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My KT88 Build

Posted: Wed Jun 22, 2022 7:23 am
by javalake
Here is my take on the Blueglow et. al. SE KT88 Amp.
Up and running.
Up and running.
kt88_up_and_running_small.jpeg (181.27 KiB) Viewed 447 times
Rear view.
Rear view.
kt88_chassis_rear_view_small.jpg (188.52 KiB) Viewed 447 times

As you can see it deviates slightly from Mark's design in that I have a separate chassis for the power supply and have used a pair of 872A's instead of the 5AR4. I bread-boarded the 5AR4 and it worked perfectly, I just like the mercury vapour rectifiers better - much more interesting to look at. I also tried a pair of 866A's and a quad, they also worked perfectly - but I'm keeping the 866A's for my next project.

Here is a snap showing the inside of the power chassis.
Power chassis internal.
Power chassis internal.
kt88_power_chassis_internal_small.jpg (199.47 KiB) Viewed 447 times

I'll add a reply to this post with more pics of the signal chassis internals and audio analyzer plots of THD and frequency response.

The amp is everything Mark said it would be, it sounds great, zero hum and it was great fun to build.

Phil Davies.

Re: My KT88 Build

Posted: Wed Jun 22, 2022 7:25 am
by javalake
Here are the other pics...
Signal chassis internal.
Signal chassis internal.
kt88_signal_chassis_internal_small.jpg (195.09 KiB) Viewed 446 times
THD.
THD.
kt88_thd.png (115.87 KiB) Viewed 446 times
Frequency response.
Frequency response.
kt88_frequency_response.png (51.28 KiB) Viewed 446 times