For those who know their way around PSUD for a tube amp: how and where do I find its indiction of ripple/noise within a circuit? Though I readily see it in the graph simulation, I wonder if it had a numerical value somewhere in the chart and more importantly, given that I don't have an o'scope, how do the numbers translate into audible noise?
Thanks
Thanks
PSUD is a fairly base level simulator, so the outcome will indicate mains frequency related ripple with a caveat being the simulation uses ideal models for parts. The peak-to-peak level of that ripple is presented as a max to min voltage of a parameter in the results table (where the parameter can be selected for visual display as well). Ripple is normally assessed as a steady-state parameter and so the simulation results need to be configured with some delay time (eg. a second or two typically, but sometimes longer) and include a duration that covers a few mains cycles at least.
That is up to your amplifier, speakers, and your ears - there is no generic answer to that query as the power supply is only an input to your amp and not an output to your speakers.
thanks /clarification
Thanks for your quick response and clear answer.
To be clear, if I have been given numbers like 515.822 (Min) and 515.829 (Max) at the final cap (from the graph), then am I to understand that the level of ripple is the difference between these two numbers?
Thanks for your quick response and clear answer.
To be clear, if I have been given numbers like 515.822 (Min) and 515.829 (Max) at the final cap (from the graph), then am I to understand that the level of ripple is the difference between these two numbers?
The Diff column calculates that peak-to-peak ripple voltage level from the min and max values. If you had a meter that can read ACV then it would likely represent the rms voltage of that ripple - the ratio of rms to pk-pk is not the same as a sinewave as the ripple waveform has lots of harmonics.
The simulation accuracy is dependent on the model parameters used for parts (eg. the ESR of a filter cap) and the realworld differences between parts and their models (such as the transformer voltage is assumed to be a sinewave from the mains, but the mains AC waveform is typically quite distorted). Also if you make a realworld measurement then the result can depend on the meter used, and where you probe, so there can be noticeable differences between simulated and metered levels, especially if you are trying to identify 7mVpp on a 515Vdc level.
The simulation accuracy is dependent on the model parameters used for parts (eg. the ESR of a filter cap) and the realworld differences between parts and their models (such as the transformer voltage is assumed to be a sinewave from the mains, but the mains AC waveform is typically quite distorted). Also if you make a realworld measurement then the result can depend on the meter used, and where you probe, so there can be noticeable differences between simulated and metered levels, especially if you are trying to identify 7mVpp on a 515Vdc level.
Ok, so if I understand you, then the implication is that not only are there more things going on in the actual working unit than any modeling program can anticipate, but also that here are few ways (if any) to get verifiable results from any modeling program.
Given (what must be obvious to you by now) that my experience in technical theory is much less than my practical knowledge, I would like to know how to maximize my limited knowledge in/on my power supply without buying more machines and learning more theory.
Please understand that it is not as though I don't want to learn more things about this wonderful world of tubes and power supplies, it is more about the music that ensues (and the lack of noise and harmonics from the p/s).
Finally, my goal: it is to design a choke p/s with an input ripple below about 7mV (7mV/45dB = 40uV). I have other design (read: physical) criteria for the p/s, but that is an issue for a later date.
Any suggestions?
Given (what must be obvious to you by now) that my experience in technical theory is much less than my practical knowledge, I would like to know how to maximize my limited knowledge in/on my power supply without buying more machines and learning more theory.
Please understand that it is not as though I don't want to learn more things about this wonderful world of tubes and power supplies, it is more about the music that ensues (and the lack of noise and harmonics from the p/s).
Finally, my goal: it is to design a choke p/s with an input ripple below about 7mV (7mV/45dB = 40uV). I have other design (read: physical) criteria for the p/s, but that is an issue for a later date.
Any suggestions?
I'd suggest you are starting to go down a rabbit hole based on some notion that improving the power supply hum will give a direct improvement in your music listening. There is a lot of innuendo from marketing and snake-oil comments and many many forum posts that attest to a direct listening improvement based on some technical tweak - I suggest you take one step back from reading those comments as fact.
I guess the contrasting analogy is like a music novice making some subtle tweak to a concerto score and saying that the whole listening experience was then much improved.
I guess the contrasting analogy is like a music novice making some subtle tweak to a concerto score and saying that the whole listening experience was then much improved.
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I can understand why you might come to that conclusion, it is a bit more fundamental of an issue for me than I had originally posted.
My desire to create lower noise floor in my p/s is based on the fact that I will be using it in an otl amp with high efficiency speakers. As such, as I am sure you already know, in the absence of an output transformer will allow what ever noise is within the system to seem more prominent.
If nothing else, I am interested in learning about the physical limitations of such a system in the real world since my goal is a viable (and elegant) otl amp.
I am open to suggestions.
My desire to create lower noise floor in my p/s is based on the fact that I will be using it in an otl amp with high efficiency speakers. As such, as I am sure you already know, in the absence of an output transformer will allow what ever noise is within the system to seem more prominent.
If nothing else, I am interested in learning about the physical limitations of such a system in the real world since my goal is a viable (and elegant) otl amp.
I am open to suggestions.
Perhaps a few things to comment on then.
Can you elaborate on what measurement equipment you have (eg. if you want to confirm/benchmark the level of ripple you have on a floating DC supply).
The ripple at idle may relate to what you can discern by listening to your speakers at close range, but any such observed noise could be from other causes in your setup. Do you have a way to confirm that any noise heard is from just the B+ ? Do you have a microphone measurement setup that allows you to compare/benchmark what you hear and what is being generated by the speaker? Is it practical to listen at a close range, and at what level does noise from the speaker exceed your ambient at your listening location? The ripple level will change with music level - how will you determine that level of ripple and if that higher level of ripple is added to the music and if it is noticeable given it is the music experience that may be your goal?
Can you elaborate on what measurement equipment you have (eg. if you want to confirm/benchmark the level of ripple you have on a floating DC supply).
The ripple at idle may relate to what you can discern by listening to your speakers at close range, but any such observed noise could be from other causes in your setup. Do you have a way to confirm that any noise heard is from just the B+ ? Do you have a microphone measurement setup that allows you to compare/benchmark what you hear and what is being generated by the speaker? Is it practical to listen at a close range, and at what level does noise from the speaker exceed your ambient at your listening location? The ripple level will change with music level - how will you determine that level of ripple and if that higher level of ripple is added to the music and if it is noticeable given it is the music experience that may be your goal?
Excellent.
My measuring equipment is limited to 2 fluke DVM meters and with them I plan to do what you originally suggested in your previous email. That technique along with changes via PSUD (however idealized/theoretical) I hope to reduce p/s noise as much as possible given the physical design of the amp. However please recall that my initial question was about how to determine noise in a modeling program like PSUD. Then I asked how that noise related to anything audible.
And to that end, I completely understand that the system can create and enhance noises of many shapes and sizes but that has to be a question for another time. Regardless, I intend to follow your suggestions upon completion of the amp to the best of my technical abilities. If the nose is too dominant from my listening position, then I will have to break down and (dare I say it?) buy an o'scope.
Thanks for you help and suggestions so far.
My measuring equipment is limited to 2 fluke DVM meters and with them I plan to do what you originally suggested in your previous email. That technique along with changes via PSUD (however idealized/theoretical) I hope to reduce p/s noise as much as possible given the physical design of the amp. However please recall that my initial question was about how to determine noise in a modeling program like PSUD. Then I asked how that noise related to anything audible.
And to that end, I completely understand that the system can create and enhance noises of many shapes and sizes but that has to be a question for another time. Regardless, I intend to follow your suggestions upon completion of the amp to the best of my technical abilities. If the nose is too dominant from my listening position, then I will have to break down and (dare I say it?) buy an o'scope.
Thanks for you help and suggestions so far.
p.s. I might have to use toroid chokes in my design of the p/s because of space considerations. Is there any reason to believe that they will saturate at high voltages even though the current rating will be correct and I will get them in an appropriately high inductance?
A meter and what you can determine from it depends on the meter model# and its spec.
PSUD2 is just a tool - it takes technical nous to set it up and to indicate what it is technically telling you. The simulated output can often be taken out of context, which is sort of why I added in the extra comments and queries, as the topic can get very technical and can be disheartening when there is a subjective outcome wanted. You are entering in to the world of engineering, where putting blinkers on and focussing just on one parameter is a poor path to take.
Selection of an appropriate choke is also quite technical. PSUD2 can indicate the AC and DC voltages and currents that the choke may need to cope with. Manufacturer data may not adequately confirm that a particular choke supports those current and voltage levels and with the inductance you are aiming. If there is not sufficient data on a part then you could just wing it and make a purchase, and even make your own measurements if you so desire - but again that gets technical. A 10H choke only provides 10H under certain operating conditions, and you wear the risk if you are not aware of what conditions an amp imposes on it and have measurements to confirm its performance.
PSUD2 is just a tool - it takes technical nous to set it up and to indicate what it is technically telling you. The simulated output can often be taken out of context, which is sort of why I added in the extra comments and queries, as the topic can get very technical and can be disheartening when there is a subjective outcome wanted. You are entering in to the world of engineering, where putting blinkers on and focussing just on one parameter is a poor path to take.
Selection of an appropriate choke is also quite technical. PSUD2 can indicate the AC and DC voltages and currents that the choke may need to cope with. Manufacturer data may not adequately confirm that a particular choke supports those current and voltage levels and with the inductance you are aiming. If there is not sufficient data on a part then you could just wing it and make a purchase, and even make your own measurements if you so desire - but again that gets technical. A 10H choke only provides 10H under certain operating conditions, and you wear the risk if you are not aware of what conditions an amp imposes on it and have measurements to confirm its performance.
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Both meters are Fluke 179.
It seems that you understand something of my situation and my limitations-- as I do. Coming onto this site was to get an understanding of the problem and hopefully to get something in the way of a solution, even if that means that I ask more questions, and learn something along the way. So far I haven not been disappointed. (What I would really like is for someone tell me: do this, buy that and do this... But then, where is the fun in that??)
I purposely did not mention the manufacturer of the choke because there wasn't a lot of information on the site and when I asked for more details, I got no response. Not a good sign-- though the company has a good reputation for their products. I do know that all chokes have their limitations depending on their operating conditions; I also know quite well that we do not live in a perfect world with perfect components.
I am aware of my desire to do this right the first time with little expense and relatively quickly is as much an advantage as it is a disadvantage; I am also aware that while learning is expensive, ignorance is more expensive.
So, given that I have few tools and perhaps the same amount of experience, where do we go from here?
It seems that you understand something of my situation and my limitations-- as I do. Coming onto this site was to get an understanding of the problem and hopefully to get something in the way of a solution, even if that means that I ask more questions, and learn something along the way. So far I haven not been disappointed. (What I would really like is for someone tell me: do this, buy that and do this... But then, where is the fun in that??)
I purposely did not mention the manufacturer of the choke because there wasn't a lot of information on the site and when I asked for more details, I got no response. Not a good sign-- though the company has a good reputation for their products. I do know that all chokes have their limitations depending on their operating conditions; I also know quite well that we do not live in a perfect world with perfect components.
I am aware of my desire to do this right the first time with little expense and relatively quickly is as much an advantage as it is a disadvantage; I am also aware that while learning is expensive, ignorance is more expensive.
So, given that I have few tools and perhaps the same amount of experience, where do we go from here?
Do you have an existing amp design and schematic that you think are appropriate to start with? Do you have power supply parts for that, and is that constructed and working? Have you simulated the power supply with PSUD2 and settled on parameter values for parts and loading to see what ripple you are likely to get for idle load condition? I'm guessing you have some indication from somewhere that you may have 7mVrms on B+ ?