Building my amp kit step-by-step

So the day has finally arrived… time to build me a valve guitar amplifier. I’d bought a combo cabinet from Chris (see earlier posts) and the kit had arrived from Ampmaker. Now I’m not lucky enough to have a workshop so it was going to be happening on the dining room table. Since dinner was due to be at 19:00 I had a deadline ahead. After a quick coffee and breakfast I got cracking at 09:30.

Kit

Here’s the kit. It was packed better than this. I removed most of the bubble wrap during the initial check.

Step 1 – Check the contents

I went through every single component and checked it against the kit contents list. This included using a multimeter to test the value of all the resistors. There was one omission (more of which later).

Step 2 – Gather all the tools and materials and prepare the work area

I’d previously made a list of all the tools I’d need for this job. So I wandered round the various rooms in the house and sheds gathering everything together and then prepared and laid out the work area.

Tools

Step 3 – Fitting parts to chassis

Not much to say other than I followed the instructions and fitted all the parts to the chassis, trimmed the volume pot posts and screwed on the chicken-head knobs. If I was doing this again, I’d trim the pot posts before mounting them into the chassis.

Chassis

Chassis

Chassis

Step 4 – Label all components

This was an additional step that was recommended by a friend, Ian Chadwick, who is also working on an Ampmaker kit. I stuck a piece of masking tape on to each component and wrote the value, and reference number (relating back to the instructions) and laid them out in order. It was amazing the difference this step made to the build. I was able to build up a really nice rhythm when soldering instead of having to go rooting around for each piece when I needed it.

Labelled components

Step 5 – Mount components

Working left to right across the turret board I would dry mount each section, check the measurements, trim the component leads and then solder them in place. After each small section I would go back across and use the multimeter to test every solder joint.

Turret board

Turret board

Step 6 – Wire up board

Kept following Ian’s advice and labeled each of the 21 turret board wires with where it was going to (i.e. VR2-3 meaning 3rd lug of variable resistor 2). Now if labeling the components had simplified the mounting on the turret board, with the wiring it was absolutely vital because when mounted into the chassis you can’t see exactly where the wire comes from (they’re soldered to the underside).

Wired board

Step 7 – Chassis mounts

The items missing from the kit were the spacers to hold the turret board away from the chassis when it is mounted. This point neatly coincided with lunch so I grabbed a quick sandwich and headed off for B&Q. I bought six M3x25mm machine screws and twelve extra M3 nuts for them and improvised the following;

Mounting

Step 8 – Wiring it all up

This was probably the most time consuming aspect of the build. You mount the chassis into the kit and then slowly an methodically work your way through the detailed steps outlined in the kit instructions. Once the turret board is mounted, it can get a little tight getting in to solder in some areas of the chassis, such as the earth lug, near the input socket. But I took my time and aside from a couple of unfortunate soldering iron/finger interfaces I emerged relatively unscathed.

Valve sockets

Wired and done

Step 9 – Testing

There are four main stages of testing the amp. Firstly working across the chassis testing some of the key safety items, such as making sure all of the relevant parts are connected to earth. Secondly is to power it up without the valves and check some key voltages across the amp, and then again with the valves installed. The last step was the scariest and best bit – plugging in a guitar and speaker and hearing the first noise come out. Oh yes – my baby worked first time!

Step 10 – Mount in enclosure

The amp neatly mounted into the cab supplied by Chris and I tidied up the speaker wiring. The original messy cabling had been put in quickly to test the speakers after buying them on eBay and needed stripping out and redoing.

Speaker wiring

Step 11 – Crack out the Telecaster and play!

Finished amp

Lessons learned

  • Labeling all of the parts before starting seemed a bit anal, but saved so much time and confusion and, at the point where you’ve got a soldering iron in hand, just allows to to concentrate on what you’re doing.
  • Test after EVERY step and don’t move on until it works.
  • Take the time to work methodically.
  • Get a highlighter pen and work through the instructions word by word and mark it through only when you’ve tested that the step has been finished.
  • I almost got the polarity wrong when soldering in a couple of the capacitors. It would have been better if I had used the highlighter pen to mark all of the components where polarity mattered (some capacitors and both of the diodes).

Initial impressions

  • Great dynamics and very responsive to the volume of guitar.
  • The sound has lovely character and warmth and yet, especially with the Telecaster, you can get a superb razor sharp clean tone.
  • Breaks up very controllably and still keeps definition in each note even with the gain wound up to 10.
  • Usable tone controls right through their range. On most amps I’ve ever owned, if you get to any of the extremes of the treble, mid, bass, it sounds awful and the “sweet” spot is very narrow. With the SE-5A, the tone controls give very usable sounds at every extreme.

When I get my music room back I’ll record and post some sound samples. In the meantime my (long-suffering) wife seems to be under the misapprehension that it is a guest room for our current visitor.

And before you ask, yes the table was set for dinner at 7:00pm, but only just! All in, excluding tea breaks, lunch and the trip to B&Q, it took about 8.5 hours.

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