PSE design by AquaBlue and build by Johan Cools in a beautifull copper polished chassis

PSE design by Aquablue and build by Johan Cools

in a beautifull copper polished chassis .

Johan is a familiar figure in the house , he has been building many amps since many years and allthough he owns a pair of mono block audio notes he finds it charming to do better for less and especially with tubes costing less and less popular then std DHT triodes like 300B.He has made a few PSE EL84 , see also on this website , he has made PSE EL34 , and used this amp for evaluating different 6L6 tubes , he tried KT66 chinese version , 7581A philips NOS , SV6550C , 5881wxt , 6L6GT ,and settled for the KT88 from china .The particularity of this design was that he was tired of using std RC coupled stages and wanted to try an inter stage , so i suggested the 6SL7 NOS ( which i knew was excellent ) and the LL1660/10mA as the perfect match , and for the decoupling of the outputstage i came up with something fancy ,also called ultrapath nowadays ( who invents these crazy names ? ).The 22µF electrolytic IMPROVES the sound greatly , only mkp is not the way to go !!!! Separate cathode bias resistors ensure low hum and easy bias , this setup is a compromise between negative bias and cathode bias , it is much closer to negative bias and therefore sounds much better then cathode .

The schematic below is the current version , allthough some mistakes ( negligible )crept into it :

output transformer is the LL1623/160mA ( and not 1663 )

5U4G is actually a 274B , and after it a small cap was used to crank up the voltage 2,2µF/630v .

Also filaments 6SL7 suppl one side to gnd .

and each 470µF/450v on schematic is actually 2 x 470µF/450v see pic

Schematic with measure voltages :