Hi, i post here because i think it is more a free speech section
And most of all i do not want to sound provocative at all.
I am starting the learning process on audio design
I am interested about the procedure to build an audio circuit
I have some questions for you audio Designers out there:
1) in the first stage of an audio design do you rely mainly on circuit simulation with various softwares ?
2) how do you select/optimize your circuits ? always with the sim SWs ? which parameters you try to maximize/minimize ? distortion ? slew rate ?
3) after you have decided for a circuit do you build it on breadboards ? both channels or just one ?
4) do you carried out circuit modifications on the basis of listening tests ?
To end i am attaching a video i have found a little naive but interesting anyway.
GML 8200 Walkthrough by George Massenburg Presented by RyanSloan.net - YouTube
Thanks a lot and kind regards, gino
And most of all i do not want to sound provocative at all.
I am starting the learning process on audio design
I am interested about the procedure to build an audio circuit
I have some questions for you audio Designers out there:
1) in the first stage of an audio design do you rely mainly on circuit simulation with various softwares ?
2) how do you select/optimize your circuits ? always with the sim SWs ? which parameters you try to maximize/minimize ? distortion ? slew rate ?
3) after you have decided for a circuit do you build it on breadboards ? both channels or just one ?
4) do you carried out circuit modifications on the basis of listening tests ?
To end i am attaching a video i have found a little naive but interesting anyway.
GML 8200 Walkthrough by George Massenburg Presented by RyanSloan.net - YouTube
Thanks a lot and kind regards, gino
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You left out the first step: define the target. That's not facetious, it's truly the most important step, and if the target is not defined, you'll go in circles forever. Intended load, power, distortion, frequency response, noise.
Hi and thanks for the kind reply. I try ...
from 10kohm up
line preamp ... so gain 2-3 no more
as low as possible ... of course
that of cd format ... nothing more nothing less
But what interests me most is the procedure, the approach
I guess that the simulation phase is very important to select the right circuit
I guess of course
I am about to start from this to see how the performance varies changing bias current ... supply voltage ... gain ... and so on
The noise i think is more related to the one coming from the PS
I do not know if the sim SWs can calculare also the PSRR ... i do not know
And then there is that oscillation thing ...
Uhmm ... maybe it is too difficult
Thanks again and kind regards, gino
OK, so if the source has (say) a 96dB s/n, why would you require the preamp to have "as low as possible"? Remember, uncorrelated noise sources add as power, so if the preamp had (in this example) a 100dB s/n, the overall system s/n is almost unchanged.
This is an example of what I'm talking about by intelligent target setting.
This is an example of what I'm talking about by intelligent target setting.
Maybe. But often it's 'What can I build with THIS'? I guess that can be considered a 'target'. I build from what's on hand or what can be obtained free/cheap. If I were to work from hard specs I'd end up spending just stupid amounts of money. And most of that on NRE getting custom cases/heatsinks/trafos/switchmode magnetics, multiple board runs....
And that's absolutely valid as part of the target spec. I'll also include esthetic choices, e.g., "voltage amplification to be done with tubes" or "lots of lights" or "under 2 kg/watt" or...
George Massenburg is an interesting guy and a very good designer. I have know him for more than 30 years.
Gino, it is difficult to get that sort of useful info here. There are too many 'hear no difference' people who will quibble with anything you ask.
Yes, we do often model on the computer, or alternatively (like me) work with prototypes to optimize the circuit.
Listening is a problem, but what sounds good will be apparent to others, as well as yourself.
Gino, it is difficult to get that sort of useful info here. There are too many 'hear no difference' people who will quibble with anything you ask.
Yes, we do often model on the computer, or alternatively (like me) work with prototypes to optimize the circuit.
Listening is a problem, but what sounds good will be apparent to others, as well as yourself.
Maybe not - maybe if you first think of a sensible target, you save lots of money that you might have spend with no return at all.
And setting as your target 'it should fit in this box' is OK.
Jan
Hi and thanks a lot for the valuable advice
You mean that the source noise could be predominant ? ok
Actually it could be even much worse than 96dB ... no i am sure is worse than that 🙄
Ok for the noise no problem ... but the distortion that should be low, shouldn't be ? 😕
Thanks again, gino
Again, how low is the distortion of the source? How low can you hear? If you're designing something for sale, what do your customers expect? "As low as possible" will send you into the realm of the exotic for no real sonic benefit, but there may be a non-sonic goal.
Gino not that I don't understand you! I've been there too: design a power amp, measure THD, 0.01%. OK, so maybe if I change this resistor... wow 0.008%! Another zero! (Although the difference is less than 2dB - nothing). Then you get excited and try more, for days on end, and you get to 0.006%, 0.005%...
In the mean time, summer and christmas and spring have come and gone and you haven't had time to listen to music... 😉
See what I mean? Tell your self: my preamp should do 0.01% and then I stop.
But, it will be hard, because going on and on and on you really learn a lot.
That's the curse of this hobby!
Jan
In the mean time, summer and christmas and spring have come and gone and you haven't had time to listen to music... 😉
See what I mean? Tell your self: my preamp should do 0.01% and then I stop.
But, it will be hard, because going on and on and on you really learn a lot.
That's the curse of this hobby!
Jan
Hi Mr.Curl, i know that the designer is very famous. His mic preamps are objects of cult for purity and low distortion.
I just find strange that he is not using a spectrum analizer as any engineer would have used to eliminate some peaks in the response.
This equalizing the peaks by ear ... i am very perplexed. I think that some digital analyzers do this even automatically pressing a button.
Thanks sincerely again but i have to ask.
You say
what tells that you are really improving the circuit performance, your ears or some measurements that i do not ask which are because i am perfectly aware of the fact that this is a personal property ?
This is the fundamental point for me ... how to assess that a mod carried-out on a prototype is beneficial, in the right direction or not.
Regarding the sim software is perfectly clear that it cannot predict precisely the real performance of a prototype.
The lay out has an influence ... the behaviour of the devices/parts could be different from the models used to simulate them
Maybe the sim SW is useful to give an idea of the overall performance.
Thanks a lot again. Kind regards, gino
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It's very simple: does it get you closer to your target or not?
Keep in mind what Jan said- without a target, you can get sucked down a black hole and never finish.
Hello and thanks for the kind reply
I swear i am not a 0,00001% guy
But still i see many Designers here that support their creation with this exceptional figures ... so it is not me
But i have to start from some points ... and i would like to start from a nice sim software to understand what impacts especially distortion of an amplification stage .. a very simple one.
Even if i am aware that a bad lay out or parts selection could be very detrimental for the same performances.
It is a learning process.
Thanks and regards, gino
Hi i think you get around my question. Again, i make a modification on a prototype ... what tells me if the modification has been beneficial or not ?
the eye ? the ear ? or an instrument ?
and in this last case ... which instrument ?
Is there an instrument that i should be kept always on the bench where i am playing with prototypes ? which one ?
I would say a scope maybe ?
If so i have learned a very important point, that a scope is the "meter" to assess the quality of a circuit.
this is dramatic ... 😀 of course when i see a good spectrum i stop and listen if the sound is convincing
I just want something nice on the ears ... but also sufficiently transparent and clean ... with a great 3d effect this is important, very important
I am collecting recordings very useful to assess this aspect
Kind regards, gino
It can either be the ear or the measurement. Usually, all else being equal, and no EXTRA feedback is added, the lower distortion measurement is better, so long as the harmonics are almost all low order.
Simple- did it get you closer to your target? That determines how you judge and what techniques are appropriate.
If, for example, your target is "less than 0.005% distortion dominated by second harmonic" and your mod reduces it from 0.01 to 0.008%, all second, it's a good mod.
If your target is "audibly transparent," and you can hear whether the circuit is being switched in and out under level-matched ears-only conditions, does your mod make it harder to hear the difference? If so, it's a good mod.
"How do you design your audio amplifiers ?"
I guess if you do it for a hobby it should always be fun, don't drive yourself crazy and always be learning. I find it to be very enlightening and rewarding.
If you do it for competition, whether it be ego driven or just competitive nature you can fall down the rabbit hole. I see a lot of 1 uppers in the audio hobby and it can lead to bickering, but it can also lead to innovation.
I would say the advice given so far is good being that just set reasonable goals and enjoy the fruits of your labor.
I guess if you do it for a hobby it should always be fun, don't drive yourself crazy and always be learning. I find it to be very enlightening and rewarding.
If you do it for competition, whether it be ego driven or just competitive nature you can fall down the rabbit hole. I see a lot of 1 uppers in the audio hobby and it can lead to bickering, but it can also lead to innovation.
I would say the advice given so far is good being that just set reasonable goals and enjoy the fruits of your labor.
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