Music Reference RM-245.1
Just completed!!! Music Reference's first single ended amplifier. We chose the 45 for its extremely transparent midrange. Unlike most 45 amps that achieve only 2 watts per channel, we achieve twice that with no added stress on the 45 (this statement applies to all 45 tubes, even the old globes). Please visit this page often for further details. Click Here to see power output of the RM-245 with different tubes. Click Here for a picture of the RM-245 rear plate. The RM-245 is available with a choice of several different knob styles, as seen Here. The knob to the far left is available only in limited quantities, as it is antique and no longer produced.RM-245 FAQ Q: How do you get twice the power without hurting the tubes? A: Roger A. Modjeski, our designer, has always created new applications for tubes in his amplifiers and preamps. These applications are generally not the ones given in the RCA tube manual that most other designers use. Those applications are only suggestions and are not the final word. The range of possible applications is limitless and Roger enjoys exploring this realm creating new applications. The standard application of the 45 results in 10 watts of dissipation. This later became the rating for the tube. Interestingly enough, plate dissipation is not given in the early manuals. Roger has the complete set of RCA manuals from RC 11 to RC 29. In the RM-245 Roger’s application uses a slightly lower plate current and a slightly higher plate voltage with the average dissipation being 8 watts. The common RCA application is 10 watts (the maximum recommended). One of Roger’s conditions is always to run below max dissipation in all his amplifiers.
Music Reference RM-245
We call this model the “Tube Roller’s Special”. The 6 silver knobs, along with the meter make tube rolling easy. The knob in front of the small driver tube controls its operating point and allows the user to easily vary the plate voltage of the driver tube so as to minimize distortion (more about this later). The second knob is for bias current of the 45 and that value can be read directly from the meter in the center. The last knob is for hum balance, which is adjusted by ear for the lowest hum. Incidentally, the hum on this amplifier is the lowest in the industry for an AC heated DHT and measures in at 0.3 mV, making the signal to noise over 80 dB re. 1 watt. and 86 dB re full power.
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