More Arriving Everyday

The first round of parts from AmpWares arrived today. Even though they don't reply to emails very well and have slow shipping, everything arrived just as described.

Now that pieces are starting to arrive, I can get a better idea of exactly how to arrange them around the chassis for best layout and minimal hum.

I purchased a book called Building Valve Amplifiers by a Brit called Morgan Jones, and although it is primarily geared towards hi-fi stereo equipment, many of the tips and principles apply to guitar amps as well.

You can see in the photos some of the parts that have come in so far.

This is the chassis. It is 17" long, 4" wide, and 3" tall.

Here is the cloth-covered wire, fuse assembly, pilot light assembly, and Carling power switch, all from AmpWares.

These are the tube sockets from AmpWares. On the left are the octal sockets, one for the power tube (6V6GT) and one for the rectifier (5Y3GT). On the right are the 9-pin sockets, which will hold 12AX7s for the preamp section.

I have ordered the turret board and a few capacitors from Triode Electronics. I will post pictures of those parts when they arrive as well.

Tiny Bits Tedium

I would have never guessed that locating all the bits required would be so frustrating. Most of the larger parts are pretty easy to obtain, but some of these potentiometers and capacitors are out of production and/or very rare. 

I ordered most of the random chassis parts from AmpWares three weeks ago, and haven't heard anything. No shipment has arrived. No emails have been returned. I called today - I got a recording stating that the voice mailbox was full. But my credit card was already charged. We'll see how that one pans out. I am hoping Mr. AmpWares is just on vacation or something, because I had intended to purchase all the resistors and most of the capacitors from his site as well.

As for the vibrato intensity potentiometer, the schematic calls for a 25K ohm reverse audio taper. Apparently, this must be the most rare pot in the universe. I checked over a dozen other Fender schematics of amps that have vibrato circuits, and NO OTHER ONE to the best of my knowledge uses this pot. Most, at least after 1964ish, utilize a 50K ohm R.A. pot, and some of the older tweed models use a 3Meg or something. I suppose I could use a substitution, but the point of this exercise is to copy the Vibro Champ's schematic as closely as possible, since I am still learning electronics; if I stick to the Fender circuit, I'll have an easier time troubleshooting this prototype.

Another rare part seems to be a 2uF @ 25 volts electrolytic capacitor. I have found the other rare 25uF @ 25 volts el. cap (of which I'll need three) from Triode Electronics, and they also have a 10uF @ 25 volts cap which might have to suffice. I am waiting for a reply from the sales department.

Weber Speakers seems to be one of the most complete catalogs of electrical components for amps on the web, at least that I have seen so far. They make the exact multi-section electrolytic capacitor (filter cap) that the schematic calls for: 20uFx 20uF x 20uF x 20uF @ 450V. They even offer it in three varieties, the stock "twist-on" style, the screw-mount wafer base, and the screw-mount clamp. I think I'll order the clamp, as it seems to be the most rugged.

On a side note, I have been considering making this amp use a single 10" speaker rather than the dual 8" speakers I originally planned for. I guess we'll see how much money I can justify spending when I get to the baffle board-building stage.

Decisions, Decisions

Well, parts are beginning to arrive. I received the chassis yesterday. I went with the aluminum Hammond box. After searching the web for a decent price, I found the best price/shipping at Mouser Electronics. 

Now that I have the chassis, I can begin drilling holes and mounting components as they arrive. Before I just go tearing into this $24 piece of aluminum, I wanted to make sure I knew exactly what the control panel was going to look like. This way I can accurately place the holes for the shafts of the potentiometers and switches. The decoration and lettering might change a little before completion, but here is my current idea for the control panel:

Keep in mind that is a view of the top of the amp.

And speaking of drilling into expensive metal, I have discovered through much research that the best way to drill the large diameter holes for the tube sockets is going to be using a Step Bit (sometimes called a UniBit) and a drill press. The bit that steps up to 1" is about $30. Looks like a trip to the hardware store is in order.