I can live with 6 weeks.........
We lived with over 1-1/2 years waiting for you to "tone down your approach".
My reasoning:
It seems simple enough to build low-level circuits, that measure and sound well without GFB. My customers seem to agree.
A power amp is a different beast. Like John, if I stick to making small Class A amps.....60 W or so, they sound better to me and my customers without GFB. So that is what I do.
Call me lazy........call me stupid........call me anything..........I would rather not have to mess with GFB. I do not care for the sound, nor do my customers care for the sound, so I can get away with being lazy/stupid/whatever.
My customers especially do not like the sound that comes with so-called "current feedback" (Let's not argue the semantics of that again, ok?)
At one point in my carrer, I would have tried to come up with reasons why what sounds like what and why. But I am too old to really care. Seriously. Making a living is hard enough, without spending time on such mental excercises.
Doesn't mean that I won't listen to someone like Mike, but I will leave it to guys like him to do my worrying for me.
So we await............enlighten us.
Just drop the attitude, ok?
Jocko
We lived with over 1-1/2 years waiting for you to "tone down your approach".
My reasoning:
It seems simple enough to build low-level circuits, that measure and sound well without GFB. My customers seem to agree.
A power amp is a different beast. Like John, if I stick to making small Class A amps.....60 W or so, they sound better to me and my customers without GFB. So that is what I do.
Call me lazy........call me stupid........call me anything..........I would rather not have to mess with GFB. I do not care for the sound, nor do my customers care for the sound, so I can get away with being lazy/stupid/whatever.
My customers especially do not like the sound that comes with so-called "current feedback" (Let's not argue the semantics of that again, ok?)
At one point in my carrer, I would have tried to come up with reasons why what sounds like what and why. But I am too old to really care. Seriously. Making a living is hard enough, without spending time on such mental excercises.
Doesn't mean that I won't listen to someone like Mike, but I will leave it to guys like him to do my worrying for me.
So we await............enlighten us.
Just drop the attitude, ok?
Jocko
Re: I can live with 6 weeks.........
So....when are you going to tone down YOUR approach?
http://www.sjostromaudio.com/jocko_homo.html
Jocko Homo said:
So....when are you going to tone down YOUR approach?
http://www.sjostromaudio.com/jocko_homo.html
I've tried many different configurations; hi GFB, no GFB, error cancellation, a few others. It seems like there is a split on most of these topologies during listening tests. About half like and half dislike. No, these were not scientific studies or double blind tests. They were done with people that know nothing about electronics so they don't care about the circuit.
Except for using a 0 GFB on a line stage. Then almost everyone liked it. I have not had success with 0 GFB on a power amp.
I agree with Jocko, it's hard enough to design and build without getting bogged down in the semantics. As I said before, all I'm interested in is if the client is happy. The client couldn't care a less about the topology used.
Mike
Except for using a 0 GFB on a line stage. Then almost everyone liked it. I have not had success with 0 GFB on a power amp.
I agree with Jocko, it's hard enough to design and build without getting bogged down in the semantics. As I said before, all I'm interested in is if the client is happy. The client couldn't care a less about the topology used.
Mike
As far as I am concerned, most of the circuits here are model T's, but I am not going to show you how to make a Porsche.
First of all, it is too difficult to get the parts for.
Matching and balancing are required.
Superior materials and craftsmanship have to be used in assembly.
From many of you, I would get arguments like:
Why to we have to super clean the components before assembly? They have only been sitting out in the air for a few weeks or months!
I want to run 7 cylinders, not 6 or 8, because I think different is cool!
Why use fuel injection? It is too complicated!
I think those white wall tires on 50's cars look great, and I want to use them, instead of modern tires.
etc, etc ;-) Get my point?
First of all, it is too difficult to get the parts for.
Matching and balancing are required.
Superior materials and craftsmanship have to be used in assembly.
From many of you, I would get arguments like:
Why to we have to super clean the components before assembly? They have only been sitting out in the air for a few weeks or months!
I want to run 7 cylinders, not 6 or 8, because I think different is cool!
Why use fuel injection? It is too complicated!
I think those white wall tires on 50's cars look great, and I want to use them, instead of modern tires.
etc, etc ;-) Get my point?
TIM/PIM and input stages
I don't recall, has the use of compound pairs for input stages been discussed as a means of reducing TIM/PIM? I've attached a picture of a circuit comparison I did between a normal diff pair and a compound diff pair. Sure looks like the compound diff pair improves the linearity of Iout vs Vin quite a bit.
I don't recall, has the use of compound pairs for input stages been discussed as a means of reducing TIM/PIM? I've attached a picture of a circuit comparison I did between a normal diff pair and a compound diff pair. Sure looks like the compound diff pair improves the linearity of Iout vs Vin quite a bit.
Attachments
Looked at the distortion of the closed-loop amp after swapping out the diff amp. This was a 20 kHz with an output voltage equivalent to 300 W into 8 Ohms. At the moment, the output stage is an idealized unity gain VCVS. I've been looking for ways to reduce the distortion of the input stage/VAS combo. Here's the strange thing. Prior to putting the compound pair in, distortion was dominated by second harmonic, with the third 20 dB down from the second (about -120 dB vs -100 dB). When I put in the compound pair, the second dropped by 20 dB, making it the same as the third, and the third did not budge! I have a theory about this but you'd think I was crazy.
Here's what's interesting. The second harmonic of the compound pair by itself is no better than the second harmonic of the simple diff pair. So I started to think in terms of PIM rather than TIM. You'd expect TIM to correspond to third-order harmonic distortion mostly. But what about PIM? Well, for frequency modulation (same beast as phase modulation really), when the modulation index is small, the FM signal consists of the fundamental, plus only two sidebands, at fc - fm and fc + fm, where fc is the carrier frequency and fm is the modulation frequency. But for plain old instantaneous phase modulation with a single sine wave, the carrier and modulation frequency are one and the same. The fc + fm term becomes the second harmonic. So I'm guessing that the second harmonic that was dominating before was actually the manifestation of PIM.
I told you you'd think I was crazy. This is just a guess though. Got relatives coming over tonight so I'll have to continue it tomorrow.
I told you you'd think I was crazy. This is just a guess though. Got relatives coming over tonight so I'll have to continue it tomorrow.
There are many Kwak, some of them i have trouble to follow what they mean
Have to think hours...and them i realise what they really mean.
This is not only language troubles, i am talking about the sub text... what is really hidden under the worlds.... the intention.... the direction the one point you to follow his logics.
Mikeks....my God!.... i saw him pushing the wires and people "moving" alike puppies...of course i can be delirating, and also he can do that without conscience...this way not his fault.
I have enormous respect related him... and afraid too.... because the one is clever as a fox
Rule number one...never say you are clever, despite you can think that, realised that or had some inputs that make you think about that...that you have a little bit more than average people.
Rule number two...use some protection, some helmet... the Maths can be the helmet.
Rule number three, you can put people nervous...but you never loose your control.... only when needed to make the people "imagine" you are a commom mortal.
My God... take a look in Graham text published....i called a friend... USA citizen..... i asked him to translate Maynard text.... i said, please...i am beeing tired... i never finish, may be the language....
The answer i had.... the text is heavy, the logic loops are too many... the references are too many.... this is this way because or this and not because of that second this , that and those....but if you do not consider that influenced factor that diminishes the error factor.....of course...those words do not make sense.... also his imagine do not make sense to me...because he is genius, and the one is not in his "best" days related use the brain.
The American guy..... those that put the "a" pronouce in the place of "o"......mother is mather pronouced.... the one said i am asking a real work, because the use of language is very impressive even to native american english people...he is translating Mr. Graham to me, as a special kindness...take a look at that "real" situation.....see his schematic.... read his texts and you Kwak, will have some idea related what i mean.
Follow "Spencer" text.... take a look in the John Curl..... follow without reflections what Hugh say...and see some gênius over there...and those things are sectional.... those ones can be special in language and week in logics....but if i can not follow the man...i have to believe he has more inteligence or more knowledge than i have.
Write to Graham Maynard... try it... and put a lot of ideas on there....he even do not consider the ideas that are checked fast and considered "stupid"...he simply erase those ones and do not answer you....he pick your needs and go direct into the point.
Yes, there are special persons....yes, they exist.... and this is good for us, we need them.... awfull for them.... the more intelligent you can be... the worst your life, because you see too much clearly the awfull things manking is doing and will do... hard ot be happy when the movie you see is sad.... the happiest guys are the stupid ones.... all is wonderfull...my god!....i feel that way..my god!
Those are the ones that cannot focus things in front of his eyes, some clear evidences are not noticed.
I was thinking Graham did not read the text i sent....i go to ask him...
Sorry Carlos, this have not importance related the subject we are discussing....the "noises" related to language communication are imediately separated by his brain.... as "junk"...he goes only inside the logic sequences, jumping from one to other that i never answer the guy without read twice and make some reflections about the "meaning".
I will ask him the part number five of his text..... some copy he can make, different from the published to avoid legal problems, some explanation about the Class Ab amplifier.... the one that is very alike the class A... do you know what he will do?
"Carlos, read the other text, this amplifier is the same with one more CCS included"
Why that...because it is this way.... everything can be deduced, all differences in current are obvious to his mind.....not to mine....i am older than the guy...i made hundred times more amplifiers than Graham.... i bougth more amplifiers than he saw in magazines all his life!>... and he is better than me..... why?....or i have to accept i am stupid or accept he is over than me in intelligence.
His amplifier was made a long long time ago.... take a look at the schematic....see the technology discovered first.....published now, when we could reach his level..now the technology is enougth to our understanding.
See the Magazine he published his material...try to publish there....only the "Men"...can published there.... see also the price, imagine if this is made of everyone?
Of course ideas, this is subjective and personal...but i like to talk alike a parrot...a brazilian damn parrot i am... but a very nice guy...i guarantee...the girls signed under the things i made...hehe
regards,
Carlos
Have to think hours...and them i realise what they really mean.
This is not only language troubles, i am talking about the sub text... what is really hidden under the worlds.... the intention.... the direction the one point you to follow his logics.
Mikeks....my God!.... i saw him pushing the wires and people "moving" alike puppies...of course i can be delirating, and also he can do that without conscience...this way not his fault.
I have enormous respect related him... and afraid too.... because the one is clever as a fox
Rule number one...never say you are clever, despite you can think that, realised that or had some inputs that make you think about that...that you have a little bit more than average people.
Rule number two...use some protection, some helmet... the Maths can be the helmet.
Rule number three, you can put people nervous...but you never loose your control.... only when needed to make the people "imagine" you are a commom mortal.
My God... take a look in Graham text published....i called a friend... USA citizen..... i asked him to translate Maynard text.... i said, please...i am beeing tired... i never finish, may be the language....
The answer i had.... the text is heavy, the logic loops are too many... the references are too many.... this is this way because or this and not because of that second this , that and those....but if you do not consider that influenced factor that diminishes the error factor.....of course...those words do not make sense.... also his imagine do not make sense to me...because he is genius, and the one is not in his "best" days related use the brain.
The American guy..... those that put the "a" pronouce in the place of "o"......mother is mather pronouced.... the one said i am asking a real work, because the use of language is very impressive even to native american english people...he is translating Mr. Graham to me, as a special kindness...take a look at that "real" situation.....see his schematic.... read his texts and you Kwak, will have some idea related what i mean.
Follow "Spencer" text.... take a look in the John Curl..... follow without reflections what Hugh say...and see some gênius over there...and those things are sectional.... those ones can be special in language and week in logics....but if i can not follow the man...i have to believe he has more inteligence or more knowledge than i have.
Write to Graham Maynard... try it... and put a lot of ideas on there....he even do not consider the ideas that are checked fast and considered "stupid"...he simply erase those ones and do not answer you....he pick your needs and go direct into the point.
Yes, there are special persons....yes, they exist.... and this is good for us, we need them.... awfull for them.... the more intelligent you can be... the worst your life, because you see too much clearly the awfull things manking is doing and will do... hard ot be happy when the movie you see is sad.... the happiest guys are the stupid ones.... all is wonderfull...my god!....i feel that way..my god!
Those are the ones that cannot focus things in front of his eyes, some clear evidences are not noticed.
I was thinking Graham did not read the text i sent....i go to ask him...
Sorry Carlos, this have not importance related the subject we are discussing....the "noises" related to language communication are imediately separated by his brain.... as "junk"...he goes only inside the logic sequences, jumping from one to other that i never answer the guy without read twice and make some reflections about the "meaning".
I will ask him the part number five of his text..... some copy he can make, different from the published to avoid legal problems, some explanation about the Class Ab amplifier.... the one that is very alike the class A... do you know what he will do?
"Carlos, read the other text, this amplifier is the same with one more CCS included"
Why that...because it is this way.... everything can be deduced, all differences in current are obvious to his mind.....not to mine....i am older than the guy...i made hundred times more amplifiers than Graham.... i bougth more amplifiers than he saw in magazines all his life!>... and he is better than me..... why?....or i have to accept i am stupid or accept he is over than me in intelligence.
His amplifier was made a long long time ago.... take a look at the schematic....see the technology discovered first.....published now, when we could reach his level..now the technology is enougth to our understanding.
See the Magazine he published his material...try to publish there....only the "Men"...can published there.... see also the price, imagine if this is made of everyone?
Of course ideas, this is subjective and personal...but i like to talk alike a parrot...a brazilian damn parrot i am... but a very nice guy...i guarantee...the girls signed under the things i made...hehe
regards,
Carlos
Research all the forum as i made 4 times.
I was reaching evidences of halojoy failures...now i know the problem clearly...have nothing to say anymore to defend or attack no one.
I found SY...take a look.... small sentences and "BOOOMMM!"...he stop all "foolishes" we make with a very small logic sequence..the perfect words, in the perfect moment he entered!...not the moderator "authority"...the brain man!
regards,
Carlos
I was reaching evidences of halojoy failures...now i know the problem clearly...have nothing to say anymore to defend or attack no one.
I found SY...take a look.... small sentences and "BOOOMMM!"...he stop all "foolishes" we make with a very small logic sequence..the perfect words, in the perfect moment he entered!...not the moderator "authority"...the brain man!
regards,
Carlos
PIM, my reasoning;
Just a preliminary view of AM vs FM intermodulation products, Am modulation (green) produces sum and difference products at 10 +/- 1 Hz = 9 and 11 Hz – not truly representative of feedback distortion, 100% AM modulation has removed the 10 Hz “carrier” and in a feedback loop that 10 Hz would be interacting with the products in the nonlinearity to produce additional distortion products that would look like the series of products in the FM modulation fft
The FM fft example (red) shows a series of distortion products at 10 +/- n* 1 Hz which decrease in amplitude by the n_th power, the green AM products @ 9&11 Hz overlay the red FM products @ 9&11 Hz and are essentially the same amplitude
I plotted the products by differencing out the FM fundamental, as you can see the amplitude and character of AM and FM modulation products are very similar (the higher order FM products are included but not discernable by eyeball in the time plot)
If you examine the 9&11 “first order” difference products, they have a relative phase of 180 degrees in both the AM and FM cases; for AM 9&11 Hz are +/-0 90 degrees relative to the (missing) fundamental, in the FM case they are 0, 180 degrees relative to the fundamental
As I pointed out this doesn’t represent the distortion generated under different feedback conditions but it does let you see the defining essential of AM vs FM IM distortion products - the relative phase of the distortion products
The amplitude of the products is determined by the depth of the modulation, (1/10 in this example) the frequencies of the products are the f_0 +/- n*f_mod
The claim that FM distortion can’t be easily measured seems strange, the (complex valued) fft result does contain the phase information of the component frequencies, and since AM and FM distortion products are in quadrature, no cancellation can occur between the products, of course since they are in quadrature and add (vectorially) there seems to be little point in resolving the amplitudes of a particular IM pair into separate AM and FM components when we can use high feedback to squash the summed amplitude of both
For the high feedback camp the argument is basically that if there is no IM product amplitude, then the relative phase of the distortion products can’t matter – no distortion product, no FM distortion
The consternating crux for me is the insistence that FM distortion is somehow worse than higher levels AM distortion – when measured by the amplitude of the distortion products, and that there is some subtle flawed trace left in the signal when the amplitude of the distortion products is reduced below the audibility limits if they were presented on their own in a anechoic chamber, much less in conjunction with the masking of the undistorted source signals, room reverberation, ambient noise and loudspeaker distortion (including Doppler-FM distortion)
Just a preliminary view of AM vs FM intermodulation products, Am modulation (green) produces sum and difference products at 10 +/- 1 Hz = 9 and 11 Hz – not truly representative of feedback distortion, 100% AM modulation has removed the 10 Hz “carrier” and in a feedback loop that 10 Hz would be interacting with the products in the nonlinearity to produce additional distortion products that would look like the series of products in the FM modulation fft
The FM fft example (red) shows a series of distortion products at 10 +/- n* 1 Hz which decrease in amplitude by the n_th power, the green AM products @ 9&11 Hz overlay the red FM products @ 9&11 Hz and are essentially the same amplitude
I plotted the products by differencing out the FM fundamental, as you can see the amplitude and character of AM and FM modulation products are very similar (the higher order FM products are included but not discernable by eyeball in the time plot)
If you examine the 9&11 “first order” difference products, they have a relative phase of 180 degrees in both the AM and FM cases; for AM 9&11 Hz are +/-0 90 degrees relative to the (missing) fundamental, in the FM case they are 0, 180 degrees relative to the fundamental
As I pointed out this doesn’t represent the distortion generated under different feedback conditions but it does let you see the defining essential of AM vs FM IM distortion products - the relative phase of the distortion products
The amplitude of the products is determined by the depth of the modulation, (1/10 in this example) the frequencies of the products are the f_0 +/- n*f_mod
The claim that FM distortion can’t be easily measured seems strange, the (complex valued) fft result does contain the phase information of the component frequencies, and since AM and FM distortion products are in quadrature, no cancellation can occur between the products, of course since they are in quadrature and add (vectorially) there seems to be little point in resolving the amplitudes of a particular IM pair into separate AM and FM components when we can use high feedback to squash the summed amplitude of both
For the high feedback camp the argument is basically that if there is no IM product amplitude, then the relative phase of the distortion products can’t matter – no distortion product, no FM distortion
The consternating crux for me is the insistence that FM distortion is somehow worse than higher levels AM distortion – when measured by the amplitude of the distortion products, and that there is some subtle flawed trace left in the signal when the amplitude of the distortion products is reduced below the audibility limits if they were presented on their own in a anechoic chamber, much less in conjunction with the masking of the undistorted source signals, room reverberation, ambient noise and loudspeaker distortion (including Doppler-FM distortion)
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