300b amp speaker driving problems

[simon2a3]

Originally Posted by Gideon300b

Hi Simon

From memory my voltages were higher than 400v on the anode. What sort of speakers are you driving wiht your monoblocks. I am guessing that your circuits is identical except for the power supply?
Thanks

Using Fostex 208e Sigma back loaded horns with supertweeter. An easy 97db load. The circuit is exactly Philip's - are you using the same with shared psu?

Can you remember how much higher your voltage was on the anode? I don't quite get Philip's stated B+ (425V), down at 402V early evening (234v AC) and 417V late evening (240V AC).

Simon.

[Gideon300b]

Hi all,

Well some success tonight - found a bad joint at the cathode. Now managed to get it singing htrough my IPL's. Also think there is bad connection on one of the negative speaker terminals as I had to twin the negatives to make it work on one terminal. Progress!!

Now I have a new problem - hum - both channels constant level - with or without input. Still with hum - sounds fantastic!

Any ideas before I dive under the covers again?

[Gideon300b]

Hi all,

Got it fully working tonight - a bit of resoldering of joints and moving the input wirring away from the heaters wiring and away we go. Been filling my room for hours now!!!

Its a good feeling. Now for the burn in!