It Works!

Last night (Thursday 19-Feb-2009) I finished connecting all of the remaining wires (so I thought). I plugged it in and nothing. No sound no lights. So I started tracing the wires and found that instead of the 6.3 volts of heater voltage to power the light. It was actually getting 600+ volts. Luckily I had ordered two bulbs. So I de-soldered the light wires from the high voltage tube socket pins, and put them on the heater pins where they should be, oh and also replaced that burned out bulb. I then flipped the power and the light glowed. The next step was to turn the standby on, but no sound. Hmmm. I then started to carefully measure voltage. I then quickly figured out that there was no voltage coming out of the rectifier tube. I looked at my plan and it looked right. I then looked at a different plan (some what similar to my version). Found it, the center tap for the High voltage wires needed to be grounded, not unhooked. Turned everything off, drained the caps and grounded the HT center tap. Plugged it back in, picked up the guitar and slowly turned up the volume. WOW! It worked. After a few minutes trying all of the inputs and such I can say that it sounds 10x better than I ever imagined it could. Though I might be a little biased.
Tonight I did a photo-op with it plugged in and the heaters on.

The transformers and most of the tubes arrived today. Both the Output and Power transformers are Heyboer's. According to the authority of the Marshall 18 watt amp, http://www.18watt.com/ these transformers are the ones that started the whole 18 watt resurgence.

This is the inside of the chassis showing the power transformer. I'm about 50% complete in wiring all of the connections. I need to finish the rear face plate and install it so I can solder the various wires to the rear components. Since most of the components on the rear side have flanges, the face plate must be in place prior to soldering the wires.

The tubes that I'm starting with are the Sovtek's for the 12Ax7's and the EL84's.

I still have the rectifier tube and a couple other EL84's and one spare 12Ax7 on order.

These are made in Russia (most tubes are made in former Communist countries as their whole military still used tubes, because they don't get destroyed by EMP (Electro Magnetic Pulse) when a nuclear bomb explodes. So when a nuclear bomb explodes, if there is anything left of this amp, it should still work :)

I also swapped out the cheapo spring clips for these snazzy real spring clips. These will hold the tubes in place a lot better.
The Power Transformer is on the left, the Output transformer is on the right.

Here is the diagram showing the output transformer. The output transformer converts the little signals from the amp to something that a speaker can use. This transformer has taps for 4 ohm, 8 ohm and 16 ohm impedance speakers. The word on the street is that the 16 ohm tap sounds best sounds the best. This might be due to the fact that the 16 ohm tap has more windings and thus will replicate the sound better than a 4 or 8 ohm tap that has fewer windings. This is what I read and hasn't been proven.

This is the diagram for the Power Transformer. The HT taps are at 200-300 volts so there is a lethal amount of voltage inside any tube amp. On this transformer there are two heater circuits. One is for the 3 12xa7's and the 2 EL84's. The second heater circuit if for the Rectifier tube the EZ81. Finally the input's that plug into the wall allow this amp to be run off of 120 or 240 volts.

Lessons Learned

I went to install the back of the amp components. They would normally include:

• 1 - 1/4" Jack for the Speaker Output
• 1 - 1/4" Jack for the Tremolo foot switch
• 1 - Speaker Impedance selector switch (4,8,16 ohm)
• 1 - Supply Voltage Switch (110v, 220v, 230v)
• 1 - Fuse
• 1 - AC Input Jack

I went with upgraded modern Marshall Voltage Selector, and Speaker Impedance switch. These required a slightly larger than 1-1/8" hole to be cut out where the two little holes in the chassis were. I liked these switches becuase of their low profile. The lesson learned is that I should have done this first before anything else, but I didn't have those switches until the front and the board were in place.

Tube Sockets are In-place

I thought the tube sockets were going to be easy. They weren't. Because of the chassis design, they have to be installed first, then you solder the various wires. It would have been easier to solder then solder the wires to the board. Next time I'll do it in that order. The heater wires weren't too bad. I went with the beefy 18 AWG wire instead of the thinner 20 AWG. By the third tube socket I got the hang of it. The heater wires need to be twisted to reduce noise so it's a lot of trial and error to get the lengths figured out. Luckily I choose to hook those heater wires up first. I recomend this, since it gives you more space without all of the other wires complicating things.

Inside so far, the heater wires are the red and black ones that are twisted.

This is the outside of the chassis. I might go with some different style spring clips. These don't look as good as the ones with two springs on either end.

Here's an example of what I think are better spring clips. These look like they will hold the tubes in place a lot better than the current ones I have in place.

Here's the inside, more detailed pictures. These two tube sockets are for the Power tubes, EL84's. The one on the left I left un-soldered. I'm waiting on the transformers to arrive before finishing that socket.

These are the 12AX7 (3) Tube sockets.

Adding the Pots and Jacks

Tonight I was able to cut and strip all of the board wire to length. I then proceded to attach all of the volume and tone potentiometers to the board. After that I still has some time to install the 4 input jacks for the front of the amp. Tomorrow it will be connecting the opposite side of the board to all of the tube sockets and rear jacks.

Click to enlarge

Wire Arrived, Soldering the board.

The Silver plated 600v Teflon Wire arrived today. I used this supplier http://www.powerwerx.com/ since teflon wire is impossible to get locally. This wire is about the best wire made next to gold. It is made for aircraft applications so it has a really tough jacket and is also good for 400 F degrees.

Here's the board all soldered up. Using high silver 4%/96% content solder and verified my variable temp soldering iron's tip temp with my IR thermometer. I also used heat sinks to protect each component from heat damage. The heat sinks are from (Radio Shack). You just clamp the Resistor or Capacitor about 1/2 between the component and the solder joint. The heat travels down the wire into the heat sink, not the component.

Heat sinks

Here is a pic of the top of the board. It's about 97% done, just a few more wires to add.

Click to enlarge

And the Bottom of the board. The thick copper wire is a ground bus for grounding the components that need grounding and to help with the sound by keeping the bus a little away from all of the caps.

Click to enlarge

Soldering the Turret Board

At this point I've added the Capacitors, resistors to the turret board. I'm waiting on some wire to arrive to start soldering these components to the board.

Installing Turret Lugs

I found the turret lugs at

http://www.hoffmanamps.com/MyStore/perlshop.cgi?ACTION=thispage&thispage=parts12.htm&ORDER_ID=201540709

These required 3/32" holes to be drilled in the Garolite Board.


Here's a picture of the Turret. I also picked up a Turret Lug Tool from www.hoffmanamps.com
This tool installs in my drill press.

Printing the Turret Board

The Tube Guitar amp that I'm building is based on the 1974X Marshall 18 watt Tube Amp.

Building a tube amp differs a bit from building a modern electronic device. A Tube amp gets hot. Modern Printed circuit boards aren't designed to handle that kind of heat. Another flaw is that a Printed circuit board is fragile. The circuit traces are only about as thick as tin foil.

The Original tube Guitar amps were built using either Turret Lugs (B) or Eyelets (C&D) (Old Fenders). The Turrets act as connection points between the various wires and components.

I went with the Turret Lug design.

The Board material I found at http://www.mcmaster.com/ (they have everything, if they don't have it, you don't need it)

http://www.mcmaster.com/#catalog/115/3560

Part Number 8557K15 (1/8" thick, 3" wide x 24" long)

Using Microsoft Powerpoint I designed the layout for the Turret Board. I verified the layout by laying all the parts on a paper and making the approximate locations. I found a technique to transfer a Laser printout to a circuit board at this address. (http://www.fullnet.com/~tomg/gooteepc.htm)

I found a better paper material (Spy Paper) to use instead of the photo paper as described in that article.

Since this needs to be transfered, I had to do a Flip Horizontal in order for the text to be readable once it was ironed onto the turret board.

The next step was to use a Monokote Iron (used for iron on coverings for RC aircraft)

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXL499&P=ML

I used a IR Thermometer and set the Iron to a temperature around 340 F. Degrees.

To prep the Garolite board I used a superfine #0000 synthetic steel wool to make microscopic valleys for the toner to adhear to when melted.

I used plenty of force to make sure the toner was melted onto the board. At this point the paper is lightly adheared to the board. If we try to pull the paper off, the paper will contain most of the toner and the board will only have trace amounts left behind.

The paper I'm using here is the key to this whole process. I found a paper called "Spy Paper". It is made in such a way that it dissolves in water. The goal is to make the paper go away and leave the toner intact.

http://cgi.ebay.com/Spy-Paper-Dissolvo-Magician-Accessory-Gospel-Trick_W0QQitemZ360121128350QQcmdZViewItemQQptZLH_DefaultDomain_0

Here is the spy paper instantly dissolving under warm tap water.

Click on pictures to zoom in

Movie of Spy Paper dissolving

This is the final product. I now have a nice guide to drill the 3/32" holes for the turrets.

"These go to Eleven"

I could just buy a face plate from one of the online part suppliers. But this amp needs to go to Eleven!
The Famous Clip from This is Spinal Tap
http://www.youtube.com/watch?v=d54UU-fPIsY

I've been up against a major technological hurdle. I saw a link on the Internet on how to make Printed Circuit boards using a laser copy/printout. When a laser printer prints, the laser printer uses heat to fuse the toner to the paper. The concept it to use heat to melt the toner to the printed circuit board or in this case a plexiglass face plate for the Amp. The technique works like this.

• Make a printout of the design.
• Place the printout toner side down in the board.
• Carefully Iron the design onto the board.
• At this point it is stuck to the board. He then went on for the next many pages telling what papers broke down after soaking a day or two in water.

The article I read, this guy worked at Staples and found a few papers that seemed to work pretty good. I tried it and it there always was some paper left embedded in the toner.

Thanks to Google!

Spy Paper! I found a product online called Spy Paper. They sell to magic shops and to spys I guess. The paper is suppose to completely dissolve in water. I figured this would be perfect for my task at hand.

I drew the dial pattern in PowerPoint using the Video Clip of that famous scene as a guide. That along with a calulator to divide the 300 degree arc into 12 segments = 27.27 degrees for each dial segment.

The plan is to applying the dials logos and text to the Chassis side of the plexiglass. Then spray paint the backside in gold or silver.

I found this Spy Paper on ebay from this eBay store (I tested it and it worked great!)

http://cgi.ebay.com/Spy-Paper-Dissolvo-Magician-Accessory-Gospel-Trick_W0QQitemZ360121128350QQcmdZViewItemQQptZLH_DefaultDomain_0

There is also this other store with greater quanitities, but I haven't tried their spy paper yet. It looks different from looking at the picture. (Un-Tested)

http://cgi.ebay.com/Spy-Paper-Sheets-10-Pack_W0QQitemZ270290930641QQcmdZViewItemQQptZBI_Security_Fire_Protection

The video is the spy paper dissolving.