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Working on the 45 version now. the plan is to be able to switch between 45 2a3 & 300b in the same amp. working out some resistor values now. If I can get my camera to talk to my computer again I will post a pic(I "upgraded" Windows)...John
Get the camera fixed. Also, can you recommend a HV (1000VDC) hook-up for my 811 project?.......Colin
Hi Colin, I need more info. is the 1000v to come from the trans you got from me? How much current? tube or SS rectifier? A look at the circuit would help. damn camera still will not work I reloaded the software but it still will not transfer...John
Here's the schematic (see link) 1) Yes, the 1000V (approx.) will come from the transformer I got from you. 2) Current I am assuming around 200mA 3) Tube rectified Any suggestions you can offer a really, really appreciated.....Colin http://www.audioroundtable.com/GroupBuild/Projects/SV811_10.gif
Hi Colin, By the looks of that schematic the B+ is 500v ~430v after the second choke. as shown it should work fine with the transformers I sent you. I would remove the fuse after the rectifier, add a bleeder resistor say 100k 5w across the first cap and maybe increse the second cap a bit...John
Just a little paranoid about the voltage coming off the rectifier. This is much greater than what I'm used to. Someone mentioned I need to be careful about arcing and that got me a little jumpy. I'm just trying to be safe and learn what needs to be done. Some dumb questions, if you don't mind: Why would you remove the second fuse? Shouldn't I add bleeder resistors across all the PS caps, or will one suffice? Why would you increase the second cap? Thanks a million.......Colin
Hi Colin, I posted to this and I look it’s not there…I hate it when that happens. Anyway. Fuses can be iffy at high voltage, most are rated at 250V. An ac line fuses should be enough. One bleeder is enough, just don’t count on it for safety. Check before you touch. Why a bigger cap; because you can! Before we glommed on to motor runs 10u was big, and expensive, and probably filled with PCB’s I increased the output tube cap on my WE91’s from 50u to 100u , Much better bass and dynamics…John
Would you change the 40 or 50uF cap in the power supply and to what (uF and voltage rating)?......Colin
Cap 1 no higher then 20u. That is the limit of your rectifier cap 2 same as guinevere 100u cap 3 after that big ass choke, what ever you got in stock 100u if you ask. 40u will be fine...John,