I have no idea of Proop's sink and ambient data.
But we can start with some assumptions to show what we might expect to see.
Ta=21degC
Rth s-a = 0.5C/W
Rth c-s = 0.4C/W
Power dissipated @ 0.6Vbias = 30W
Delta T s-a = 30 * 0.5 * de-rating Factor (try 1.3 for dT=15C) = 19.5Cdegrees.
Delta T c-s = 30 * 0.4 = 12Cdegrees.
For 0.71Vbias the dissipated power rises to 35.5W
Delta T s-a = 35.5 * 0.5 * DF (try 1.28 for dT= 17.75C) = 22.7Cdegrees.
Delta T c-s = 35.5 * 0.4 = 14.2Cdegrees.
The data for these sets of Vbias assumed conditions would be
Vbias=0.6 Ts= 40.5degC, Tc= 52.5degC
Vbias=0.71 Ts'=43.7degC, Tc'= 57.9degC
One can insert the data for one's own hardware/ambient and predict (model) the temperatures to be expected before one even buys the hardware.
In this case increases the bias current by 18.3% should increase the FET temperature by ~5.4Cdegrees. From there one can estimate the reduction on SOAR for the higher bias.
But we can start with some assumptions to show what we might expect to see.
Ta=21degC
Rth s-a = 0.5C/W
Rth c-s = 0.4C/W
Power dissipated @ 0.6Vbias = 30W
Delta T s-a = 30 * 0.5 * de-rating Factor (try 1.3 for dT=15C) = 19.5Cdegrees.
Delta T c-s = 30 * 0.4 = 12Cdegrees.
For 0.71Vbias the dissipated power rises to 35.5W
Delta T s-a = 35.5 * 0.5 * DF (try 1.28 for dT= 17.75C) = 22.7Cdegrees.
Delta T c-s = 35.5 * 0.4 = 14.2Cdegrees.
The data for these sets of Vbias assumed conditions would be
Vbias=0.6 Ts= 40.5degC, Tc= 52.5degC
Vbias=0.71 Ts'=43.7degC, Tc'= 57.9degC
One can insert the data for one's own hardware/ambient and predict (model) the temperatures to be expected before one even buys the hardware.
In this case increases the bias current by 18.3% should increase the FET temperature by ~5.4Cdegrees. From there one can estimate the reduction on SOAR for the higher bias.
Last edited:
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-148.html#post2120209
post #7367 last measurements
post #7305 The amplifier heatsink 280x280x70-40
ambient 20.5 oC
this type of fins
Last edited:
Thanksvitalica,
I was wondering a few things...
what do you hear as the difference in the sound between the balanced and regular?
My friend who is a pianist says the sound is very neutral, especially the voices feel the difference.
what did you use for the resistors in series with the Mosfets?
Output MOSFETS are 2SK1530/2SJ201.
Source resistor 0R22 & 0R18 respectively.
whose balance schematic did you use?
The scheme is of Patrick (EUVL) - XF5.
I thank you very much for the help of the PCB and comp
what are those three pin devices that are in the front on the bottom??
Can you tell me exactly what you mean?
and finally, after how long did you measure the temperature of the heatsinks??
I too thought they might not be large enough and/or perhaps in that orientation they would not work so well...
Did I answer yesterday because I wanted to measure once again
I left the amplifier to function without signal 3 o'clock.
Over a time temperature was 45 degrees
50 degrees in two hours
more than 3 hours 54 degrees.
Do you think we should see what happens more than 5-6 hours?
Oh, you said "2A" bias - measured how?
I measured the voltage drop 0,22R (0,44V)
_-_-bear
Forgot to mention - very nice looking job!
Last edited:
.. revival ....................................... 
without revealing too many "secret details" over this way a number of experiments have been run regarding the power supply rails to the front end of the F5. It is daunting. Changes in that path appear at this point to radically effect the sound presentation!
FYI, and FWIW...
Anyone who wants to post pix of their competed F5s and comment on their sound may feel free to do so...
_-_-bear
FYI, and FWIW...
Anyone who wants to post pix of their competed F5s and comment on their sound may feel free to do so...
_-_-bear
You mean necroposting?
ahh, a chi, chi, approaches................ 
Bear :
Are you saying how it is connected to the board is also very important as to , distance ? wire size ?
.
Last edited:
wire size and length might have an effect.
it seems that everything has some sonic effect with this amp, so far.
the question is degree and significance to any given listener in any given system?
there are all sorts of variants that one can experiment with in a circuit... some have been tried here and seem to alter the sonic presentation more than one might anticipate, that's what I said...
_-_-
it seems that everything has some sonic effect with this amp, so far.
the question is degree and significance to any given listener in any given system?
there are all sorts of variants that one can experiment with in a circuit... some have been tried here and seem to alter the sonic presentation more than one might anticipate, that's what I said...
_-_-
Hey Vitali,
> After several days, I finished two F5 balanced monoblock.
That PCB looks familiar !!
I am glad that they are now sitting in a housing that is worthy of them.
Very well designed.
And I recognise that transformer as well.
But I still see Fairchild MOSFETs in your photos.
When did you change them to Toshiba's ?
> without revealing too many "secret details" over this way a number of experiments have been run regarding the power supply rails to the front end of the F5.
> It is daunting.
> Changes in that path appear at this point to radically effect the sound presentation!
You mean you are running separate rails for the input and output stages ?
Good luck.
Patrick
> After several days, I finished two F5 balanced monoblock.
That PCB looks familiar !!
I am glad that they are now sitting in a housing that is worthy of them.
Very well designed.
And I recognise that transformer as well.
But I still see Fairchild MOSFETs in your photos.
When did you change them to Toshiba's ?
> without revealing too many "secret details" over this way a number of experiments have been run regarding the power supply rails to the front end of the F5.
> It is daunting.
> Changes in that path appear at this point to radically effect the sound presentation!
You mean you are running separate rails for the input and output stages ?
Good luck.
Patrick
I'm not sure why there are 'secret' details. The circuit is patented, and Nelson has been so generous as to share, as have Patrick, Peter, Magura, ZM, etc. That's how this forum works.
All I said is that there are all sorts of variations on supplying power to the front end that can be tried. We tried a few - on paper at least there ought to be no audible difference - in reality things seemed to change by a fair amount depending on what was done. Take your pick of ideas...
Similarly there are all sorts of variations on the main supply - they all seem to have some sort of effect on the final "sound".
(shhh... let's keep this secret, just between you and me, ok?)
_-_-bear
Similarly there are all sorts of variations on the main supply - they all seem to have some sort of effect on the final "sound".
(shhh... let's keep this secret, just between you and me, ok?)
_-_-bear
The circuit is not patented. It is not even highly original.
One man's ceiling is another man's floor.
> Hey EUVL, if you don't mind me asking, did you share your pcb design?
No, and I do not have a habbit to. But you can see my original build here :
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-30.html#post1538826
and another hint :
http://www.diyaudio.com/forums/pass-labs/155599-f5-listening-impressions-discussion.html#post1994725
Patrick
No, and I do not have a habbit to. But you can see my original build here :
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-30.html#post1538826
and another hint :
http://www.diyaudio.com/forums/pass-labs/155599-f5-listening-impressions-discussion.html#post1994725
Patrick
Last edited: