Show Audio System Uses a Grid Impedance The years year's ears one new ne Id idea a In quality audio amplification Is the system which makes use of or a grid Im fm Impedance colt coll When a transformer Is used the grId potential has to be kept negative e As soon as the grid goes oes positive there Is a partly partir shortened circuit In the secondary of the transformer and It a temporary reduction of the lie magnetic coupling The result Is distortion The system has lias been developed de find and mn magnetic coupling has been eliminated In the Illa diagram ram Is Illustrated the figure 8 lamination by 11 means monni of ot which the tw choke coils colis plate pinte and grid Id are mounted on the same lamination Through the i fixed condenser linking tile the lie two coils colls P 6 at f A M Mat 1 Diagram Illustrating the Figure S 8 Lamination the tIle frequencies pass from froni rota the plate to tile the grid of the succeeding tube The effect of his coupling Is nut not changed by grin currents Conse Conse- Consequently Consequently with this system full utilization tion of ut the lie natural grid voltage voltage- voltage plate plate curr current nt Un curve of the tub b made twice as much as us you can with witha a transformer As the comparative e power output Is the square of the olta voltage e fluctuations one Is la able to ob- ob ob obtain tarn tain the square of two or four times the power output as a compared with a transformer By replacing the usual grid resist resist- resistance resistance resistance ance of on nn Impedance-coupled Impedance amplifier fier ller with n It snit con a happy py combination I I tit us the result which affords n It volume I limit or blocking point 20 2 tines times I that of the usual single Impedance circuit u using Ui ln n II 5 grid look leok ud aLd the of ot the signal Is over o n a million mutton ohms ut ot ordinary free tre- fre frequencies Tills fits feature e enable enables each I e to have e an amplification factor whIch Is very ry high compared with either resistance or single Impedance circuits The amplification factor Is kept con con- constant constant stant slant within a er very small percentage from the lie lowest notes recel received d to the hIghest harmonics or overtones Re Re- Regarding Regarding garding the amount of ot three stages stagE's of ot the system will 1 give a greater rater amplification than two stages es of or transformer In a ratio of about 5 toI to 4 I It bias lias been found helpful to add odd J a fixed d resistor of ohms connect connected connected ed between the V F I post of ot the lie first coupler and the lie common ground round and A minus lend lead In series erles with tile the grId coil coll |