Monday, December 16, 2013

Sabbatical Entry 4

Well let's see, where do I begin on this one? 

Since entry #3 I hopped a flight to Texas for a 10 day trip starting in the capital of Austin.  I had the opportunity to spend three days at the Colling's Guitar Company and would like to thank everyone there for the opportunity.  If you are familiar with their instruments you know it can be argued these are the finest production instruments being made today.  Currently there are four graduates working there and it was great to see them again and have the opportunity to learn from them!

The first day there I had a chance to visit with Steve who oversees all aspects of the Colling's company and Ruth who is head of HR.  It gave them the opportunity to ask about our program and learn more about what we do here in Red Wing.  From there Steve was gracious enough to give me a tour of the factory, different shop areas and an overview of how things are done.  After peppering him with questions along the way (and running into our alumni) I was free to roam the grounds and take a few pictures.  Everyone there was incredibly gracious with their time and telling me anything I wanted to know.  Over the years the vast majority of people I've met in the industry are more than happy to share how they do things and believe there are no "secrets" to their work.  Often folks with this mentality are the most successful people in lutherie.

On the second day I once again was free to roam around, take pictures and ask questions.  Let there be no doubt I took advantage of that opportunity.  I'm not sure how many questions I asked but at the end of the day there were about 650 new pictures on my camera.  Before leaving I made it a point to head back to the finishing area to talk with Joe who completed both diplomas in our guitar program.  We chatted about a few things related to finishing and planned to spend final day  going over the processes he does every day.

A quick little snapshot of acoustic tops with a few production notes included.

Here is an all Koa acoustic that was just removed from the outside mold.  The instrument will stay in an mold from the time the ribs are bent until the top and back are glued on.

There are no shortcuts when prepping an instrument for finish.  Many hours are spent even in a production setting making sure the surface is perfect.  I really like the vacuum fixture holding the mandolin so he can rotate it as necessary.

On my final day there I met up in the finishing department around 9am where Joe was already a few hours into his work day.  He had set aside some instruments to show me some of the finishing steps he does on acoustic guitars.  It was great to see the information he learned in the program being put to use and better yet, having the skills to develop his own approach to what he has learned working at Colling's over the last two years.  One of the most important things to me was seeing the pore filling process he refined so instruments can get through that step in a matter of minutes instead of hours.  To say I was impressed is an understatement.  I took some notes notes and plenty of pictures while he worked and am already prepping some test panels to give it whirl myself.  Just one of the great things in this work is you never stop learning and striving for a better way to get something accomplished.  Well, at least for the folks that know W.O.R.K. is not a radio station.

Here Joe is cleaning up the binding after the excess filler has been removed.  No detail can be missed in this job.

It takes a little practice to get this good at cleaning up purfling.

Amp Building

While in Texas I also spent four days building a guitar amp.  The 4 day workshop wasn't exactly what I expected (based on my interactions with the person offering the course) but the fact remained I finally had the opportunity to build a tube amp.  The gentleman slated to help me was extremely knowledgeable and a great all around guy.  Finally I was able to get my hands on a different set of electronic components and work through each stage of the build.  The amplifier design I chose was about the most intense one they offer for a first time build. There were times I wondered if I'd complete it in time for testing and troubleshooting, but after twenty years of wiring electric guitars those skills kept things moving along quite well.  

Day 1 

The first thing I wanted to do is go through what is in the kit and get it organized.  A little overwhelming at the start but I had help!  I quickly got the tube sockets mounted so I could wire up the filament circuit which provides power to all the tubes.
Apparently a lot of people spend the first day wiring up the filament circuit.  Here I've got it wired by lunch and was feeling pretty good.  I was cautiously optimistic at this point but I could tell the hard work hadn't actually begun.
After lunch I got the transformers, filter capacitors and circuit board mounted.  The filter capacitors hold a dangerous amount of DC voltage but at this point there was no charge in them. 
The project started to look like something when I mounted this circuit board.  It holds the different components for each of the tube circuits.  Little did I know there was a rogue wire!  I wouldn't know I goofed up until the last day....more on this to come.
Here is just one of the spots for grounding components.  It's important to separate the grounds appropriately so one circuit doesn't interfere with another one causing excess noise.
By the end of Day 1 I was feeling good about the progress but still slightly nervous about the time frame because I "didn't know what I didn't know".  Since this was my first amp build I had a sense of how much wiring I'd need to do but couldn't predict how long it would take.

Day 2

The morning began with another round of organizing things for the day and easing into the reality of what's ahead.  There's a brass strip inside the chassis with grounding points for each circuit.  Reality was just beginning to sink in as I reviewed the schematics and pictures included with the amp kit.

It took me a little bit to sort through the resistor values.  We use variable resistors in electric guitars known as potentiometers.  Those are easy because the values are stamped using handy things called "numbers".  Regular resistors have colored bands on them indicating their value and tolerance.  One sneeze at this moment and I would have started over.
Here's a potentiometer with a resistor and capacitor.  I wanted to get as many components wired before mounting the control pots because it's much easier to do outside of the amp chassis.
Since potentiometers have different values it was important to make sure each one going in the amp was sorted out before wiring anything more.  (It isn't just my OCD flaring up I promise)
Now the controls are in the chassis and it's time to get them wired into each circuit.
I started where the guitar enters the amp and worked my way from one end to the other focusing on wiring in the control pots.  Since I really didn't know how far I'd get in one day I'd save the bulk of the tube sockets for later.
Here's more of the first gain stage where we plug into the amp.  I took my time and tried to make sure I knew each connection was correct because I had no idea how much of Day 4 would be available for troubleshooting any problems.
Just working my way across the controls from the input side of the amp towards the output section.
Here is how my brain felt at the end of Day 2.  I'd been wiring all day and then thought about the rest of the tube sockets, all those wires and really began to wonder if I'd get this all done!  Why couldn't I just have built a single-ended Champ design to keep things simple?  Because my mentality has always been to jump in the deep end of the pool to see if I can swim.  Oh, and I wanted an amp with plenty of different "tones".

Day 3

So after an evening studying the schematic some more I felt I had a pretty good game plan for Day 3.  My goal was to have everything wired by the end of the day so Day 4 could be dedicated to troubleshooting the amp, trying different tubes and learning about different techniques for working on an amplifier.  This pictures shows.........more wiring.
Now I'm basically working my way from the input side of the amp to the output side of the amp but working each tube socket and components on the back of the amp trying to make sure I don't miss anything or make any mistakes.
Here is the completed amp.  Little did I know there was that "rogue wire" between two of the boards inside the amp.  This was a mistake I made on the very first morning but fortunately during final inspection we discovered it and got it resolved.

Day 4

There were only a couple of things I wanted to fix the morning of Day 4.  A couple resistors had been on my mind and how I had soldered them to wire extending the length to where they needed to go.  I couldn't get it out of my head and knew it needed to be a physical connection twisted together before soldering it.  I jumped right to it so we could begin troubleshooting any problems. 

Needless to say I was beyond anxious to hear how the amp sounded and was relieved when the power was turned on and nothing exploded.  In fact the amp powered on just fine and after some bias adjustments I was able to hear it for the first time.  It was a deja vu feeling similar to the first time I heard the guitar I made in 1994 as a student in our program!!!  

The amp sounded fantastic and then it was time for some "tube tasting".  I brought several different brands of 6V6 output tubes and a few different options for preamp tubes.  It was a great opportunity to hear the subtle differences from one set of tubes to another.  These days companies buy in bulk from overseas manufacturers.  They test all of the tubes and match them up according to a set of measurements.  While everyone raves about "new old stock" (N.O.S.) tubes that were made in America the reality is supply is dwindling and what's left tend to be tubes other people haven't wanted.  It was important to me that I use what is currently being made to hear the differences and have a sense for how to voice an amp later on.

After playing the amp with many different tube combinations I decided which ones to use and had the bias reset to that specific pair of 6V6's.  The amp was shipped back to Minnesota where it awaits a cabinet and speakers.  Oh, I also have to design and build a cabinet then learn the joys of covering it with material.  It's kind of like having a high performance motor sitting in the garage and needing the car to go along with it.  Just another item on my "to do" list.  Once it's done I'll put some pictures up on the blog and who knows, maybe a sound sample?

I know I took quite a few pictures during on Day 4 but for some reason those have also gone rogue.  I'll be sure to look for them and include it another blog post