New member

[Stephen C]

Hi all, I built a K881 Mk II back in December 1997 (best Christmas present). I was initially disappointed with the lack of bass, so upgraded the signal capacitors (to PiO) and the cathode bypass (to Black Gates), which improved the sound.
I retired from full time employment a couple of years ago, and have decided to spend some of my leisure time with DIY electrical projects. My first was a small single-ended amplifier with ECL82 valves (i had in my stash). This is based on Caledonian Audio amplifier PCBs, but with Hammond iron and a EZ81 valve rectifier HT supply with C-L-C reservoir and High Pass filter smoothing. I have left the heaters AC, and the hum is inaudible (after the valves warm up). . I have switches to select different output impedances, and Negative feedback on or off. The sound from this small setup is surprisingly good and I prefer the open sound with NFB off, although the measured frequency response is not as wide. I am looking for better output transformers.

[Greg.]

Welcome, Stephen. Enjoy the forum and join in whenever you like.

[Richard]

Yes, welcome Stephen, it's a nice hobby we can dip into and out of isn't it. Your ECL82 single ended is interesting. WAD did KECL82 push/pull 8W channel which you might know of.

Do you still have the Kel84? Did you try changing the value of C6/7? I'd be interested to hear what change you hear/find with it increased to 2000uF (from 1000uF, another 1000uF could perhaps be tagged parallel onto the existing ones, if the leads/pads are accessible, for initial testing to save removing the pcb). I once heard one at home with a similar mod iirc and it was very nice indeed, sounding like a much bigger amp at modest levels, though these things depend on system/room/ears of course.

[Stephen C]

Originally Posted by Richard

Do you still have the Kel84? Did you try changing the value of C6/7? I'd be interested to hear what change you hear/find with it increased to 2000uF (from 1000uF, another 1000uF could perhaps be tagged parallel onto the existing ones, if the leads/pads are accessible, for initial testing to save removing the pcb). I once heard one at home with a similar mod iirc and it was very nice indeed, sounding like a much bigger amp at modest levels, though these things depend on system/room/ears of course.

I have a WAD5881, not the Kel84. Are you confusing me with another Stephen/Steve?

[Richard]

Originally Posted by Stephen C

I have a WAD5881, not the Kel84. Are you confusing me with another Stephen/Steve?

Hi Steve, apologies yes I must have read your amp model incorrectly and was thinking of a listening session 10 or 15 years ago with another Steve.

[bob orbell]

Welcome Stephen, it makes a change to have a new member with a sensible name . Bob