Hi and really bad i am afraid ... and very closely placed.
I wil try to post some pictures by the way soon.
From next week i will start with some desoldering and soldering
When i see sometimes very clever Members here taking equipment litterally out from the garbage bin and make them better than new i am sincerely admired.
Not only ... simplifying the circuit and addressing specific parts in the end they sound even better than the original.
Even only bypassing tone controls and balance can give a nice improvement in transparency ... and i find really surprising that someone feels the need for them
Thanks again and regards, gino
P.S. is it possible to edit the signature ??? how ?
So in the end i could not be more wrong
In reality, you're not understanding what the capacitors are doing in the circuit. Different types of capacitors are used in different parts of the circuit for different reasons. If you don't know what a capacitor is doing, you won't be able to pick the right capacitor for the job without coming here and asking
. The voltage I'm referring to is signal voltage. If a coupling cap has a signal voltage across it, then it is introducing distortion. The signal voltage is AC so it must be checked with a high impedance AC voltmeter.
You really should read Bateman's work on capacitor distortion. http://www.scribd.com/doc/2610442/Capacitor-Sound He measures it and documents his results. He shows that the distortion from a properly chosen electrolytic coupling capacitor is so low that it has to be extrapolated. He also shows that other popular choices do in fact produce less distortion.
In the quest to reduce distortion in preamplifiers, there are bigger fish to fry than coupling capacitors. A proper ground scheme will make a big improvement, even to a modest circuit. Here's a good primer. Grounding Principles - The Signal - Archives - TI E2E Community And proper buffering of filters and tone controls makes a difference in both distortion and accuracy of filter circuits. As a designer you can investigate and control these various aspects of circuit behavior. Otherwise, it is prudent to copy a known circuit, and use the recommended board layout too. Ad hoc assembly and layout will completely ruin any circuit.
It's easy
and fun.Even only bypassing tone controls and balance can give a nice improvement in transparency ... and i find really surprising that someone feels the need for them
Every commercial tone control I have ever seen was terrible. Graphic equalizers are worse. The fact is that these designs are all compromises, as well as poorly thought out. They use poor designs, and they use the wrong parts almost every time. I have seen electrolytic capacitors in stupid values like 0.47 uF and 0.68 uF in the bass circuit too many times. Turning up the bass is just turning up the distortion with these controls; and you can hear the distortion increase as the bass is turned up too.
Tone controls are necessary in many practical sound systems, and a custom designed tone control can be an asset to most any system.
One trick is to choose different turnover frequencies. Use 300 Hz and 2000 Hz turnover frequencies instead of the industry standard of 1000 Hz for both. I think engineers do this simply because the calculations are easier. And this is the place to use your uber fancy and expen$ive metal film capacitors. Buffer the input and output. Put the money where it will make a difference!
Hi and thanks again for your very valuable advice.
I guess that they are there to block DC and let the AC signal through.
To isolate two points in the circuit at different potential ?
Different types of capacitors are used in different parts of the circuit for different reasons.
If you don't know what a capacitor is doing, you won't be able to pick the right capacitor for the job without coming here and asking
The voltage I'm referring to is signal voltage.
If a coupling cap has a signal voltage across it, then it is introducing distortion. The signal voltage is AC so it must be checked with a high impedance AC voltmeter.
You really should read Bateman's work on capacitor distortion. http://www.scribd.com/doc/2610442/Capacitor-Sound He measures it and documents his results.
He shows that the distortion from a properly chosen electrolytic coupling capacitor is so low that it has to be extrapolated. He also shows that other popular choices do in fact produce less distortion.
I promise i will try but i am slow in understanding.
I had an examination many years ago in basic electronics.
First time i was rejected.
The second time i was lucky to find a circuit that i had studied by hearth and passed the examination without knowing what i was really doing.
I divide people in two main groups: those who understand math and those who do not understand math.
The first ones are the smartest. The other are maybe more creatives
But do not rely on them for anything practical.
The world evolves only for the first group by the way.
So it is a big godsend to understand math.
Needless to say that i am in the 2nd group
But if you tell me that a good generic PP is fine i am done.
But as i said i will try because i am always interested about discussions on distortion ... i am a zero distortion guy
Thanks a lot again and yes my intention was to copy in future a schematic of a nice commercial unit, i have the Blowtorch in mind presently
No seriously ... i am only interested in line preamp (no phone and not power amps) of the very minimalist type, like the single mosfet Bride of Zen, to give an example
The layout is a very big issue i understand now.
This is very unfortunate.
My approach anyway would be to do just one channel and listen a mono track with both speakers.
Then when i like the result doubling it for a stereo preamp.
It's easy
absolutely no tone controls and moreover no balance here
Only selector and volume control, not remote controlled also
Very basic preamp
There was a preamp a vintage one .... composed like this: 1st pot > 1st preamp stage > tone controls section > 2nd pot > output stage
I am almost sure that just one pot > preamp stage would sound better ... this is technical perversion for me ...
Unacceptable ... the preamp being the old Radford ZD22
http://www.acousticpsychos.com/Files/Radford-HD250-ZD22-int-sm.pdf
Buffering the input … is this always mandatory ? Because this complicates a lot the circuit
I would like to do without buffering the input possibly
This is difficult
To end thanks a lot again. I understand now that just good caps are enough for signal coupling in a preamp. I am more positive now.
Kindest regards, gino
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You say that you're a "zero distortion" guy, then you reference circuits like this. Simple does not automatically mean lower distortion.
I can tell that you've been pumped full of audio hogwash. There's so much of that. I referenced a couple of articles for you to read that will give you a better understanding of sources of distortion. I suggest that you read them and understand them. Walt Jung has some explanations of sources of distortion in active circuits in his IC Op-Amp Cookbook. If you can read and understand this book then you could design your own stuff.
I'm an engineer, not a marketing goon. You can choose objectivity or you can choose $600 speaker cables, capacitors bigger than your thumb that do nothing, and minimalist circuits that introduce 3% harmonic distortion. Pick your poison.
To be creative in engineering you need maths, lots of maths. You can be creative in arty things without maths, although even there some maths might help with appreciation of symmetry and structure etc., but unfortunately audio design is not an arty thing; it is an engineering thing.ginetto61 said:
Hi do you mean that this is not a low distortion preamp ?
I was completely convinced of that ...
I see that you recommend instead op-amp based line stages ?
I have no prejudices at all on opamp ... but i wonder if a line stage minimalist and very low distortion is really possible
I mean, if i see a line stage with let's say 30 active parts and another with 1 or two active devices and the latter sounds better than the first i am shocked
I understand that i am trivializing but anyone says that his design is the better one ... who is true ?
I know that there are opamp with incredibly low distortion figures
Is that the way to go for a line stage ?
Thanks and regards, gino
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Mathetmatics and creativity
Bach understood maths and used it in helping with his creative compositions.
There is an early painter, I think maybe Italian, that understood maths and used it to create a good 3D representation in his creations.
Then, there was Leonardo ! Call him non-creative !
Bach understood maths and used it in helping with his creative compositions.
There is an early painter, I think maybe Italian, that understood maths and used it to create a good 3D representation in his creations.
Then, there was Leonardo ! Call him non-creative !
Yes is what i meant. And i agree on unfortunately ... because if not i would have studied that. I tried but it is too difficult.
When i see a schematic i am astonished ... how could someone be so clever ?
Thanks and regards, gino
P.S. but i was better with instruments ... i can read a manual i mean
I am without hopes for design but for measurements ... i think i could do it.
Hi and yes, but i associate math with rational thinking
I think of an artist as less rational, but there are many forms of Art that is sure
Also circuit design is an art
Regards, gino
No, no, no. The techniques that Jung presents in his work are applicable to discrete circuitry too. However, properly implemented op amp circuits can excel.
The difference between minimalist and traditional feedback controlled circuits is the distortion profile. Simpler circuits produce lower order distortions, but usually more (a lot more) of it. More traditional designs, with large loop gain, produce much more complex distortions; but with much lower levels.
I suggest that you read the articles that I went to the trouble of dredging up for you. They are the real deal. They are written by engineers. They do not indulge in marketing hype and sophistry; they measure results and display them for all to see.
And what's the issue with math? Audio circuit design employs the most basic algebra, logarithms, and trigonometry. That's high school stuff. Don't you have an engineering calculator? You can buy them for around $20, and they'll do everything you need to design these circuits.
circuit design is not ART.
One can turn it into art, but that often introduces compromises into the layout that will interfere with performance.
The LOOK of a layout does not need to show as ARTistic.
Many on this Forum makes comment like:
Ooh lovely, That looks good, etc.
Thanks again and sorry but i have to ask. What do you mean for to excel ?
To exhibit extremely low distortion ?
You are right when you say that i am confused but i always look at distortion and noise figures. Then i read the review and equipment with inferior performances are said to sound better. And this is disorienting.
I can tell you that i have tried without success to read very basic texts on power supply design and another one on amp design.
They are difficult. They are not a novel that flows easily.
I think that if something does not come reasonably easy better to do other things. And i have given up with circuit design definitely.
Then a step down is to draw a lay-out having the schema.
I understand now that also this is very very challenging.
Another step down is to build a kit. This maybe with the right tools and some practise i could do ... maybe.
And this is exactly what i am looking for.
A line preamp kit able to give a nice sound (not with tubes).
In the meanwhile i play with some equipment and usually i end destroying them (like and integrated of which i wanted to reduce the gain. Destroyed).
The issue with math is that is difficult for most people.
I have never see more students scared of other disciplines.
Because math is challenging the mind. It gives headache.
The math ability is a good way to measure intelligence.
It is like computers, some are much more powerful than others
They can do more calculations in the same amount of time
In many countries the math geniuses are monitored by the governments
Because they are a very rare kind of people
They are geniuses. You can give them complex problems to solve.
Just think for instance to the Keplero laws ... amazing !
Kepler's laws of planetary motion - Wikipedia, the free encyclopedia
The mathematicians have helped human race to understand the nature,
In my religion they are the real Saints.
They are just superior.
Especially if they use their genius for something good of course.
Thanks and regards, gino
It's a simple adverb. There is no hidden meaning.
If you are unwilling to learn basic mathematics, then a kit is for you. Don't ask me which one; I don't do kits.
My major point is that there are many sources of distortion, and coupling capacitors are way down on the list. Read the links I provided. The important article is the one addressing grounding. No circuit can live up to its potential with a poor grounding scheme.
HI and i am sure you are right about the layout and actually i stopped thinking about starting only from a schematic.
I am sure i would not be able to get an acceptable result.
And of course art is not science and audio design is science not art.
But i promise ... if you direct me to a line preamp kit low in gain (max 2) i will stop with all the ramblings ... even ac coupled
Thanks again and kind regards. gino
... even ac coupled
Since you seem to be quite oblivious to facts, I would highly recommend that you do not tackle a direct coupled amplifier. In the real world there is no benefit whatsoever, no matter what the wacktarded spin doctors claim. But hey, it's your money.
Not really even with no computer.
May-be the reason can be found, searching for "Fletcher & Munson" ?
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It would be wonderful if it were that simple.
It is true on paper, and simulation. Once you have to deal with real life components etc. evils are so complex, our measuring instruments so primitive, our ears and brain so mysterious that we have to lie to our senses and culture too.
And here, there is certainly a pinch of art ;-)
After all, audio (musical) production and reproduction is a 'make believe' game, a representation of an imaginary reality.
But, i agree with your words, if you agree that all 'engineering' require some feeling, added to correct and scientific understanding.
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