I finally decided on an old NAC32 because it was the closest thing I could find that would fit into the system (other than an old NAP110 which were not available at the time).
The Donor Box .... (click on photo to enlarge)
Not a bad old '32' but sadly not required for it's primary purpose ...
Since I had no real use for the innards, I gave most of them away to a good home. As you can see, this is an old 'bolt-together' type of Naim box which makes it quite easy to assemble components inside.
1 2 3
Having removed all of the boards and the main PCB, the first thing in was the transformer (refer picture 1), this is a real live Hicap tranny which I 'acquired' for a reasonable price from [Classified] sorry, I can't reveal my source here but suffice to say they live in Salisbury !
Below are the details of the newer 'Talema' transformer used by Naim in the Hicap, taken before I wired it in (just to be sure).
As you can see (refer to picture 2), the rear panel looks a little different from the stock 32 version by the addition of the mains socket, on/off switch, fuse etc. I decided not to use any of the original front panel components/switches as they were not rated for the current, so they stayed in as dummies only (refer picture 3).
I decided to mount the Superregs on the base of the box using the standoffs supplied by Andy (of the Weekes variety, what a thorough chappy he is !), and to make my heatsink out of some industrial copper earth bar which I 'rescued' out of a skip somewhere. I personally think it looks cool (sorry about that), and appears to do the job well enough.
As you will see, I'm using some BHC 15,000 Microfarad smoothing caps arranged as per the instructions on the PFM site (since I luckily have the twin centre-tapped secondaries), and a pair of bridge rectifiers wired in Naim fashion (i.e. as full wave, using only two diodes each). I'm also keen to follow Naim's good example with regard to the wiring as I consider that this is an important factor in the end product.
Picture 4 shows a close up of the regulators and caps, Andy's superregs really are a smart (in more ways than one) addition to any piece of Naim (or DIY Naim) kit. Picture 5 shows some detail of the heatsink which is 'suspended' between the regulator boards.
The Final Result
Not too out of place next to the newly serviced and upgraded 250, but it sounds just like a Hicap !!!!.
This site was last updated 11/06/04