Kinman & Dimarzio Hum-Cancellers

Guitar Pickups

Published in SOS November 1998
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Reviews : Accessory

KINMAN & DIMARZIO HUM-CANCELLING GUITAR PICKUPS

Computers may have revolutionised home recording, but for the recording guitarist who prefers the sound of single-coil pickups, they have taken the age-old problem of radiated-field noise to a new level. Dave Lockwood checks out a new generation of pickups promising a real solution without compromising the classic sound.

Don't worry. You haven't picked up a guitar magazine by mistake! There's a perfectly valid reason why this month's Sound On Sound contains a review of guitar pickups. If you happen to fall into that half of our readership that our reader surveys tell us are guitar players, then this is one you won't want to miss. The fact that half of you are guitar players means that, statistically, something in excess of a quarter of you must be playing a guitar with single-coil (as opposed to humbucking) pickups on it. In which case, you will already know that computers and single-coil pickups don't make particularly good companions in the studio. If you attempt to use a single-coil pickup, especially with distortion or compression, anywhere near a computer and monitor, the radiated field is picked up by the coil at nearly the same level as the strings, making your guitar totally unusable!

DIMARZIO VIRTUAL VINTAGE PICKUPS
pros
Good immunity to induced noise.
More authentic sound than previous models.
cons
Lacks full brilliance of real single-coil sound.
Requires pot change to maximise performance.
Unscreened output wire.
summary
A big step forward from previous models, but one that doesn't go all the way. The Virtual Vintages nevertheless offer a valid alternative for those seeking a darker-voiced pickup, combined with a stock appearance.

Nevertheless, the uniquely bright, 'open' qualities of the single-coil pickup remain as popular as ever, and consequently there have been many attempts over the years to overcome their inherent susceptibility to induced noise. Of course, you can just mount two smaller coils side by side within a Strat-sized casing and achieve a hum-cancelling pickup which still approximates a single-coil tone as a result of sensing a fairly narrow string area -- there are some very nice-sounding pickups which use this method, but no-one would claim that they possess the uniquely airy, open quality of a true single coil (see the 'Genesis of the Humbucker' box, below, for more on this). The second approach is to use a stacked-coil configuration (first patented in 1972), with one coil placed on top of another around a common magnet structure, offering the added benefit to the traditionalist of looking just like a normal single coil.

DiMarzio, the American company that practically invented the large-scale replacement pickup market, was one of the first manufacturers to offer a stacked pickup as a standard production model, in the form of their HS (Humbucking Strat) range in the early '80s. However, the HS pickups failed to satisfy most players (Yngwie Malmsteen being a notable exception). The hum cancelling was certainly effective, but the sound was somewhat flat and lifeless, offering neither the tonal sparkle, nor the dynamics of a proper single coil. Even pickup guru Seymour Duncan's stacks were no more convincing, and for many people that was a sign that the principle itself was fundamentally flawed.

At this year's NAMM show in Los Angeles, however, there were two new stack designs on offer, both making the usual extravagant claim of sounding "identical to a vintage Strat pickup, without the hum". DiMarzio was championing its Virtual Vintage range, using a distinctive new metal shield on the top coil, whilst Australian pickup designer Chris Kinman debuted his 'AVn' (Authentic Vintage Noiseless) stacked coil pickup, also with an inter-coil shield of intriguing design (for more on the theory behind these pickup designs, see the 'How Stacked-Coil Pickups Work... Nearly' box on page 126).

The review models were evaluated by mounting them in turn on the same guitars (Fender USA '62 Re-issue Strat with rosewood board, and Fender 1971 maple-neck Strat), with the results, using a variety of amps and DI processors, being recorded to multitrack digital tape to facilitate direct comparison. SOS Editor Paul White conducted his own listening tests in parallel with mine, mounting the pickups into his Strat Plus (see the 'Second Opinion' box elsewhere in this article). Both manufacturers recommend that to really maximise immunity to noise, you should screen the whole of the control cavity with metal foil or conductive paint. Whilst this is certainly true, the majority of the noise undoubtedly emanates from the pickups themselves, and in the end I chose not to screen the control cavity for the tests as I seriously doubted how many other people would bother, and I felt it was important to establish how well this 'hum-cancelling pickups but unscreened guitar' combination worked. I did, however, take the sensible measure of adopting a shielded output cable from the volume control to the jack socket on the test guitars.

  The Genesis Of The Humbucker  
 

The typical 'Fender-type' single-coil guitar pickup is the simplest electro-magnetic pickup imaginable -- economical, easy to mass produce, and more than up to the job of producing a simple voltage analogue of a vibrating metal string. The susceptibility to interference was always a known limitation, but when they first appeared on mass-produced electric guitars from the early 1950s, the world was a considerably less hostile place in terms of stray magnetic fields and RF emissions. Any hum or buzz that you encountered when playing a Strat or Tele could usually be alleviated just by taking one step further away from the source of the problem. Nevertheless, an electric guitar that did not hum, even when you sat right next to the amp, was obviously going to offer the manufacturer a powerful marketing edge, and in 1957 Gibson introduced their famous 'Humbucking' (or hum-cancelling) pickup. Gibson employee Seth Lover's design cleverly utilised what was effectively two single-coil pickups placed side by side, but wired with the two coils electrically 'out of phase' with one another. The physical proximity of the two coils meant that any noise current induced into one coil was certain to be introduced equally, but in opposite phase into the other, so that it was cancelled out when the two signals were combined. The wanted signal from the string is not cancelled out along with the noise because the string's vibration is sensed not by the coils, but by its disturbance of the field produced by magnetic polepieces within the coil. The two coils have polepieces of opposite magnetic polarity, making the signals induced into them out of phase with each other, a situation neatly reversed by the 'out of phase' combining of the two coils. The design results from a delightful piece of lateral thinking which truly appears to give you something for nothing, especially as Lover chose to connect the two coils in series, not parallel, thereby gaining a higher output and further improving signal-to-noise ratio, as less gain was then needed in the amplifier.

The downside was that whilst the coils did not hum, they didn't sound the same either. With its side-by-side coils, a humbucker senses a broader area of the vibrating string, and combining the coils in series raises the inductance and thereby lowers the resonant frequency of the pickup. The net result was a pickup that was punchier and darker than the bright, twangy single-coil sound players and audiences alike were used to, and it was no surprise that it was jazz and blues players, with their generally more mellow tonal palette, who took to it first. Only in the mid-'60s, as the distorted sound of overdriven valve amplifiers became popular, did the humbucker come to be really appreciated, primarily for its powerful output. Whilst the die-hard Strat or Tele player may have looked on with envy at the humbucker's immunity to interference, most felt the tonal and dynamic compromise to be too great to justify the benefit.

 

Both ranges of pickups incorporate a number of models; in Kinman's case, these are defined by the year they replicate ('AVn62' and so on). DiMarzio's pickups are distinguished more by function ('Blues', 'Solo' etc). Both ranges offer direct replacement of a stock Fender pickup, with no additional routing or mounting hardware. Like all stacked pickups, they are a hint deeper than a conventional single coil, but not so much so as to cause any mounting difficulty.

Virtually Vintage?

I was able to test nearly all of the Virtual Vintage models, beginning with the classic stock Fender sound of the DP401. The range consists at present of six models:

  • DP401 -- the 'basic' Virtual Vintage model, replicating a classic Fender sound.
  • DP402 -- Virtual Vintage 'Blues'; could be used in the bridge position in combination with the above.
  • DP403 -- Virtual Vintage 'Heavy Blues'. A hotter version of the above.
  • DP404 -- Virtual Vintage 'Solo'. Darker and more output than the Heavy Blues.
  • DP405 -- Virtual Vintage '54'. Brighter -- even more vintage than the 401.
  • DP406 -- Virtual Vintage '54 Bridge'. A touch hotter, just to compensate for the lower string excursion in the back position.
    KINMAN AVN PICKUPS
    pros
    Superb-sounding pickups.
    Excellent immunity to noise.
    Totally authentic sound on 'vintage' models.
    Works with stock volume and tone pots.
    Screened output lead.
    cons
    There just aren't any!
    summary
    Chris Kinman has finally nailed it! This really is a totally authentic-sounding vintage Stratocaster pickup which does not hum.

DiMarzio supplies installation notes that recommend the use of a 500k(omega) volume pot "for best all-round performance". Don't take this lightly and think that it won't make a difference -- it does. On a 250k(omega) stock Fender (and clones) pot, even the brightest VV sounds a bit flat and lifeless. The installation notes suggest that you can use a 250k(omega) volume in conjunction with a 1M(omega) tone pot to achieve a "warmer, vintage (1950s) response". I have to say that this didn't work for me - I found I needed at least a 500k(omega) and preferably 1M(omega) on the volume control to squeeze the maximum amount of high-end out of all the DiMarzios, and therefore stuck with this setup for the rest of the testing on the VVs. Both these pot values are readily available from guitar parts suppliers or repairers.

The Virtual Vintages' immunity to unwanted noise pickup is immediately impressive. With the rest of the guitar unscreened, the VVs' unscreened output leads are the limiting factor, and there is still some noise susceptibility if you get too close to any sources of interference. However, they certainly represent a vast improvement over normal single coils in the studio, in this respect. The sound of the DP402 Virtual Vintage Blues pickup in the bridge position was impressively edgy and responsive, with a healthy dose of that characteristic 'wiriness' that a good Strat must offer. Moving forward to the middle and then the neck pickup, the sound was far more recognisably Strat-like than any stacked pickup I had previously tried, and certainly more so than a side-by-side Strat-sized humbucker. However, the 'in-between' position sounds (ie. bridge and middle, or neck and middle pickups on together) lacked some of the complexity of tone that normally gives these their unique character. Referring back to a real Strat set showed the VVs' combined selections to be both harder and thicker-sounding. The same referral showed the individual pickups, whilst beguilingly sharp, almost glassy, on first listening, to have, in comparison with the real thing, a significantly attenuated high top end. It's almost more Tele than Strat, which can actually be quite useful in the bridge position, but loses some of the essential 'open' character of the other pickup positions. Installing the DP406 '54 Bridge' and DP405 'regular 54' in the middle improved things a touch, bringing back a hint of the characteristically hollow 'cluck' on the 'bridge and middle' combo, but again, reference to the real thing shows it to have a different, darker overall tonal balance. Output on the 54s is roughly comparable to that of a vintage Fender, and on the standard DP401 VV, a touch higher, but there is a hint of reduced dynamics - it just doesn't do as much as a real single coil when you dig in to it hard. Some players could well find this more a benefit than a drawback, particularly in a recording situation, whilst other will be bugged by it - something very much in the realms of individual taste and playing style.

  How Previous Stacked-Coil Pickups Worked... Nearly  
 

In essence, the principle behind the stacked-coil humbucking pickup is that it relies on only the top coil sensing the string, thereby producing something like a normal single-coil sound, whilst the bottom coil only picks up induced noise which is used in antiphase to cancel the noise also picked up by the top coil. However, in practice, it is not quite so simple. With both coils in close proximity and wound around a common magnet structure, interaction is inevitable, and the simple fact that the two coils are connected together changes the the DC resistance, altering the inductance, and thereby the resonant frequency... I could go on, but you've probably got the point! In spite of the efforts of some very clever designers over the years, no amount of innovative juggling with magnet strengths, wire gauges and the number of turns in the coils has seemed able to produce anything closer to the desired result.

The two highly significant differences in this latest generation of stacked single-coil designs lie in the fact that both the new DiMarzio and Kinman designs employ dissimilar coils on the top and bottom of the stack, and both also utilise magnetic shielding between the two coils to reduce the effects of interaction. In both designs, the magnets (vintage style, lightly chamfered on their top edges, configured south pole up), which in previous stacks passed through both coils, now sit only within the upper coil. The pickups also have something like the normal DC resistance of a conventional single-coil pickup (about 6k(omega) for a vintage Fender, rising to about 7.5 for a 'hot' single coil); however, the lower coil seems to measure only around 20 percent of the upper coil, thereby reducing its effect on the overall pickup when connected to the upper one. What makes this possible is that the lower coil is wound around its own set of steel rods, making it into a sufficiently effective inductor to still pick up the same amount of interference as the upper coil whilst employing a lower-resistance winding (this is vital in order to achieve full cancellation when combined in opposite phase).

DiMarzio's Virtual Vintage pickups incorporate a 'U' section metallic shield (partially cut away on the bass side), within which the upper coil sits. Kinman too shields between the coils, but his design uses a more open structure for the top coil plus the addition of a partial bottom coil shield as well.

 

Moving on to the other VV models produced progressively darker, more weighty results. For players using a lot of distortion, the extra output and attenuated high top may prove useful in generating a smoother, more punchy tone. These higher-output VV models are not really all that Strat-like at all, but the sound is certainly a valid alternative to that of a miniature side-by-side humbucker. The DP404 Virtual Vintage Solo (a hefty 8k(omega) on the top coil) could well prove popular with those wanting something to sonically rival a humbucker whilst retaining an almost stock, vintage appearance.

Authentically Vintage?

Australian pickup designer Chris Kinman's AVn ('Authentic Vintage noiseless') range also utilises a stacked-coil configuration, appearing, like the VVs, almost totally conventional with the cover fitted. The Kinmans will actually take a standard Fender cover (the DiMarzios are just a shade too fat) if you want to keep an aged vintage guitar looking as close as possible to original. The only giveaway, and even then only to the eagle-eyed, is the unconventional magnet stagger which, like the DiMarzios, has been compensated for modern string gauges (ie. high D pole, low G and level B). The Kinman AVn magnets are considerably lower gauss than a conventional single coil, however, allowing the pickup to be adjusted much closer to the strings than normal without producing any unwanted effects -- no reduced sustain, no pitch warble. There is actually some useful tonal adjustment available in the height setting (far more than with a conventional pickup), with the overall character of the sound changing from bright and wiry at 2mm to a softer, more woody tone at 4.5mm and beyond. However, output drops off more quickly than normal if you drop them down too far.

  Reverse Wound/Reverse Polarity  
 

Many Strat players involved in recording to any serious degree have adopted the partial solution to the noise problem of using a special 'reverse-wound, reverse-polarity' middle pickup (Seymour Duncan's RP/RW seems to be the most widely available). This allows the two classic Strat 'combined pickup' sounds -- positions two and four on a five-way switch (often erroneously referred to as 'out-of-phase') -- to become hum cancelling, without affecting their sound. The only drawback to this situation is that, when working in an electronically hostile environment, you are limited to just those two sounds, and a good Strat, of course, has an awful lot more to offer than that.

The DiMarzios' four-conductor wiring will also allow you to integrate a single VV (most likely in the bridge position, for high-gain work) into a guitar which already employs a reverse-wound/reverse-polarity centre pickup, without losing the hum cancelling you already have in the combination positions. By moving the tone control connections to the other side of the pickup selector switch, you can then use the now-free side to 'auto-tap' the VV pickup in 'position two' (solder the pickup's series connection to the bridge pickup position and run a ground wire to the centre pickup position) so that only the top coil is active, effectively leaving you with a 'south-up, conventionally wound' coil, which will work fine in a noise-cancelling combination.

 

Although the AVn pickups are available singly, the Kinman range consists of a number of pre-designated sets (usually with a different bridge p/u selected to balance with the others) to help point the buyer in the right direction:

The Kinman sets tested were:

  • AVn-T -- 'Traditional Vintage': two AVn-'56s and an AVn-'62 in the bridge position.
  • AVn-W -- 'Warm Vintage': two AVn-'62s and an SCn at the bridge.
  • AVn-H -- 'Hot Vintage': two AVn-'62s and an SCn at the bridge.
  • CV-HMS -- 'Hank Marvin Set, Classic Vintage': two AVn-'59s and an AVn-'63 at the bridge.
  • FV-HMS -- 'Hank Marvin Set, Fat Vintage': two AVn-'63s and an AVn-'64 at the bridge.

The Kinman models feature a screened single-conductor output cable, and require no change to the 250k(omega) volume or tone pots found on a stock Strat, which keeps the installation job within the DIY domain for more players, and allows you to retain more of your original instrument.

With the 'maximum vintage' AVn-56s still making their way over from Australia, I began testing with the HMS-V set, consisting of two AVn-'59s and an AVn-'63. In comparison with the stock reference Strat, the sound was slightly darker, and a touch deeper, but there was an openness about it and a speedy attack that marked it out as totally convincing as a single coil in character. I have to admit that these are the first 'stacks' ever to really make me sit up and take notice -- for once the manufacturer's claims really did seem to have some substance to them. Adjusted up to about 3.5mm from the strings (measured with the string held down at the twelfth fret), the sound from the neck and middle pickups was superbly bell-like -- reminiscent of the highly characteristic sweetness of Seymour Duncan Alnico IIs. The 63 balanced well with the others, and worked well on its own, putting a useful bit of extra grunt into the bridge position. Immunity to noise pickup was spectacular, even without the rest of the guitar being screened (the Kinmans' screened output wire is undoubtedly responsible for this) allowing me to use a high-gain sound whilst sitting directly in front of a 17-inch monitor and with a rack of outboard by my side. Previously, to record with this sound I had to retreat to the far corner of the room and keep the Strat's neck pointed precisely out the window! Even the 'in-between' positions retained enough of the hollow character necessary to make those sounds work properly, but the sweeter, fuller voicing of the pickups doesn't produce quite the same set of cancellations as real single coils, to my ears. Nevertheless, this is a particularly fine-sounding set of pickups, with a valid alternative voicing.

"This is a set of pickups that I might well choose to use even if they weren't hum cancelling!"
Chris Kinman's AVn-T set, consisting of two 56s and one 62, when it arrived, was even more of a revelation. To my ears, these really do sound exactly like vintage single-coil pickups but without the noise! Reference back to the real thing shows the overall tonal balance to be identical. The same snappy, fast attack, the same crisp detail revealing from note to note whether the string has been struck by pick, skin or nail -- the very reason why some of us choose to play Strats and Teles. No hum-cancelling pickup has previously come close to this degree of authenticity -- I believe that, for most players, these are probably as close as makes no difference (indeed, I know there are some real vintage Strats out there with pickups that actually sound nothing like as good as this!). The bridge pickup in this set is an AVn62 which has a slightly higher output to compensate for the lesser string excursion near the bridge. This pickup too is simply gorgeous, offering all the spit and grind of a good Strat -- pinched harmonics just whistle off the pick whilst picking up near the neck produces that uniquely sweet, pedal steel-like tone that you can only get from a really open-sounding single coil. Of all the sets tested this was the one that, to my ears, didn't compromise the 'in-between' settings at all. All the hollow character, all the 'ping' and, most importantly, all the touch, is retained (provided that the paired pickups are properly adjusted for comparable output). Simply glorious. This is a set of pickups that I might well choose to use even if they weren't hum cancelling!
  Second Opinion  
 

The DiMarzios produced a very glassy, lively sound that was initially quite impressive, but after a short while I realised that the tonal peaks didn't have quite the same character as the classic Strat. This became more obvious on the in-between pickup positions -- these sounded quite different to the real thing, but in their defence, they're able to produce a very nice, if slightly brash, jangly sound. The susceptibility to interference was much reduced compared both to the Lace Sensors fitted as standard to my Strat Plus and Fender's own single-coil pickups.

Like the DiMarzios, the Kinman pickups offer a completely traditional appearance, apart from the revised polepiece staggering. When you plug in and play, however, the tonality is so close to what you'd expect from a regular single-coil Strat pickup that it's almost difficult to believe that these are humbucking pickups at all. In fact, the only giveaway is when you suddenly realise your amp isn't humming any more, and even the computer monitor isn't giving you any trouble!

There's no question that the Kinmans came closest to the traditional Strat sound as well as providing the best interference immunity. They have just the right amount of edge and shimmer, and when you use the 'in-between' pickup positions, the results are authentically hollow. All the pickups in this review have their positive attributes, but for sheer authenticity and freedom from noise, the Kinmans are the clear winners. Paul White

 

Like the Virtual Vintages, the other Kinman sets gradually part company with the goal of directly replicating the vintage Strat tone, getting progressively darker and richer. The low-gauss magnets seem to produce not only the expected longer sustain, but also a noticeably 'creamier' distortion, less ragged at the edges and more focused. The SCn 'hot' bridge pickup is the real star here -- think vintage P90, but with a bit more 'air' in the sound. They are effective, but if you want a darker-voiced Strat, other options have always been available to you. One other point to bear in mind is that Kinman models are optimised for a specific fingerboard radius -- there is a '7-to-12-inch' contour which should be fine for any real Strat, and a flatter '12-to-18-inch' option for modern compound-radius necks.

The Ultimate Challenge

A good single coil is, in my opinion, the most musically versatile of pickups. It can be sharp, or deep; it can be sweet or nasty; it can respond to your loudest or softest touch. To achieve noise-free operation without destroying these subtle nuances of musicality has always been the ultimate challenge to the pickup designer. To my ears, Chris Kinman has finally achieved that goal, and I have no hesitation in recommending his pickups as the only choice for players who want hum cancelling whilst changing the sound of their Strat as little as possible from its stock pickups. However, I recognise that this may not necessarily be your goal -- thousands of people play Strats, wishing all the while that they had a bit more oomph and worked a bit better with distortion. If you fall into that category, the DiMarzios, with their treble peak occurring further down the spectrum than normal, could well offer precisely the kind of extra punch you are looking for.

Few products that I have come across have ever fired my enthusiasm quite as much as the Kinman AVn56/62s, perhaps as a result of the 25 or so years I have spent wishing that something like this existed! These pickups do exactly what Chris Kinman says they do. The DiMarzios, whilst apparently seeking the same goal, sound significantly different. As always, let your ears be the judge of what's right for you. At least we Strat players now have some real choice in this area -- at last, the future can be noise-free for Fender players too!

 information
DiMarzio Virtual Vintage pickups £69.90 each,
£209.70 for set of three.
Prices include VAT.
MIRep +44 (0)1392 438900.
+44 (0)1392 499773.
www.dimarzio.com
Kinman AVn pickups £69 each,
£199 for set of three.
Prices include VAT.
Washburn UK
+44 (0)1462 482466.
+44 (0)1462 482997.
www.kinman.com

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