Marshall Super Lead Tone Tips and Tricks

The following Marshall Super Lead tone tips and tricks will enable you to get much more versatility out of this legendary amplifier. Some of these may even surprise you. One thing to note – NONE of these involve modification to the original Marshall circuit. Those looking for the true “Marshall” sound only need use an original, unmodified Super Lead.

Channel Switching and Linking

The Marshall Super Lead is a two channel amplifier with high and low sensitivity inputs for both channels. For those interested in taking advantage of both channels to employ a clean sound as well as a dirty one, you need only use an A/B box. Plug the guitar into the input of the A/B box and then plug the box’s A and B outputs into channels 1 and 2 of the Super Lead. By incorporating an overdrive or booster of some type to one of the channels, you’ll be able to effectively take advantage of the Super Lead’s dual channel characteristics.

The Super Lead’s channels can also be linked or patched together so that you can use both the high and low sensitivity channels at the same time. Since channel 1 is voiced for trebly “bite” and channel 2 features extended lows, this is a popular tone trick. Plug the guitar into channel 1’s high sensitivity input (top left). Then, using a patch cable, plug into channel one’s low sensitivity input (directly beneath), and plug the opposite end of the cable into channel 2’s high sensitivity input (directly to the right of channel 1’s high-sensitivity input). Using this technique, you’ll be able to take advantage of using both of the Super Lead’s channels at the same time. If interested in using multiple Marshall heads, Super Leads can also be linked together using this same technique.

Driving the Input voltage for maximum distortion and sustain

The 80’s were a time when many musicians opted for the hot-rodded Marshall sound  spawned with the 80’s wave of metal – desiring a tone that was tight and responsive as the Marshall is naturally, but with added amounts of gain. Unfortunately as a result, many great vintage amps were destroyed by these extreme modification jobs. Some modifications sounded decent for getting high gain, however there always seemed to be a compromise of some sort with many of these modifications. You could no longer get the amp to clean up; often there would be a greater amount of system noise and hiss; and inherently, reliability overall suffered because of increased wear on the tubes.

One clear way to expand the punch, sustain, and drive of the Super Lead is to increase the input voltage signal going into the amp. What does this mean? It means sending a “hotter” signal into the front end of the amp. This will allow the amp to really open up and respond even more dynamically. This does NOT mean, however to add all your distortion to the front-end of the amp. Adding too much distortion in front of a Marshall will produce a sound that is very compressed, with little dynamic character or touch response – in essence it will make the amp “feel” like a solid-state device. By sending a hotter signal to the front end or input stage of the amp, you can effectively achieve the “California Sound” without harming the originality of the amplifier or damaging any of the components.

High-output pickups are one way to help “drive” the Super Lead. The drawback is that the added windings and resistance inherent with high-output pickups tends to reduce much of the high-end presence and can give too much of a flatter, muddied sound and feel. However, some like this particular tone, others do not. That is why many still love the expressive sounds offered with standard Stratocaster and Gibson pickups – they only wish they could have more drive. One area that can help out with humbucking-style pickups is to use 500K or 1 Meg Ohm volume pot. These volume pots will help send as much of the signal as possible to the guitar’s cable. Stock Fender Stratocasters mainly use 250K volume pots and can be moved up to a 500K for a brighter and slightly punchier sound. As a general rule, pickups with higher resistance will benefit from the higher-valued volume pots; in effect, you’re opening up the signal and allowing the pickup’s electrons to flow more freely. Gibson Les Pauls obtain a much more open signal when using 1 Meg Ohm volume pots.

Another area that will dramatically increase the response and gain characteristics of the amp is to use an overdrive/distortion unit in the front end. However, the key is to use the unit for its volume boost characteristics and NOT primarily for its distortion. As a result, “metal” type of boxes that are high-gain won’t work well for this application (e.g. Boss’ Metalzone, DOD’s Grunge, ProCo’s Rat). Boxes that are suitable include any of Boss’ Overdrive/SuperOverdrive units or Distortion boxes, Tube Works’ “Real Tube” driver, Ibanez’s Tube Screamer, etc. To use these boxes properly with a Super Lead, start by thinking backwards and turn the box’s volume control all the way up and the distortion control to zero. Now turn the distortion control to a minimal level to where a good amount of boost is achieved when the pedal is turned on and off. You’ll notice the Super Lead really come alive with this technique. There are some pedals coming out soon that are actually designed specifically for this “clean boost” application, notably Fulltone’s Full Boost box. The technique works well for any amp really, especially so with the Marshall Master Volume series of amps. The end result is a sound that is lively, full, and retains its dynamic tube character. Try this technique before you decide to go out and buy the latest “super gain” amp – you’ll be surprised.

100 Watt to 50 Watt

This is a simple and effective way to reduce some of the output power to lower the overall volume of the Super Lead. First, open the back panel of your amp and then remove the outside two power tubes, leaving the two in the center. That’s basically it, but then there is one important thing to do – If you are using one 16 ohm cabinet, you’ll need to “halve” the ohm rating on your head and change it to 8 ohms. If you are using two 16 ohm cabinets, where your normal ohm setting is 8 ohms, you will need to set the head now to a 4 ohm load.

When running at 100 watts with all four tubes in the head, the rule of thumb to remember with impedance settings is that the amplifier’s ohm load must NOT exceed the load of the speaker cabinet. That is, don’t ever run a Super Lead head at 16 ohms into an 8 ohm cabinet as it puts a strain on the head and could damage it. It is quite o.k. however to do the opposite. An 8 ohm (or even a 4 ohm) head setting into a 16 ohm cabinet will just produce less output power but will not damage the head.

VARIACs and Attenuators

Eddie Van Halen was the famous user of the VARIAC. A VARIAC (think of “Variable A/C”) is a unit that changes the voltage coming out of the wall to a lower amount. A simple example of a VARIAC is a light dimmer. You plug your light dimmer into the wall socket, and then your light plugs into the dimmer itself. As you adjust the slide and the light dims, it does so because you are dropping the voltage present.

When a VARIAC is used in conjunction with a Super Lead, it can act loosely as a Master Volume. You can crank the volume controls up to ten on the Marshall and then bring down the overall sound using a VARIAC so it can be controlled. Varying accounts have been told regarding whether the use of VARIAC’s do indeed cause damage to an amp. Most technicians will agree that increasing the voltage of an amplifier beyond specifications will most certainly cause damage. There is debate however about whether damage can be caused when reducing the amplifier’s voltage. Undoubtedly, the tone will change somewhat as the bias of the power tubes will change corresponding with the reduction of voltage. My personal theory: all the parts within the Super Lead (or any other amp for that matter) are designed to operate at a given set voltage. Tampering excessively with that voltage will potentially wreak havoc with how the tubes, transformers and components all work together and respond together. The keyword I used was “excessively”. In some instances, especially with early plexi model Super Lead amplifiers built for export to the United States, the 120 volts of A/C current is a bit much and so the actual input voltage can be lowered by a few volts to allow the amp to run a bit more reliably. All said, exercise caution if you choose to play with a VARIAC. You’ve been warned!

An attenuator works quite differently from a VARIAC although some of the elements are similar. An attenuator dampens the signal volume from the head’s speaker output and sends the reduced signal to the cabinet. Attenuators can do this because they take the output signal load and absorb it (converting the signal to heat rather than sound)– the rest of the signal goes to the cabinet.

So how do attenuators sound? O.k., but they do change the signal and add some tonal coloration. Again, some don’t mind this change and others do. And another important fact: an attenuator will reduce the overall volume, but running a Super Lead on 10 and reducing the signal with an attenuator will still cause the tubes to wear out at a faster rate than if you set the volume on the amp to a lower setting. Marshall also produces its own attenuator called the Power Brake. Check it out and see if it is for you.

Speakers and Cabinets

Not all 4×12 (that’s four 12 inch speakers for those that didn’t know) Marshall cabinets were created equally and models do sound different primarily because of two reasons: 1) the speakers types within them, and 2) the grill cloth materials used.

Originally, Marshall speakers were made by Celestion and rated at 15 Watts and “broke up” fairly easily. Many players loved the sound of speaker distortion coupled with their power tube distortion from their Super Lead heads, but of course these cabinets were not designed to be used with 100 Watt heads since the four 15 watt speakers only added up to a collective 60 watts of power handling capability! Also, when a speaker is distorting, it is doing so because the voice coil has gotten too hot with excessive movement of the cone that is again technically, beyond its power handling rating. As a result, these lower-powered speakers often blew.

The famous 25 watt “Greenback” speaker was, and still is a favorite of many players. It does a better job handling the output of the Super Lead when put in a 4 x 12 cabinet and helps give the Super Lead that famous smooth Marshall crunch that many enjoy hearing. It also does something that higher wattage speakers do less of – they compress as you play. This makes the 25 watt G12M Greenback a favorite of rock and blues players that want the added dynamic expression available when a speaker “softens” in feel through compression as the guitar’s attack is increased.

Celestion speakers of various power ratings have been used throughout the years and the most common modern cabinet design uses four Celestion speakers rated at a power handling capacity of 75 watts each. Sonically, the 25 watt speakers will distort  and compress more easily, while the 75 watt models obviously handle power more efficiently and stay clean at louder volumes. Seems like a strike against the 75 watt speakers doesn’t it? However, one important area the 75 watt speakers do a better job of, besides better power handling, is to produce a more solid and stronger low frequency tone. For those that complain about Marshall’s lack of bottom end, a 4 x 12 cabinet loaded with modern 75 watt Celestions may be the cure.

Often overlooked, but important nevertheless is the type of grill cloth used on Marshalls. Earlier Marshall cabinets used a basket weave style cloth material that didn’t let the full sound signal of the speaker go through. We call this characteristic “transparency” and the basket weave cabinets were not 100% transparent. The higher pitched sounds were the first to be absorbed by the cloth. Later cloth designs such as the checkerboard grill were nearly fully transparent. By the time the JCM 800 series cabinets and beyond were produced, the grill material was considered fully transparent. You may prefer the sound of the basket weave or checkerboard cabinets as many do, or go for the more acoustically accurate and transparent modern cabinet. As is the case with guitar tone, this is a personal judgment call.

Author acknowledgement: While these days, there are many internet articles and opinions about what to do, how to do it, and endless back and forth…the earliest reference I found that really taught me many of the initial techniques referenced in the above article were by John Boehnlein and his excellent book, “The High Performance Marshall Handbook.” Published in 1998, it’s a great historical guide and offers a high-level and non-technical overview and perspective on Marshall amps and how to get the most out of them. Check it out and if you love Marshalls, show some support for John who is also quite passionate about them!