Hi all - here are some pics of my KT120 monoblocks at partially built stage. I'm in New Zealand, so I ordered the 230v Thermionics transformers and chokes. Any questions, ask away.
Here are a few more pics - 1 unfinished and 3 in my system. Stephe, you'll see my Decware SE84UFO2.1 amp (bottom shelf) which I waited 2.5 years for, and which I'm about to sell 😉. The monoblocks only have about 10 hours on them but I already prefer them to the Decware. I started running them biased at 70ma and have gradually increased to 90ma with no sign of overheating. Is it quite obvious when they overheat?
My speakers are about 96db efficient so the Decware drove them quite well, but the monoblocks don't show any stress at louder volumes, and the bass is better controlled.
Thanks for all your efforts, info, and honesty Stephe 😉
Yes it will be very obvious in a darkened room, watch the crease area of the plate under the side getter, at 90 degrees to the part of the plate that has holes in it. That's where the heat is concentraited.
I am trialling a couple of USB fans which seem to be helping - they are silent, and I guess extra airflow over the tubes and tranformers can't do any harm. I'm up to 95ma with no apparent overheating.
In order to replace the KT120's with EL34's or 6550's (leftovers from my Willsenton R8 days), do I need to do anything other than change the bias to the appropriate setting? And how much influence on the sound do the driver and rectifier tubes have? Is it worth trying alternatives?
The resistor will have 0.6W across it so should be OK at 1W for temp use but for long term reliability 2W would be safer. And 5% resistors are OK, I would just try to get them as close to 10ohms as possible.
Here are a few more pics - 1 unfinished and 3 in my system. Stephe, you'll see my Decware SE84UFO2.1 amp (bottom shelf) which I waited 2.5 years for, and which I'm about to sell 😉. The monoblocks only have about 10 hours on them but I already prefer them to the Decware. I started running them biased at 70ma and have gradually increased to 90ma with no sign of overheating. Is it quite obvious when they overheat?
My speakers are about 96db efficient so the Decware drove them quite well, but the monoblocks don't show any stress at louder volumes, and the bass is better controlled.
Thanks for all your efforts, info, and honesty Stephe 😉
Looking so good!!!!!