This is the simulation in a .txt format.........yuo can paste it into notepad, and then save it with .asc.
http://www.2shared.com/document/pFvYW_Q7/CLASS_D__80V__82_Hz.html
(as posted in the first post)
then it can be run in the simulator....but remmeber you need the two text files that.txt and that1.txt in the same folder as the .asc file
Could you not run the attached .asc file?.....its the same as the .txt one.
http://www.2shared.com/document/pFvYW_Q7/CLASS_D__80V__82_Hz.html
(as posted in the first post)
then it can be run in the simulator....but remmeber you need the two text files that.txt and that1.txt in the same folder as the .asc file
Could you not run the attached .asc file?.....its the same as the .txt one.
eem2am!
Is it really neccessary to make such effort to proove a single number which is already accepted? Yes, peak power is twice the average output power in case of sinewave and resistive load. This is trivial, and not related to ClassD. So what? If you want to design PSU to be able to provide this much power continuously, feel free to do it! At 60 W (or 350W) this is not a big deal. But does it mean every PSU of ClassD amps have to be designed this way? Absolutely not! And in real life usage there won't be an observable difference. (Or will: the weak PSU may protect the speaker from burning in case of an unwanted oscillation. Do you want a speaker destroyer, or an amplifier? It's your choice!)
A real life test: I've driven a 400W 4Ohm eminence bass speaker with ClassD amp (+SMPS) from a laboratory power supply set to 14.4V, with 16A current limit. Output peak voltage was over 65V (-> 480W calculated nominal power), average current draw was slightly below 8A (-> 112W), voltage never sagged below 13.2V.
The explanation of the apparent perpetum mobile: 1. music signal, 2. reactive and high speaker impedance around resonance.
Is it really neccessary to make such effort to proove a single number which is already accepted? Yes, peak power is twice the average output power in case of sinewave and resistive load. This is trivial, and not related to ClassD. So what? If you want to design PSU to be able to provide this much power continuously, feel free to do it! At 60 W (or 350W) this is not a big deal. But does it mean every PSU of ClassD amps have to be designed this way? Absolutely not! And in real life usage there won't be an observable difference. (Or will: the weak PSU may protect the speaker from burning in case of an unwanted oscillation. Do you want a speaker destroyer, or an amplifier? It's your choice!)
A real life test: I've driven a 400W 4Ohm eminence bass speaker with ClassD amp (+SMPS) from a laboratory power supply set to 14.4V, with 16A current limit. Output peak voltage was over 65V (-> 480W calculated nominal power), average current draw was slightly below 8A (-> 112W), voltage never sagged below 13.2V.
The explanation of the apparent perpetum mobile: 1. music signal, 2. reactive and high speaker impedance around resonance.
Pafi
If you want your class d amplifier to be able to sound out 82Hz sinewaves like the one in the simualtion then it is not trivial, and it is related to class d after all.
So you are saying that in real life, a SMPS that powers a class d amplifier does not have to be rated to supply twice the average maximum power dissipated in the speaker?
..If so, then supposing i have a class d amplifier that has a maximum average power of 350W, then what power rating of power supply would you recomend for it?
If you want your class d amplifier to be able to sound out 82Hz sinewaves like the one in the simualtion then it is not trivial, and it is related to class d after all.
So you are saying that in real life, a SMPS that powers a class d amplifier does not have to be rated to supply twice the average maximum power dissipated in the speaker?
..If so, then supposing i have a class d amplifier that has a maximum average power of 350W, then what power rating of power supply would you recomend for it?
Rating of a PSU must be not only 1 number. There must be at least a long time, thermally limited rating and a short time rating limited by voltage drop. Or a current limit + capacitance. Depending on the application and your special circumstances the overload behaviour can be designed differently. There is no single rule. I prefer good PSRR amp + sagging, power limited PSU (1.1 x Pmax short term, 0.5 x Pmax long term) + big capacitors. Maybe this is not the best for guitar, where sustained, overdriven signal can occure, but good for complete music signal.
BTW: the speaker will not dissipate 350 W. 1. heat increases resistance. 2. impedance at 82 Hz will probably be much higher then the nominal, and it will be not purely resistive. 3. hopefully you will drive the speaker with music, not sinewave.
BTW: the speaker will not dissipate 350 W. 1. heat increases resistance. 2. impedance at 82 Hz will probably be much higher then the nominal, and it will be not purely resistive. 3. hopefully you will drive the speaker with music, not sinewave.
Pafi:
In your estimation, what rating of SMPS would you use to power this class d amplifier.....
ID:100TVP Guitar Amplifier - Blackstar Amplification
JRKO
....The low E string is one out of 6...and its a very important one, because its good to sound out those bass notes to give a full, rich sound instead of a tinny cheap sound.
A guitarist who is playing gigs wants a classy sound, they dont want to stand up there plucking away and sounding like a bluebottle stuck in a jam jar.
Speakers are coils, and surely there impedance will be less at low frequencies, and not more?
It is surely agreed that to get a good sounding class d guitar amplifier you need an smps that can supply twice the maximum average power of the class d amplifier
In your estimation, what rating of SMPS would you use to power this class d amplifier.....
ID:100TVP Guitar Amplifier - Blackstar Amplification
JRKO
....The low E string is one out of 6...and its a very important one, because its good to sound out those bass notes to give a full, rich sound instead of a tinny cheap sound.
A guitarist who is playing gigs wants a classy sound, they dont want to stand up there plucking away and sounding like a bluebottle stuck in a jam jar.
Speakers are coils, and surely there impedance will be less at low frequencies, and not more?
It is surely agreed that to get a good sounding class d guitar amplifier you need an smps that can supply twice the maximum average power of the class d amplifier
still do not understand what's the problem again?
just an example. our DPS-400 unregulated, has been developed and dimensioned for a good ripple, to provide continuous peak (continuous burst 33/66ms) of 500w. (even for 6 hours in this condition, with delta t of 50°)
Obviously, you can not connect to an amp 500wrms.
also, it is obvious that simple peak / rms value, to know this in formulas but not everyone knows that we perceive the vP out. vP is this that through the speaker causes the change in ambient pressure (not a rms value), so why fatigue and focus on rms power? This is another old story very confusing.
for your simulation, I think you have an error on the dead time (possibly in the cross point of the two MOSFETs).
the frequency of 82Hz or 400Hz does not change the peak power (obvious that changes from the side of psu, for the reasons that we know, relative to the low frequency of charging)
just an example. our DPS-400 unregulated, has been developed and dimensioned for a good ripple, to provide continuous peak (continuous burst 33/66ms) of 500w. (even for 6 hours in this condition, with delta t of 50°)
Obviously, you can not connect to an amp 500wrms.
also, it is obvious that simple peak / rms value, to know this in formulas but not everyone knows that we perceive the vP out. vP is this that through the speaker causes the change in ambient pressure (not a rms value), so why fatigue and focus on rms power? This is another old story very confusing.
for your simulation, I think you have an error on the dead time (possibly in the cross point of the two MOSFETs).
the frequency of 82Hz or 400Hz does not change the peak power (obvious that changes from the side of psu, for the reasons that we know, relative to the low frequency of charging)
Last edited:
The cheap tinny sound is distortion and not the good stuff - everything being turned up to 11 etc etc frying the voicecoils and overdoing the xmax
Most gigging guitarists don't appear to know what sounds classy to the audience unless they have a roady or someone who knows what they are doing with regard to the sound, they just play LOUD. And I hear a quite a few....
Heres a link http://www.eminence.com/pdf/Legend_1518.pdf to an Eminence bass driver. At 82Hz it about 22ohms and rises towards 100hz rapidly. Its the same shape of slope for almost every driver
Your math is correct - nobody is arguing that. But your presumption that the answer given is the only way overlooks 10's of millions of fully function class D amps from a few $ to $$$$ that dont use a power supply as you state. Therefor under the burden of that proof your presumption is shown to be wrong - simple math
As you didn't understand or know about a drivers ohm/freq relationship and are relying on a simulation only for the power supply I think you need to buy, build and see for yourself.
No. I already answered this before. And whether or not the PSU can supply twice the average output or not is irrelevant in a guitar amp. As is the maximum output. The most important thing in a guitar amp is it's sound characteristics and how it matches with your preferred guitar, strings, picks and pre-amps.
eem2am:
Of course the max instantaneous power draw is about double of the rated output power.
Simply also watch the instantaneous power in the load resistance, which you get by the direct multiplication of the load voltage times the load current.
The instantaneous power in the load resistance will show a sin² function.
It swings between zero and double of the rated power. Frequency of the power modulation is double of the frequency of the voltage modulation.
It is not like a 300W class D amp would draw 600W and dissipate 300W. No. It always draws a little bit more power (typically between 5% and 20%) than it transfers to the load. During the max of the sine you will find it drawing slightly more than double of the rated output power, during zero crossing of the load sine it will draw just very few power.
And yes, this gives headache to smps, which are designed for constant load of the rated power of the amp.
Electrically the smps must be able to deliver the max value of the instantaneous power. Thermally the smps can be designed much more relaxed than a smps for continuous power, because normal music program has a low average power (... how much lower is another discussion...)
Of course the max instantaneous power draw is about double of the rated output power.
Simply also watch the instantaneous power in the load resistance, which you get by the direct multiplication of the load voltage times the load current.
The instantaneous power in the load resistance will show a sin² function.
It swings between zero and double of the rated power. Frequency of the power modulation is double of the frequency of the voltage modulation.
It is not like a 300W class D amp would draw 600W and dissipate 300W. No. It always draws a little bit more power (typically between 5% and 20%) than it transfers to the load. During the max of the sine you will find it drawing slightly more than double of the rated output power, during zero crossing of the load sine it will draw just very few power.
And yes, this gives headache to smps, which are designed for constant load of the rated power of the amp.
Electrically the smps must be able to deliver the max value of the instantaneous power. Thermally the smps can be designed much more relaxed than a smps for continuous power, because normal music program has a low average power (... how much lower is another discussion...)
AP2
,....there is no error wih deadtime.....the high spikes of current that you see are are due to the DS capacitance of one fet being charged as the opposite fet turns on.......ferrite beads can be put in to lessen this in a real circuit but in a simulation its not worth it.
JRKO
yes i agree that there are lots of class d's out there that dont have the right power supply, and no one cares because they can still thrash their guitars with it....
But if you want a quality sound, such as the quality that you get from a Blackstar ID:100TVP amplifier then you need to use a power supply rated to twice the max avaerge power of the class d
ID:100TVP Guitar Amplifier - Blackstar Amplification
Chocoholic: You seem to be agreeing with me?...i believe you agree with me.....you are saying that the smps would need to be capable of supplying power at twice the max average power of the class d.
,....there is no error wih deadtime.....the high spikes of current that you see are are due to the DS capacitance of one fet being charged as the opposite fet turns on.......ferrite beads can be put in to lessen this in a real circuit but in a simulation its not worth it.
JRKO
yes i agree that there are lots of class d's out there that dont have the right power supply, and no one cares because they can still thrash their guitars with it....
But if you want a quality sound, such as the quality that you get from a Blackstar ID:100TVP amplifier then you need to use a power supply rated to twice the max avaerge power of the class d
ID:100TVP Guitar Amplifier - Blackstar Amplification
Chocoholic: You seem to be agreeing with me?...i believe you agree with me.....you are saying that the smps would need to be capable of supplying power at twice the max average power of the class d.
Last edited:
There is no such thing as a "quality sound" in guitar amps. The only thing that matters is if it produces the noises the player has in his head, or noises that inspire him/her to experiment. "Quality", whether in engineering, build or even reliability is definitely second place after sound. I've worked on tours where the tech has had to fix stuff after, (or even during), every gig, even when the musician is rich or well known enough to have any amount of "better" kit. If that sound is produced by an underrated psu then so be it.
AP2
Well all have spoken, but no one has really told what is the required power rating of smps to supply a class d amplifier such as the one in ID:100TVP amplifier
ID:100TVP Guitar Amplifier - Blackstar Amplification
Pinkmouse
Yes, i agree, but if you undersize the smps for a class d amplifier, then you will have a lesser range of sounds to offer from that class d amplifier.
This is why i am going on about this.
you need an smps that can provide the current for those peaks.....such as in the simulation provided in the first post.
My question still stands:
What power of smps is needed to supply a class d amplifier such as the ID:100TVP class d amplifier?
ID:100TVP Guitar Amplifier - Blackstar Amplification
Or are you saying that you do not know?
Its a simple question now.
What power of smps would be needed to supply the ID:100TVP?
Well all have spoken, but no one has really told what is the required power rating of smps to supply a class d amplifier such as the one in ID:100TVP amplifier
ID:100TVP Guitar Amplifier - Blackstar Amplification
Pinkmouse
Yes, i agree, but if you undersize the smps for a class d amplifier, then you will have a lesser range of sounds to offer from that class d amplifier.
This is why i am going on about this.
you need an smps that can provide the current for those peaks.....such as in the simulation provided in the first post.
My question still stands:
What power of smps is needed to supply a class d amplifier such as the ID:100TVP class d amplifier?
ID:100TVP Guitar Amplifier - Blackstar Amplification
Or are you saying that you do not know?
Its a simple question now.
What power of smps would be needed to supply the ID:100TVP?
Why are you posting here? You are sure your argument is correct and want to convince others but refuse to listen to those that know better
You dont understand how speaker drivers work (assumed it's a coil) how can you design a power supply for an amp that drives one? You obsess with 200% power coverage thinking it makes an important difference to the way the guitar will sound. ANY guitar player knows that the pickups, the strings, the pedals, the amp (saturated valves etc) and the player dictate the sound - the amp is also used to create 'tone'. Guitar amps are not hifi. They are deliberately hobbled to make a tone, to be overdriven etc etc
As you only appear to know the Blackstar(?) amp maybe try a few others that have been around a while. Marshal, orange etc
Please tell us what experience you have, what hifi gear you have, what you have built, what designs you have come up with that make you the expert and everyone else wrong
You dont understand how speaker drivers work (assumed it's a coil) how can you design a power supply for an amp that drives one? You obsess with 200% power coverage thinking it makes an important difference to the way the guitar will sound. ANY guitar player knows that the pickups, the strings, the pedals, the amp (saturated valves etc) and the player dictate the sound - the amp is also used to create 'tone'. Guitar amps are not hifi. They are deliberately hobbled to make a tone, to be overdriven etc etc
As you only appear to know the Blackstar(?) amp maybe try a few others that have been around a while. Marshal, orange etc
Please tell us what experience you have, what hifi gear you have, what you have built, what designs you have come up with that make you the expert and everyone else wrong
If you insist ingoring that power capability can not be described properly with only 1 number, if you are denying that power is depending on the waveform and other factors, then you will never be able to understand what we say. Also you ought have to learn what a speaker behaves like.
But build whatewer you like!
Just don't ask, if you are not willing to notice the answers.
If you have purely resistive load it will behave as said, but the smps does need to supply the extreme power just for some ms.
And in class AB it would be similar plus a higher adder for the amp losses.
Nevertheless the other comments here, that tell that a speaker is NOT a purely resistive load are valid.
What you really need will depend very much on the final use and speakers.
BTW: The discussed short term factor two is something that Hypex is stating and promoting for their smps since ages.
Please, concerns following table attached in an article I published in my web site:
In the table you'll see what power can charge amplifier at certain voltages and classes of operation, and electrical power required for its supply.
Article you can find here (use google translate):
Surse de alimentare liniare pentru amplificatoare audio - calcul, teorie, concluzii - Surse de alimentare - Tehnium Azi - Articole (Articles) - Comunitatea Tehnium Azi
If you have further questions, please ask me.
I am on the verge of building a "class d amp powered by smps", but first want to see exactly what is the lowest power of smps that i can get away with and still get a good guitar sound.
As you may have seen , my simulation shows that to sound out pure low frequencues needs a smps with a high power capability which is bad news....because its expensive.
I know that guitar sound quality is in the mind of the beholder, but i think there is a certain sound where everyone thinks its rubbish....
Anyway here is the Blackstar ID:260TVP
ID:260TVP Guitar Amplifier - Blackstar Amplification
It has two 12 inch speakers. Each of the class d amps is "60W"
...So what power level of SMPS would Blackstar likely have used to power the class d amplifiers in this combo amplifier?
Bearing in mind that Blackstar is a commercial company, and though their amplifiers are of the highest quality found anywhere in the world, they want to save money, because cheap Far Eastern imports are on the way.....
So now we know the class d power, we know its 12 inch speakers, so what power level of smps would be required to power this ?
I would think that you would have a general idea about the power level of smps.
(Also, I agree that i need to do homework on the variation of speaker impedance with frequency of audio signal applied to it....accepted)
However, the question still stands.....and i am very grateful for any answer concerning power of smps to supply the blackstar ID:260TVP.
(by the way, Thankyou DonPetru, much appreciated, i am looking for a translation program, but it appears to show some very good info)
As you may have seen , my simulation shows that to sound out pure low frequencues needs a smps with a high power capability which is bad news....because its expensive.
I know that guitar sound quality is in the mind of the beholder, but i think there is a certain sound where everyone thinks its rubbish....
Anyway here is the Blackstar ID:260TVP
ID:260TVP Guitar Amplifier - Blackstar Amplification
It has two 12 inch speakers. Each of the class d amps is "60W"
...So what power level of SMPS would Blackstar likely have used to power the class d amplifiers in this combo amplifier?
Bearing in mind that Blackstar is a commercial company, and though their amplifiers are of the highest quality found anywhere in the world, they want to save money, because cheap Far Eastern imports are on the way.....
So now we know the class d power, we know its 12 inch speakers, so what power level of smps would be required to power this ?
I would think that you would have a general idea about the power level of smps.
(Also, I agree that i need to do homework on the variation of speaker impedance with frequency of audio signal applied to it....accepted)
However, the question still stands.....and i am very grateful for any answer concerning power of smps to supply the blackstar ID:260TVP.
(by the way, Thankyou DonPetru, much appreciated, i am looking for a translation program, but it appears to show some very good info)
Last edited:
- Status
- Not open for further replies.