KRILL an amplifier (still) worth looking at

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Bigun

Bigun

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Joined 2009
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#1
lgreen

Thread 'Krill is complete!'

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

An externally hosted image should be here but it was not working when we last tested it.


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

An externally hosted image should be here but it was not working when we last tested it.


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'm the new 'owner' of this amp and it has been in use for several months now. The pre-amp being my Kondo M7, vinyl source and single large Audio Nirvana 15" speaker.?

I am hoping that I can rekindle some interest in this design. The sounds is good and the design is an interesting one because it exploits what is normally a weakness - the charge storage in the base region of the power output devices - to provide a smoother cross-over at h.f.

Steve Dunlap

Thread 'Krill - The little amp that might...'

This new thread is a split from the thread at:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=132367

I'm doing this to eliminate the 90% or so off-topic posts and to get a better to feel for any interest in this project.

This schematic was drawn by the same program I use for simulations. It simulates very much like it measures in the real world so I am reasonably certain that it is correct. No doubt there will be some problems found that I can correct later.

I both simulated and built this with the parts shown. You may substitute other brands of transistor and it...

Anybody else out there still playing with this amp too ?
 
#3
Try here too:

Steve Dunlap

Thread 'Krill - The Next Generation'

I would like to start this thread off by looking at three different biasing methods. The first is class B, followed by class A and finally my method which has come to be known as the Krill. I will be looking at the voltage across one of the emitter resistors to determine if that transistor is conducting or not. I will be doing this over a number of posts to keep the size of any one post reasonable.

I don’t expect to change certain minds with this, but those of you that believed me earlier may find it interesting. As many of you know, I can no longer run tests in the physical realm, so...



I had kept some notes from others on their impressions of the sound:

http://www.parttimeprojects.com/audio/diy/Krill.php
"And this amp is not at all bass-shy, it has no problem putting out some deep base. The amp is smooth and mellow, the highs are not as detailed or crisp as the DX or gainclones so even with speakers that have sensitive tweeters the Krill does not sound shrill. I'd characterize the sound as more like a relaxed tube sound from the midrange up, and powerful solid state below the midrange. If you are the kind of person who thinks digital audio is bright, edgy and fatiguing, you should think about this amplifier. "

and same author here:http://www.diyaudio.com/forums/solid-state/159954-krill-complete.html#post2061736

Igreen: "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."

http://www.diyhifi.org/forums/viewtopic.php?f=5&t=1748&start=60
Charles Hansen: "The odd thing is that (unlike just about every other output stage around), there is nothing tying the two driver transistors together. Normally there would be a resistor from emitter-to-emitter (in a good design that keeps the drivers in class A) or resistors that tie to the output stage (in a less-good design that lets the drivers go into class B along with the outputs). I've listened to differering resistor values at that location, and all I can say is that using no resistor there made for quite a strong (but pleasant!) sonic signature."

c2cthomas: "I'm currently building up 2 of Steve's 50W monoblocks and have seen and listened to his "big" (300W) amp driving his Magneplanar's. So I can confirm that in fact this amp does exist - and so does Steve. The amp works and sound great "

Carlos: "About the Krill...yes... the Steve Dunlap one...it beats my amplifiers..the difference is not so big..but it beats."
"I use to play the Krill and the Dx Standard in my home and to offer a candy to the one discover the one is the Krill..... after some try and error people finally can do that...Krill is sligtly better, when it's electronic performance is MUCH better than my amplifier..but sonically, to achieve some advantage is something very hard."

Romeo Tiu: "Krill, you have to make them in order to hear it for yourself. I like it as it is that's why I build them 55 and 100 W, the tone of the piano sounds really good and lifelike, high is there and the bass is also there, the only thing it lacks is some gain compare to AKSA/TGM.."
 

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#6
In any other context starving the driver transistors of current would rightly be considered clueless and stupid. Those drivers are just conducting the base currents of the output devices and that will have dire consequences for linearity particularly at higher frequencies where cross-conduction will be exacerbated.

That biasing circuit is completely nonsensical, and added to all of this mess, the output stage is run open loop to boot! Crap like this provides incontrovertible evidence of just how non-discerning, tin-eared or just plain freaking deaf the golden-eared audiophile brigade really is in reality, outside of it's alternately constructed delusional universe.
 
#7
I was kind of "missing" the driver emitter-emitter resistor myself, but I ever so often post nonpleasing comments that I chose to refrain this time.

It would, however, seem that we think more or less alike here.

R
 
#8
It is the cross-conduction, at a non-destructive level, that provides this design with a unique way of operating and at h.f. the harmonics are outside of our audible range. Given all the sins of this design, it sounds very good and that makes it worthy of our attention - you don't know until you try it.
 
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#11
I didn't make my own, I was lucky to benefit from the generosity of "Igreen" but sometime ago I did make a pcb design and I had a batch of boards made at a board house. I have not built these boards up to prove them. But it's my own interpretation and whilst it has the Krill output stage I chose an open loop voltage amplifier with simple one-transistor regulator as my design so that the entire amplifier is devoid of any feedback (other than degeneration perhaps) and this means it isn't fully Steven D's design. It's in a thread called TGM11.

Perhaps there are some Gerber files in one of the original Krill threads that I posted earlier.
 
#12
Bigun said:
It is the cross-conduction, at a non-destructive level, that provides this design with a unique way of operating and at h.f. the harmonics are outside of our audible range. Given all the sins of this design, it sounds very good and that makes it worthy of our attention - you don't know until you try it.
Click to expand...

If the unnecessarily excessive distortion due to cross-conduction is, as you are trying to argue, outside of audibility, then how does it impart this allegedly wonderful sonic signature?

I guess logic is of no value or consequence in this argument.

I know what crossover distortion sounds like and do not have to try it. Crossover distortion is the most intrusive and objectionable distortion mechanism of an otherwise linear solidstate amplifier and minimising it has been the #1 engineering objective since the dawn of class B and class AB linear audio amplification.

But here in the tin-eared audiophile land alternate universe, we are presented a design bodged to perform exceptionally badly in the most objectionable type of distortion mechanism and it is lauded for its sonic greatness.
 
#14
Krill certainly did spur some discussion back in the days when Dunlap introduced it due to its unconventional biasing of the output stage without providing any conventional means of discharging the base charge of the transistors around the output stage, on the surface it appears to be logically incorrect engineering, however I am still curious how the output stage actually behaves and its impact on cross-conduction, but so far I can't recall anyone having provided any oscilloscope snapshots and/or distortion measurements laying the myth about krill finally to rest.
I guess I have to build one some day.
@Bigun do you intend to do some measurements?
 
#16
I have found this.
Who knows if it is correct?
 

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#19
Wise words indeed - from what I've read, there aren't many Class AB amplifiers that can survive testing with a 20kHz square wave into a slightly capacitive load when looking for strange behaviours.

My TGM8 amplifier cross-conduction was fairly well characterized by measuring the current draw with h.f. sine waves.
 
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