{"text_format":"3","workbook":"xls","n_sheets":4,"sheets":["Home","Instructions","Extra","Values"],"not_rendered":{"images":25,"external_links":1,"defined_names":12,"comments":4},"read":"whole","date_system":"1900","formulas":"cached_only"}

{"sheet":"Home","index":0,"n_rows":67,"n_cols":10,"rows_kept":67,"flags":["formulas_cached_only"]}
[null,"Headphone Resistor Network Calculator"]
[null,"by Rob Robinette",{"$nulls":3},"V1.3.1"]
[null,"Add Speaker Load for Tube Amp with Output Transformer"]
[]
[]
[{"$nulls":6},"Enter Values in Yellow"]
[{"$nulls":6},"Headphone Impedance",32,null,"--Headphone's rated impedance"]
[{"$nulls":6},"Amp Output Impedance",0.1,null,"--Usually < 0.1 ohm. Use 0.1 unless you know it."]
[null,"Effective Speaker Load",{"v":7.619047619047619,"d":"7.6"},{"$nulls":3},"Amp Output Voltage*",0.357,null,"--*This is optional. It is used in the amp and headphone calculations below."]
[null,"Effective Headphone Output Impedance",{"v":0.09900990099009901,"d":"0.1"}]
[null,"Amplifier Attenuation","None"]
[]
[null,"Preferred Headphone Resistor Network – Adds Attenuation & Speaker Load"]
[{"$nulls":6},"Resistor1* 10 to 25 watt",10,null,"--Resistor 1 adds Effective Speaker Load"]
[{"$nulls":9},"    *Up to 30 watts per channel amp use 10 watt resistor, 30 to 80 use 15 watt, above 80 watts use 25 watt resistor."]
[{"$nulls":6},"Resistor2  5 watt",6]
[{"$nulls":6},"Resistor3  3 watt",2]
[]
[{"$nulls":6}," Recommended Starting Values"]
[{"$nulls":6},"R1",10,null,"Rated Amp Speaker Load + 2"]
[{"$nulls":6},"R2",6,null,"R3 x 3"]
[{"$nulls":6},"R3",2]
[]
[null,"Effective Speaker Load",{"v":7.882352941176471,"d":"7.9"}]
[null,"Effective Headphone Output Impedance",{"v":1.5061728395061729,"d":"1.5"},{"$nulls":4},"Amplifier Output to Preferred Resistor Network"]
[null,"Amplifier Attenuation",{"v":12.43909640089803,"d":"12.4"},"dB",null,null,"Amplifier Power",0.016168902985074625,"watts"]
[{"$nulls":6},"Amplifier Current",0.0452910447761194,"amps"]
[null,"Add Attenuation Only"]
[{"$nulls":7},"Headphone Input Through Preferred Resistor Network"]
[{"$nulls":6},"Headphone Power",0.22713120962352418,"milliwatts"]
[{"$nulls":6},"Headphone Current",2.6641791044776117,"milliamps"]
[]
[{"$nulls":7},"R2 and R3"]
[{"$nulls":6},"R2 Power Dissipation",12.307672421474715,"milliwatts"]
[null,"Effective Speaker Load",{"v":38,"d":"38.0"},{"$nulls":3},"R3 Power Dissipation",3.634099353976387,"milliwatts"]
[null,"Effective Headphone Output Impedance",6.1,{"$nulls":3},"R2 Voltage Drop",0.2717462686567164,"volts"]
[null,"Amplifier Attenuation",{"v":1.4926723659380838,"d":"1.5"},"dB",null,null,"Headphone + R3 Voltage Drop",0.08525373134328358,"volts"]
[]
[null,"Alternate Dual Resistor Network – Adds Attenuation & Speaker Load"]
[]
[]
[]
[]
[{"$nulls":7},"Preferred Single-Ended Headphone Resistor Network"]
[]
[null,"Effective Speaker Load",{"v":7.916666666666666,"d":"7.9"}]
[null,"Effective Headphone Output Impedance",{"v":6.099009900990099,"d":"6.1"}]
[null,"Amplifier Attenuation",{"v":1.4926723659380838,"d":"1.5"},"dB"]
[]
[null,"Three Resistor Network – More Complicated Than Needed"]
[]
[]
[]
[]
[{"$nulls":7},"Single-Ended uses the same formulas as"]
[{"$nulls":7}," the Preferred Resistor Network at upper left."]
{"$rows_empty":8}
[null,"Effective Speaker Load",{"v":4.407894736842105,"d":"4.4"}]
[null,"Effective Headphone Output Impedance",{"v":1.5061124694376529,"d":"1.5"}]
[null,"Amplifier Attenuation",{"v":12.43909640089803,"d":"12.4"},"dB"]

{"sheet":"Instructions","index":1,"n_rows":30,"n_cols":1,"rows_kept":30,"flags":["formulas_cached_only"]}
["Instructions"]
[]
["A headphone resistor network helps to electrically match a pair of headphones to a speaker amplifier's speaker terminals."]
["The first step is to try the headphones connected directly to the speaker amp with no resistors. Many amps sound great this way."]
["If you're using a tube amp with an output transformer and you don't need attenuation use an R1 resistor to match the speaker load."]
["If you hear hiss or have too little volume knob movement add a series resistor (R2) for attenuation. If you also want to match"]
["    your amp's speaker load then add a parallel resistor (R3) which is the “Preferred Headphone Interface.”"]
[]
["The Preferred Headphone Resistor Network Interface is an L-pad attenuator and is the most commonly"]
["   recommended headphone-to-speaker-amplifier interface."]
["Fill in the yellow boxes"]
["1. On the Home page input your Headphone's Impedance rating and"]
["    the Amp's Output Impedance (if you don't know leave it at 0.1) into the yellow input boxes."]
["2. Enter the recommended values for Resistor1, Resistor2 and Resistor3. These recommended starting values are in the blue box"]
["    just below the input box."]
["3. Adjust the value of Resistor2 and Resistor3 to get the desired Effective Speaker Load while trying to maintain a 3 to 1 ratio for their values,"]
["    i.e., if Resistor2=6 then Resistor3 should be approximately 2. The greater the ratio between Resistor2 and Resistor3"]
["     the higher the Amp Attenuation."]
["4. The Amp Attenuation value is used to indicate how much of your amp's power will bypass your headphones and lower its output."]
["    The higher the Amp Attenuation the lower the amp's output and the more the volume knob will have to turn. More attenuation can"]
["    help reduce the amp's noise floor hiss that can sometimes be heard using headphones with powerful speaker amps."]
["Note: You can cut-and-paste the “Resistor2 and Resistor3” yellow input box anywhere on the spreadsheet to make entry easier."]
[]
["I built my Headphone Resistor Network Interface using these resistors:"]
["    Vishay/Dale wirewound non-innductive resistors. The exact parts from Mouser.com were: "]
["        Mouser part# 71-RS0056R000FB12 Vishay part# RS0056R000FB12 5watts 6ohms 1% "]
["        Mouser part# 71-NS2B-2 Vishay part# NS02B2R000FB12 3watts 2ohms 1% "]
["The resistors were about $2 each with $5 shipping."]
[]
["See this DIY on how to build a Headphone Resistor Network Interface Box"]

{"sheet":"Extra","index":2,"n_rows":15,"n_cols":4,"rows_kept":15,"flags":["formulas_cached_only"]}
{"$rows_empty":8}
["4 Resistor Network – Way More Complicated Than Needed"]
["    Adds attenuation and speaker load"]
["Enter R4's Value",10,null,"Resistor 4 increases Amp Attenuation"]
[]
["Effective Speaker Load",{"v":4.416243654822335,"d":"4.4"}]
["Effective Headphone Output Impedance",{"v":0.09850724209281703,"d":"0.1"}]
["Amplifier Attenuation",{"v":-19.084850188786497,"d":"-19.1"},"dB"]

{"sheet":"Values","index":3,"n_rows":18,"n_cols":10,"rows_kept":18,"flags":["formulas_cached_only"]}
["Preferred Resistor Network Common Values",{"$nulls":6},"Attenuation Only"]
[]
[]
[]
[]
[]
["With headphones of 32 ohms of Impedance",{"$nulls":7},"With headphones Impedance of: ",32]
["R2","R3","Speaker Load","Attenuation",null,null,"R2","Speaker Load","Attenuation"]
["Ohms","Ohms","Ohms","dB",null,null,"Ohms","Ohms","dB"]
[2,7,7.7,2.6,null,null,15,47,3]
[3,6,8.1,4,null,null,40,72,6]
[4,5,8.2,5.6,null,null,70,102,9]
[5,4,8.5,7.6,null,null,110,142,12]
[5,3,7.7,9,null,null,220,252,18]
[6,2,7.9,12.4,null,null,540,572,25]
[7,1,8,18.3,null,null,1000,1032,30.2]
[8,0.5,8.5,25,null,null,3000,3032,39.5]
[8,0.25,8.2,30.4]