Maybe not bad ,but different. Now that I have both in the house
and listen everyday I must conclude that I like to "crank" up the
Rock in the bootstrapped room, but for listening to classical
me and my daughter both prefer the Self amp w/css.
So I have 2 types of amps that are preferred for 2 different
tasks. The bootstrap actually gives the vas active loading
on it's non-active (normally CCS loaded)side.
After much simulation I'm about to have the solution to
the current mirror issue and the bootstrap/CCS issue
combined using a CM'ed VAS(like sysmasym). I've been able to get LTP currents
equal to a microamp (for the good highs/sound stage)and
the VAS (what we are really listening to)to slew perfectly
negative and positive (unlike a CCS ,as said in self book)
OS
We are 180 millions Pavel... what an emergent market
This one here is "the market"
This state i leave is the smallest in my country and have more population than your entire country (8 to 9 million i suppose is more than your country population)... this is a big market for cars... and people do all sacrifices to have a car here... this is status here...people prefere not to have confort inside house to buy a good car (this is a shame!)
Brazil área is bigger than Australia.
But really... to talk frankly.... i do not think we are emerging country...i think we are submerging... big troubles here... employement is awfull...also education...also not safe.
regards,
Carlos
This one here is "the market"
This state i leave is the smallest in my country and have more population than your entire country (8 to 9 million i suppose is more than your country population)... this is a big market for cars... and people do all sacrifices to have a car here... this is status here...people prefere not to have confort inside house to buy a good car (this is a shame!)
Brazil área is bigger than Australia.
But really... to talk frankly.... i do not think we are emerging country...i think we are submerging... big troubles here... employement is awfull...also education...also not safe.
regards,
Carlos
Ahahahaha....i can't remember the name.
not moonshine!..... ahhh!.... it is Ethanol!!!
But i still think US folks use another name.
Carlos
............................
Enjoy my new car:
http://www.youtube.com/watch?v=qgUCOb4nZCg
not moonshine!..... ahhh!.... it is Ethanol!!!
But i still think US folks use another name.
Carlos
............................
Enjoy my new car:
http://www.youtube.com/watch?v=qgUCOb4nZCg
CCS vs. Bootstrap
Carlos.
This topic is about Current Mirrors and not mainly about Current Sources
and posting Our Pictures of CARS ...
You should know the difference between a mirror and a source
What you have mixed up, is the use of CCS. CCS is not Mirror.
That attachment from Precision is one typical LED CCS, constant current source.
And yet, you say prefer Bootstrap.
So, if believing your own words, DX Precision is not the good sound amplifier
but the old AKSA/DX-Amp is the one that we must have and listen to.
And this older uses Bootstrapping.
I wont go much into bootstrap vs. ccs here.
Or using resistor biased vs. ccs biased long tailed pair, LTP.
I have stated my opinion in other topics:
That in fact many times the sound of bootstrap/resistor biased is prefered
and that ccs is not superior to use of the good old bootstrap.
--------------------------------------------
I use bootstrap sometimes. It is simple, no added transistors. And it is good!
Here is my latest circuit SCHEMATIC suggested, where I use BOOTSTRAP instead of active bias:
Improved Diamond Buffer Design
http://www.diyaudio.com/forums/showthread.php?postid=1660361#post1660361
As can be seen in my attachment: C2, C5 = bootstrap
.. sorry I do not post some images of cars .. not here
destroyer X said:
Carlos.
This topic is about Current Mirrors and not mainly about Current Sources
and posting Our Pictures of CARS ...
You should know the difference between a mirror and a source
What you have mixed up, is the use of CCS. CCS is not Mirror.
That attachment from Precision is one typical LED CCS, constant current source.
And yet, you say prefer Bootstrap.
So, if believing your own words, DX Precision is not the good sound amplifier
but the old AKSA/DX-Amp is the one that we must have and listen to.
And this older uses Bootstrapping.
I wont go much into bootstrap vs. ccs here.
Or using resistor biased vs. ccs biased long tailed pair, LTP.
I have stated my opinion in other topics:
That in fact many times the sound of bootstrap/resistor biased is prefered
and that ccs is not superior to use of the good old bootstrap.
--------------------------------------------
I use bootstrap sometimes. It is simple, no added transistors. And it is good!
Here is my latest circuit SCHEMATIC suggested, where I use BOOTSTRAP
instead of active bias:Improved Diamond Buffer Design
http://www.diyaudio.com/forums/showthread.php?postid=1660361#post1660361
As can be seen in my attachment: C2, C5 = bootstrap
.. sorry I do not post some images of cars .. not here
Attachments
Hello stinius.
I can only give my conclusion, after testing 4-5 different mirrors in simulation.
That mirror in my attachment should be great.
The good thing is, it only needs 3 Transistors.
For DC precision current there are more complex mirrors.
This one is for audio signals = AC Current
I have drawn one for positive and one version for negative.
The exact value of resistors for absolute optimal performance will be dependent on the actual current level and the circuit.
I do not know if there is some rule of the thumb for deciding on the resistor values.
For smaller currents like 0.5-2 mA, 2k2 will be alright for R2 and R5, I think.
One can try with values between 1k5-4k7.
For those emitter resistors 100-330 Ohm will will work very well.
100 Ohm is never wrong.
I can only give my conclusion, after testing 4-5 different mirrors in simulation.
That mirror in my attachment should be great.
The good thing is, it only needs 3 Transistors.
For DC precision current there are more complex mirrors.
This one is for audio signals = AC Current
I have drawn one for positive and one version for negative.
The exact value of resistors for absolute optimal performance will be dependent on the actual current level and the circuit.
I do not know if there is some rule of the thumb for deciding on the resistor values.
For smaller currents like 0.5-2 mA, 2k2 will be alright for R2 and R5, I think.
One can try with values between 1k5-4k7.
For those emitter resistors 100-330 Ohm will will work very well.
100 Ohm is never wrong.
Attachments
CM Discussion
I believe that the attached from AKSA sums it up very well :
This is the eternal squabble between the two camps; math/measure v. golden ear, left v. right brain.
Neither side is interested in the others arguments; each thinks the other side is stupid, belief ridden, unobjective, rigid, inflexible, etc, the list goes on.
During these furious debates there is a large number of potential customers out there wanting a truly musical amplifier, willing to pay money, and enjoy their music.21193 showed there was no THD difference between the diode trick on a CM and the short; yet, we can hear it. This should ring alarm bells.... but then, being uncomfortable with something which cannot be objectively explained is patently not the way the math/measure approach works. More research required."
I am awfully glad that Ostripper doesn't have his feet firmly stuck in either camp, and is continuing to use not just simulation, but then construct the designs and post his findings.
SandyK
I believe that the attached from AKSA sums it up very well :
This is the eternal squabble between the two camps; math/measure v. golden ear, left v. right brain.
Neither side is interested in the others arguments; each thinks the other side is stupid, belief ridden, unobjective, rigid, inflexible, etc, the list goes on.
During these furious debates there is a large number of potential customers out there wanting a truly musical amplifier, willing to pay money, and enjoy their music.21193 showed there was no THD difference between the diode trick on a CM and the short; yet, we can hear it. This should ring alarm bells.... but then, being uncomfortable with something which cannot be objectively explained is patently not the way the math/measure approach works. More research required."
I am awfully glad that Ostripper doesn't have his feet firmly stuck in either camp, and is continuing to use not just simulation, but then construct the designs and post his findings.
SandyK
If it wasn't for math and measurements and all good amplifier designers
that has created amplifiers from those data in the past decades
audio would not be where it is today.
I agree there is much research need to be done about how we perceive sounds.
I have lately changed my view very much on THD figures.
It is one value that can be very misleading and absoute no certain guarantee for good sound.
We all should be grateful for anyone using any method to give us more information.
There is never any contradiction between science, measure and a good experienced sound.
What we need to find out more about is how they are related.
There are always people that will try to see us as being 2 sides that are at war.
When in fact we are all in the same boat because we have this common interest.
If there is good sound it can be explained in a logical and verifiable manner.
There is no magic involved. Only physics and physiology.
This we can agree on. Can't we?
Regards
Lineup
that has created amplifiers from those data in the past decades
audio would not be where it is today.
I agree there is much research need to be done about how we perceive sounds.
I have lately changed my view very much on THD figures.
It is one value that can be very misleading and absoute no certain guarantee for good sound.
We all should be grateful for anyone using any method to give us more information.
There is never any contradiction between science, measure and a good experienced sound.
What we need to find out more about is how they are related.
There are always people that will try to see us as being 2 sides that are at war.
When in fact we are all in the same boat because we have this common interest.
If there is good sound it can be explained in a logical and verifiable manner.
There is no magic involved. Only physics and physiology.
This we can agree on. Can't we?
Regards
Lineup
Yes, Lineup,
I largely agree.
You hit the nail on the head. The word is physiology.
When does anyone talk about it, the work of the acousticians who have painstakingly mapped the human ear response to sound - and to music - much of this information has been exploited in digital compression codecs, MP3 being the obvious example. A great deal of large sample listening was done to achieve this, and the results are all around us, regardless of how we feel about Ipods.
THD would be fine for purely objective measurement (and as a measure of linearity), but the effect of music on the human animal is physiological, with all the subjectivity this implies. Perhaps more mention should be made of research in this area, WHY we perceive the way we do, and WHY little things like CM technology is so audibly apparent despite almost immeasurable THD correlation.
In closing, will we ever get a metric of excellence playing say Rachmaninov's 'Danse Macabre' (irony intended). At this stage, I believe not, and until then we are forced to use test tones, which are not the same as music because they do not have the same effect on the human animal.
Or, we can use large samples of human listeners (or cats, like JLH once commented!), and face the controversy square on. I think SandyK knows exactly how I feel about this..... and I too applaud OStripper, gudonya, mate, you are really moving fast!
Hugh
I largely agree.
You hit the nail on the head. The word is physiology.
When does anyone talk about it, the work of the acousticians who have painstakingly mapped the human ear response to sound - and to music - much of this information has been exploited in digital compression codecs, MP3 being the obvious example. A great deal of large sample listening was done to achieve this, and the results are all around us, regardless of how we feel about Ipods.
THD would be fine for purely objective measurement (and as a measure of linearity), but the effect of music on the human animal is physiological, with all the subjectivity this implies. Perhaps more mention should be made of research in this area, WHY we perceive the way we do, and WHY little things like CM technology is so audibly apparent despite almost immeasurable THD correlation.
In closing, will we ever get a metric of excellence playing say Rachmaninov's 'Danse Macabre' (irony intended). At this stage, I believe not, and until then we are forced to use test tones, which are not the same as music because they do not have the same effect on the human animal.
Or, we can use large samples of human listeners (or cats, like JLH once commented!), and face the controversy square on. I think SandyK knows exactly how I feel about this..... and I too applaud OStripper, gudonya, mate, you are really moving fast!
Hugh
Thank you for the answers "lineup" and "sandyK"
I’m not sure that the conclusion is right.
Maybe it’s possible to build a CM that is both “correct” and “musical”
I don’t think the mirror with the resistor is the thing.
Maybe the resistor should be replaced with an active circuit that sinks the current?
I’m not sure that the conclusion is right.
Maybe it’s possible to build a CM that is both “correct” and “musical”
I don’t think the mirror with the resistor is the thing.
Maybe the resistor should be replaced with an active circuit that sinks the current?
Stinius,
If you take steps to ensure the LTP is in balance at the base bias level, you can use a simple current sink/source set to [one half LTP stage current - VAS base bias current] on one leg, connected to the VAS, while the other is routed direct to rail.
This will work very well, give identical transconductance to a CM LTP, and has been used by JLH IIRC.
Can't vouch for the sonics though, suspect it would be fine.
Hugh
If you take steps to ensure the LTP is in balance at the base bias level, you can use a simple current sink/source set to [one half LTP stage current - VAS base bias current] on one leg, connected to the VAS, while the other is routed direct to rail.
This will work very well, give identical transconductance to a CM LTP, and has been used by JLH IIRC.
Can't vouch for the sonics though, suspect it would be fine.
Hugh
AKSA said:
Hello Hugh
THD measurements are quite all done in a static way.
But it is far from a living musical signal with it's complex dynamics interactions between all fundamental and harmonics and their signal phases interactions, including very low level musical signal..
Doing dynamic measurements of very low and high output signal level THD and IM, phase and freq. resp. etc... would be much better. I mean doing measurements of a musical signal on few representatives loud-speakers to a have real life load, and using some digital analysis of the music signal by making a map of the music signal input by making dynamic THD and IM, freq. resp. measurements and dynamic phases correlations and keep them in the computer ram memories and doing same at the amp output to compared the in and out dynamic signal, so you see the dynamic behaviour or the amp by analysing the comparative results, it would give a kind of global and details map of the amp behaviour with a musical signal, to see, at least, a live portrait of all of those measurements. But we would need a very fast computer and measurements and analysis and data aquisitions equipments and the software to do the job, so the practical implementation could need lot of maths and tech works.
But it would still far from human physiological and subjective results of a good listening session but at least we would have better measurements.
Bye
Gaetan
I think I stuck my foot in "poop"... I have CM problems
. When I use one in a VAS it becomes non-linear unless I raise
the idle current to 15-18ma on a mje350/340 "symasym" type
topology. I simmed both my new one and the symasym to
see where I might of messed up.
One good thing , all this frustration has allowed me to
optimize my first amp, even acheiving near perfect balance
in its CM (.01mA).
I have all the materials to start my mirrored VAS amp,
but I'm scared to commit as long as these problems still
exist.
PS.. glad to see you here Hugh...
OS
