PLUTO-2.1 Eq/Xo/Amps 

NOTICE - The entire web page is strictly confidential - containing proprietary information, which is for PLUTO Construction Plan owners only. If you are not the intended viewer you may not use, disclose, distribute, copy or print this information.  | Terms & Conditions |

PCB Rev. 110111 

A - Circuit schematic
B - Component placement
C - Material list
D - Input-to-output frequency response
E - Frequency response spot checks
F - Mechanical construction
G - Revisions

  
PLUTO-2.1 prototype circuit assembly. 
The heat sinks and power IC subassembly should be soldered to the pcb as the last operation to avoid stressing and flexing the IC leads. The transformer, power cord and speaker leads should have been soldered before that. Finally the circuit assembly is screwed to the mounting plate.

A - Circuit schematic

Top

B - Component placement

Top

C - Material list

pluto21 material-newpcb-112311.xls

Parts supply sources: DigiKey, Mouser, Newark, Allied, Jameco, Farnell, CALRAD, ZACK and others.

Capacitor availability search at Mouser

Capacitor availability search at DigiKey

Agilent Technologies makes a U1701B Handheld Capacitance Meter ($158) for selecting capacitors to 2% or tighter tolerances. 

D - Input-to-output frequency response 

Top

E - Frequency response spot checks

Derive output-to-input voltage ratios  y = Vout/Vin  from the frequency response plots above. 
For example for the midrange channel Test Point 14 at 300Hz reads Y = 6.1dB when attenuated by 20dB or a factor of 10. The same applies to TP15.

y = 10^(Y/20) = 2.02  conversion from Y dB to its corresponding factor y

Thus for a 100mV input Vin the output voltage at TP14 will be Vout = Vin x 10 x 2.02 = 2020mV = 2.02V
What you measure should be within +/-5% or +/-101mV, which corresponds to +/-0.42dB.

For the tweeter at TP8 and 10kHz the graph indicates Y = 10.3dB, thus y = 3.27. 
For Vin = 100mV the output should then be Vout = 327mV +/-16mV
TP9 reads 0.2dB higher but has 20 dB attenuation. Thus Vout(TP8) = 1.02 x 10 x 327mV = 3.35V

The resolution of the graphical reading is about 0.2dB. The curves are for a single prototype and carry within themselves the deviations of components from their nominal value shown in the circuit diagram above and how that affects the frequency response. A 2% or 0.17dB variation of a component does not affect the frequency response necessarily by the same amount. It depends upon where in the circuit and signal flow the component is located. To determine the uncertainty of the measured frequency response curves is not a trivial matter and requires a 'Monte Carlo' analysis of the circuit diagram, an analysis of the test method and of the instrumentation uncertainty. 

Top

F - Mechanical construction

Note item  --- (46)  1/16/09  PLUTO-2.1 Construction ---  from the original Pluto owner support page. 
In particular accommodate the increased height of the heat sink (B), which requires 3.5" internal height for the base (C).

G - Revisions

23 November 2011 - Material list: Added 470uF. Corrected 10k resistor placement

6 November 2011 - First posting  

Top

--------------------------------------------------------------------------------