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Components Quality?


This is a question that comes up all the time. "Is there a difference between using different component types? If so, which is best?". The natural response of most people is to say that whatever sounds best to you is the correct choice, but that doesn't really answer the person's question, does it? The effects world seems to be about sales of over-hyped mojo. "This component will make your playing 150% better and make you sounds exactly like artist 'X' - that sort of thing. All I can do now is laugh at the amount of ridiculous bull that I've seen people trying to pedal (pun intended, yes), when it seem the people out there who are actually building the best gear are sitting back and humbly letting people decide for themselves. I offer these semi-coherent ramblings as my opinions only. I'm somebody who likes to learn a little every day so if you have any disagreements, corrections or additions then please get in touch with me so that I can learn from you.

So does it all make a difference? The answer is yes, no, and sometimes. If you built a stomp box using the cheapest parts you could find from your local electronics store, then it would probably sound pretty much the same as one built from expensive audiophile parts. You might even like it better because it has a DIY/indie mental warmth to it. As my general rule, it's the circuit and the circuit's values that give the largest influence on tone. But if you want to build a stomp box properly, there's a lot more than just connecting electronics components together in the right order. How will your pedal hold up with regular gigging? What's the chance of failure mid-set if it's on stage in front of thousands of people? It could happen...

Capacitors

Probably the most debated subject on mojo. Some capacitors can be described as sounding sweet and others gritty, harsh and noisy. The general sensis from the audio world seems to be that film capacitors sound best, electrolytic capacitors don't pass linearly, and ceramic capacitors are harsh and noisy. Can we prove this? Luckily in electronics it's maths and we can prove just about anything! Steve Bench has done some research and written an interesting article on his findings. If anything, it seems to confirm that most film caps are pretty much the same, and pass more linearly than ceramic. I like using MKT's in the signal path. They can give better tolerance ratings (±5%) than greencaps (±10%) and are conveniently sized for PCBs, they just look kind of ugly. For supply filtering and where large values are needed, I try to use low ESR electrolytics with a small value film or ceramic capacitor to help with RF. I stay away from mylar caps as they always seem to be the first component to deteriorate.

Is replacing all the capacitors in a circuit with film caps a good idea to upgrade the circuit? It's probably not going to benefit you much. Another thing to keep in mind is that electrolytics have a more limited life span. Some of them only have the shelf life of 10 years. It's a good idea to over-rate the voltages by 30-100% to increase the life span.

Resistors

Resistors limit the amount of current that can pass, and dissipate some of that current off as heat. Originally resistors only came in carbon composite packages. The early produced ones had tolerances of ±10% or ±5%. Now we also have a choice of metal film resistors in ±1% tolerance. Some people claim that carbon-comp can give a smoother and more vintage sound. This may be true in the case of amplifiers, where larger voltage changes (ie. a preamped guitar signal) can cause a swelling effect in the resistor, which people claim is sweet sounding, but in low voltage effects this is not the case. They certainly can look pretty, especially the 1 watt ones. Carbon comp resistors tend to be nosier, followed by carbon film, followed by metal film. For reasons of noise and tolerance I use metal film. We can't get away from the fact however that potentiometers use a carbon taper and have horrible tolerance ratings.

Tolerance

This seems to be the biggest selling point when people try to tell you that they use the best components. The idea is that if you want to match your original design, you want the values to be as close as possible. Why is this a problem? If, for example, you have high/low pass filter tone control, it will be made with a resistor and a capacitor. We will explore the values of a 1KΩ resistor and a 0.1μF capacitor. If they were both within ±10% tolerance, they have the potential to be from 0.9KΩ/0.09μF to 1.1KΩ/0.11μF. This changes the roll off frequency from approximately 1.97kHz to 1.32kHz - which could be somewhat noticeable.

I think it's a bit of a misconception sometimes that people think, for example, if every component was within ±10% tolerance, than it could all at up (10%+10%+10%+10% etc.) to a product that has potential to stray miles from the original. In reality, if every component in a circuit had a tolerance rating of ±10%, then the difference from one whole circuit to the next would be ±10%. Over all, it's not a shocking difference, but if you can keep the tolerances tight then you may as well.

Electromechanical

This includes things like the enclosure, foot switch and sockets.

Any audio socket will work the same as another when it's first installed. If it's making electrical contact where it's supposed to then that's all it needs. But will it remain rigid for years to come? How long will it take before corrosion kicks in and you need to clean the contact points? I personally like the Switchcraft brand sockets. The are well machined with an extra large nut and give a very assuring clunk when you put a jack in, similar to closing an expensive car door. They are all pressure tested and come within very fine physical tolerance. They seem a fair amount better than the Neutrik ones, and especially better than generic cheapies.

You are probably aware that switches have a certain duty life. If you are unsure of products reputation, based on tested history, then you don't know how it will perform down the track. Latching foot switches should be rated for line voltages with a very fast and firm action to minimize arcing and bouncing, not that audio signals will arc. For most purposes, I prefer true bypass. So do many people who are very specific about their tone.

The quality of enclosures varies quite a bit. Obviously metal enclosures will not only be stronger than plastic ones, but they can be Earthed and used to shield your circuit from RF and EFI. I use diecast aluminium enclosures rather than folded steel ones because I like that it is solid, does not bend, and is easier to drill, but they both do the same thing. Aluminium isn't cast in its pure elemental form, and is alloyed down with all sort of metals. The cheaper alloys can be very weak. Some are cast too thin. Some of the worse one's I've seen would dent the whole surface when I went to centre punch before drilling. I was drilling a thin one with an indented logo branded on the inside, leaving that surface a fraction of a millimeter thick. When I went to drill where the logo was a whole chunk came out with it! That being said, the Hammond/Eddystone enclosures are very good. They are extra thick and the surface needs less preparation for finishing.

Other places where more money can be spent is things like IC sockets. Machined ones give a more reassuring contact than cast ones. In extreme cases, heat cycles of expansion and contraction can slowly creep the components out. I generally don't like the idea of using either in pedals.

Noise levels and ICs

Noise figures can be measured in distortion levels. This doesn't necessarily mean the distortion you get from clipping a signal while overdriving an amp, it can just mean any variance in the shape of the wave compared to the original. Keep in mind that most people will not be able to hear 1% distortion levels. Jack Ormon has a nice blind test where he adds 1% second harmonic distortion to a pure sine wave. Some ultra hi-fi opamps have distortion figures as low as 0.00008% (the OPA2134). The TL071 is considered low noise and has 0.003%, so you'd need the equivalent of 333 TL071's to reach 1% distortion. The lower the distortion figures, usually the higher the current the opamp consumes.

Opamps with FET inputs tend to have a higher input impedance and give a better buffering effect.

Swapping out ICs in a distortion pedal isn't always going to change the character of the tone. The most important thing is the circuit and values around the IC. There might be a more significant change if you are swapping opamps that are being hard saturated and self-distorting.

Wires

'Mojo/boutique' choices here are made more often for cosmetics rather than functionality. It will often be claimed that only solid core wire gives lowest resistance and highest reliability, when it's actually the contrary way. Solid core certainly helps to make a very neat build and has a very good place in point-to-point amp constructions where proximities are critical, but not always in effects pedals. Solid core wire can only be worked (bent) a few times before you run a risk of weakening the metal. If you scratch the protective coating, you run the risk of weakening the wire also. Should it break, the circuit becomes open. Stranded wire however is much more flexible and offers heaps of backup strands should one ever have a problem.

Teflon wire is an absolute pleasure to work with as it has very high temperature insulation, holds a solid shape and is multi-strand. It can have brittle ends making it easy to snap if soldered poorly however.

Shielded wires can in some instances offer protection from noise generated by LFOs (low frequency oscillators) or diminish oscillation in high gain circuits. This can sometimes come at a compromise however as you are increasing capacitance to Earth, which can cause loss of high frequencies.

Similarly cotton insulated wires won't make you sound any better, except perhaps in your mind.

Any bare wires or components leads that have a potential to short should be insulated with heat shrink. If it can happen, chances are it eventually will. Imagine every possible thing that can come loose or spin.

Untinned copper wires will eventually corrode. Unprotected copper circuit boards will also similarly corrode over time.

Solder

You may have seen pedals being advertised as being made from silver solder, or lead-free solder. Silver solder is sometimes hyped-up for mojo reasons. It's not a solder made entirely out of silver, rather an alloy containing a small percentage of silver. Why do they do this? Typical solder is made from tin and lead at a ratio of around 3:2. Parts of the world (Europe, Japan) comply with a standard called RoHS (Restriction of Hazardous Substances) which came into effect in 2003. This is enforced mostly to restrict certain substances finding their way into land fills by means of discarded products. This causes a few issues with electronics. Lead-free solder costs more. It melts at a higher temperature. It is more brittle. It can also have a whiskering effect over time which can cause shorts in a circuit. There's no benefit in using silver solder other than complying with RoHS.

Germanium and Silicon

We've all heard about how great the semiconductor is. There's billions of them delivering this web site to you. Germanium was the element used as the semiconductor in the first transistors and diodes. The transistor was the revolution that replace the vacuum tube, at least for the general consumer. They are smaller. They don't require dangerously high voltages or heavy, bulky transformers. Great! The first series of transistors made with germanium were not very consistent though. They suffered from an effect called leakage. Gains varied all over the place and biasing was a nuisance. So, the silicon transistor was made which generally has no leakage and consistent gain levels.

What's the difference? Germanium sounds closer to the vacuum tube. When you push it to its limits instead of cutting off harshly it flattens the top of the signal with rounded edges. Silicon gives hard clipping. A lot of people say that germanium can introduce richer harmonics. Noise levels on germanium devices may not always be as good as new production hi-fi circuits.

 

 

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Copyright © Darron Thornbury