We have put all our design knowledge together to start bringing a series of hi end valve(tube) audio designs for the DIY market starting with this power supply for a valve phono pre-pre-amp, to be followed soon by the phono amplifier its self.
The PSU was designed to drive up to 4 12Ax7/ECC8x series valves running at a nominal HT of 280 volts and heater voltage of 6.3V and although designed for alpha2delta own phono pre-amp, it is beautifully suited to drive the very popular 3 valve phono pre-amp clones found in kit form from selling sites world wide. Although these phono kits are based on a very well known design the PCB can be split into PSU and AMP boards or as purchased as two separately PCB's. The amplifiers are very good but the power supply is wanting, Using an Alpha2delta power supply dramatically improves what is a already a good design
The design concept
The heater supply is designed to produce a very clean, stable and regulated 6.3V that is capable of driving 3-4 small signal valves with both low supply ripple and low common mode ripple with ground. The 6.3V is floated 36V from ground. The regulation is provided by a very low drop programmable regulator allowing it to be driven from a 6.3V RMS transformer without degradation of output. High quality filtering and rectification help the supply to provide the best heater drive.
The HT (B+) supply is close to zero ripple and provided as two independent 280V supplies one per channel giving outstandingly low channel crosstalk. The supply channels are regulated from a constant current source allowing for a simple design that is failsafe. There has been some improvements in the PCB design for 2019, silicon carbide rectifiers are now used plus the latest PCB can now be built in two versions KIT1 using the original two electrolytic capacitors in the HT supply and for the initial PI filter, all the others are high audio quality polypropylene and PET foils provide very low ESR and leakage current, long life and very high stability and KIT2 using polypropylene in the PI filter
Input: 6.3V - 8V RMS LT (2A), 240-280V RMS HT
Output: Heater current 1.2A Voltage 6.3 +/- 0.05V, voltage lift 36V, common mode ripple -75db 100Hz, 6.3V ripple -75db
HT (B+)280V nominal 35mA per channel with better than -100db ripple @100Hz and a voltage drop from nominal of < 0.2V
1. The PSU is available in kit form providing all the components to build it (except mains transformer). The components are all high quality parts chosen specifically for their purpose with no compromise
2. Fully built using the same KIT of parts
3. Also new for 2019, the PCB, and build instruction can be purchased separately to allow for local component purchase
Order can be made using the PayPal link below and prices exclude postage and packing. Please add postage and packing to cart before checkout. If no postal option for your region please contact the email address above