Tuesday, March 2, 2010

1977 Marshall JMP 50 watt Combo MKII Master Lead

The JMP (James Marshall Products)
We classic rockers are all intimately tied to the massive tone that exploded onto the 60's rock scene courtesy of Marshall Amplification. Super Lead heads married to matching cabinets loaded with speaker quads, teamed to deliver 100 watt walls of sound, and for many, defined that era of classic rock & roll.

But many are not aware that Marshall also made more portable combo versions of the 1987 lead circuit, including the rare mail order Lead and Bass model. Different from the Lead and Bass Head circuit that was just 20 watt, these were 50 watts, basically a 2x12 Bluesbreaker cabinet design stuffed with two channels and 4 inputs. One channel a 1987 circuit (lead) and the second a 1986 circuit (bass).

Here's a clip we did, both channels jumpered, 3/4 volume, goosed with an 80's Black box Marshall Guv'nor & Boss RV-3 Reverb, camera mic only...



We had the good fortune at Tone Classics to find an even rarer combo, a 2 channel, 4 input, non-master volume, 2x12. This "latter day bluesbreaker style" combo model (2187) was produced in small numbers between 1974 through 1987, according Michael Doyle's famous book... The history of Marshall: the illustrated story of "the sound of rock." And like the Lead and Bass model, it too features two circuits. Plug into Channel I and you tap a 1987 lead circuit. Plug into Channel II and you tap a 1987 circuit voiced with more bass. Jumper both channels, and yes, you get a thick, warm, very usable tone even at lower volumes, that absolutely loves pedals.

Classic Marshall, Period.
This is one of those amps that has an instantly recognizable tone, be it through a Strat or Les Paul. It is the super lead sound and circuit, but with half the wattage in a 50 watt non master volume combo form with yes, an extra channel. Run one channel clean, one dirty, jumper them both, either way you will exploit warm, woody tones and superb Marshall harmonic content and saturation regardless of volume. The bottom is tight, probably the tightest bottom end we've ever played. The power tube compliment is a pair of creamy JJ EL-34s. The preamp features 3 12ax7's and is solid state diode rectified. Speaker compliment is two 1977 Made in England Celestion Blackbacks with rare 55hz bass resonance cones.

So where do I plug in?
You have 2 channels and 4 input jacks. Channel I is a 1987 lead circuit, Channel II is a 1987 lead circuit voiced with more bass, similar to the 1986 bass circuit but much more flexible and usable. You can plug into low or high inputs Channel I, low or high inputs on Channel II, or best part, jumper the two channels for a great thick tone that fattens up nicely for low volume work, and commands attention at cranked, saturated levels. Either channel or both together accept pedals well. Duane Allman is well documented using Marshall bass circuits with a fuzz pedal to create a rounder, smoother, singing tone. We recommend an a/b/y foot switch (we have one by Whirlwind, that is super quiet due to its optical switching) to switch between channels or combine channels with a tap of the toe.

Speakers
This combos design is almost identical to the early bluesbreaker design, in size and shape and speaker compliment. It is loaded with two 12" 1977 Celestion Blackbacks. These Made in England Blackbacks are similar to greenback speakers but constructed with the famous 55 hz bass resonance cone. This cone smooths attack, and rounds the amps tone (especially popular for stratocaster work). Like typical greenbacks they are rated at 25 watts each and famous for their ability to break up at relatively quieter volumes, this speaker breakup is integral to the early Marshall sound we all know so well. You have multiple speaker connection options on the underside back chassis panel. There is a tap for selecting 4, 8, or 16 ohm speaker impedances, and two speaker input jacks, wired in parallel, are on the ready.

What's inside
A very clean chassis, with all original big, old Iron, heavy and glorious in tone and capability. While many are disappointed with Marshalls switch to early circuit board designs in the 70's, most electrical engineers will tell you there is no appreciable tone differences, and the main advantage of point to point (PTP) wiring is that is more easily serviceable. The chassis screws in with large heavy machine screws and is road rugged.

What's outside
Its wrapped in its original classic black Elephant tolex, tattered a bit here and there, but nothing extreme. The speaker baffle is mint and covered in my favorite Marshall grill cloth, the large gray check style. The entire wood baffle is screw removable from the inside.

The JBL D120F Experiment
Want to experience a real treat, try running a vintage Marshall into the vaunted JBL D120F speaker. We keep this classic speaker (a 1969 doped version) loaded in a deep, over sized, open back cabinet to test amps potential that we run through the store. The JBL is a clear, uncolored (to an extent), quality speaker that really allows an amps tone potential shine through. This took the blackbacks out of the tonal equation and wow, you could really appreciate what a special amplifier circuit on its own the 1987 is. With the Celestion blackback tone coloring removed you could hear this amps circuit in a different yet classic familiar way. Think Duane and Dickey back in the day. Full of bells and beautiful harmonics and a clean singing sustain, with a perfect breakup and a touch of mid range honk.

We're fortunate to have come across such a special find.


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An epic voyage into classic guitar and amplifier tone. Please visit our website www.ToneClassics.com to view our latest inventory.