according to fifth element its like adding more valves to the engine. So adding more valves will not increase the quality but quantity. The drive pleasure even if you drive 6valve or 12 valve engine is same. Not different cars...
same engine type and here when you add more valves for the engine it becomes more complicated in the design and same getting applied for the amplifiers...
same engine type and here when you add more valves for the engine it becomes more complicated in the design and same getting applied for the amplifiers...
not really....it's more like adding more cylinders and I have a 4 a 6 and a 8 cylinder cars and they all 3 drive significantly different getting better as the number of cylinders goes up and Valve's number goes up because bymber of piston goes up.
Engine gets more complex as well, but no question that is is going to have a better response and a better drivability overall!!
ahahahahah!!!
No but seriously the higher the bias the better the sound.
The fact that ideally less paralleling of FET would of course be better that is also another trade off.
There are so many variables involved that is hard to determine what is actually going to be the best/most suitable solutione.
Being unable to read the future, I like to go with the amp that is capable of driving anything (or almost).
What I am trying to figure out at this stage is the rough calculation upfront such as power dissiopation and bias per device and I am still not understanding well how can XA200.5 have 400W Class A but yet dissipating only 700W!
No but seriously the higher the bias the better the sound.
The fact that ideally less paralleling of FET would of course be better that is also another trade off.
There are so many variables involved that is hard to determine what is actually going to be the best/most suitable solutione.
Being unable to read the future, I like to go with the amp that is capable of driving anything (or almost).
What I am trying to figure out at this stage is the rough calculation upfront such as power dissiopation and bias per device and I am still not understanding well how can XA200.5 have 400W Class A but yet dissipating only 700W!
oh Gosh!!!! To begin with my name is Stefano.
After having understood this....why don't you delight me and instead of just speculating actually show me your skill and answer to my question?
This has nothing to do with the current production but rather a general mathematical question, so please don't give me that Cr**!!!!
Since I have detailed the simple formulas in my previous posts and these are 100% correct, now you match my question with that dude and show me where my flows are instead of posting your useless sarcasm!!
Somehow I get the impression you do not actually know what a push-pull output stage is/does.
A standard 200W class A power amp with a bipolar complementary PP output stage has a dissipation figure in the order of 450W.
700W is actually exceptionally high.
Part 1 is due to using vertical MOSFETs, the spare 5 volts on the rail story.
Part 2 is due to balanced operation : the extra rail losses double.
In a regular output stage : on top of the max output voltage comes 1 time the 5V.
For the bridged/balanced output : max output voltage, plus 10V (5V from the positive rail, plus 5V on the negative rail)
A regular push-pull output stage, biased at 5A, can do 10A peak in class A before it crosses over to AB.
400W peak class A in 8 ohm is ~56.6V and 7.1A
For the output node to be at 0V at idle, total current from the positive rail has to be identical to the current flowing to the negative one.
So current times rail voltage is the same for all quadrants (identical rail voltages)
So for 700W idle dissipation, 5A per rail.
0.75A single-ended current is about 4.5W
Ergo, to negative rail : 5 minus 0.75 = 4.25A bias for the P-channels.
Problem with single-ended current through resistors in parallel with active devices : it never stops flowing, and can get only get bigger !
Suppose the amp delivers 400W peak in 8 ohm :
=> +28.3V peak at one output node
=> 63.3V across the SE resistors (28.3V + 35V rail)
=> 80% more current flowing through the SE resistors (63.3/35 times 0.75A = 1.4A)
At the verge of crossing over to class AB ;
1 - P-channel output devices as good as closed
2 - current through the SE resistors from output to negative rail is ~1.4A
3 - output current to loudspeaker is 7.1A (7.1 *7.1 *8 = 400W)
1+2+3 => Current through the N-channels has to be 7.1 + 1.4 = 8.5A
(= Part 3 of the dissipation saga)
Part 1 + Part 2 + Part3 are the reasons why the dissipation level would be 700W to deliver the 200W class A.
Part 3 is the reason why SE power is in the order of 5 watts.
The 0.75A SE bias leads to a peak dissipation of close to 100W in the SE resistors at full amp output level.
Make it 1.5A (20W SE power):
- peak dissipation of ~200W in the SE resistors
- close to 100W more idle dissipation for the entire amp channel, 800 instead of 700W
Better picture =>
(pfff, me over and out)
A standard 200W class A power amp with a bipolar complementary PP output stage has a dissipation figure in the order of 450W.
700W is actually exceptionally high.
Part 1 is due to using vertical MOSFETs, the spare 5 volts on the rail story.
Part 2 is due to balanced operation : the extra rail losses double.
In a regular output stage : on top of the max output voltage comes 1 time the 5V.
For the bridged/balanced output : max output voltage, plus 10V (5V from the positive rail, plus 5V on the negative rail)
A regular push-pull output stage, biased at 5A, can do 10A peak in class A before it crosses over to AB.
400W peak class A in 8 ohm is ~56.6V and 7.1A
For the output node to be at 0V at idle, total current from the positive rail has to be identical to the current flowing to the negative one.
So current times rail voltage is the same for all quadrants (identical rail voltages)
So for 700W idle dissipation, 5A per rail.
0.75A single-ended current is about 4.5W
Ergo, to negative rail : 5 minus 0.75 = 4.25A bias for the P-channels.
Problem with single-ended current through resistors in parallel with active devices : it never stops flowing, and can get only get bigger !
Suppose the amp delivers 400W peak in 8 ohm :
=> +28.3V peak at one output node
=> 63.3V across the SE resistors (28.3V + 35V rail)
=> 80% more current flowing through the SE resistors (63.3/35 times 0.75A = 1.4A)
At the verge of crossing over to class AB ;
1 - P-channel output devices as good as closed
2 - current through the SE resistors from output to negative rail is ~1.4A
3 - output current to loudspeaker is 7.1A (7.1 *7.1 *8 = 400W)
1+2+3 => Current through the N-channels has to be 7.1 + 1.4 = 8.5A
(= Part 3 of the dissipation saga)
Part 1 + Part 2 + Part3 are the reasons why the dissipation level would be 700W to deliver the 200W class A.
Part 3 is the reason why SE power is in the order of 5 watts.
The 0.75A SE bias leads to a peak dissipation of close to 100W in the SE resistors at full amp output level.
Make it 1.5A (20W SE power):
- peak dissipation of ~200W in the SE resistors
- close to 100W more idle dissipation for the entire amp channel, 800 instead of 700W
Better picture =>
(pfff, me over and out)
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Its not sarcasm and I am typing on a phone, sorry. I am not the one claiming to know anything, but you continue to argue with ANYONE who does not just accept anything and everything you say. Why not just get the parts and start building. You act as if all the variables you speak of cannot be modified or changed in circuit. You can easily get the parts. You can easily get the heat sinks. You can easily get a custom Piltron toroid. What is stopping you. Drop $1500 and get to work. I am sincerely interested in the results. Don't know what else to say so I'll stop bothering you.
Jacco, you ever heard the phrase " beating a dead horse". Here ya go.
Jacco, you ever heard the phrase " beating a dead horse". Here ya go.
oh my gosh!!!! it is sarcasm from the phone. Just get and build? Are you an engineer or you sell horses?
Before building anything you study and model and analyze and count cost!!!
I am not starting now like I said I am finishing up other projects and I have just limited time available like anybody else in the world.
Tjhe project will start in the next few months.
In the meantime I take advantage to do the upfront work and to locate the right parts needed for the project.
Don't you see your contribute is extremely useless?????
Just go back and re-read your posts in this thread (I hope your contribute to other thread is better)!!!
You only make sarcastc comments that have no point!
So if that is your style of partecipating, then thanks but don't bother!
In other words...bye bye!
Yes except that you've missed one very important point, it's the bias PER DEVICE, that matters for the sound quality, not the total bias of the amplifier (unless you're leaving class A and then you're on a hiding to nothing).
With a low power class A you will say use 1 amp worth of bias and 20 volt rails with a single pair of output transistors. Each device dissipates 20 watts at idle. With a bigger amp you would use two pairs of output transistors biased to 1.5 amps on 30 volt rails, with each device seeing 0.75amps of bias total and dissipating 22.5 watts at idle. Maybe we want to go one step further and use 2 amps idle, 35 volt rails and 6 pairs of output transistors. Now each transistor is has 0.66 amps of current flowing and each one will dissipate 23.31 watts at idle.
Notice something? As the power rails increase in voltage, the bias PER DEVICE drops, to keep the dissipation for each device in check. If you're after an amplifier with the highest bias current, for supposedly the highest sound quality, then going for a lower power design is the only thing you can do!
Stafanoo, you need to be very careful when you make comments like that when your understanding of simple amplifier basics appears to be almost non existent.
It does mean lower quality, it is very simple, the output stage of the power amplifier will produce more distortion when driving a difficult load. A simpler crossover also does NOT give you better sound if the design is poor because of its simplicity - which the B&Ws are most certainly a consequence of. Ignoring that though, applying impedance compensation to the loudspeaker, so that it's easier to drive, does not impact on the frequency response or filter transfer functions one bit. All it does is reduce the stress put on the output stage, giving the amplifier an easier time and reducing the distortion that it will produce. Given a class A setting, if you've got a loudspeaker which is a bitch to drive, you might find you're leaving class A most of the time anyway. Compensate the loudspeaker design and now you're always in class A = better sound quality.
It is in my opinion that some loudspeaker manufactures like producing speakers that are difficult to drive because it helps encourage the whole 'I need a Krell' philosophy, that lots of audiophiles would be very happy to adopt.
As an example though KEF and Dynaudio have both used impedance compensation in some of their flagship designs to make them easier to drive. Why most don't do this is beyond me.
Price has nothing to do with it. If you've got a difficult loudspeaker to drive, then not even the XA200.5 is going to cut it. You need a monster Krell or a Kilowatt from MF. This is the point, difficult to drive loudspeakers and class A amps do not make for happy bed fellows. The loudspeaker has put a limit on your system which says, do not even consider class A as it's ill advised. The class A amp might cost $1,000,000 so surely you're not skimping, but it will sound terrible. This is one of the reasons why it would make lots of sense for you to measure what you need, even if you were going to buy something from the XA series measuring would make sense then too, because you might find you don't even need the XA200.5 and can easily do with the model below it, saving you some pennies and the planet from the reduced energy consumption.
None of that makes any sense. Even a monster Krell will sound better if the loudspeakers are easier to drive.
No, it seems that anything with a large price tag, in your opinion, is going to sound wonderful.
Building something like an XA200.5 as a first DIY amplifier project has the potential to turn into something the opposite of fun. This is one of the reasons why I recommend you build something lower power with less invested and a lot less to go wrong. At the very least measure how much voltage swing you need to reproduce music at a normal listening level, so you actually know how big you need to go, for it to work appropriately.
oh thanks for your insight 5th.
I didn't notice that current drops down as voltage goes up to check the fixed 19W Power dissipation's target!
Thank you so much!!!!
Ok now seriously, there are trade offs on both worlds and if you read NP's comment on Aleph X thread, he states that a good low power amp can sound just as good as a well designed high power's and vice-versa.
You might decide that dynamic and realm are not your cup of tea and decide that you don't need the extra power and you might go for a very high-efficiency low power approach which can be very neat too.
Myself, I go for the high power and wouldn't like to debate this since it is my personal choice I am the one who is gonna make it and listen to it.
This is not my first project, maybe you don't understand my background which is ok, it doesn't matter!
About speaker manufacturer desing's choice I don't criticize them as behind those there is a team of very experienced and skilled engineers who have worked on speakers for a long time.
If you don't like B&Ws don't get them and move on, but I wouldn't say they haven't forgotten something that you see because obviously they have noted the same thing long before you and that there is a reason as to why they have done that and you have to be willing to accept that they might be right as well.
Ultimetly the sound of the speaker is wonderful and the simple X250 can drive them very well with no problem, so I don't agree with you AT ALL that 800 are hard speakers to drive.
I see that needle moves a little out of the Class A zone which means that the speaker requires more than what the X250 can offer in terms of pure Class A.
Once more, I don't need to audition the XA200.5 to know it is a wonderful amp.
Obviously when I will bring my self to buy one I will audition that against 600.5 just because they are significantly different and I might prefer one over the other but no question they are both state of the art amplifications.
So bottom line I don't want to argue or I will stop posting, because it seems that people here are in the mood for argument and attacking and sarcasm.
I ask honest questions, if you don't feel like answering then don't, if you do, just asnwer polite that is my policy!!
I didn't notice that current drops down as voltage goes up to check the fixed 19W Power dissipation's target!
Thank you so much!!!!
Ok now seriously, there are trade offs on both worlds and if you read NP's comment on Aleph X thread, he states that a good low power amp can sound just as good as a well designed high power's and vice-versa.
You might decide that dynamic and realm are not your cup of tea and decide that you don't need the extra power and you might go for a very high-efficiency low power approach which can be very neat too.
Myself, I go for the high power and wouldn't like to debate this since it is my personal choice I am the one who is gonna make it and listen to it.
This is not my first project, maybe you don't understand my background which is ok, it doesn't matter!
About speaker manufacturer desing's choice I don't criticize them as behind those there is a team of very experienced and skilled engineers who have worked on speakers for a long time.
If you don't like B&Ws don't get them and move on, but I wouldn't say they haven't forgotten something that you see because obviously they have noted the same thing long before you and that there is a reason as to why they have done that and you have to be willing to accept that they might be right as well.
Ultimetly the sound of the speaker is wonderful and the simple X250 can drive them very well with no problem, so I don't agree with you AT ALL that 800 are hard speakers to drive.
I see that needle moves a little out of the Class A zone which means that the speaker requires more than what the X250 can offer in terms of pure Class A.
Once more, I don't need to audition the XA200.5 to know it is a wonderful amp.
Obviously when I will bring my self to buy one I will audition that against 600.5 just because they are significantly different and I might prefer one over the other but no question they are both state of the art amplifications.
So bottom line I don't want to argue or I will stop posting, because it seems that people here are in the mood for argument and attacking and sarcasm.
I ask honest questions, if you don't feel like answering then don't, if you do, just asnwer polite that is my policy!!
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Me been spanking Stefanoo for the last 6 years : http://www.diyaudio.com/forums/solid-state/31077-krell-ksa-50-pcb-130.html#post919106
So, why give up now ?
Who knows, maybe some other folks like to read my dribble on mixed SE-PP trivia.
ahahahaha....that was fun old time!!!
I was back in Italy back then...ohhhh...nice...miss that!!!
I think that the insight you are giving on the SE-PP are really usefull for everybody! but hey don't forget I like to learn new things and that is why I don't give up either and you are definitely more expert than I am in audio design.
I was back in Italy back then...ohhhh...nice...miss that!!!
I think that the insight you are giving on the SE-PP are really usefull for everybody! but hey don't forget I like to learn new things and that is why I don't give up either and you are definitely more expert than I am in audio design.
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