Unbalancer 9-pin.pdf - Tube CAD Journal

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$Radiotron Designer's Handbook Tube CAD does the hard math for ...$

12Unbalancer 9-Pin PCBInput XLRFemale JacksPin 1 left floating or attaching to chasisOutput RCA JacksIsolated from chassisRight132132LeftBottom ViewVolume Control
GlassWare Audio Design 13Configuring the Unbalancer as a Line AmplifierThe Unbalancer circuit makes a perfect line amplifier, as it offers low distortion and alow output impedance. The input and output tubes do not have to be the same typeor even share the same heater voltage; and the following design examples are notexhaustive by any means. For example, the 6H30 and ECC99 would make powerfuloutput tubes and the 5693 might make a stellar input tube (followed by a 5695 in theBroskie cathode follower position would make an all-computer-tube unbalancing linestageamplifier). In general, we want low-mu triodes for the differential amplifier stageand high-gm triodes for the Broskie cathode follower stage. An excellent pairing is the12AU7 and the ECC99.Typical Part Values() Parentheses denote recommended values(input) V1, V2 =B+ Voltage =AC Secondary =DC Heater Voltage =R1,2,15 =R3,4 =(without CCS) R6 =(with CCS) R6 =R7, 8 =6CG7/6FQ7 12AU7 12BH7 6DJ8 1240V 240V 240V 150V330Vac 330Vac 330Vac 120Vac6.3V or 12.6V 12.6V 12.6V 6.3V or 12.6V1M 1M 1M 1M100 - 1k (300)* Same Same Same287* 370* 499* 87*6.81* 6.81* 6.81* 6.81*24k/1W* 24k/1W* 24k/1W* 15k/1W*Jumper J7 =None None None Use(output) V3, V4 = 6CG7 6H30 1 12AU7 12BH7 ECC99 6DJ8 1R9,10,11,12 =R13,14 =100k* 100k* 100k* 100k* 100k* 100k*300-560* 150-400* 300-845* 240-470* 240-470* 100-200(120)**High-quality resistors essential in this position.1. Low-Voltage OperationC1 =C2 =C3 =C4 =C7, C8 =0.1 - 1µF* Same Same Same Same Same0.1 - 1µF* " " " " "0.22 - 4µF* " " " " "150µF* 400V 270µF 200V " " " 270µF 200V47µF 450V 220µF 200V " " " 220µF 200V*Voltage rating must equal or exceed B+ voltage; Film or PIONote that the assumption here has been that the differential input stage runs under atotal idle current of 10mA, the optimal value for most Unbalancer setups. Thesecond assumption is that plate resistors, R7 & R8, will split the B+ voltage. forexample, if the B+ voltage is 300Vdc, the voltage drop across should equal 150Vdc.Of course, the 10mA is not set in stone; it is, unfortunately, it is limit that theLM334 can sustain.The Broskie cathode follower portion of the Unbalancer circuit is much moreflexible in possible idle current settings. The formula for setting the BCF idle currentis an easy one:Iq = B+/2(rp + [mu + 1]Rk)
Page 1 and 2: GlassWareAUDIO DESIGNUSER GUIDEIntr
Page 3 and 4: GlassWare Audio DesignWarning!This
Page 5 and 6: GlassWare Audio Design 3The Broskie
Page 7 and 8: GlassWare Audio Design 5The Broskie
Page 9 and 10: GlassWare Audio Design 7To bypass o
Page 11 and 12: GlassWare Audio Design 9R12 Imax mA
Page 13: GlassWare Audio Design 11Tube Selec
Page 17 and 18: GlassWare Audio Design 15Double-Sid
Page 19 and 20: GlassWare Audio Design 17Configured
Page 21 and 22: GlassWare Audio Design 19GroundingT
Page 23: Top Side PCB Mechanical Layout6.0 i

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