"Another, maybe less obvious sonic influencer as well as a visual striking one - the unique grille cloth found on the originals. This heavy duty, multipurpose cloth (one of its uses was covering seats on London's now iconic double decker buses!) features rubberised stripes (orientated horizonally in the 1962) embedded in a fabric backing. In addition to its unique look, this, pinstriped cloth also has a tonal effect due to its density - rolling-off (read: hindering!) certain high and low frequencies, resulting in a muscular sounding, musical midrange."
The MARSHALL Chassis and CELESTION Speakers provide the signature GAIN and BREAKUP characteristics, but this "HOLY GRAIL" Grill Cloth is irrefutably the source of that unpredictable BARK, BITE, GRUNT & GROWL - That unmistakable "X-Factor" (as defined in the 1993 MARSHALL Catalog), which has equally eluded all of us, For the Past 40 YEARS!
Grill Cloth is absolutely one-of-a-kind! Because its surface is covered by wide, heavy and dense rubberized stripes, which are divided only by narrow areas of venting, IT IS NOT ACOUSTICALLY TRANSPARENT! This "odd" feature - considering that grill cloths typically strive for total transparency - creates a unique equalization filter that reconfigures the tone. When stretched, this considerable and "weighty" displacement lightly impedes AIRFLOW and dampens the free movement of the speaker's cone. Most importantly, THE CONE DELIVERS 100% OF THE SOUND with AIR as the transmitting medium, but the cone also weighs mere grams and is by far the lightest, most acoustically sensitive component in the entire amplifier. It really doesn't take much to "generally" manipulate its performance (as chemically removing the edge doping or using a closed vs. open back cabinet can demonstrate), but it does take quite a lot to precisely "improve" a speaker cone's tone in an AUTHENTIC "JTM" WAY!
In Michael Doyle's acclaimed book The History of MARSHALL, he states on Page 124: "It is worth noting that not all grille cloths are acoustically transparent. In fact, I refer to the Bluesbreaker-type cloths in particular as 'tone cloths,' because they are of such a heavy weave that they alter the sound."
THE TONE: As the front side of the cone is mildly restricted and subjected to a significant amount of reflected sound, phase cancellation is a considerable factor. This causes the highs to be sweetened in a "musical" way, but they are not over-attenuated, nor do they lose the critical definition needed to "cut through." The lows are similarly affected, yet also "nudged" to a higher, tighter frequency range, partially through the slight reduction of "pushed air." The "toughness" in the midrange is essentially accentuated, as those frequencies continue to flow through more-or-less unimpeded. The "Tone" this cloth brings forth is more focused and fused as a cohesive whole, highlighting the harmonic content with a thick, burnished, and almost reed-like throatiness, which IS NOT OBTAINABLE IN ANY OTHER WAY.
If you critically compare Jimi Hendrix's 1967 tone in "Jimi Plays Monterey" (JTM 45/ 100 w/ KT66 power tubes) to his later live concert tone, you can hear a distinct difference. Monterey sounds much more harmonious and musical, with a noticeable "Grunt & Growl" (especially with feedback or fuzz), while his later performances sound "edgier," with a dry brashness that is not present in his earlier tone. In 1968, after the short-lived Sunn & Dual Showman period, The Experience "re-amped" with a new wall of MARSHALLS that featured the replacement "Salt & Pepper/ Basketweave" grill cloth. Circuit tweaks aside, this "cloth swap" was perhaps the most tonally significant change from his original "Bluesbreaker-Pinstripe" stacks, whose tattered faced cabinets were still in use as late as Yale University, November 17, 1968 (the famous "Jimi's shadow in the spotlight" w/ Tremolo 100s photo). Of course, there was also the shift from KT66s to EL34s, but this wasn't the primary source of the change as Hendrix was using both tube types by June '67 (During the "guitar smashing" in the film "Monterey Pop," you can see that the spare head leaning against his stack was a reverse screened "Black Flag" JTM 100, which would have utilized EL34s). MUCH of Hendrix's mid-career change in tone can definitely be attributed to the swap in grill cloth.
THE TOUCH: Because the air is being forced into a tighter sonic space, pressurized damping causes a slowing of "cone reaction speed." This creates a subtle breathing effect as resistance builds with hard/ fast playing and releases as you relax the speed or attack of your phrase. THE AIR PRESSURE IS CONTINUOSLY CHANGING AS EACH NOTE DECAYS! This "feature" produces an ever-shifting harmonic and dynamic complexity, which is "touch sensitive" and varies greatly with amplifier volume and technique. "Lay back" and the response is diffused and three-dimensional with a considerable "swirl" - "Hit it hard" and it suddenly struts with a surprising snarl that begs to be "worked." This inherent instability makes the amp almost feel alive as you discover yourself interacting and playing differently to explore the new nuances and possibilities.
You can hear a great example of this phenomenon beginning at about 1:20 into "All Your Love" (track one), from "Blues Breakers, John Mayall with Eric Clapton." In the opening "A minor triad" lead break you can really hear the pressure from the feedback build up and "smolder" beneath the "Bluesbreaker-Pinstripe" Grill Cloth before exhausting itself as Eric applies vibrato and sustains the phrase. From the brutal raunch of "Steppin' out," to the staccato intensity of "Have you Heard," there is an indescribable "something extra" that is perhaps most readily observed during his "punctuated outbursts" or "unison bends." If you listen for it, you'll know it when you hear it - It's no less than the tension and volatility that gives a player the confidence to work any note for all it's got! The solo in "Sweet Wine," from "Fresh Cream," is a brilliant example of how Eric "works the cloth" to squeeze out every possible shade, inflection and nuance. Indisputably, this unique cloth greatly contributed to the signature "Bark & Bite" of the "CLAPTON IS GOD" tone.
"THE SOUND" of this High-Cholesterol "HOLY GRAIL" is both MORE AGGRESSIVE and LESS ABRASIVE than any other grill cloth ever made:
- It's Angry yet Smooth
- It's so Musical and yet so Mean
- It really "Shows some teeth," but also keeps an
Unleashed 100w Stack
from "Tearing your head off!"
Classy and Profane, all at the same time!
"SIGHTS" & "SOUNDS"