Monday, May 25, 2009

shared ground mundorf

the mundorf m-lytic have a common ground, rendering it unsuitable for the janus design as i wanted to use the capacitor in C3 and C4 positions.

bummer bummer... got to get a few more capacitors for the janus section. i ended doing everything up on a perf board as the whole lot is quite heavy to be mounted by double-sided tape and zip cord. also, there is not enough space for the GE oil capacitor as the first capacitor.

i'm doing up the amp bit by bit... slowly, but surely...

Wednesday, May 20, 2009

hybrid power supply

now i'll have the opportunity to try the hybrid power supply. the good thing about a blog is the "diary"-like effect. I use it to write notes to myself... and in this case, is to remind myself that I need to use this topology for the Mighty Midget since my r-core power transformer (R0080-043) does not have a center tap.

according to the original author, there was no difference in measurements between a pure tube based power supply and this hybrid power supply. so, what then, is the advantage of implementing this? purely to cater for power transformers without a center tap... notably the Lundahls in this case. ;)

Tuesday, May 19, 2009

compactron sockets

horror of horrors... the 6D10 compactron socket that I got are not the correct ones! I got the 9 pins instead of the 12 pins... argh...

guess i have to wire up the rest of the connections and the power supply sections first...

above is the work in progress janus shunt regulator, with 12w ohmite rheostats and kiwames in key locations. the power supply will be rectified by rca 6ax5gt, then 22.5uF GE oil capacitors, then the janus shunt regulator with mundorf m-lytics.

i reused the moskido chassis for the 6t10 mighty midget. had to drill new holes for mounting of the r-core power transformer (R0080-043) from and also additional holes for mounting of the james output transformer. the moskido chassis had 2 octal tube holes already drilled. i will have to use the front one for the rca 6ax5gt and the rear one for the ge 6t10 compactron. the janus regulator will be on a separate copper plate. i sawed it from my m10 preamp chassis (an early project that was decommissioned).

no matter how i planned, i will miss some parts... this time round, i missed the 200R cathode resistors for the mighty midget. all of the resistors to be used there are takman rex carbon film resistors. got to replace with kiwame...

some pics here.

Monday, May 18, 2009

moskido terminated

The moskido schematics have changed since the last time I looked at it. Now they are Direct Coupled, using a DC servo to get rid of the large output capacitor. Apparently this new version is much better than the original version.

But this requires another pair of mosfet per channel and the heatsinks that I got are not enough to dissipate the additional heat... Guess I'll have to KIV this project.

In the meantime, I am going to convert the chassis that I did previously for the 6D10 Mighty Midget. Gonna go grab some parts later.

There are not enough audio DIY related posts... hopefully I'll update with some progress tomorrow. I need to work out the tube rectifier and also Janus Shunt regulator stages for my Mighty Midget.