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I attached the stepped attenuator and switches to a aluminium plate which divides the space in the enclosure to two separate sections. The other side is for signal and the other side is for active accessories (for example Bent Audio remote control module ). All possible interference sources should be isolated from signal route.

In addition to flawless sound I wanted to create a good looking device. I didn't wan't to settle with some commercial knobs so I had to had them made in a metal workshop. They weren't that expensive, only 30 euros for three knobs and the rings.

The extension shaft is made of 6 mm brass rod. Aluminium is also fine but brass is much stiffer and also non-magnetic, so it was the best choice. The shafts also look good after polishing :-)
The price was about 5 euros/metre.

The extension shaft is attached to switches and stepped attenuator with aluminium spindle coupling. They cost about 1 euros each and can be found atleast in RS or Farnell catalogues.

I felt that it is necessary to get exactly right touch to the knobs. I thought about several options bu I eventually chose nylon as bearing. The touch is great, very convincing.

The front and side panels are made of zebrano wood. I have used zebrano also in my DIY TV rack and surround back speaker. Zebrano wood fits to many kinds of interiors. The dark stripes goes with dark wood (macassar ebony) which I have used in my DIY coffee tables and the light coloured wood goes with our oak parquet.

I'm embarrassed to say that for now the panels are made of veneered chipboard. I intend to use massive wood but it is not being sold in the city I live in so acquiring the wood is a little bit difficult.

So these panels are only temporary but they look so good that I don't have to hurry with the massive wood panels. I have vaneered several times before so making those panels was a piece of cake and it took one evening. I finished the panels with matte spray lacquer.
By the way, when you use massive wood you should let the wood dry for quite a while. If you use wood that has been stored in open air it will shrink and possibly bend when it dries.

I attached the panels to the casket with screws so that the panels can be easily detached and changed. In other words the preamp has changeable covers like mobile phones :-)

I attached plastic counterparts to the panels so that the screw threads tolerate many times of attaching and detaching the panels.

You can see the white round disks in the front panels. They are the vinyl bearings that I mentioned before.

There's the wiring. On the right side you can see the line inputs that goes to 2x6 rotary switch which has been restricted to 2x4 switch.

The wires go from the switch to the stepped attenuator. The poles are marked IN, OUT and GROUND so you don't have to guess anything. The earthing of the stepped attenuator has been connected to earthing point with teflon insulated stranded silvered copper wire. I connected the signal cable screenings to the same wire. The screens of the other cables have been soldered to the earthing rod.

The capacitance of the signal path from stepped attenuator to power amp should be as low as possible. The poles of the stepped attenuator are pointed to the left. This way the cables are as short as possible and therefore the capacitance is lowest possible.

The wires go to the second rotary switch. This switch is needed only if you need to connect another preamp to the power amp. There are two separate inputs for additional preamps and they are also connected to the second rotary switch. You can see the wiring diagram on the first page.

The output of the rotary switch is connected to two outputs so that the preamp can be connected to subwoofer or to two power amps for bi-amping.

KLICK the pic to see a larger pic!

The top and bottom plates are 3 mm thick aluminium. The material is cheap but cutting it is what costs.

The knobs turned out exactly as I wanted and the rings around them are spot on (IMHO).

I haven't decided yet if I want to anodize the aluminium parts. It would cost only 15 euros or less.

Screws don't affect to sound but they are important factor in appearance. The only right screw type is acid resistant. They look great with aluminium but they cost a lot more than normal screws. You should go to a decent screw store since these kind of screw cannot be found from a normal hardware store. The screws, in the picture above are normal. Acid resistant screws look much more impressive.

I'm quite happy with the wiring. I have used the same cable in some of my DIY interconnects and they sound great. The cheap sockets are fine but phychologically displeasing. I might consider replacing them with high quality sockets some day. The WBT sockets are attractive but the price is too high :-(

The feet have to be replaced with a little sturdier ones. It is "important" that the feet are isolative. Ceraballs and other similar feet aren't suitable here because their function is to drain the internal vibrations (e.g. vibrations from CD player power supply) to the rack. It is obvious that Ceraballs don't isolate very efficiently.