Analysis: Irongear Hot Slag Pickups

This article follows on from my previous post, discussing modifications to my Ibanez GRGR121EX, “Tess”. Recordings were made before and shortly after the new pickups were installed. The set of strings is the same (Rotosound pinks), as the new locking tuners made it fairly easy to detach and re-attach the strings as needed. However, the A-string broke and had to be replaced with a spare from a set of Ernie Ball Regular Slinky. This is a higher gauge so may have some influence on the recorded output of the new pickups in this range. However, I did not notice any dramatic change following the next re-stringing (more Roto-pinks).

Disclaimer

Many of the branded products referred to here are trademarked. I am not affiliated with any of the companies involved, and make direct reference to their products in the interest of accuracy and repeatability.

On online shopping

I spend countless hours trawling the internet looking at pictures of musical instruments and studio equipment. I purchase such items 2-3 times per year. This strikes me as a remarkably unproductive activity:

Useful information

  • Ability to fit into existing rigs and workflows
  • Reliability in practical scenarios
  • Quality of sound produced relative to other equipment
  • How it compares with similar items produced by different manufacturers
  • Ability to inspire new creative ideas
  • Ergonomics; comfort, ease of use

Information from manufacturers’ websites and online stores

  • How it fits into some common applications
  • Detailed specifications, from which other applications may be confirmed
  • Instruction manuals, from which ease of use and advanced capabilities may be inferred
  • Quality of sound through several arbitrary combinations of recording equipment
  • Where it fits into the range of products offered by the same manufacturer

Information from online reviews

  • Whether it survives being unwrapped and playing “smells like teen spirit” a few times
  • Whether it blows up spectacularly several years later
  • A blow-by-blow account of the argument/cosy agreement you will have with the store
  • How good it will look in a photo-shoot
  • Whether it sounds as good as your £10,000 rig (no)
  • Whether it sounds as good as your friend’s £10,000 rig (yes)

Even where the criteria are quite clear, it can be difficult to piece together the information you really need. Items such as guitars can be tried out in a store; but even then you are using an unfamiliar amplifier. For items such as recording interfaces demos are rarely available. Virtually all of my MIDI equipment has been purchased largely based on their user manuals; the free PDF user manual is a godsend for  a synth geek trying to construct a flexible clock-synchronisable program-changeable remotely-controllable live rig. Whether it will sound any good is completely unpredictable.

Pickups

A guitar pickup is not a terribly complicated device. However, there are many conflicting approaches to making the best pickups. Hand wound or machine wound? Scatter winding? More powerful magnets for high output with less noise? Weaker magnets for less string pull? I will not go into a detailed discussion of the different types of pickup here, as it has been done elsewhere many times, but it is difficult to avoid a little cynicism. Why do some pickups cost so much more than others, when the construction should be identical?

I decided on the Irongear Hot Slags for my project (see previous post): the reviews were good from a range of websites, and they seemed to offer a “modern” sound with some character. I was particularly intrigued by a helpful graph, promising a hot, mids-heavy sound. My stock Ibanez pickups have the styling of EMGs, but this says nothing about their sound. It is unlikely that they give the “flat” sound that EMG’s active range are famous for.

Method

All recording was done into Logic Pro 8 at 24 bit 44.1kHz,  using the direct guitar input of an Edirol UA-4FX interface. The Match EQ is an inbuilt effect used for calibration. I used the calibration mode to produce a graphic representation of the material it is exposed to. For each pickup configuration I played a simplified version of the guitar part for a song called “No More Days”. This is a song I originally wrote for a band at University, and has subsequently been adopted and adapted by one of my other bands, Broken Console. The studio recording is free to download.

Old vs New

Ibanez GRGR121EX Factory Pickups: Bridge (left) & Neck (right)

Examining the curves generated by the factory pickups: the bridge pickup gives a surprisingly flat response, while the neck pickup has a pronounced hump in the bass end. The small peaks and troughs may be disregarded as a consequence of the source material, which is all in one key and heavily favours some notes (and hence frequencies). The neck pickup may be expected to show a strong bass response as the string movement is greater at the neck pickup for low notes. High harmonics, on the other hand, dissipate quickly and are usually more prominent in the bridge position.

Irongear Hot Slag pickups: Bridge (left) & Neck (right)

Examining the frequency response of the Hot Slags, the bridge response is surprising; it appears almost identical to that of the factory pickup. The overall level is around 2 db higher, which is an audible difference but not huge. The neck pickup displays a similar increase in output, but the bass frequencies are even more dominant.

It is not practical to examine all of the coil-tapping and phase-flipping possibilities of “Tess” following modification. However, there is one combination I have been using a great deal, which merits inclusion. The pickup selector is in the middle position, the bridge pickup is set as a standard humbucker, the neck is coil-tapped and out of phase. This gives a very distinctive “hollow” sound.

Tess' control panel. Just as bewildering on-stage as it is in this terrible diagram.
Irongear Hot Slags: Bridge in parallel with neck pickup coil-cut and out of phase

It can be seen from the figure that the output drops substantially due to the phase cancellation, and a “gap” appears in the low-mid frequencies around 300 Hz. This gives a “scooped” sound which interacts well with high-gain amplifier settings.

Conclusions

On paper, the frequency response of the new pickups is very similar to the frequency response of the factory pickups. The “character” of the guitar has not significantly changed. However, the new options open up a range of new sounds, and a higher output is available.

This graphical examination has not addressed the subjective measure of “clarity”. It is claimed that high-quality pickups make it easier to distinguish the individual notes of chords, even with distortion. The source material is made available in compressed form below. I you would like a copy of the recordings in a lossless format, please get in touch.

Stock pickups: Bridge

Stock pickups: Neck

Irongear Hot Slag: Bridge

Irongear Hot Slag: Neck

Irongear Hot Slag: Bridge + Coil-cut neck (out of phase)

Potential developments

While the Match EQ is very convenient, I would prefer to use something a little more rigorous, and capable of returning a numerical output. It’s possible that my dabblings in programming will arm me to write something appropriate. If you know of a suitable existing tool, preferably FOSS, please let me know!

Playing back a piece is difficult to do consistently, and far from ideal. One option for future tests would be to try to directly stimulate the pickup with an e-bow or a headphone earpiece playing pink noise. A more appealing option is to construct a consistent “guitar-plucking machine”, possibly using LEGO. Any designs or suggestions are welcome.

Further experimentation is needed to confirm the claim that some pickups are “clearer” and “more dynamic” than others.

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