http://www.novacron.com/index.php/main/index/ (mis)Adventures in Life en Kurt Copyright 2010 2010-02-07T05:09:37+00:00 http://www.novacron.com/index.php/main/view/building_a_guitar_from_scratch_-_the_goldnut_variation_1/ http://www.novacron.com/index.php/main/view/building_a_guitar_from_scratch_-_the_goldnut_variation_1/#When:05:09:37Z Part one of a scratch-built Les Paul-style singlecut guitar. I’ve been loitering around the MyLesPaul.com Luthier’s Corner for a while now, soaking up all that I can about building guitars. The many talented builders who contribute to MLP have inspired me with their builds, and given me the confidence to jump in and try to build my own LP-style guitar from scratch. This being my first try, I decided not to go crazy with mahogany and a stunning maple top. Instead, I raided my garage and started pulling out walnut and rock maple lumber that’s been sitting, waiting for a suitable project, for many, many years. This will save both save me a big chunk of change and, by deciding to use walnut, let’s me break out of the traditional LP build mentality that it has to be a perfect replica of a ‘59 burst and try some subtle variations on the theme. I’ve done some woodwork in the past, but nothing recent and certainly nothing this exacting. I have the typical hand-held power tools as well as a drill press and table saw but nothing more elaborate and may use a nearby rental workshop for some of the build. What I don’t have is a load of spare time, maybe a few hours a week but not much more, so don’t expect this build thread to go too quickly. As for the name, “goldnut variation #1,” it’s a silly play on words - goldtop walnut and, hopefully, the first of many builds. With apologies to J.S. Bach, here we go: This evening, I pulled out an 1.5” x 3.5” x 29” blank of rock maple and resawed it down to 1/2” strips for the neck. The center strip is walnut, resawn down to 1/2”. The outer walnut billets were ripped from a single piece of stock, leftover from another project. I came pretty close, especially considering the fence on my table saw is only accurate to about a yard, so I want to run them through a planer and try to get everything as close as I can.  I’m going to take my time on this one and do it right, even if it takes a while. The Goldnut Variation 2010-02-07T05:09:37+00:00 http://www.novacron.com/index.php/main/view/my_new_old_wood_08_r9/ http://www.novacron.com/index.php/main/view/my_new_old_wood_08_r9/#When:03:16:01Z After 14 years of waiting and looking, I’m now the proud owner of a Gibson Les Paul.  A stunning 2008 1959 Reissue, to be precise. I’ve wanted a Les Paul for years. I remember going around to different guitar stores and checking out the historics when they first came out around ‘94.  (I still have the original Gibson Historic Collection brochure I got from Victor’s House of Music.) I was just out of grad school and there was no way I could afford one at the time. A couple years ago and I started playing again and could afford better gear so I started looking around but was discouraged by the limited choices I had locally and put off by the usurious asking prices. I wound up buying other equipment and telling myself I was happy. But GAS for an R9 proved irresistible. About a year ago, I started trying to hunt down an LP that would get me close to “old wood.” The few times that I found a great guitar, it was snatched up before I could get my act together. When a MyLesPaul.com forum member listed this one on eBay, I jumped. In addition to the old wood top, he thoughtfully upgraded it with all the good stuff—Peter Florence Voodoo ‘59 pickups (amazing), Dr. Vintage ‘50s wiring, Vintage Clone ABR-1, RS Guitarworks tailpiece, Historic Makeovers inlays. This is a great guitar. Maybe it’s just the honeymoon, but I don’t think I’ve even picked up another guitar more than once in the past two weeks. Guitars 2009-03-15T03:16:01+00:00 http://www.novacron.com/index.php/main/view/my_old_yamaha_pacifica_1412_lives/ http://www.novacron.com/index.php/main/view/my_old_yamaha_pacifica_1412_lives/#When:02:30:00Z I had this guitar for over a year with the best of intentions to fix it up, but never got around to it.  There were always other guitars, different projects, so I traded it away toward a Yamaha Weddington Classic at the beginning of the year.  In less than a month, the new owner cleaned it up, had a setup done, reinstalled the pickups and had the guitar back on the road.  It looks great, he’s happy with it, and I’m happy with the Classic.  Win-win all around.  How cool is that? Guitars 2009-02-06T02:30:00+00:00 http://www.novacron.com/index.php/main/view/jmp50_clone_build_part_10/ http://www.novacron.com/index.php/main/view/jmp50_clone_build_part_10/#When:00:30:01Z A shakedown run with the new JMP50 clone.  It lives! After I finished the building and running through the basic tests I dragged my 2x12 cab and guitar down to the basement for a shakedown test.  I started with the presence and tone controls at 5 and the channel volumes and MV at 0.  Gradually increasing the MV and channel volumes, I was thrilled—and a little surprised—that everything worked the first time!  The tone controls did what they were supposed to do, and the volumes worked correctly.  Ramping up the MV and channel volumes, the 50W was getting loud… fast.  I didn’t keep it cranked for long for the sake of marital harmony. I did notice that in addition to what I expect is normal gain-stage noise, there was a fair bit of hum.  Too much.  Poking and prodding the leads going to V1-V3 didn’t seem to have any effect on the hum, so I began to think there was a problem with a ground point.  Up to this point each cap can and the transformer each had their own ground point.  The turret board and input jacks shared a common ground lug, drilled into the chassis between the volume pots and the input jacks (I noticed this on Greg Germino’s amps).  I re-ran the input jack grounds over to the buss bar on the turret board, next to the volume grounds, and then took another lead off the buss bar from the presence end back to the same point the transformer is grounded.  This helped a lot.  There’s still some hum when I start to turn the amp past home playing volumes that I need to work on.  I’ll probably take things apart again and ground each of the cap cans back to the same mounting point, creating a true star ground and see if that solves the problem.  Othewise, I’m still getting used to the overall sonic signature.  Ch. 1 is a little brighter, and ch. 2 is a little muddier, than I would want individually.  Combine them, however, and things start to sound pretty good.  I would describe it as woody or stringly, but that doesn’t mean much.  Higher gain than I was anticipating, but still relatively articulate.  And I’m enjoying the “kerrang.”  Even my wife noticed the difference and said she prefers the JMP50 over my last build, a Matchless DC30 clone. What’s next?  I just ordered a head case from Metro and will probably make some minor tweaks before I wrap it all up.  I may try a .022uf coupling cap and different bright cap in ch.1, and some different values in ch.2 to see if I can tame ch.1 and make ch.2 a little more aggressive.  I also want to swap out the 3A diodes for 1A fast recovery diodes and see how that sounds.  I might replace the 10k bulk resisters in the power supply with Vishay/Dales just to be consistent.  And, if I get really adventurous, I may try mounting the 5.6k swamp resistors on the turret board with leads down to V4 & V5, but I’m not sure how I would stake the turrets without taking the whole board out of the amp.  Otherwise, there’s not much else I feel compelled to do other than get some playing time in. Marshall JMP50 (1987) Build 2009-02-02T00:30:01+00:00 http://www.novacron.com/index.php/main/view/jmp50_build_part_9/ http://www.novacron.com/index.php/main/view/jmp50_build_part_9/#When:00:17:00Z Final setup and initial testing on my JMP50 clone While the rest of the world—at least everyone in the US—was watching the Superbowl, I was finishing up my new JMP50 clone build.  After the pictures were taken, I use a compressor to blow all the stray bits of solder and strands of wire out of the chassis and got ready to test per George’s instructions.  There was a lot of junk in the chassis and I wanted to make sure I got it all out so some little piece of wire didn’t short something out when the amp was turned on. Initial power-on revealed a big problem - no voltage anywhere. No heater voltage, no HT voltage. Nada. I had reversed the twisted leads that run from the on/standby switches to the HT fuse and mains voltage selector. Easy to fix and no harm done. A few minutes later, I had this corrected and began testing voltage. Almost everything was within normal range for an amp without tubes installed. The exception was V1, which showed nearly 2x the correct voltage on one pin and no voltage across pin 3. This was because in my late-night building, I had forgot to add a jumper between two cathode resistor/cathode bypass cap turrets that are done differently on a typical 1987 build. Again, this was an easy fix once I figured out what was wrong. After that was sorted out, all the voltages were within their normal ranges. I began installing tubes and the voltages all stayed in their normal ranges. So far, so good. When I tried to bias the EL34s with a 47k bias resistor, I was only able to bring them up to about 28mA. A quick change from 47k down to 33k let me bias the tubes at 40mA, so that was good too. So, how did it work??? How did it sound???  To be continued! Marshall JMP50 (1987) Build 2009-02-02T00:17:00+00:00 http://www.novacron.com/index.php/main/view/jmp50_build_part_8/ http://www.novacron.com/index.php/main/view/jmp50_build_part_8/#When:22:47:00Z Nearing the end of building my JMP50 clone.  The turret board is populated and a Lar/Mar PPIMV is wired in.  But does it work?   Sage advise is to build the basic amp first and test it to make sure it works before starting on on the mods.  Did I follow the sound advise?  No, I did not.  I went ahead and added a Lar/Mar PPIMV before firing it up for the first time.  It took a while to get the connections so I was happy with them, but I think it turned out very well in the end.   The other end of the PPIMV is connected to pin 5 of V4 and V5 where the 5.6k resistors usually go.  I wasn’t comfortable leaving these to hang in the breeze so I put a piece of stripped wire insulation on the resistor leads.  It isn’t a rugged as I’d like, but it’s a good start.   The obligatory gut shot.  You might not notice, I haven’t installed an indicator lamp yet.  I was going to use a Fender-style jeweled lamp that I have, but that requires a fairly large hole in the chassis so I’m undecided.  I need to take a few more better pictures of the guts so that the components are clearly visible.   The back.  The transformers are still wrapped in paper at this point to prevent the black paint from getting scratched up. JMP50-20090131-05.jpg Marshall JMP50 (1987) Build 2009-01-31T22:47:00+00:00 http://www.novacron.com/index.php/main/view/jmp50_build_part_7/ http://www.novacron.com/index.php/main/view/jmp50_build_part_7/#When:04:50:01Z A long night’s work on the JMP50, soldering the leads onto the turret board before installing it in the chassis. I wanted to push on tonight and mount the leads on the turret board and get it installed in the chassis.  I thought this would be quick and easy.  And while it wasn’t difficult, it did take a lot longer than I expected, mostly because I was going back and forth between Ceriatone layout pictures and Metropolis’ excellent 50 watt build guide.  I was trying to adapt Metro’s colors to the Ceriatone layout and double-checked my work frequently.  I figured that it would be easier to do it right now rather than having to pull the board out of the chassis after it was all together.   This gives a pretty good idea of the wiring.  The power supply end of the board is as the top right of the picture.  Both pairs of twisted yellow wires will connect to the chassis-mounted cap can, the one in the middle of the board goes to the cap can mounted next to the choke.  You should also be able to make out a yellow/green wire at the power supply end; this goes to the cap can that feeds the power supply.  The twisted red leads go to the HT taps on the power transformer.  Black/red leads are jumpers that connect various turrets.   And here’s what it looks like from the top.  Not as much to see.  The twisted orange/green pair will to V4 and V5, pin 5.  These are usually routed beneath the board, but I put them up to so I can remove them easily when I install a Lar/Mar PPIMV.   I used 8-32 standoffs from Mouser to secure the board.  Even though there are no clearance problems, 8-32 was probably too big and I should have used 6-32 instead.  And, oh fuck, one of the standoffs broke while I was tightening up the lock nut.   The leads to the HT taps on the power transformer and cap cans are connected. You get the idea.   Here the here the flying leads are connected to the PEC pots.  Notice also the ground wires connected to a buss bar a the back of the turret board.  This idea came from Ceriatone and was necessary because you can’t solder buss bar to the stainless backs of the PEC pots so another grounding scheme had to be used.   Why did I take another picture of the power transformer?  Because I was tired? I was verytired at this point.  This was after Midnight, and I had worked on the amp for three or four hours.  My judgment must have been impaired by this point because instead of stopping for the night, I went on and started mounting components in the turret board.  No pictures, though.  (Note to self: stop working on amps when you’re so tired you can’t read resistor codes.) Marshall JMP50 (1987) Build 2009-01-29T04:50:01+00:00 http://www.novacron.com/index.php/main/view/jmp50_build_part_6/ http://www.novacron.com/index.php/main/view/jmp50_build_part_6/#When:04:13:00Z The JMP50 build saga continues as I fabricate the turret board from scratch, drilling and mounting nearly 70 wee small turrets.   I’ve drilled and mounted turrets by hand in the past and, well, they weren’t that pretty.  This time around I used a laser-guide drill press and full-size paper template that I marked up so that all the turrets would line up.  With a guide mounted on the table, all I had to do was slide the Garolite along and drill each hole.  This is the next-best-thing to using a drilling template.   I’m very happy with how the holes came out—they’re all lined up in neat rows and look very tidy and professional.  One thing I would do differently in the future is to cover both ides of the Garolite with masking tape so it doesn’t show the faint scratch lines you see.   Here’s the finished turret board.  I used the same drill press with a turret staking tool in the chuck to swage the turrets.  I didn’t take a picture of the process, but it went very quickly—just push the turret into place, put the long end into a small mandrel, and crank down on the drill press.  I think the whole process of cutting the Garolite, drilling the holes and swaging the turrets took less than two hours. Marshall JMP50 (1987) Build 2009-01-26T04:13:00+00:00 http://www.novacron.com/index.php/main/view/jmp50_build_part_5/ http://www.novacron.com/index.php/main/view/jmp50_build_part_5/#When:04:18:00Z I’m making good headway on the JMP50 clone build.  Tonight I installed the Marstran power transformer, mains voltage selector switch, output jacks and output impedance selector switch.  Looking at these pictures, it seems like I didn’t actually do much on the amp today.  (Truth be told, I’m very cautious when working with fixed leads like the transformer leads—I don’t want to cut them too short.  I usually start out cutting them too long, then triming them back until I think they’re just the right size.)   Underside of the laydown power transformer from Brian Wallace at Marstrans.  The top bell is painted black to match the chassis.   A close-up of the power tube sockets, output impedance selector switch (left), mains selector switch (right) and HT fuse holder.  I’m pretty happy with how my soldering skills are progressing and the work looks neat and tidy over all.  You can also see the lock nuts I used wherever possible.  Almost all the hardware is stainless steel.    Speaker jacks and impedance selector switch.  Yawn. PEC potentiometers mounted in the chassis.  The PEC pots are stainless steel and you can’t solder the buss bar to the back of the case like you can with other brands, so I’ll need to change the grounding scheme around a little to accomodate this. Marshall JMP50 (1987) Build 2009-01-25T04:18:00+00:00 http://www.novacron.com/index.php/main/view/jmp50_build_part_4/ http://www.novacron.com/index.php/main/view/jmp50_build_part_4/#When:03:08:00Z The JMP50 build continues with a new amp work stand and heater wires installed. Before working on the amp any more, I though it would be a good idea to knock together a work stand to support it securely.  (It also gave me a great excuse to setup and test the used table saw I bought from my neighbor a few months ago!)  Putting the stand together was actually very easy thanks to the new saw.  A few cuts, some glue and screws, a couple coats of polyurethane and presto! amp work stand!  It is much easier to work on an amp when it is angled and securely supported.  Compared to my DC30 clone build, this was a big improvement.   I spent an hour or two twisting and soldering the heater wires.  I’m trying to emulate the neurotically neat wiring I’ve seen on some Marshall clones.  I don’t know if I’ll be 100% successful, but it’s a good goal.   I also installed and grounded the IEC plug socket.  Not very exciting, but it felt good to get some work done on the amp while waiting for the replacement power transformer to arrive.   This is a good shot of the new amp stand.  It’s sturdy, even while working on the amp.  Peek under the amp and you can see the transformer and choke wrapped in paper and taped up—I don’t want to scratch it any more than I already have. Marshall JMP50 (1987) Build 2009-01-23T03:08:00+00:00