Krill - The little amp that might...

[east electronics]

well ...

Sakis,
I'm sure Steve will answer this but I don't believe you have read the thread carefully - all Steve's schematics shown so far have been from working circuits and I'm sure this is from that stable also.

In fact there were times when some simulations of his first schematics didn't show the real operation of those circuits but the simulation s/w proved to be at fault in all cases.

So I don't think this new 200W schematic should be ignored even if it does contain subtleties that are difficult to understand - this is DIY audio after all & a forum for learning!

Edit: Tinitus posted while I was writing & said it much more succinctly !

this is not personal ...has absolutelly nothing to do with steve .... and also with so many other nice people that have been working arround the thread and related circuits .......

this come in to my mind given the complexity of the amplifier .....

( for example ....alex mm designed some pcb for carlos and also for this paricular amplifier ...if you ask various forum members you will get various opinion about the pcb..... In real life alex mm pcb to my opinion has 10 very good things and another ten that i would do diferent way ......probably other forum members might have similar opinion ..... dont you think that this applys also to steves amp ???? i am not questioning the design i am just wondering if the design is ready to go public )

 

[jkeny]

Sakis, I know it's not personal - you're just expressing your opinion - that's also what the forum is about

If you see areas for improvement on Alex's pcb then please let them be known - collaborative design is often the secret to good implementation. "The wisdom of Crowds" perhaps applies (I know this isn't what the term means but I thought I'd just bend it's definition to my needs).

 

[KLe]

Sakis, 😕 🙁 ... (John, you are a fast poster🙂 )

 

[troystg]

Keep in mind the schematics Steve has posted have had lots of issues DRAWING WISE that have been slowly found and fixed by helpful members. He is continuously redrawing the schematics to get them to the "correct" layout.

However, ALL of the designs offered were from proven designs and worked.

I wouldn't expect anything different here.

 

[Steve Dunlap]

Re: Output stage offset adjustment

Steve,

In post #288 you introduced R32 & R33 for the adjustment of offset in the output stage of the 100w amp. In post #370 you described how to fit these extra trim pots on the underside of the boards you supply.

How critical is it that these parts are fitted if matched transistors are used? How much offset could be expected if the trimpots are omitted? I ask this since the parts may not be very accessible if they are mounted under the board.

I am also wondering why you have chosen not to use this method for adjustment of output stage offset in the 50w amp.

Thanks
Dave

There were two reasons I left the trim pots off the 50W amp. One was my desire to start with the simplest circuit for the DIY crowd. The other IS because fitting these pots to the bottom of the board is somewhat difficult and will leave them difficult to adjust. The adjustment can be made easier if you leave access to the bottom of the board when you build the case.

Originally, I used these trimmers only in the higher power amps, but they serve the same purpose in the lower power amps.

If closely matched transistors are used, the offset will not be an issue. The offset is adjusted with the trim pot in the VGA. The addition of the trimmers in the output stage allows more precise adjustment of both the VGA and the output stage. This results in lower distortion.

 

[Steve Dunlap]

Re: i feel like a kill joy

but i think that the 200w is far too sophisticated to be published or to debugged out in a thread ....

something is telling me that a lots of bits and bytes to be resolved and further analysis is to be made before go public

been involved in the past in designs that worked in simulators but practice is a hell of a diferent thing and real life tests prooved that design was poor .....

at the particular design i was simply a victim of the designer who simply through a schematic on the internet that looked attractive and simple but had alot of problems ....

i hope this is not the case here .....

please forgive me there is nothing personal here .....that is just an opinion ....

The 200W amp is simply a scaled up version of the 100W amp. The 50W is a scaled down version. Schematically, they are all the same with the exception of some resistor value changes to keep diode currents within design parameters as supply voltages are changed. The other changes are the power supply and the number of outputs.

I have shown different methods for adjusting the DC offset both because they all work and to illustrate the fact that there is more than one way it can be done.

Everything I post here will and does work. The 200W amp has been used both in home and professionally for about 20 years. It may present a more complex build for the novice, but it is a proven design.

 

[Steve Dunlap]

Keep in mind the schematics Steve has posted have had lots of issues DRAWING WISE that have been slowly found and fixed by helpful members. He is continuously redrawing the schematics to get them to the "correct" layout.

However, ALL of the designs offered were from proven designs and worked.

I wouldn't expect anything different here.

Yes, I have been a little sloppy with the drawings. It would have been much easier if I could find the files from when the original work was done. I only have paper copies. Re drawing is a slow and tedious effort on my part. Drawing programs are all mouse driven. I have to push the mouse around with my fist (I can't open my hands anymore) and try to click by hitting it with my fist. This makes for both alot of errors and frustration. When I get frustrated I fail to catch a lot of these errors.

I am sorry if this has caused problems for anyone here.

 

[troystg]

To be clear, my comment was not a complaint.

It was to explain that we must be patient and not expect perfection the first time.

 

[Steve Dunlap]

No opinions on the servo yet? Once we discuss that I will move on to improvements in the power supply. Remember, this design started over 25 years ago. I have made improvements through the years, but these do not make the original design invalid. Many people still listen to the original amps and are very satisfied still when comparing them to new high end gear.

 

[Steve Dunlap]

To be clear, my comment was not a complaint.

It was to explain that we must be patient and not expect perfection the first time.

I did not take it as a complaint. I took it as something of a defense and I appreciate it. Any one not following the thread from the beginning might not know why my work can be so poor. I was simply offering an explanation to them.

 

[jaycee]

Just a thought Steve, I am wondering if you have ever tried a graphics tablet? I'm assuming that you can at least extend a single finger, and figured that a touch pad of some kind might work better for you.

I've re-drawn the 100W amplifier already. I'd be happy to redraw the others if you wish.

 

[Steve Dunlap]

Just a thought Steve, I am wondering if you have ever tried a graphics tablet? I'm assuming that you can at least extend a single finger, and figured that a touch pad of some kind might work better for you.

I've re-drawn the 100W amplifier already. I'd be happy to redraw the others if you wish.

Not even one finger. Touch pads don't respond well to fists. I also have a lot of muscle control issues which make my arm movements, and hence my fist, even more clumsy.

You are welcome to re draw them. I have no trouble following them, but I already know what they are doing. That is one of the reasons I miss so many small errors. In my mind, the circuit is correct. It just doesn't always translate to the screen correctly.

One of the reasons I have not done a circuit board to go with this (I have done circuit boards, just not new ones) is the difficulty drawing. Another reason is circuit board layout seems to be even more personal to some people than the choice of tubes or solid state. No matter what I present, many people will not like it.

 

[c2cthomas]

Hi Kids, ('cause I'm older than just about anyone hanging around here - including Steve)

I took the liberty of doing a redraw of the component placement guide for the 50 watt monoblock Krill. Steve has looked it over before and is ok with the layout as is. Questions, comments, small unmarked bills, appreciated. I will go to work on the 100 watt version next and am currently working on a Bill of Materials (BOM) (parts list) in MS Excel that I should have ready to go in a day or two.


BTW - this was uploaded in .gif format. If you click on the image and then select to save it do so in .gif format and you can zoom in for details.

 

[Samuel Jayaraj]

Steve, especially considering your situation, I just want to express my appreciation and gratitude for all your efforts thus far and all that you intend for the DIY community. With not even a finger, how do you manage to type so much? And that too with such prompt replies?

Hats off to you, Steve!!!

 

[c2cthomas]

With not even a finger, how do you manage to type so much? And that too with such prompt replies?

Steve uses speech recognition software for most of the typing stuff. I would too but I haven't found one that will automatically edit out the xxxxing swear words. Hey - I was in the Navy for six years - what more do I need to say?

 

[Variac]

A big trackball has the advantage that trying to click the button doesn't move the cursor. Might be better, I can roll the ball with my fist!😉

 

[DavidK]

50w stuffing guide

Hello c2cthomas,

Thanks for your new stuffing guide for the 50w amp it will be a great help to those using Steve's layout.

I notice that there are 2 resisitors labeled R28, one large 5W above C14 and another smaller one overlapping R1 near the input. I assume this is an error?

Best wishes
Dave

 

[c2cthomas]

Re: 50w stuffing guide

Hello c2cthomas,

I notice that there are 2 resisitors labeled R28, one large 5W above C14 and another smaller one overlapping R1 near the input. I assume this is an error?

Best wishes
Dave

Thanks for the feedback Dave - good catch. I shall need to consult with the master and make necessary corrections. This problem started out by correcting for 2 resistors labeled R20. Steve will put me right - no doubt.

 

[Steve Dunlap]

A big trackball has the advantage that trying to click the button doesn't move the cursor. Might be better, I can roll the ball with my fist!😉

I tried a trackball, but didn't like it. Too old to change everything I guess.

 

[Steve Dunlap]

Re: 50w stuffing guide

Hello c2cthomas,

Thanks for your new stuffing guide for the 50w amp it will be a great help to those using Steve's layout.

I notice that there are 2 resisitors labeled R28, one large 5W above C14 and another smaller one overlapping R1 near the input. I assume this is an error?

Best wishes
Dave

The small R28 near the input is not on the schematic and is not used for these amps. R28 and the row of holes, 1 through 8, were placed there to allow the use of a discrete op amp for crossover use or phase inversion.