Thanks guys
I think we have had a very good debate and cleared many thoughts
I see no reason not to like a good debate
To me its been a good lesson in understanding how Nelson Pass have been able to design very cost effective products, without any loss in quality, and still rated as the best around, within its natural limits
This way FirstWatt products are available to everyman, and not just to rich people
One of the previous F# amps have been rated one of the 4 best amps in the world
Personally I dont like such ratings, but nonetheless it does tell something
But this is probably as good as it gets
Well, you know that
And we get this offered for free
When I tell my friends about whats going on here, they look at me like Im telling a fairy tale
I have fine amps already, and admit I bought boards just to have them, for later use
I now know I have to build these soon
Makes me feel good to think about it
Until then all I can do is talk
I think we have had a very good debate and cleared many thoughts
I see no reason not to like a good debate
To me its been a good lesson in understanding how Nelson Pass have been able to design very cost effective products, without any loss in quality, and still rated as the best around, within its natural limits
This way FirstWatt products are available to everyman, and not just to rich people
One of the previous F# amps have been rated one of the 4 best amps in the world
Personally I dont like such ratings, but nonetheless it does tell something
But this is probably as good as it gets
Well, you know that
And we get this offered for free
When I tell my friends about whats going on here, they look at me like Im telling a fairy tale
I have fine amps already, and admit I bought boards just to have them, for later use
I now know I have to build these soon
Makes me feel good to think about it
Until then all I can do is talk
ups
Hello mr Pass
Im looking
I think it was Srajan Ebaen at 6Moon saying that, Im quite certain
But it could be hiding somewhere in a speaker test
I will try and find it
Maybe it was another amp tested, and considered good but not to be compared with the FirstWatt amp, but that one should have in mind that the FirstWatt was considered among the 4 best in the world
something like that 🙂
Hello mr Pass
Im looking
I think it was Srajan Ebaen at 6Moon saying that, Im quite certain
But it could be hiding somewhere in a speaker test
I will try and find it
Maybe it was another amp tested, and considered good but not to be compared with the FirstWatt amp, but that one should have in mind that the FirstWatt was considered among the 4 best in the world
something like that 🙂
Ehh, I also think I remember that a FirstWatt amp was the one making Srajan Ebaen reconsider his status as a 100% tube amp fanatic 😀
I'm sure that you feel sick. So, I will post this as my last one about the power transformer sizing for F5, admitting that the content in my post#4016 had to be correct . . .
Here is the new one.
First, I assume that 300VA transformer is a minimum size for the F5 to operate for pure class A output powers for all different loads.
And, I have newly tried to approximate what should be the minimum size necessary for the F5 to operate up to "continuous" full 100W output power (class AB) with 2-ohm load as shown in the attachment. 700VA has be approximated for the continuous 100W sign wave with the 2-ohm load on the time axis . . .
But, the continuous 100W is considered unrealistic because I think that the music waves can't be so. The power of average music signal waves must require below 700VA . . . or might accept far below . . .
Therefore, if I choose the power transformer inbetween 300VA and 700VA, I must be in reasonably okay area . . .
Not insisting, just want to find myself going to right diection . . .
I have enjoyed all the discussions very much . . .
Thanks !!!
🙂
Here is the new one.
First, I assume that 300VA transformer is a minimum size for the F5 to operate for pure class A output powers for all different loads.
And, I have newly tried to approximate what should be the minimum size necessary for the F5 to operate up to "continuous" full 100W output power (class AB) with 2-ohm load as shown in the attachment. 700VA has be approximated for the continuous 100W sign wave with the 2-ohm load on the time axis . . .
But, the continuous 100W is considered unrealistic because I think that the music waves can't be so. The power of average music signal waves must require below 700VA . . . or might accept far below . . .
Therefore, if I choose the power transformer inbetween 300VA and 700VA, I must be in reasonably okay area . . .
Not insisting, just want to find myself going to right diection . . .
I have enjoyed all the discussions very much . . .
Thanks !!!
🙂
Attachments
jacco vermeulen said:
Finally, you learn the real meaning of "babo"
babo = not intelligent or able to judge things carefully, or silly . . .
I suggest we organize a vote in order to determine the size of the transfo. That would be democracy.
Electronics is not an exact science like pure mathmatics . . .
Approximate answers are adequate and even desirable . . .
Voting . . . Democracy . . . Yeah!
🙂
Approximate answers are adequate and even desirable . . .
Voting . . . Democracy . . . Yeah!
🙂
The 6Aac is the continuous AC current rating of the transformer. This extracted straight from the Pass F5 manual.Babowana said:
I have used "ac" to differentiate (to avoid confusion) it from a dc rating after the rectifier and capacitor input filter.
If you care to check you will find that 6 * [18+18] = 216VA
Babowana said:
isn't that 6A stated is the 6Adc, which is the continuous rail current for +/-24V?
I think we take the problem by the wrong bit. (not shure this is correct as direct french to english)
300va are plenty for 2x25w class A operation. (6 times the power)
300va are enough (100va margin) for 2x100w class Ab.
Has the F5 been designed to work continuously at 100w ? Although she can do it, do not think so. Her qualities lie in an other area. She is a bird rather than an elephant. The 2 ohms load capability permits to drive complex loads, this is what counts. The 100w have to be compared to the maximum speed a car can reach. Who drives ones car at its max speed continuously?
That is why, in my opinion, 300VA are plenty for two channels.
300va are plenty for 2x25w class A operation. (6 times the power)
300va are enough (100va margin) for 2x100w class Ab.
Has the F5 been designed to work continuously at 100w ? Although she can do it, do not think so. Her qualities lie in an other area. She is a bird rather than an elephant. The 2 ohms load capability permits to drive complex loads, this is what counts. The 100w have to be compared to the maximum speed a car can reach. Who drives ones car at its max speed continuously?
That is why, in my opinion, 300VA are plenty for two channels.
bobodioulasso said:
Class A is a constant load at max (driving at top speed- consuming fuel at max - the volume knob is just transferring the RPMs from the engines to the wheels... or not...). That is why 300VA is a minimum for a dual channel F5. I have 400VA for two channels, each working in a limited frequency range (low and high pass Xover in front) and around 500VA for two channels is about a bit of overkill, but not really. F5 would work with with less than 150VA per channel, but would not be happy with it... It's audible: the musical performance is just bearable with a 300VA transformer. With a proper 400VA and up for a two channel F5 one can hear the positive effects... So, when they ask me which one to use, I always tell them that F5 will work with 300VA, work very well with 400VA and excel with 500VA... (adding a couple of mFs also helps, some motor run caps speed the things up, fast diodes also, avoiding the use of the series resistors in the PS rails also helps, and there are many small things the amplifier depends on. F5 is a great amplifier even in a basic configuration, all the things I mentioned spice it up, bit by bit...
Hi Stein2
As an experiment could you try running those big motor caps along with a 1000uF cap in parallel and directly connect them to the source pins of the output mosfets and the other end of the caps run to ground.
I tried this on another amp and it made quite an improvement.
It is worth a try if you are the type that likes to experiment a bit.
As an experiment could you try running those big motor caps along with a 1000uF cap in parallel and directly connect them to the source pins of the output mosfets and the other end of the caps run to ground.
I tried this on another amp and it made quite an improvement.
It is worth a try if you are the type that likes to experiment a bit.
calvinhpk said:
As you see from the sketch in post #4065 . . .
I flipped over the negative wave to the positive side with respect to +24V rail to get the continuous 6Adc. Opposite way has the same effect with respect to -24V rail.
🙂
A ClassA amplifier dissipates maximum power in the quiescent state, if it is never asked to exceed the ClassA current limit.bobodioulasso said:
As the output current increases from zero to maximum ClassA output current the dissipation in the output stage progressively falls.
If our 27W into 8r0 amplifier is biased @ 1.3A and runs on +-24Vsupply rails, then during quiescent state the output stage dissipation is 1.3 * [24+24] = 62.4W.
When the sinewave output to a resistive load is 1W the dissipation drops to 62.4 - 1 = 61.4W
When 10W is output the dissipation is down to 52.4W.
When 27W is output the dissipation is down to 35.4W.
If that same amplifier goes into ClassAB then dissipation starts to increase again from that 35.4W minima.
At 100W output the dissipation has increased to approximately 60W.
Much the same as it dissipates at the quiescent state.
The F5 can operate all day at any power output from zero to 100W all day long. That is what is really nice about a properly designed push-pull ClassA amplifier.