Would two BOSOZ's in series drive the F4 enough to power regular speakers as well as say, Aleph 30's
How about using a couple of LM3875 as preamp? With one of them inverting it should be possible to run the F4 balanced. Maybe...
🙄
Iwahn
🙄
Iwahn
I thought all the First Watt product used the same chassis...assuming that the gears of my cognition have not stripped (no guarantees), it'll look the same as the other fellas.
Grey
Grey
I specifically asked because this one seems to need a LOT of heatsink- more than most of the previous amps I think? Members seem to be happiest with heatsinks that are almost 30x30 by 50 cm per channel I believe and that's a lot bigger than the typical First Watt chassis I think.
If in fact Nelson uses the same heatsinks as before, with their horizontal orientation, it shows that the requirements are not quite as onerous as implied..
PLus the face plate will look different....😉
If in fact Nelson uses the same heatsinks as before, with their horizontal orientation, it shows that the requirements are not quite as onerous as implied..
PLus the face plate will look different....😉
Variac said:
As far as I recall the F4 actually dissipates a bit less than the usual SE/CCS amps from NP. Approx 80 watts per channel.
Usually this figure is 100 watts.
Steen🙂
Let's say 2 amps bias per SE channel bij 44 volt is 88 Watt in class A to dissipate in a heatsink. So lets see the specs for thermal resistance of a irfp240
Tj-c =0,83K/W, Tc-s = 0.24K/W 0,5 K/W for an isolation plate and lets put al six on one 0,3 K/W heatsink (200mm SK56 from fisher).
Thats 1,8K/W best for a single FET. Gives me a total of 3.37K/W from junction to ambient.
One FET dissipates 88/6 Watt multiplie that by the 3,37K/W gives 49,4 K above ambient for the junction temp.
I think or was it to quick and simple ??
Tj-c =0,83K/W, Tc-s = 0.24K/W 0,5 K/W for an isolation plate and lets put al six on one 0,3 K/W heatsink (200mm SK56 from fisher).
Thats 1,8K/W best for a single FET. Gives me a total of 3.37K/W from junction to ambient.
One FET dissipates 88/6 Watt multiplie that by the 3,37K/W gives 49,4 K above ambient for the junction temp.
I think or was it to quick and simple ??
That fiendish Nelson seems to design his projects to fit the case!
Actually I'll bet he figured that first Watt will probably never exceed 25w/ch class A and ordered the case from there..
Ok OK - I guess I now know what it will look like....
Best advice on the heatsinks was "Crank up the bias until its at max allowable temp" Then I guess you can measure the bias and decide if that's enough. There never seems to be "too much" 😉
If not enough: mas heatsink.
Actually I'll bet he figured that first Watt will probably never exceed 25w/ch class A and ordered the case from there..
Ok OK - I guess I now know what it will look like....
Best advice on the heatsinks was "Crank up the bias until its at max allowable temp" Then I guess you can measure the bias and decide if that's enough. There never seems to be "too much" 😉
If not enough: mas heatsink.
Not completely true.
NP announced the F6, a monoblock Power Jfet Amp delivering approximately 40 watts into 8 ohms.
It may share the same case or it may be bigger.
NP announced the F6, a monoblock Power Jfet Amp delivering approximately 40 watts into 8 ohms.
It may share the same case or it may be bigger.
Say What, power JFET ?
There goes my Lovoltech power amp wish, and what happened to numero cinque ?
There goes my Lovoltech power amp wish, and what happened to numero cinque ?
Yes, F6 is a "double" F3
He didn't mendioned F5.
You can read the full story at 1stW web site / watt's new
He didn't mendioned F5.
You can read the full story at 1stW web site / watt's new
Ah, i see WattPapa is into dice and shooting Mon Capitaine Crab games as well.
For a minute there i thought the F6 had the JFEts on the booty side.
For a minute there i thought the F6 had the JFEts on the booty side.
massimo said:
first thought.......probably susy-ed stereo F3 in mono block ;
that means "in the form of the F6, which is a two stage direct coupled circuit delivering approximately 40 watts into 8 ohms" from Papa's FW site
Maybe not excactly a Blues frontend, which is mostly working as a J-fet buffer, but I guess too that if there is an additional gainstage its a J-fet thing. Maybe more like a diffpair, assuming its a X'ed F3? The F5 could be the active crossover for mating a woofer to a fullrange speaker. Seems we are not gonna get bored for a while😉massimo said:
Steen 🙂