So … the wood arrived from Dsavitsk:
The first thing to do is to mark the mounting holes, using one of the casework sides:
This is necessary for drilling pilot holes. The screws are #4 self-tapping wood screws, but you don’t want those gorgeous wood sides to split when screwing in the screws. Pilot holes are a must.
My first attempt a couple of years ago did not include enough respect for what could happen if not enough planning and caution was used. I thought a small, handheld twist drill would work best. I ended up drilling straight through one of the sides, ruining it. What I needed was a good drill press. I’ve had one for quite a while that I used to drill through aluminum Hammond cases, but it was large, unwieldy and now stuffed into a garage with less than favorable lighting.
What I needed was a very small drill press, but one that was accurate and had great precision. That left out some combo Dremel tool drill press device or a small Harbor Freight tabletop drill press, both of which would be wobbly.
I found this one through Amazon. The same drill press is sold under a different name at Micro-Mark, too. It’s made in Luxembourg and has very little runout with tiny twist drills, especially with the collet chuck:
So after marking the holes, I drill them - ensuring the press is set so that the travel stops well before reaching the outside of the wood.
A closer look - there are three holes required. All three are needed to keep the wood from spinning on the metal plate and to ensure it’s flush along the entire length:
To the right is a case side with the wood screwed in place.
A closer look:
And with all twelve sides (two per amp) completed:
Note that Dsavitsk included some extra pieces of wood!
The next step is to attach all of the wood sides to the six amplifiers nearing completion:
Each side is attached to the interior front plate with a single 82-degree undercut, counter-sunk screw, a black button-head socket screw on the black plate, and two button-head socket screws on the bottom plate. The two remaining brackets on top, along with the brackets on the interior front plate and back plate, form the eight screw positions that attach the lid to the amp.
You might wonder what happened to the power transformers we completed a while back and why I never installed them in the amps. The reason is that that I try to keep all of the wiring leads from the power transformers on the left side, next to the side. I do this in an effort to keep all of the AC current as far away from the rest of the amplifier circuit as possible. It may not make much of a difference, but there’s no reason not to be cautious about it. I read sometimes about DIY-ers installing torroid transformers in giant cases and still having issues with hum. It could be the wiring. So, no reason not to include every precaution.
Anyway, you can’t tell how to scrunch up the wiring until the case side is attached. So, installing the power transformers is next once the case sides are attached. This is fairly simple, due to our previous work with the Molex connectors and the single bolt, washers, and nut:
Above you see the PT, the depressed-center flat washer and two rubber washers, supplied by SumR with the transformers. In addition, you see a single bolt (metric socket), a fender washer, lock washer, and nut, purchased separately by me.
Attachment is pretty simple. Insert the bolt from the bottom, through the fender washer and case bottom plate. Place one rubber washer on the bolt at the inside bottom of the case, and slide the toroid transformer into place over the bolt. Plug in the Molex connectors, ensure the wiring is tucked away at the side, then slide the other rubber washer over the bolt and on top of the transformer, followed by the depressed-center steel washer, lock washer and nut. I tighten down with a Bondhus metric socket head driver on the bottom, while holding the nut with a wrench on the top. I tighten until the lock washer is compressed and my hand/fingers can’t move the Bondhus driver anymore. I do not torque down on the nut with the wrench. I’m afraid that might damage the transformer! So, more than finger tight, but not enough to really torque it.
A view from the top (wrench and Bondhus driver at the right):
And the bottom:
You can clearly see the transformer center bolt and fender washer.
Next up are the primary front plates:
The closest one is turned over so that you can see the circular, masked spots around the XLR openings. Again, these are to continue the consistent ground path throughout all pieces of the casework. Along with two other blind-tapped holes, those holes are used to attach the primary front plate to the interior front plate, already assembled on the amplifier. These primary front plates are massive pieces of laser-cut and machined quarter-inch aluminum, anodized and laser etched.
You’ll see in a later pic that these plates are anodized into a darker finish than the volume knob. That’s OK, because the front plates are brush-finished before anodizing, whereas the volume knob is a smooth, machined finish. The volume knob appears brighter as a result, but the anodizing on the casework is much thicker with the brushed finish. (The anodizing is also thick enough to cut down on errant scratches.) The final effect and feel is quite pleasing.
As mentioned, four screws attach the front plate into position. This also requires some adjustment by feel. Dsavitsk cuts the wood at very high precision. The metal casework is likewise finished. However, there is enough tolerance and play in the various mounting holes and screws that the primary front plate has to be adjusted so that it’s perfectly flush with the sides and bottom plate. That’s another reason for having no less than four screws attaching the primary front plate to the interior front plate.
From the outside:
And inside:
You can see the four attachment screws (4-40 button-head socket screws) that fix the primary front plate - one to the left of the choke, two to the sides of the XLR jack (at the un-anodized circles), and one screw above the Z-switch.
Let’s look at the volume knob next:
The knob is fairly simple, but a massive hunk of machined, solid-billet aluminum and anodized in black.
Another nice touch that Dsavitsk added is that the set screw hole is just about as small as practically possible. It’s a 4-40 set screw, but because of the knob’s great thickness, the set screw can be made long, allowing it to be stable and lock-sure, despite it’s small size. A typical 4-40 black socket head screw is shown for comparison. The smallness of the set screw and hole enhances the great touch and feel of the knob.
Once the knob is attached, we basically have a completed amplifier, except for the top plate:
I still have some work to do on the top plates with the ECP logo badge and mount, but the amplifiers will be completed and tested this weekend.
Speaking of testing, all of the amplifiers are complete enough to begin testing without the lids. First, a basic power check to ensure the leds and tubes light:
Not very apparent in the daylight, but the red LED in the power circuit, the LED used to light up the ECP logo in the top plate (atop the white nylon mount behind the XLR jack), and the tubes are all lit.
Next, we move to my listening table:
After all this work, imagine the satisfaction of knowing everything worked the first time it was plugged in!! YAYYYY!!
The amount of bass coming through those HD800 headphones is unbelievable with Billie Eilish’s Bad Guy! Of course, the high end is there with all the plankton and no harshness. This stage takes a tremendous amount of time, as I switch from music selection to music selection, listening for any abnormalities, but eventually settling in to just listen to the music, and sometimes hours pass by without realizing it.
I’ll have one more post for the case lids, but these six T4 amplifiers are essentially complete!!
