Mesa/Boogie 45, 100, 55 guide

DIAGNOSING PRE-AMP TUBE PROBLEMS: Because your amplifier is an all tube design, it is quite possible that you will at some point experience minor pre-amp tube noise. Rest assured - this is no cause for alarm and you can take care of the problem yourself in a matter of minutes by simply swapping tubes.

Let us begin by saying; It is a “very good” idea to keep at least a couple of spare pre-amp tubes on hand at all times to insure uninter- rupted performance. These minor pre-amp tube problems can take many forms but can generally be described in two categories: Noise and Microphonics. Noise can be in the form of crackling, sputtering, white noise/hiss and/or hum. Microphonic problems usually appear in the form of a ringing or high pitched squealing that gets worse as the gain or volume is increased thus are more noticeable in the higher gain “HI” modes. Microphonic problems are easily identified because the problem is still present even with the instruments’ volume off or unplugged altogether - unlike pick-up feedback which ceases as the instrument is turned down. Microphonic noise is caused by mechanical vibration and shock: think of banging a microphone around and you’ll understand where the word came from.

The best way to approach a pre-amp tube problem is to see if it occurs only in one specific mode or channel. This should lead you to the tube needing replacement. Then all that remains is to swap the suspect tube for a known good performer.

If you cannot narrow down the trouble to a specific mode or channel, the problem may be the small tube that drives the power tubes which is operational in all modes and channels. Though rare, a problem with the driver tube would show up in all aspects of perfor- mance - so if you can’t narrow the problem down to being mode or channel specific, you may want to try replacing the driver tube. Driver problems generally show themselves in the form of crackling or hum in all modes of performance and/or weak overall output from the amplifier. Occasionally an anemic driver tube will cause the amplifier to sound flat and lifeless, but this is somewhat uncom- mon, as worn power tubes are a more likely suspect for this type of problem.

Sometimes making the diagnosis is more trouble than it’s worth and it’s faster and easier to merely replace the small pre-amp tubes ONE AT A TIME with a replacement known to be good. But MAKE SURE you keep returning the tubes to their original socket until you hit the one that cures the problem. You’ll notice that tubes located nearer to the INPUT jack always sound noisier...but this is because they are at the start of the chain and their noise gets amplified over and over by the tubes that follow. The tube that goes into this “input socket” (usually labeled V1) needs to be the least noisy of the bunch. The tube that goes at the end of the preamp chain - just ahead of the power tubes - can be quite noisy without causing any problem at all. The tubes in your amp have already been located in the most appropriate sockets and this is why you should NEVER pull them all out at once and ALWAYS swap them one at a time. ALWAYS return a perfectly good tube to its original socket. Also it’s a good idea to put the amp on STANDBY when swapping tubes to reduce the heat build up in the tubes themselves and to prevent explosive noises (which can still occur even if you are pulling the tubes away from their sockets gently) from coming through the speaker.

Remember, take your time, be patient and chances are real good that you can fix your amp yourself by finding and replacing the bad tube. It kills us to see someone who has shipped their amp back to us...and all it needed was a simple tube replacement! If you must send back your amp, unplug the power cord, speaker and reverb cables then remove the chassis from the cabinet by unscrewing the four mounting bolts on top. The chassis then slides back like a drawer and comes out. Remove the big power tubes and mark them according to their location from left to right 1, 2 etc. They need to be wrapped separately with plenty of wadded up newspaper around them and put in a smaller box within the larger carton.

To wrap the chassis, use plenty of tightly wadded up newspaper so there is at least six inches of “crush space” between the chassis and the cardboard box. Bubble wrap also works well, but please DON’T use styrene peanuts - they will shift during transit and get lodged inside your electronics as well as allowing your amp to end up at the bottom of the box unprotected and possibly damaged. Pre- amp tubes don’t normally wear out as a rule.

Therefore, it is not a good idea to change them just for the sake of changing them. If there isn’t a problem - don’t fix it. If there is no result from your substitutions, it may be possible that you have more than one problematic tube. Though rare, this does happen and though it makes the troubleshooting process a little more intimidating, it is still possible to cure the problem yourself.

NOTE: It is normal to hear a slight metallic ringing sound when tapping on the preamp tubes. As long as the tube does not break into oscillation or start crackling or any other form of bizzare noise, it is considered normal and functional.

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45, 55, 100 specifications

Mesa/Boogie, a name synonymous with innovation in the guitar amplification world, has carved out a niche in the hearts of musicians with its formidable lineup of amplifiers. Among these, the Mark series stands out, particularly with models like the Mark 100, 55, and 45. Each model brings its unique flavor and versatility, allowing players to craft their sound with precision.

The Mesa/Boogie Mark 100 is a powerhouse in the 100-watt category. It boasts multiple channels, allowing guitarists to switch between clean, crunchy, and high-gain tones effortlessly. One of its standout features is the onboard EQ, which facilitates fine-tuning for different guitars, pickups, and musical styles. The Mark 100 is engineered with Mesa's signature Dyna-Watt technology, providing a dynamic response at various volume levels without sacrificing tonal quality. This responsiveness makes it ideal for both live performance and studio recording, as it yields rich harmonic overtones and a wide dynamic range.

Moving to the Mark 55, this model offers a refined approach with 55 watts of power. It retains many features present in the Mark 100 but is more accessible for players who prefer a slightly lower wattage. The Mark 55 excels in mid-gain settings and is popular among blues and rock guitarists. Its Dual Rectifier circuitry can dial in everything from smooth, bluesy overdrive to tight, aggressive rock tones. The amp also incorporates a versatile effects loop, providing seamless integration with pedals and processors, making it a favorite among pedal enthusiasts.

The Mark 45, perhaps the most compact of the trio, brings 45 watts of power to the table, making it a versatile choice for players seeking portability without compromising tone. It retains critical features such as multiple channels and a powerful EQ section while being lighter and easier to transport. The Mark 45's sweet spot is found in its ability to deliver rich, saturated tones at manageable volume levels. Often favored for intimate gigs and home recordings, its versatility allows players to explore genres from jazz to metal with equal flair.

All three Mesa/Boogie amplifiers utilize high-quality components designed for durability and peak performance. Their construction is robust, ensuring reliability on stage or in the studio. With advanced features such as power scaling and tube rectification options, musicians can tailor their sound precisely.

In summary, the Mesa/Boogie Mark 100, 55, and 45 each present guitarists with distinctive tonal characteristics and features that enhance playability and sound. From the powerful performance of the 100 to the compact yet versatile 45, these amplifiers deliver the high-quality, rich tones that Mesa/Boogie is renowned for, catering to the diverse needs of players across genres.