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Guitar Finishes: Is Lacquer really better than Poly?

January 25th, 2015

In the guitar world, there are two major categories of chemistries used to finish electric and acoustic guitars. One is the traditional “Nitro” nitrocellulose finish, and one is the modern “Poly” or polyurethane finish.

Early guitars used the Nitro style finish because that was the available chemistry of the day for both classical instruments and electric guitars. Many of the techniques for making classical instruments transferred directly to electric guitars, especially the traditional set-neck hollow body models.

Nitro finishes have many desirable qualities: They are thin, repairable, flexible, and don’t inhibit the vibrations of the wood. For a purely acoustic instrument these are highly desirable qualities, and a bad finish will kill the tone of an acoustic instrument. Nitro finishes are also labor intensive to apply, slow, are highly flammable, and toxic. They are a VOC (volatile organic compound) and subject to environmental limitations. Special permits are required to have a spray booth that uses lacquer finishes, which also raises the cost.

The Knaggs Kenai is a Nitrocellulose finish

From a pure standpoint of manufacturing efficiency and cost, the more modern Poly finishes are the dominant method. They cure using a catalyst, which can be accelerated with heat or UV light, and compared to a Nitro finish, can be applied in a fraction of the time. They are also extremely glossy, durable, and don’t tend to crack or check over time.

The wrap on a Poly finish is that they are thick and inflexible, and don’t allow the instrument to vibrate and resonate as well as a lacquer finish. This is completely possible, but there are many variables in how the finish is applied, the amount of wood fillers, undercoats, etc. Environmentally conscious companies such as Taylor have put a lot of research into thin, flexible modern coatings that provide great sound quality but are safe for the environment and their employees.

Almost all G&L guitars are a Poly finish

Lacquer finishes by their very nature are a good match for instruments, but their cost makes them viable only on higher end products. So are Nitro guitars better sounding because of the finish, or better sounding because they are only applied to guitars of higher overall quality? It’s probably a little of both, and because of that it’s hard to separate the two.

Some players will only play Nitro guitars, and if you have the means to own that level of instrument, you’re unlikely to be disappointed. However, a guitar is always the sum of its parts and workmanship, and finish is just one of the components. Nitro guitars make up a tiny fraction of the market, so obviously there are scores of wonderful guitars made every year utilizing modern finish chemistries. The finishing method is an indicator, but always let your ears be the guide.

Improve your Guitar Tone: Optimize your Volume and Tone Controls

January 25th, 2015

I would wager that if you took an informal survey, you’d find that most guitar players play with their volume and tone controls full up 90+% of the time. More likely than not most players get their tone figured out at the amp and just leave the guitar up at the max.

We don’t we use our guitar knobs?

On many of guitars, turning down the volume control causes an unacceptable loss of high frequencies and dulls the tone of the guitar. This might be desirable in some instances, but not if you like the sound of your guitar but just want less of it. The volume control is a potentiometer – which is really a variable resistor – that is supposed to attenuate all frequencies equally. But the sensation is that more high frequencies are lost first. This is partially the nature of signals and partially that human hearing is not linear, and we hear high frequencies less at lower overall volumes. The tone control is a potentiometer with a capacitor, which is a passive electronic component that filters out specific frequencies. The tone control on most guitars is a “low pass filter” that bleeds off increasing amounts of high frequencies as the control is turned down.

How To Optimize Your Volume And Tone Controls

Step One: Turn your amp up. The gain section of a guitar amplifier is often not linear, and amplifier barely cracked open may far from developing optimal tone. We’re not necessarily talking distortion, just nice harmonically rich sound. If your amplifier volume is at 2 or 3 and your guitar is at maximum, try turning your amp up to 4 or higher and turning your guitar down. On most amps this will start to get them into the sweet spot of their range and you may notice a noticeable improvement in overall tone. You may also notice that even with the guitar turned down the tone is not so muddy. Oftentimes the controls on the guitar appear to work much better once the amp is getting some exercise. Plus now you have some room to play with volume-wise on the guitar, and a whole bunch of new sounds open up. Many amplifiers – especially early tweeds – don’t really get a lot louder past “5” on the dial, they just get dirtier and richer. If you’re amplifier is just too loud anywhere past 2 or 3 on the dial no matter what, go amp shopping. While you’re at it get a smaller one.

This is also a good time to mention that several guitar makers have moved to printed circuit board (PCB) volume and tone control assemblies. This clearly optimizes their manufacturing and assembly process, but makes modifications more difficult if not impossible. The subjective tonal quality of a PCB assembly is a hot topic, and there are many players not happy with the notion of a $3000 guitar having board-mounted pots and capacitors. In general, if your guitar has a PCB assembly and you want to tweak it, you’re going to have to take it out and start from scratch. With that said, let’s look at possible control improvements.

Install quality potentiometers – Guitar manufacturers must watch cost, and they’ll sometimes skimp on the quality of the electrical hardware, knowing that most players never look under the hood. But like anything, some stuff is better than others. Many import guitars use the “mini” pots, which due to physical construction limitations, often just don’t work as well. A high quality audio taper pot will make a difference in the ability to control volume and tone. Our Emerson Custom wiring kits use their own special version of CTS pots, and Mojo and others offer high quality replacement parts too.

Change Potentiometer Values – Traditionally, single coil type guitars use a 250K ohm potentiometer, and humbucker guitars most often use 500K. The higher impedance of a 500K pot for the tone control will retain brightness a little better, while a 250K pot will sound warmer. For a very dark guitar, you might want to even try a 1meg pot for the tone control.

Try a treble bleed – While this sounds painful, it’s a small resistor/capacitor network soldered between the input and output lug on the volume pot. The purpose of the treble bleed is to bypass the volume control with a small amount of high frequency signal regardless of where the volume knob is turned. The effect is to retain acceptable high frequency response at lower volumes. It works, and it’s a matter of taste and experimentation whether you like the effect or not. Emerson wiring kits all come with this feature (installation is optional), and you can find lots of information on this little circuit on the Internet and guitar magazine websites.

Vintage versus Modern Wiring – This is another topic that is all over the Internet. The primary difference is that modern wiring has the tone capacitor grounded to the tone pot case (shunting high frequencies directly to ground) while the vintage wiring has the tone capacitor connected between the volume and tone pots (the entire signal is being sent through the capacitor before it is attenuated). Modern wiring allows for independent control of volume and tone, while vintage wiring produces some interaction between the volume and tone controls (the tone control works differently depending on where the volume control is set). Many players feel that vintage wiring retains tone better as the guitar volume is turned down. I would agree, and find that the vintage wiring schematic gives a greater, more musical range of tonal options. If my guitar isn’t wired this way, I change it.

Change Capacitor Values – The general rule of thumb is that for tone controls “Gibson” guitars use .022 mfd (micro-farad) capacitors while “Fender” guitars use .047. Generally speaking, the greater the capacitor value, the more aggressively they roll off high frequencies. With single coil guitars being typically brighter, the .047 value makes sense (although many G&L guitars with the MFD pickups use the .022 value). One trick on neck humbucker pickups is to use a .015 value, which roll off highs even less abruptly and helps to keep the pickup from getting too muddy. If your tone control does not seem to “do anything” try a higher value.

Capacitor Construction – Here we enter the world of Voodoo. A capacitor can be made of many different materials, and for cost purposes guitar companies will often the lowest cost component, typically a ceramic disc capacitor.  These are felt to be the least “musical” sounding, and there are various varieties of “film” capacitors — usually a foil and mylar film construction – that are preferred for audio applications. The Holy Grail capacitor is thought to be a paper-in-oil capacitor, and tone freaks will spend big bucks finding old “PIO” caps from the 50’s and 60’s. The PIO capacitors are expensive because they are expensive to make, and are made in small volumes for special purposes, like high end audio circuits. As with tubes, the mainstream world dropped this style of capacitor years ago due to cost. Capacitors can affect your sound, and also how your tone control reacts. PIO capacitors do tend to have a very smooth tonal effect on the high end. But don’t think you have to spend $50 on a NOS Cornell Dubilier oil filled capacitor to get good sound. The hands down bargain cap is a 715 or 716 “Orange Drop” film capacitor, which is typically under $2.

Optimizing your guitar controls can be a fun and low cost way to improve your sound. You can buy complete drop-in kits, or if you like to solder, it’s a great DIY project. The Internet is full with information and there are countless variations of control schemes. But the most important lesson is to use your amp and guitar controls together as a team – not separate components — and explore the full range of what your rig has to offer.