Krill is complete!

[lgreen]

Well it took a while but my Krill is finally complete.



With a little help from member PH104, and in turn Steve Dunlap, the Krill is up and running.



The solution to the issues I was having (bias/ osciallation) were to make a few changes. First, to mount the driver transistors to the main heatsink. Also, a few resistors were added and heatsinks were installed on all the big transistors still on the board.



I will let PH104/ Steve comment on what was done for what purpose.

I put in a dual 7 segment LED display driven by a voltage regulator from the unused secondary windings. I didn't know what text to use so I just hardwired it to say "On". I attached a front panel from FrontPanelExpress to a chassis from an old Harmon Kardon AV receiver, using the existing speaker outputs (a mistake) but installing new RCA inputs.

The Krill's sound is kind of unique. It sounds like a bigclass A amp in the Bass, deep and powerful. The treble however is more relaxed and liquid. Its not detailed and sharp like a Gainclone or DX. Its like having tubes on top and SS on bottom. Its easy to listen to the amp for hours without any fatigue. I can see why DX/ Carlos liked it so much, it easily can grow on you. I even used it to temporarily drive a pair of Infinity Kappa 7's that I am restoring, and it handled the notoriously tough impedance without problem.

There is a slight turn on pop, and the amp easily does 100 WPC/ 8 ohms. Its square wave response is great and it is stable. It plays for about 10 seconds after you turn it off. The heatsinks are about 40C after 1 hour. There is only a slight buzz at the tweeters barely audible from 1 foot away with no input. DC offset starts at about 74 mV and goes down after an hour to < 20 mV.

And best of all this project showed me that people here can actually cooperate with each other rather than slinging mud. PH104 and Steve jumped in despite busy schedules and personal commitments and helped get this thing working. They did this not because they had to but because they are nice people and wanted to assist, they showed me that there are still a few good people here on this forum. I think people's biggest fear about building amplifers they don't really understand is that they will get stuck and have no one to turn to. Well this happened to me and I'm glad for the help, so thanks guys for turning the boat anchor into an amp.

[Rob_S]

Nice build and comments. Good to see some builds happening, just makes me want to start my build, just need to save some more money for parts!

Look forward to Phil and Steve's comments on the changes

Congrats
Rob

[AKSA]

Lgreen,

Congratulations, deeply impressed. I agree with your comments on slinging mud. I have had wonderful collaborations with a number of people here, and it's a big plus for the forum.

Interesting comments on the sound. Jury is still out on whether it actually switches or not, I guess, but there can be no doubt it sounds good and that is what it's all about....

Hugh

[KLe]

Excellent Guys

So now are we ready to look at the 200 & 500 watt version?

Also, can the 100 watt version be converted into a 200 watt version?

cha, cha, cha

[c2cthomas]

Outstanding Build LGreen!

Thanks for the tip about using the existing connectors on your HK chassis because I have an HK chassis that I'll be using to case my 50W amps with. That tip will save me a bit of grief when I get around to finishing up!!! Now that wife is over her health problems and the family situation with granddaughter etc. are in hand I'm hoping to find some building time soon.

BTW - in your photo's I spy a small PS in the right side front corner of your unit and am wondering if that is being used for your front panel display and lights or if you are running some other things such as switch on relays with it?

I enjoyed reading your listening review - very informative - Thanks!!!

[PH104]

Looks great lgreen! Glad I could help out.

KLe -- You should be able to get 200W from the 100W version with few changes. I've only modified the output stage. The output shown in post 174 of the 100W Krill builders thread shows one way to do it:

Krill construction thread - 100W version

I mounted Q7/8/10 and 11 to the main heat sink which also helps with bias stability. That leaves more room on the board for heat sinks on the current source transistors Q9 and 12. I've used 4 pairs of output transistors with the Krill boards but Steve can address this better and also the changes to the voltage gain stage.

[jkeny]

Ah, this is the aspect of the forum that makes it worthwhile - build it, evaluate it, report on it - wonderful Lgreen. Great build - I like using re-furbed cases but the one I attempted caused me endless grief - still waiting to be completed.

Nice report on the sound - what you describe is the sort of relaxed sound that is the goal of many here, who cares if it's switching or not. Well done on the build & well done to all who helped. Well done Steve on the concept, it would be great to hear about the evolution of this circuit in time.

[Steve Dunlap]

Hi lgreen,

After the problems you had, I'm glad it is complete and you like the sound. I wish more of the people that have built my amp would comment here. Several have E-mailed me saying they like the amp, but didn't want to post here because of the controversy surrounding the design. Thank you for being willing to share your listening impressions.

It may be time to start the evolution thread. I will address specific questions about any changes anyone would like to make in that thread.

[jkeny]

Excellent Steve!

[Spiny]

Welcome to the Krill owners club

My ( much lower power ) version sounds good as you describe.

Nice case and build

Alan