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  DISCUSSION ABOUT AMPS & CLASS D FROM THE DESIGN TEAM  

 QUESTION  

   What makes this new amplifier so small and light weight?

 

  ANSWER  

   This amplifier uses new technology, both an SMPS (SwitchMode Power Supply) and a CLASS D power 

amplifier to decrease the size and weight. These designs are carefully implemented and fully tested to insure robust, reliable 
performance in real world conditions night after night

  QUESTION  

   How can a light weight amplifier deliver solid bass? I was always told that an amplifier has to be heavy to produce 

acceptable bass.

  ANSWER  

   By operating in a non-linear fashion (with the power devices that are either fully on or fully off) the output 

stages no longer have to accommodate reactive load inefficiencies, overly sensitive protection of “safe operating areas”, and 
dissipate waste heat like output devices operating within the linear region. This means more power and better low frequency 
control. In fact, the pro audio industry has been using SMPS and Class D almost exclusively in the large scale touring market 
for about 10 years now, driving massive arena and stadium subwoofers night after grueling night on the road. In fact, much 
of the technology in our power amplifiers comes from the high reliability touring pro audio world.

  QUESTION  

   How do I know that these amplifiers will be reliable?

  ANSWER  

   The design engineer of the ROSETTE

®

 amplifier project has over 10 years of successful SMPS and Class D 

amplifier experience, both in bass and acoustic amplifiers as well as in the touring pro audio world. We have worked closely 
with the European engineering team on the development of these new power modules, including extensive testing, not just 
in the lab, but real world testing on real stages with real musicians and real audiences, night after night.

  QUESTION  

   Why is the power supply so small and light weight?

  ANSWER  

   An SMPS is just like any other power supply, except for the fact that it operates at a much higher frequency 

(typically around 80-100kHz) than a line frequency power supply (either 50Hz or 60Hz). The higher the operating frequency, 
the smaller the power supply’s transformer core needs to be. Since most of the weight of a power transformer is in the core 
(and the copper wire around the core), making the core smaller reduces size, weight and the amount of copper needed to 
wrap around the core.

  QUESTION  

   How does the SMPS work?

  ANSWER  

   Without getting too technical, a switch-mode power supply takes the incoming AC mains (50-60Hz) power, 

rectifies it to a high voltage direct current (HVDC). This HVDC is then filtered and stored in the input filter capacitors as reserve 
energy for discharge as needed into dynamic loads. This HVDC is then chopped/switched at about 100kHz into a high volt-
age, high frequency alternating current (HVHFAC), which is then fed through a high frequency transformer which converts 
the HVHFAC into low voltage, high frequency alternating current (LVHFAC) which is then rectified and filtered into low voltage 
direct current (LVDC) that the power amplifier’s circuitry uses. 

PAGE 18

Summary of Contents for Rosette 300 Two:Eight

Page 1: ...Owner s Manual...

Page 2: ...u are the new owner of an amp bred of fine heritage benefitting from the many pioneering and patented MESA circuits as well as fresh cutting edge research and development efforts leading to this new a...

Page 3: ...________________ 10 LAYERED CHORUS REVERB PROGRAM_____________________________________________________ 10 ROOM HALL REVERB PROGRAMS_______________________________________________________ 10 11 EFFECTS...

Page 4: ...atus which extend past the rear edge of its cabinet When Rack Mounting this unit proper ventilation space must be maintained Do Not cover or block Front and Rear and allow at least 2 of open breathing...

Page 5: ...the accurate reproduction of that beauty While staying true to the concept of Do No Harm few products or companies seem to share this perspective forAcousticAmplification And when it comes to the ele...

Page 6: ...s and can end at the Input Stage We re not about to let the latter happen on our watch Note that the lower Channel 2 may be used with a Microphone by using a standard Line Matching Transformer availab...

Page 7: ...ot light indicating the AC MAINS Power has been switched on BLUE The on board Effects Suite includes three effects choices ROOM REVERB HALL REVERB and REVERB AND CHORUS These effects programs create m...

Page 8: ...eeds your acoustic voice to live venues and recording applications with something as important as your music INSTANT GRATIFICATION The ROSETTE is a professional and comprehensive amplifier for acousti...

Page 9: ...I PASS controls feedback by taming excess low frequency resonances and if your instrument is feeding back at a lower pitch increasing the HI PASS filter stands a very good chance of remov ing the offe...

Page 10: ...nel The microphone preamp features a discrete low impedance balanced input amplifier which provides appropriate loading approx 3k ohms and gain to the microphone The MICROPHONE INPUT jack provides DIN...

Page 11: ...ustic instrument and bass amplifiers within the past few years with a few notable exceptions This variable filter helps you coordinate and control the sub sonic harmonics generated by the acoustic cav...

Page 12: ...than trying to boost frequencies Don t frustrate yourself by ignoring this time proven Golden Rule of Audio and you will arrive at great Tone quickly and easily LOW MID BAND With the BASS set at 10 0...

Page 13: ...necessary to set the MIC GAIN or INSTRUMENT GAIN control a little lower and maybe increase the MASTER control a little to obtain a reasonable playing volume and avoid overdriving the input stage Simi...

Page 14: ...to the generated reflections Because the time offsets are longer it s helpful not to use too much of this program in a mix especially with long reverb times and a high setting of parameter 2 s low pa...

Page 15: ...t stage clipping It s acceptable for this amplifier to operate in output stage overdrive mode if that s the tone you re after with the LED flash ing roughly 25 of the time on Rear Panel Controls Featu...

Page 16: ...help avoid accidental ear damage NOTE IMPORTANT It s advisable to use caution whenever sticking any sound source in or in close proximity to your ears as hearing damage is possible due to unintended...

Page 17: ...still best to introduce the least possible cable capacitance in the FX LOOP to ensure the best performance and Tone AUX INPUT The Rosette provides a 1 4 6 5mm T R S AUX INPUT This Tip Ring Sleeve ster...

Page 18: ...h allows you to best match whatever the requirements are of the equipment you are connecting the DI OUTPUTS of your amplifier to so set this switch according to those needs and you will always enjoy g...

Page 19: ...REST AREA PAGE 15...

Page 20: ...n turn the controls up 3 Defective speaker cable or cabinet test known good speaker cable and cabinet 4 Defective pickup or cable test with known good pickup and cable 5 There is indeed a problem with...

Page 21: ...ck all wiring for missing grounding earthing pins have qualified electrician check building power wiring for missing ground earth connections and correct as necessary 4 Problem with wiring or a device...

Page 22: ...Class D amplifier experience both in bass and acoustic amplifiers as well as in the touring pro audio world We have worked closely with the European engineering team on the development of these new po...

Page 23: ...WM digital audio recorder but at a much higher frequency at 5 volts conventional computer logic level This PWM pulse train is level shifted by large solid state switching power transistors that operat...

Page 24: ...RUS ROOM REVERB HALL REVERB LIMIT FX BYPASS PROTECT POWER LOW MID HIGH MID 300 TWO EIGHT ROSETTE PICKUP PHASE PICKUP INPUT PICKUP INPUT CH 1 CH 2 MIC INPUT PLAY MUTE CLIP IN OUT IN MIC PICKUP PHASE PL...

Page 25: ...TWIST LIFT ADJUSTMENT Adjustment of the Twist Lift is as simple as turning the threaded stand on the bottom side of the cabinet counter clockwise to RAISE the amp or turning the threaded stand clockwi...

Page 26: ...ones For this reason specifications and information in this manual are subject to change without notice SERVICE INFORMATION USA CANADA Customer Support For technical support troubleshooting tone ques...

Page 27: ...ROSETTE 300 TWO EIGHT BLOCK DIAGRAM PAGE 23...

Page 28: ...CONSUMPTION 250W MAINS FUSE INTERNAL T4A 250V h AMPLIFIER 44YV 100V 240VAC 50 60HZ INPUT POWER RATED POWER PICKUP PHASE PICKUP INPUT PICKUP INPUT CH 1 CH 2 MIC INPUT PLAY MUTE CLIP IN OUT IN MIC PICKU...

Page 29: ......

Page 30: ...18 02 13 MESA Boogie 1317 Ross Street Petaluma California 94954 USA Phn 707 778 6565 www mesaboogie com Fax 707 765 1503...

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