Re: DIY SHOWCASE ROOM
Posted: Mon Nov 12, 2012 7:27 am
to the organisers Tonyboy, and Francis and John Agner, many many thanks for the chance to display our stuff...it was a whole lot of fun....
the EL34 pushpull was built with a quad of Shuguang tubes pulled out of a Cayin amp, circuit topology was based on the Mullard 5-20 but used a russian 6J9 pentode as input and the 6CG7 at LTP splitter instead of the ef86/12at7 in the original design, justification being the 6J9 has higher transonductance, and the 6CG7 can run higher currents to drive the EL34 grids with more gusto....
the 6C33 set used M18 cores which admittedly was it's achilles heel, upgrade path would be to use C cores, Edrel has some to try....as usual, the sets were very good at the mids and highs as expected...
truth to tell, no boutique parts, no exotic branded caps/resistors were used is building the amps, but generous filtering was incorporated into the power supply, and then the use of common mode chokes wherein both the positive and negative side of the psu was choked up so that noise common on both sides of the line are attenuated well..
Tony and I achieved a milestone i am proud to tell......there was this guy who came into the room to listen, looked at the sony 4 inchers and them came up to me and asked, sir where is your subwoofer?
that we were able to trick his ears that he was listening to non-existing subs was the greatest compliment we got in two days.....
the EL34 pushpull was built with a quad of Shuguang tubes pulled out of a Cayin amp, circuit topology was based on the Mullard 5-20 but used a russian 6J9 pentode as input and the 6CG7 at LTP splitter instead of the ef86/12at7 in the original design, justification being the 6J9 has higher transonductance, and the 6CG7 can run higher currents to drive the EL34 grids with more gusto....
the 6C33 set used M18 cores which admittedly was it's achilles heel, upgrade path would be to use C cores, Edrel has some to try....as usual, the sets were very good at the mids and highs as expected...
truth to tell, no boutique parts, no exotic branded caps/resistors were used is building the amps, but generous filtering was incorporated into the power supply, and then the use of common mode chokes wherein both the positive and negative side of the psu was choked up so that noise common on both sides of the line are attenuated well..
Tony and I achieved a milestone i am proud to tell......there was this guy who came into the room to listen, looked at the sony 4 inchers and them came up to me and asked, sir where is your subwoofer?
that we were able to trick his ears that he was listening to non-existing subs was the greatest compliment we got in two days.....