I use a 9V 2A transformer and the regulator is heatsinked well so that's not the problem. I wonder what will happen if the triode a not balance, can it make that noise? I don't have 6GM8 or 6n27p so i can only use 6h6n now.
No, it's not 60 or 120hz hump, it's like some one playing sine wave at some where between 4k-6khz. What do i need to compensate for higher heater current tube? My tube sound fine in another amp so the problem must come from the EHHA. I currently haven't cased it up so i can't do the ground loop breaker.
I have finished my EHHA RevA, both channel sound fine but it has very annoying noise like a sine wave at 5khz, it increase a bit if i turn the volume up. Everything measure fine, my build using bc546/556 for the servo booster and the current source for tube like the EHHA 1 (because i don't have the CRD), 1145/2705 for the rest and i use a shunt regulator to power it. I use both the original wiring and alternative wiring but nothing change. The tube i'm currently using is...
I was wondering can i change the transistor in the servo booster from C2705/A1145 to BC546/556? I use spice to simulate and it's working fine but in real world performance do you guy think it will affect the sound quality?
Don't take that post too seriously, O2 is very good indeed but it has its limit. I think the guy who posted that comparison just doesn't have really good hearing ability. I haven't heard the B22 with my own gear and setup but O2 is still 1 step down compare to my PPAV2 and 2 step down compare to my friend's Dynalo, with me i can hear the different very clearly and the O2 is definitely not up to level of these two so i don't even care to compare it to B22.
You're right. I dont' have TLE2426 so i made a simple divider by 2 resistor and the distortion's gone but now i got about 90mv dc offset, it sound very good but i'm not sure if it's better than the regular 2 or 3 channel . Thanks for your very informative topic :D