Monday, March 13, 2017

Mavis Flying V Acrylic Guitar

The Mavis “Flying V” guitar featured today represents a first of sorts for me, because I'd never laid my hands on an acrylic-bodied instrument before this. I expected it to be unbearably heavy, but it was not. Frankly, if you’re comfortable with Les Pauls, you’ll be right at home with this Mavis.

Besides my initial reservations about the weight of this axe, I was also expecting it to sound thin and hollow. After all, tonewise, how could an acrylic body ever compare to one made of wood? However, as it turned out after rewiring and servicing, I was dead wrong. In a blindfold test, I’d expect to have a hard time distinguishing between the two. Now, I must admit that the V-shaped body makes playing sitting down rather uncomfortable. However, resting the crook of the V against one’s thigh solves the problem.

Sad to say, I could not find any information concerning this particular guitar on the web. I did, however, find out that “Mavis” is a house brand for Japan's Ishibashi Music Corporation. All said and done, this is a fine instrument loosely patterned after the Gibson Flying V Custom. The reader might also find it interesting that this rare gem was discovered in a used goods store in Cambodia, of all places!

This guitar sports a 24.75" scale 22 fret maple bolt-on neck with a rosewood fingerboard. Stringing is through-body, with a stylish chrome V-shaped face plate (think Flying V Custom) that the strings pass through before meeting a Sun Il tune-o-matic bridge.

Both pickups are humbuckers: a Select Model SEHG "Designed by EMG" (neck), and a Bill Lawrence U.S.A. (bridge). Controls consist of individual volume pots for each pickup, a 3-way toggle switch, and a coil tap for the Lawrence. Besides general setup and a string change, the owner wanted me to troubleshoot the wiring and components, and replace the coil tap with a kill switch.

Other than worn-out pots, gnarly soldering, and a corroded output jack; there were two major problems with this guitar. The first was that combining both pickups produced a thin, hollow sound, as if they were out of phase. The second was that on its own, regardless of whether the coil tap switch was engaged or not, the sound produced by the bridge pickup was weak and nasal. There was virtually no bass, but only upper mids and highs.

After time-consuming research on the web, I learned that the first (closest to the neck) coil of the bridge pickup was actually its south coil instead of north, and vice-versa. Bearing this in mind, I rewired the pickup "backwards," so to speak. Now, with both coils in phase and in series, the Lawrence was finally able to live up to its true potential. The difference was like night and day -- from wimpy and nasal to full and beefy, with nicely balanced highs, mids and lows. Totally satisfying!

Good for me, but I still had to solve the out-of-phase problem when both pickups were combined. As I’d already determined the correct wiring scheme for the Lawrence, the only solution was to reverse the wiring of the neck pickup. This solved the out-of-phase problem, but at the same time, introduced a new one. Now, since the ground and hot leads had been reversed, the body of the neck pickup itself was "live," resulting in an audible popping sound whenever I touched its height adjustment screws. Eventually, I was able to minimize this unwanted side effect by coating the screw heads with a couple layers of lacquer.

Having taken care of these problems, I proceeded to overhaul the entire control cavity, replace the faulty mini pots and output jack, and wire in a kill switch.

Monday, March 06, 2017

Aria SB-404/5 Bass

Here's an Aria SB-404/5 bass that, stock, would have featured active electronics, a Mahogany body, Maple/Nato five ply neck (thru body construction), 24 fret Rosewood fingerboard, 34 inch scale length, two BDS-5 humbuckers, black hardware, and a Stained Natural (SN) finish. However, looking at it today, the only stock features are the strings-through-body bridge, neck and body. The owner had long ago upgraded this bass with gold-plated tuners, EMG 45HZ pickups and a Ram Bass preamp system (master volume, pickup blend, and boost/cut treble/bass controls).

He loves this bass to bits, but was troubled by intermittent hum and noise. While evaluating the electronics, I noticed a couple of problems  i) the control cavity was totally unshielded, ii) the back of the control cavity cover was bare, iii) connecting wires had not been trimmed to length; and iv) the preamp module had simply been shoved into place.

I suspected the lack of shielding and excess wire length to be the main culprits behind the hum and noise. Thus said, I proceeded to 1) shield the control cavity walls with shielding paint and a ground tab, ii) add an aluminium plate to the back of the control cavity cover, iii) trim excess wire length and resolder components; and iv) secure the preamp module. I'm glad to report that these measures succeded in minimizing the problem.  

Further Reading

Aria SB-404/5 Ovangkol 5-String Electric Bass Guitar | Music123

Bass Review - For Bassist : Aria SB 405/5

SB-404 / 5

Aria Pro SB-404-5 | Reverb