Covers - In Detail Explained

This article goes into a little more depth on the topic of covers, and, whilst the overview is, really, in relation to “The covers we fit to our humbuckers” – I’ve lifted a few of the articles sections from other products on the website (so there may be some sections that read as If we’re talking about “just covers” – the information is still true, don’t worry too much on it)

Colours Explained

I think this is a little bit redundant to be honest, because the site has the "smart swatch" system, which shows you how everything looks once you've assembled it, and whilst its a bit "too perfect", it is pretty accurate to what your going to get. However, i will concede that sometimes, real pictures of real things, can be helpful, so, heres another photo dump, detailing as many of the colours as i can.

Covers
Now, i've detailed what covers do, what how they affect the sound of your pickup, and if you can live with that, its probably worth knowing what the things actually look like.

I'll go into a little more detail on some of the finer detail about some of the topics i've covered above.

Covers and Base Material

I think I’ve covered pole spacing pretty well under the “pole spacing” header, so, whilst bases and covers are impacted by that aspect of humbucker “design”, I’ll gloss over it in this section and concentrate a little more on the impact covers and bases actually have on the signal being produced by the coils.

Its one of those weird things with humbuckers, I wont say its overlooked as such, but its certainly not widely embraced as you’d think.

So, with humbuckers – you’ve usually got 2 options of material when it comes to covers and base plates, either Brass or German Silver (sometimes called Nickel Silver, or just Nickel) and its commonly believed that “brass is ‘bad’ because it sucks out top end” and “German Silver is ‘good’ because it doesn’t effect the tone” – and, broadly speaking, that’s actually correct! But, as with most things, its not as clear cut as we’d like as engineers, so, I’m going to try to drag this topic well and truly into the light!

Ace of Base
So lets start at the bottom, and deal with “base plate material” – Brass vs. Nickel!

	Swap Graphs?
	Base #1 (Purple) Brass German Silver No Base
	Base #2 (Blue) German Silver Brass No Base

We can see from the above, that, really? There isn’t a great deal of difference between the two options (I’ve included “no base” too, for completeness’ sake). If anything, a brass base plate, compared to German Silver, isn’t actually sucking out any top end, its sucking out a little of everything up to the resonant peak, but past that, its comparable to German silver – so we’d perceive that, not as “sucking out top end”, in fact, the complete opposite, we’d hear that as the pickup gaining a little definition, and likely, being a shade brighter! However, it’s a fairly small change in that regard, its certainly not as drastic as we’d be lead to believe in the old “Brass bad/Nickel good” argument.

And, we can see that both German Silver and Brass, and both having an effect on the signal compared to the “no base” version of the pickup (and this is telling, because the same happens on a Telecaster® bridge pickup, or a P90) – without a base, we’re actually retaining a little more of the signal above the resonant peak. Its an unrealistic dream to say “humbuckers without bases sound better”, simply because the mounting system for the pickups is pretty reliant on a metal base, but we can certainly see that the base material, whilst only a minimal change, is always losing “something”. They’re always going to cause a loss of something.

Real world, we’re probably going to “hear” a German silver base as being a little warmer, a little smoother, a little more forgiving (evident in the wider peak) and we’re going to “hear” a brass base as being a little brighter, a little more cutting, a little crisper.

So, with that in mind, it does beg the question – is brass as bad as we’ve all been led to believe?

Well? Probably not, at least from a tonal point of view – we’re not seeing any enormous impact on the signal, we’ve not seeing a huge change to the shape of the plot, frankly (with uncovered pickups!) Brass vs. German silver bases is little more then an extra option for “seasoning”, and I suppose, that’s to be expected, the base is on the bottom, it’s a long way away from the strings, and with all of this stuff, the bigger impacts are things that sit between the coils and strings, not beneath!

However, there are one huge point of note here.
Soldering to Brass!
Brass is an absolute pig to solder to! Its far more conductive than German Silver, so it wicks the heat away from the point you want to solder to, making it difficult to make a good, solid joint. This isn’t a massive issue when the only solder joint you need to make to the base is the ground wire for the hookup, but it can be a real pain if you’re fitting a cover, where you’re making a couple of small spot weld to hold the thing in place. German Silver, by comparison, is a poor(er) conductor, it doesn’t wick the heat as effectively, so soldering to it is much easier.

Frankly, when the humbucker was invented, chances are, German silver wasn’t chosen as the preferred material because it had some wonderful, musically adjacent alloy that left the humbucker sounding closer to the “ideal” – it was probably chosen because it was easier to solder to. It costs more to produce then brass, but, frankly, its quicker to work with, introduces less risk during pickup assembly (better to make your spot welds with a solder iron then with a small gas torch!) meaning less tools required, meaning less training, and less fire risk! (a weirdly big deal in guitar manufacturing!)

Bases – a conclusion
If you’re building an uncovered humbucker, and your happy soldering the ground connection onto the base, brass is as good as German silver! Its slightly cheaper, and it’s brightening the pickup ever so slightly. It’s probably so small a change that its below our comprehension, but at least you know now, what’s happening. You can lean into it if you want to, or don’t. Just be aware, brass isn’t bad! (And that’s likely going to be the last time I type that, because things are about to get interesting!)

Covers
I know this is purely a personal taste thing, but I don’t think they’ve ever invented anything that looks as good as a covered humbucker in a Gibson® (and I’m a Fender® man!) so I certainly won’t be using this section of the write up as a stick to beat anyone who feels the same way! Covered humbuckers are beautiful! However, they’re one of those things where, the “truth” about their impact on pickups has become lost along the way, so, just like bases, let’s see if I can bring a bit of perspective to the whole thing.

So, just like base plates, you’re dealing with 2 different materials when it comes to covers – either Brass or German silver again (the “no cover” option is at least viable here though, where with the base plate, its more of a hypothetical, and, technically speaking, Stainless steel covers did exist, but it was short lived, and I don’t believe it ever went past the prototype stage of the initial humbuckers!)

And, we’re back to the old trope! “Brass sucks out top end, German silver doesn’t affect the sound” – so lets get straight into the graphs.

	Swap Graphs?
	Base #1 (Purple) Brass German Silver Cover #1 (Purple) German Silver Brass No Cover
	Base #2 (Blue) Brass German Silver Cover #1 (Blue) Brass German Silver No Cover

Now, that graphs actually REALLY unfair, but, real world? Its true I’m afraid. If I go grab you a Classic 50s, slap a Chrome plated German Silver cover on it, that’s what’s going to happen to your signal. I think we’d all agree, that that is definitely “an affected sound” right?
Now, before we get into what’s going on with German Silver, lets agree too, that brass is doing EXACTLY what we thought it would do too. Its sucking out a huge amount of voltage from the resonant peak, and its making the pickup sound very woolly. We’d definitely perceive that as “top end has been sucked out”.

So, the weird thing here, is that German silver is actually sucking out a lot of top end too! Not as much as brass, but its still having a big impact! Now, the reason as to why, is quite interesting.

To explain this well, is going to get pretty boring, but, considering your entertaining the idea of winding a humbucker, presumably for fun, this might be right up your street, and its worth knowing, so bare with.

The ”problem” with humbucker covers, isn’t actually to do with their material per se. Its more to do with the conductivity of the things, and, as I said earlier – when something is placed between the coils and the string? That’s when we see a big impact.

So the above graph, is a Chrome plates cover in both instances right? The thing with electroplating, is that, primarily, it’s a cosmetic thing, its got to look great hasn’t it? And the way you get an absolutely immaculate finish on your electroplating, is to first, plate the part in copper.

That gives the plating material (be it Chrome or Nickel or Ruthenium or Gold) a better “bed” to adhere, so its less likely to show the “grain” of the Brass/German silver, and its less likely to fail in the short to medium term. Copper “underplating” is most definitely “the norm” when it comes to humbucker covers (and most electroplating) because it gives the best possible finish.

However – copper, is also, VERY conductive! (Way more than brass or German Silver!) so what we’re actually seeing with the above graph, whilst real world (you buy a chrome cover? Its got a copper underplating!) – its not really a true reflection of Brass vs. German Silver – its Brass + Copper + Chrome vs. German Silver + Copper + Chrome!

THIS, is a true representation of Brass vs. German Silver (vs. Brass + Copper+ Plating vs. German Silver+ Copper + Plating vs. Nothing)! A pickup fitted with a completely unplated covers! Just the bare alloy! (its actually a Telecaster® neck pickup, simply because we don’t carry humbucker covers in raw brass – no ones ever asked for them to date!)

	White - Uncovered - [email protected] Red - German Silver w/No Copper Unplate - [email protected] Pink - German Silver w/ Copper Underplate - 16.4dBv @ 7.37kHz Blue - Brass w/No Copper Underplate - [email protected] Green - Brass w/Copper Underplate - 9.8dBv @ 7.81kHz

And we see something very interesting! Raw German Silver actually isn’t as bad as we think, is it? We’re still losing a fair bit of voltage at the peak, but no where near as much as we are with a copper underplate.

And we can see that in a slightly more “real” test with a humbucker, comparing a copper Chrome plated/coppered German Silver cover to a Chrome plated cover WITHOUT a copper under plate!

	Blue - Uncovered - [email protected] Green - German Silver w/No Copper Unplate - [email protected] Purple - German Silver w/ Copper Underplate - 18.7dBv @ 7.21kHz

So that does give some credibility to the “brass bad/German Silver good” argument. I still can’t sit here and say “German Silver doesn’t affect the pickup”, but we can say that, if German silver covers aren’t plated/aren’t copper underplated, they have the least effect, the copper underplate has an impact, and brass is having a huge impact. Covers affect pickups. Its as simple as that. If you’ve got a humbucker you adore that’s currently uncovered? Chances are fitting a cover, regardless of material, is going to change it considerably.

Now, to round this out before we get into the next part, it may seem that I’ve not covered all the angles here. I promise you; I have! I’ve just had to trim this down so it doesn’t turn into a dissertation – so, quick and dirty? “What I’ve missed”
Cover material behaves the same regardless of base material.
The characteristic changes from having either brass or German Silver as the base remains after the cover has been fitted, but the affect of the cover is unchanged (so a brass base plate will still suck out a little of the signals voltage before the resonant peak AND a Nickel cover will still do its thing – so, moving forward from here, we’ll just be focusing on German silver bases and covers, just to keep it stream lined)

If this is all an expression of conductivity between coil and string, does the “colour” matter?
It does! But only one with gold! And, the higher the grade of gold, the more it matters! To keep it brief (as brief as it can be and still contain a graph) – gold is more conductive, so gold plated covers have a greater impact on the pickup then Chrome/Nickel/black/etc (which, seemingly, don’t cause any more or less effect – even to the point of a Chrome plated/no copper cover behaving the same as an unplated cover!)

Gold, however, does, arguably, sound worse!

	Blue - Uncovered - [email protected] Purple - German Silver w/ Copper Underplate & Chrome Colour- 18.7dBv @ 7.21kHz Green - German Silver w/ Copper Unplate & Gold Colour- [email protected]

So covers are bad?!
Now this ones a very loaded question, and I don’t really have an answer for you to be honest. Electrically? If I was sitting here trying to sell you a Hifi, I’d definitely say that any, essentially, cosmetic component that altered the signal to as big an extent as a humbucker cover does, is a very bad thing indeed, however, guitars/pickups aren’t hifi!

As holistic an approach as this might be, as much as this might sound like “feel good mumbo jumbo” – pickups, really, are more a case of “we like what we know” – and considering most of us will have heard humbuckers with covers (and I’d go further then that, most of us have liked humbuckers with covers, we’ve liked humbuckers with copper under plate, we’ve liked humbuckers without copper, we’ve liked humbuckers without covers and we’ve liked humbuckers with brass covers! We’ve liked humbuckers with gold covers!... you get the idea) – its just a case of horses for courses.

As a very rough rule of thumb – covers are going to make the pickup feel more rounded, softer, and less defined. (and the more conductive, the greater that effect) – its not good or bad. Its just what it is. You might absolutely love the tone of a brass cover, you might hate it. It all depends on your frame of reference I’m afraid.

Is this true for all specs of pickup?
I’ve got partial graphs for this which prove the point, but I’ll spare you those. In short, yes – it doesn’t matter if it’s a humbucker wound with 42 AWG plain enamel or 44 AWG Polysol, it doesn’t matter if its 12 screw Alnico 5 or 12 slug ceramic, it doesn’t matter if the pickup cost £300 or it cost £3, it doesn’t matter if it’s a Telecaster® Neck or a P90 or a Strat® single coil you’ve buried under a humbucker cover -the cover is always having the same general affect. Sometimes it works in the pickups favour (Historically accurate humbuckers do sound better with covers!) sometimes it works against the pickup (Epiphone® Casino P90s, even with unplated covers, don’t sound quite right!)

And I think that about covers cover and base material, in very broad strokes, but there is, I’m afraid, one more aspect to this. So, lets get it over with!

Cover style

With cover material and plating options seen to, I think its probably worth while taking a look at cover “style” too. However, from our point of view, and within the scope of this kit, its not really “true”.

We offer this kit with a cover specific to the pole choices (so traditional is 6 screw poles, 6 slug, it takes a traditional cover with 6 holes, a 12 screw kit comes with a 12 hole cover, a 12 slug kit comes with a cover with no holes, you get the idea) and whilst I’m going to prove that cover style DOES effect the tone of a pickup, and its worth considering, you’ve got to remember that the pole choice on your pickup has its own effect separate to a cover.

This is because we are increasing/decreasing the amount of ferrous material within the coils. A screw pole is 3mm diameter (roughly) a slug pole is 4.75mm – a slug contains more iron then a screw – and this will increase the inductance of a pickup, which will cause the resonant peak frequency to be lower. As a quick rule of thumb, a 12 slug humbucker will be darker then a traditional and a 12 screw humbucker will be brighter – quite considerably too.

It’s a little beyond the scope of “covers and bases”, so I’ll go into greater detail in a separate section, but for the time being, know that your pole choice is having an impact AND your cover choice is having an impact.

So, for clarities sake, I’ve done these tests using a traditional humbucker, with a German Silver base – 6 screw poles, 6 slug poles, regardless of cover style, and all covers are chrome plated over copper over German Silver (again, its not the “tonal ideal” but it’s the most common composition you’ll find in the real world)

The common believe is this. “the more/bigger the holes in the cover, the ‘better’ the pickup is going to sound” – so, in theory, a 12 hole cover is going to sound better then a 6 hole cover is going to sound better then a no hole cover. And that makes sense considering what we’ve seen above, and, really, this is just an exercise in “sticking conductive material between coil and string” right?

<Insert Graph for Cover Style>

As we can see from the bode plots, on the whole, there isn’t really a great deal of difference between the 6 hole, 12 hole and “half open” covers. There are minor differences between them, but, they’re so small that you’re never going to taste those in the real world. If anything, I’m actually quite surprised that the half open cover has as much impact on the signal as the more traditional covers, simply because one coil is, essentially, open, but you can’t argue with the results, so, there we have it*.

Where we do see a difference, is with the “open” cover and the “closed” cover. The closed cover is having the greatest impact on the signal, and the open cover is having the least, but, equally, the open cover barely looks like a cover at all, so maybe that’s to be expected.

And that about covers it! (pun intended) – covers are best thought about in broad strokes, anything “with holes”, regardless of how big they may be, is going to behave the same as any other cover “with holes” (assuming all other variables stay the same), as soon as you take away the holes, you get more of an impact, and as soon as you make one massive hole, you get less of an impact (but less of a cover!) – the “myth” isn’t quite right, but equally, its not exactly wrong either.

*the “Half cover” is interesting – when testing, we’re exciting the coils through inductance coupling, with the drive coil directly over the middle of both coils. We, obviously, keep this positioning the same from one cover/base/pickup to the next. There is the potential that the half open cover will behave differently then a traditional cover, but our test isn’t accounting for that. I wouldn’t want to throw the baby out with the bathwater and say outright “half open cover makes no difference” – but, equally, if it is, and its not translating into our test? Maybe its not a big enough difference to really worry about.

**For completeness’ sake too – there are options I’ve not shown on the graph, but we have tested. The 11 Gate, H gate, Black top, the “other” H gate, the “tall” and the “3x3” covers – they all behave exactly the same as the traditional/12 hole/half open plots, so, rather then confusing the graph more then we have to, we’ve omitted them from the final results.

***All “rules” for all other variables still ring true, regardless of the cover style – so a gold open cover has a greater impact then an unplated one, a brass closed cover has more of an impact then a German silver one. Again, I’ve omitted these results for simplicities sake.

Now, all this brings me to the elephant in the room.

Covered humbuckers aren’t the same as uncovered humbuckers
Sadly so I’m afraid – the cover on a pickup is having such a big impact on the signal produced by the pickup that, really? If I was more of a purist, I’d argue that the pickup has become “a different pickup” – in the same way if I produced an uncovered humbucker with a resonant peak of 20dBv@5kHz, and then made another with a peak of 15dBv@5kHz... I’d be giving them different names, and pitching them at different roles within music.

We don’t do that with humbuckers though – we really over simplify the whole cover thing. As players, have a vague idea that something different is happening, but, really? Fitting a cover, or comparing 2 identical pickups, one covered, one not, is as drastic a change as using a completely different design of coil. The numbers may look the same, but the sound will be totally different.

However, whilst its tempting to say “they’re different pickups”, eventually (and this will happen a lot if your winding pickups!) you’ve just got to bow down to common sense. Covers are, primarily a cosmetic consideration, if someone wants your pickup, with a cover, by all means, explain the effect of a cover, but, you’ll never talk someone out of a shiny silver humbucker for their Les Paul®… trust me! I’ve tried.