KSTR said:
Ok, I now get about 2.2% THD. So I think we are simulating the same circuit now. What I had done before was to take the liberty of putting a 22 ohm bias resistor between the emitters of the drivers. Unbiased drivers are a source of extra distortion in my experience. Certainly, doing this seems to me to reduce the distortion to around 0.15% when Rbias is about 6k.
traderbam said:
Hi Brian,
I was mainly trying to keep the bias current within guidelines called out by Steve earlier in the thread. I don't remember the exact numbers, but it was something like 20 mA to somewhat above 200 mA. So there was some guesswork involved 🙂.
andy_c said:
My question arose out of a mistake I made rather than one you made. I had added a bias resistor to the drivers to run them in class A. This caused the min distortion Rbias value to rise to about 6k. Incidentally, I find the linearity of the output Z simulation is an order of magnitude better when this is done.
I also found that shorting the CEs of Q9 and Q10 with massive caps made negligible difference to the distortion size. Which suggests the saturation characteristic is not having a significant impact on linearity.
MJL21193 said:
I never got the reason for the exile. This circuit keeps looking like a triple that's best biased at the same old Barny Oliver optimum point.
ostripper said:
Hi, I'd like to see his version too. Here is my version,
but it has glitches in the Zout. I included the .plt file
so you get the plot automatically after the sim runs.
Not sure what I'm doing differently. Anyone care to
comment?
Mike
Hey, there's no magic here 😎
Mike, in your version you run to high a frequency, 10kHz, and this causes the curve to fall apart into two legs when you zoom in (to 0.5Ohms or so). That's what I've shown in another plot, http://www.diyaudio.com/forums/showthread.php?postid=1760326#post1760326
I've used 10Hz, Brian used 1Hz.
Another thing is to discard the start of the waveform, that is, wait until things have settled after the initial start of the sine wave. That's where your glitch comes from, it seems. I simmed 10 cycles, but only the last 2 are used for plotting to avoid that problem.
EDIT: Last thing, please omit the 8R load resistor... although it doesn't change much (only a small and linear error term, as the X-axis term isn't reflecting the proper situation).
I also have glitches in the Zout, but in my case these are simming/plotting artifacts when using .STEP runs. If I change Rbias manually and plot Zout, each at a time, these glitches disappear.
LTspice really is sort of a swiss army knife, some people can build a complete house with it as their only tool, while others will cut themselves in the thumb. On that scale, I think I'm able to open a bottle of wine with it...
- Klaus
Attached: the .asc in question (renamed as .txt). Contains some irrelevant things to0, leftovers from other sims.
Mike, in your version you run to high a frequency, 10kHz, and this causes the curve to fall apart into two legs when you zoom in (to 0.5Ohms or so). That's what I've shown in another plot, http://www.diyaudio.com/forums/showthread.php?postid=1760326#post1760326
I've used 10Hz, Brian used 1Hz.
Another thing is to discard the start of the waveform, that is, wait until things have settled after the initial start of the sine wave. That's where your glitch comes from, it seems. I simmed 10 cycles, but only the last 2 are used for plotting to avoid that problem.
EDIT: Last thing, please omit the 8R load resistor... although it doesn't change much (only a small and linear error term, as the X-axis term isn't reflecting the proper situation).
I also have glitches in the Zout, but in my case these are simming/plotting artifacts when using .STEP runs. If I change Rbias manually and plot Zout, each at a time, these glitches disappear.
LTspice really is sort of a swiss army knife, some people can build a complete house with it as their only tool, while others will cut themselves in the thumb. On that scale, I think I'm able to open a bottle of wine with it...
- Klaus
Attached: the .asc in question (renamed as .txt). Contains some irrelevant things to0, leftovers from other sims.
Funny, the first time I run into this weird thing of some quoting a line that I deleted afterwards...traderbam said:
Great simile, Klaus. LTSpice provides speed, precision and utility. And I still have to figure out what some of those blades are for.
And considering that LTspice is freeware, it's functionality and stability is absolutely breathtaking (speaking of versions III and IV). It took a while to fully realize that -- at work we always used PSpiceAD but since we switched to LTspice, no way back.
- Klaus
A question for Steve Dunlap:
Why did you choose not to bias the drivers into class A? Assuming you didn't - there are several schematics about. Simulations appear to show this reduces distortion.
Why did you choose not to bias the drivers into class A? Assuming you didn't - there are several schematics about. Simulations appear to show this reduces distortion.
scott wurcer said:
You can drop out if you want. I going to. I make a statement that I did build and test many units and give my results then others state flatley that I either did not or that I am incorrect in the results I measured and reported. To me, this seems you are saying I am lying about what I have done or I was to stupid to interpret the test results. I find either conclusion on your part, with no effort to duplicate my work, insulting.
MJL21193 said:
Coming from someone that already called me a "peed off school girl" this is about what I would expect. The depth of your discourse and vocabulary have simply overwhelmed me.
juma said:
When I started this thread I didn't even know I had boards that could be used. Hardly a commercial venture. Some people ask if boards were available. After a friend found boards in my shop I made them available to those that wanted them. I suppose further evidence of my capital nature was my offer to GIVE parts and use of my shop to someone to build and report on the amps.
That offer is now rescinded.
I made the, perhaps erroneous, assumption that anyone attempting to build electronics from a pile of parts would have the intelligence to orient the polarised caps with the polarity of the power supplies. I still think most are. Sorry if you are not, but I doubt you were planing to build one anyway.
One last post.
I will continue to help in any way I can those of you building the amp. Contact me by E-mail. I will not be back here to read or reply to post.
I do find it interesting that the results of the simulations are all over the place. If it is so easy, accurate and strait forward then why don't you all get the same results? That is a rhetorical question. Don't bother.
I also find it interesting that some of the most vocal of you telling me what I was doing wrong never attempted to say how it should be done right. It is very convenient that your work cannot be shared with the forum. It is much easier to claim you are right if you never submit your work for peer review.
I am fairly certain at this point that I will not be offering up any more of my work or input here.
I will continue to help in any way I can those of you building the amp. Contact me by E-mail. I will not be back here to read or reply to post.
I do find it interesting that the results of the simulations are all over the place. If it is so easy, accurate and strait forward then why don't you all get the same results? That is a rhetorical question. Don't bother.
I also find it interesting that some of the most vocal of you telling me what I was doing wrong never attempted to say how it should be done right. It is very convenient that your work cannot be shared with the forum. It is much easier to claim you are right if you never submit your work for peer review.
I am fairly certain at this point that I will not be offering up any more of my work or input here.
Steve Dunlap said:
You don't need to be sorry for me, I learned my way around caps decades ago. I understand that you are having a hard time, but as the publisher of this circuit you ought to feel responsible for its implementation (IMO). And if you find time to read other threads I'm sure you'd be surprised how daring some people are - trying to build stuff that are way beyond their level of knowledge.
My remark is not an attack and you don't have to defend yourself - it's just a safety warning - I'm sure you don't want anyone scar himself by building this amp.
And yes, I'll probably build this (or similar) amp in next 3 months - I can't spend another summer with class A amp in my living room.
Steve,
I would counsel that you stick around for a bit more...
Those who you find irritating do not need to be replied to, and certainly not immediately.
It is a better idea to NOT reply to everyone or everything that pricks you or "pushes a button." Simply reply selectively. Ignore the posts that do not need a response at all.
I think that many have made a sincere effort to simulate (some apparently are building) the amp in an effort to understand the design in some depth. This is a good thing. No matter who says that it doesn't do x,y or z as a result, you do not need to defend it every time. You have already made the same statement a sufficient number of times that as designed the circuit meets the specs you stated.
It seems that the question that those who are "skilled in the art" have is how does it meet the spec? This is not a bad thing as it leads to discussion, insights for others and a general dissemination of information.
If you follow even part of other threads you will see that there are those on here who are contentious, some of them are highly skilled and trained, others not so much - bottom line: it doesn't matter what their attitude is.
The skills in diplomacy and courtesy are not usually taught in academia, nor in industry, so one can not rightly expect them to be displayed to the same extent that engineering chops may be.
No need to pick up your marbles and go away. You have created significant interest, don't let those whose attitudes or approaches are irritating to you effect your experience here, nor your interest in participating. Those who are interested and are appreciative will be the ones who are harmed.
To wit, note that there are far more "hits" than posts, which shows that many read and do not post.
Please continue.
Please simply ignore those things that appear to be personal in nature, deal with the positive. Think positive! 😀
Regards,
_-_-bear
I would counsel that you stick around for a bit more...
Those who you find irritating do not need to be replied to, and certainly not immediately.
It is a better idea to NOT reply to everyone or everything that pricks you or "pushes a button." Simply reply selectively. Ignore the posts that do not need a response at all.
I think that many have made a sincere effort to simulate (some apparently are building) the amp in an effort to understand the design in some depth. This is a good thing. No matter who says that it doesn't do x,y or z as a result, you do not need to defend it every time. You have already made the same statement a sufficient number of times that as designed the circuit meets the specs you stated.
It seems that the question that those who are "skilled in the art" have is how does it meet the spec? This is not a bad thing as it leads to discussion, insights for others and a general dissemination of information.
If you follow even part of other threads you will see that there are those on here who are contentious, some of them are highly skilled and trained, others not so much - bottom line: it doesn't matter what their attitude is.
The skills in diplomacy and courtesy are not usually taught in academia, nor in industry, so one can not rightly expect them to be displayed to the same extent that engineering chops may be.
No need to pick up your marbles and go away. You have created significant interest, don't let those whose attitudes or approaches are irritating to you effect your experience here, nor your interest in participating. Those who are interested and are appreciative will be the ones who are harmed.
To wit, note that there are far more "hits" than posts, which shows that many read and do not post.
Please continue.
Please simply ignore those things that appear to be personal in nature, deal with the positive. Think positive! 😀
Regards,
_-_-bear
It's easier said than done, disregard them, dont pay attention, ignore the post, etc...etc... there are so many ways to kill a cat. I fully agree with Joshua's conclusion...Insulting words have been said in many different ways just like killing a cat and people deny and seem to say to just forget it. Believe i'm not the only person who perceive those being just an observant, how much more for the owner of this thread?
It's a shame, the self righteousness is just above the head of the wise men, no one can teach them for they are pinnacle of all knowledge.
no cheers this time,
mannycc
It's a shame, the self righteousness is just above the head of the wise men, no one can teach them for they are pinnacle of all knowledge.
no cheers this time,
mannycc
While complex, it could just as well be sharing a "new" muffin recipe. While a couple pointers might be okay, when there's too many, the cook might well feel put off.
But it gets even worse, next you have the muffin simulators! Gods yes. EasyBakeSpice!!!
Any blockhead can simulate with it! It's fun! You don't even have to eat the muffin anymore, you can simulate it, and than ask the cook a bunch more questions about why the hell they didn't account for the cocoanut dielectric?
Tact. Discreetion. Self- control. (Don't send the submit reply button when you've been drinking). He offered the forum a present. Consider him your friend. Would you tell your friend you've got questions about your relationship based upon your loyalty simulator?
I do not believe the moderators have an alogrithm at their disposal for these instances, but it makes me wonder why the simulation maniacs couldn't of had their own thread split off from this one where they could set one another's heads on fire with how brilliant, daring, and maniacally theoretical they could be.
Steve's amplifier, based on applied science, knowledge, experience, judgement and WORK is offered up free, gratis for all. Magnanimity-- selflessness. Some people built it. They raved about it. You can bet Steve has listened to it.
I read the entire thread in one sitting, and got more and more sickened by the thoughtless, niggling, stultifyingly hair-splitting idiocy served up as poorly-disguised poster ego foder--whaaaaaaaaaaaaaaaaaa
enough to make glutton sick.
Punk x simulated this, wants to know that. Punk gets uppity, sheesh.
Given Steves circumstances, and the intial intent of what he offered, this thread got way off topic. There's some really good stuff, but no one should be surpised if the op got fed up.
Bear makes some really good points.
I disagree with this one though,
"The skills in diplomacy and courtesy are not usually taught in academia, nor in industry, so one can not rightly expect them to be displayed to the same extent that engineering chops may be."
People here, a public forum, Do need to be diplomatic, and courteous.
This isn't acadamia or industry.
Miss Manners would be very cross...very.........
But it gets even worse, next you have the muffin simulators! Gods yes. EasyBakeSpice!!!
Any blockhead can simulate with it! It's fun! You don't even have to eat the muffin anymore, you can simulate it, and than ask the cook a bunch more questions about why the hell they didn't account for the cocoanut dielectric?
Tact. Discreetion. Self- control. (Don't send the submit reply button when you've been drinking). He offered the forum a present. Consider him your friend. Would you tell your friend you've got questions about your relationship based upon your loyalty simulator?
I do not believe the moderators have an alogrithm at their disposal for these instances, but it makes me wonder why the simulation maniacs couldn't of had their own thread split off from this one where they could set one another's heads on fire with how brilliant, daring, and maniacally theoretical they could be.
Steve's amplifier, based on applied science, knowledge, experience, judgement and WORK is offered up free, gratis for all. Magnanimity-- selflessness. Some people built it. They raved about it. You can bet Steve has listened to it.
I read the entire thread in one sitting, and got more and more sickened by the thoughtless, niggling, stultifyingly hair-splitting idiocy served up as poorly-disguised poster ego foder--whaaaaaaaaaaaaaaaaaa
enough to make glutton sick.
Punk x simulated this, wants to know that. Punk gets uppity, sheesh.
Given Steves circumstances, and the intial intent of what he offered, this thread got way off topic. There's some really good stuff, but no one should be surpised if the op got fed up.
Bear makes some really good points.
I disagree with this one though,
"The skills in diplomacy and courtesy are not usually taught in academia, nor in industry, so one can not rightly expect them to be displayed to the same extent that engineering chops may be."
People here, a public forum, Do need to be diplomatic, and courteous.
This isn't acadamia or industry.
Miss Manners would be very cross...very.........
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