The project started with a custom chassis from Par-Metal.com. I chose a variant of their Series 12 all aluminum cabinets, 17" wide by 3.5" tall chassis that was 11.5" deep. It was a custom configuration as their standard Series 12 cabinets have vent holes (I wanted none) and usually come with a rack mount front panel ( which I did not need) in addition to the sub panel. I've has a number of custom enclosures made by Par-Metal, and I've always been happy with their work. These are very high quality chassis, they fit together well, and they use pressed-in threaded steel inserts for assembly. I don't use the black anodized screws they include, but instead substitute stainless hardware.

Work started by cutting the holes in the front and rear panels. This shows the 1/2" Greenlee punch I use for cutting the holes in the rear panel for the RCA jacks.

I designed the front panel using FrontPanelExpress.com, which allow online design, ordering, fabrication and delivery of the panel in a couple weeks. This panel is actually similar in some ways to the Tortuga LDR preamp I built last year, details here.

FrontPanelExpress allows you to print an actual size paper copy of the panel before you order to ensure everything will fit as expected. Here you see my printed copy with notes above the real thing.

This photo shows the assembled chassis with both front and rear panel cutouts complete. The rear panel also includes a cutout for the IEC power connector (made with a Dremel tool), and the front panel includes a large cutout for the VU meters. The long cuts were made on a table saw with a non-ferrous blade and the end cuts were made with a jigsaw.

One note: I always wait for the front panel (above) to arrive before I cut the holes in the front sub-panel. I use the actual faceplate as a drill guide to ensure the faceplate and sub-panel holes line up correctly.

The assembled power supply and buffer board, from the schematic above. The rectifiers are visible on the left (with inputs from the power transformer), followed by filter caps, then the heatsink-mounted regulators in the center, and the actual buffer circuit on the right. The trimpots are to zero DC offset. The heatsinks are way overkill, as the circuit draws little current and the don't even get warm.

Closeup of the audio end of the PCB showing the B1R2 buffer. The two SK170 and two SJ74 FETS are in the center. The buffer is just a handful of parts, as you can see here.

For power, I used a Plitron 50VA dual 12volt transformer, ideal for the dual 12V DC supplies I used for the Pass buffers.

I used an updated version of a PCB I had designed some time ago for the VU meter buffer/amp, shown here. The meter circuit was reverse engineered from the Levinson LNP-2 preamp of long ago, and modified for switchable gain. The PCB includes +/-15v regulators on the top edge for the IC.

The meter sensitivity is switchable, and is shown here pre-assembled for testing. It is highly accurate, calibrated in dBv (also known as dBu, referenced to 0dBv at 0.775V). Using vintage true VU meters, of course.

For Volume and Balance controls, I was fortunate to find some used but very high quality Alps "Black Beauty" RK40 pots, shown here.

The MODE switch. Not much to look at, but allows for stereo, reverse, mono and either left or right only channels to be selected. I frequently use the latter for speaker setup/testing and room optimization.

Assembly started with the back panel. The RCA connectors are Vampire gold/teflon units. The IEC input connector on the left contains an integral fuse and power line filter, and is a Qualtek 860-04/003, recommended by Gary Galo in audioxpress 3/2005.

I'll comment on those binding posts later...

Inside view of the rear panel before wiring it up.

I wanted the power switch to be mounted without a nut showing on the front of the faceplate, so I made a little sub-panel where the switch actually mounts, shown here. That allows for a cleaner look on the finished front panel.

I added a 12V trigger output to remotely start/stop an amplifier, so I build a small 12V regulator shown here, with a resettable fuse (Littelfuse RXEF010) the left.

This photo shows the front panel wiring. From left to right: the volume pot, balance control, input selector switch, and mode control. Note that I used shielded wiring for all the inputs as the input wiring is in close proximity to each other.

My standard color code is red for right channel audio and blue for left, maybe obviously.

Unlike the power supply. buffer pcb and the VU meter amp PCB, which were designed by me but fabricates professionally, I made and etched some small unusually shaped PCBs to hold the LEDs to illuminate the meters. This shows the PCBs just after cutting to shape and etching them.

This shows the PCBs cleaned up with the LEDs (amber color to look like incandescent lamps) mounted.

I first found the LEDs a bit bright, so I sanded the down-firing ends of the LEDs with 100 grit sandpaper to get a more diffuse light into the VU meters.

Inside view of the VU Meters (Hoyt brand), along with the meter level switch to the right, and the LEDs on their custom PCBs above the meters.

Completed preamp internals, view from the front. Starting in the upper left: remote trigger and IEC, RCA inputs and outputs along the back panel, center rear is the power supply/B1R2 buffer PCB, power transformer center left, and meter buffer/amplifier to the right of that.

The star ground is on the heavy wires running between the RCA jacks (where all the black wires converge).

Completed view from the rear. There's a great deal of open space in the preamp, but I've intentionally left room (on the right side in this photo) to later add an ICEPower 125ASX2 stereo amplifier module if I ever decide to convert this into an integrated amplifier.

You may have noted that I already drilled for and added the speaker output binding posts on the rear panel, shown earlier on the back panel and visible here on the lower right.

The completed preamp, front view.