Monday, 8 October 2007
From 300B to 45
After some weeks of research, dialogue and thinking, the 300B amp has been put on hold for the moment, to make way for a 45 DRD monoblocks. The main reasons behind this change is; lower operating B+ voltage and availability of quality new and NOS tubes (there are no NOS 300B easily available). To this effect, I have ordered the chokes and reactors from Electra-Print, and they arrived within a few weeks. In addition, I have started to place the other components on order. In the signal section, I am using Caddock MK132 resistors, Mills high wattage resistors, Ohmite adjustable rheostats, Blackgate NH driver cathode bypass, and Solen PPE Ultrapath. Tube sockets will be teflon type. In the PSU section, I will basically using the same design as Electra-print design. The diodes will be changed to hyper-fast diodes, the filter caps will change in value. At this moment, I am considering filter values in the range of 500uF to 1100uF. Apart from some minor changes in component specification, it is very similar to the schematic as provided by Electra-print. The irons will all be Electra-Print, except for the Power transformer, which may be sourced from another supplier. Though the change from a 300B to 45 reduces power significantly, from around 8W to 1.5W, I believe that tandem with a 95dB+ speaker, and given my listening room is a small room, I shouldn't be too concerned. Full schematic, photos and progress will be available shortly. About half the components have already arrived, so looking forward to completing all parts, ready for construction and audition!