Samuel Jayaraj said:
I agree with thermal coupling of Q1 and Q2. I don't show caps across the front end diode stacks and that is probably why Alex missed them. Since this is a regulated supply with very little ripple, they aren't as much benefit as the caps across the diode strings in the output. Adding them will not hurt of course.
I have no clew what you guys talk about, what so ever
But its nice to see a skilled pro designer "play along", and not getting angry 😎
I would sure like to build this amp, but fear that it takes too much skills, with all those odd things that are suggested
Will there be an optimised design, "ready to go" with no tricks 😕
But its nice to see a skilled pro designer "play along", and not getting angry 😎
I would sure like to build this amp, but fear that it takes too much skills, with all those odd things that are suggested
Will there be an optimised design, "ready to go" with no tricks 😕
jkeny said:
The bias transistors are Q8 and Q11. Q7 and Q10 are the input pair and also contribute 0.6V drop each (1.2V from emitter to emitter) towards the bias. The rest is provided by Q8 and Q11 and the diode string between their bases. Q9 and Q12 are the CCS.
tinitus said:I have no clew what you guys talk about, what so ever
But its nice to see a skilled pro designer "play along", and not getting angry 😎
I would sure like to build this amp, but fear that it takes too much skills, with all those odd things that are suggested
Will there be an optimised design, "ready to go" with no tricks 😕
I find it odd that when I quote your message more shows up than I see in the thread. Why is that?
The design is ready to go now. The adjustments only require a multimeter.
I'm trying to explain what I have done in a way that will help teach the non pros why it was done this way. There is no reason for me to get angry. That would simply put off the ones who are learning.
Well now I have double posted. The first time I received a message that the web site could not be found. Apparently it could. On the re post is when I noticed the quotes were different.
Steve, Im sorry about that
But you are allowed to edit, and quote just the part you want to respond to 😉
Not always the most respectfull to the poster, but mostly make things easier and clearer
But you are allowed to edit, and quote just the part you want to respond to 😉
Not always the most respectfull to the poster, but mostly make things easier and clearer
tinitus said:
I just checked the quote button, I didn't edit anything out. I see that now your post appears the same as in my second post. I did check that before. I'm confused😕 , but I still don't understand why E-mail can take up to 2 days to arrive either.
I edited my post, probably while you responded
Normally we have only a short time allowed fore editing, probably to not cause too much confusion
This time you were just very fast on the bottoms 😀
🙂
Normally we have only a short time allowed fore editing, probably to not cause too much confusion
This time you were just very fast on the bottoms 😀
🙂
Thank you Steve for explaining the biasing part of the circuit & clearing up my misconception!
Alex, so the heatsink that Q7 to Q12 are attached to is not needed (if this is what the yellow square is?) - I wondered how R30 & R31 were attached here anyway as they seemed to be under the heatsink.
You just need the extra pots across R30 & R31 and some way of attaching the diodes to the heatsink ( probably like Steve did on a small pcb). Are there two heatsinks or how are the output trannies heatsinked?
I've only looked at the output stage
Alex, so the heatsink that Q7 to Q12 are attached to is not needed (if this is what the yellow square is?) - I wondered how R30 & R31 were attached here anyway as they seemed to be under the heatsink.
You just need the extra pots across R30 & R31 and some way of attaching the diodes to the heatsink ( probably like Steve did on a small pcb). Are there two heatsinks or how are the output trannies heatsinked?
I've only looked at the output stage
Nice job Alex, I see you also corrected the Zobel connection problem on the last pcb.
The heatsinks on the O/P stage can probably be left off as these TO220 devices are intended to run warm - it helps to swamp any signal induced thermal changes in these devices, I think. Can you remove the heatsink to see the traces underneath.
What software do you use? I'm looking for good/easy circuit design s/w.
Edit: I'm wondering if you can produce a pcb for the output stage only & incorporating the 470uf caps?
The heatsinks on the O/P stage can probably be left off as these TO220 devices are intended to run warm - it helps to swamp any signal induced thermal changes in these devices, I think. Can you remove the heatsink to see the traces underneath.
What software do you use? I'm looking for good/easy circuit design s/w.
Edit: I'm wondering if you can produce a pcb for the output stage only & incorporating the 470uf caps?
I have faced some minor problems into the off set
The amplifier,... the ones i have built.... have worked better having some off set... from 1 to 2.5 volts.
Of course, i use to do repeat mistakes..the fact i have assembled five only means i have made the same mistake five times and could not find the reason.
I have just used an electrolitic condenser into the output and have enjoyed the amplifier a lot... a superior sonics.
I will have, in 10 days, the real factory boards here, and for sure i will not have those minor things i have faced.
I am still listening...enjoying... the amplifier has crispy trebles, nice controled bass...excelent dinamics and very low perceived distortion even when hard used.
regards,
Carlos
The amplifier,... the ones i have built.... have worked better having some off set... from 1 to 2.5 volts.
Of course, i use to do repeat mistakes..the fact i have assembled five only means i have made the same mistake five times and could not find the reason.
I have just used an electrolitic condenser into the output and have enjoyed the amplifier a lot... a superior sonics.
I will have, in 10 days, the real factory boards here, and for sure i will not have those minor things i have faced.
I am still listening...enjoying... the amplifier has crispy trebles, nice controled bass...excelent dinamics and very low perceived distortion even when hard used.
regards,
Carlos
PCB rev 9. Krill 100 w
...... no more PCB for today ....🙂 http://i43.tinypic.com/2qx1e0o.jpg or http://i40.tinypic.com/az99w4.jpg to bee continued tomorow with new ideas .regards alex mm .😀
...... no more PCB for today ....🙂 http://i43.tinypic.com/2qx1e0o.jpg or http://i40.tinypic.com/az99w4.jpg to bee continued tomorow with new ideas .regards alex mm .😀
Good idea, using trannies as diodes mounted underside of pcb - easier/better fix to heatsink.
It would be perfect as an output stage only if there was room for 470uf Caps, maybe if ground trace ran down through the output trace & electro caps were connected where pos/neg come in across + to ground & - to ground?
Carlos, good to hear you're still building - hope blood pressure & circulation are OK & continue to improve? Any noticeable sonic difference between your build with matched devices versus unmatched?
It would be perfect as an output stage only if there was room for 470uf Caps, maybe if ground trace ran down through the output trace & electro caps were connected where pos/neg come in across + to ground & - to ground?
Carlos, good to hear you're still building - hope blood pressure & circulation are OK & continue to improve? Any noticeable sonic difference between your build with matched devices versus unmatched?
If I wanted to use the O/P stage in balanced mode would I just leave out Q7 & Q10 & feed the balanced signal to the common gates of Q8 & Q11? (I have a preamp that I would like to use whose outputs are balanced)
Is there any inherent advantage to balanced mode - better PSRR? BTW what is the PSRR of the Krill?
Is there any inherent advantage to balanced mode - better PSRR? BTW what is the PSRR of the Krill?
Feel better...
I hope you're feeling better Carlos.
You need to take care of yourself as we would miss you if you were gone...
I hope you're feeling better Carlos.
You need to take care of yourself as we would miss you if you were gone...
jkeny said:
First, that would not work. Second, if you drive both sides of the output stage with a balanced signal (I assume you mean the two outputs are 180 deg out of phase), it would turn on both sides. You would get a lot of current flow, but no output signal.
To use the output stage in balanced mode you will need two output stages. One would be driven from each preamp output.
The only drawback to balanced mode, IMO, is the lack of understanding among the public (consumer). A proper balanced amp will always outperform an unbalanced amp. You will get lower distortion and better PSRR. And contrary to the popular myth, a balanced amp will not have a higher output impedance.
I don't know what the PSRR of the Krill is just off the top of my head. Those measurements were made years ago (I have moved three times since then) and I don't know where that data is. I can only tell you that the PSRR is very good. It also depends on the actual unit (design) in question as a number of changes to improve that were made down through the years.
A number of small things have been pointed out concerning differences between the schematic, the stuffing guide and the boards.
R20 on the board is not shown in either the schematic or the stuffing guide. This resistor is current limiting for the LED used as an on indicator. Its value and wattage rating will depend on your supply voltage, the current needed by the LED you use and how bright you want that LED to be.
I had said that there was no place on the board for R60 in the schematic. This is not correct. R60 is labeled R26 on the board. The style pot I used at the time seems to no longer be available. Some lead extending will be necessary to make the new smaller ones fit. Since this location IS there, I would recommend using it for the 50W amps also just as shown in the 100W schematic. I will make these changes and re post the schematics.
There are two C22 caps shown on the board. The small one in the row of 5 caps is not used. Replace it with a jumper.
Q101 and Q102 on the schematic are the same as Q17 and Q18 on the board.
I hope this hasn't caused anyone to much trouble.
I have contacted moderators twice now about updating the older incorrect schematics. I have not yet heard back from them.
R20 on the board is not shown in either the schematic or the stuffing guide. This resistor is current limiting for the LED used as an on indicator. Its value and wattage rating will depend on your supply voltage, the current needed by the LED you use and how bright you want that LED to be.
I had said that there was no place on the board for R60 in the schematic. This is not correct. R60 is labeled R26 on the board. The style pot I used at the time seems to no longer be available. Some lead extending will be necessary to make the new smaller ones fit. Since this location IS there, I would recommend using it for the 50W amps also just as shown in the 100W schematic. I will make these changes and re post the schematics.
There are two C22 caps shown on the board. The small one in the row of 5 caps is not used. Replace it with a jumper.
Q101 and Q102 on the schematic are the same as Q17 and Q18 on the board.
I hope this hasn't caused anyone to much trouble.
I have contacted moderators twice now about updating the older incorrect schematics. I have not yet heard back from them.
Thanks Steve, my misunderstanding of the input trannies on the O/P stage led me to conclude that they worked as phase splitters & so I thought I could just feed my balanced signal as I outlined.
Oh well, guess I'll have to convert to SE to feed the Krill.
Thanks for the corrections re the board/schematic,etc
Oh well, guess I'll have to convert to SE to feed the Krill.
Thanks for the corrections re the board/schematic,etc
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