Bespoke Dual Control Pre-amplifier, featuring Elma Mono Jumbo stepped attenautors

Here are some excellent images and a write-up by a customer detailing the thought process around building his custom-built amplifier set-up. Thank you to Mr L, from Chesterfield.

"I have a very awkward listening room with an offset listening position that can't be changed, so I needed a solution to centre the stereo imaging. The Elma jumbo switches looked ideal for fine adjustment, so I bought them as kits along with the Seiden 2-pole 6-way selector switch. I had planned to have them in a plain acrylic case to match my modern NVA cases, but I soon felt they were too pretty to hide. That's when I thought I could have a transparent face plate. I was even sad enough to make a little leg-bending jig to ensure a neat job with the resistors. The case depth is relatively short to minimise internal wire length. I've tried to make the layout as logical as possible to keep signal paths to a minimum, hence mounting the selector switch sideways. It also seemed logical to place the ground wires around the outside and between the two channels to minimise any external pick-up.

The hook-up wire is Neotech SOST-26 since it's technically superior to others. KLE Innovations' classic RCA sockets appealed to me with their low mass and well-thought-out design.

The case has been put together similarly to the older NVA cases, where the front, rear, top and bottom are bonded to thicker sides, with the front and rear plates neatly hiding the joints. The sides are 10mm thick, the faceplate is light tinted 5mm, and the rest of the sections are 3mm. There was some bowing in the rear 3mm plate when I tightened up the sockets, but I left it overnight with a bit of weight, pressing it the other way, and it seems to have worked out fine. If I were to do it again, I'd probably use 5mm for the rear, too.