Member
Joined 2002
twitchie said:
I think i have the same heatsinks 🙂 when you power yours up im interested in knowing the tempature.
Jase
I had a chance to run F4's on a pair of Quad 989's last
Saturday. The sound was terrific (I was really impressed by the
speakers as well). The only problem was taking them home.
😎
Saturday. The sound was terrific (I was really impressed by the
speakers as well). The only problem was taking them home.
😎
Nelson Pass said:
What about the ol' "Well... would you look at what followed me home?" gambit?
Nelson Pass said:
The local shop is just breaking in a pair now... they sound really promising. And with the price of hi-end speakers today, they might well be classed a bargin
dave
Nelson Pass said:
As never before I can sense a real enthusiasm on Nelson’s part about the sonic abilities of one of his creations. That say a lot about the F4 and I’m looking forward to building one for my enjoyment.
Thanks once again Nelson for sharing this wonderful design. 🙂 😎
This is about the most off topic and giddy thread ever in the Pass forums!!!
But how can I blame you guys? Nelson just keeps coming up with "the coolest thing ever" .
This one gives wimpy amps "the power to do what needs to be done" and gives preamps "a reason to keep living..."
Party on.....
But how can I blame you guys? Nelson just keeps coming up with "the coolest thing ever" .
This one gives wimpy amps "the power to do what needs to be done" and gives preamps "a reason to keep living..."
Party on.....
.
Mr. Nelson Pass.
I'm very curious, which would you prefer driving a pair of B&W Matrix 801 S2's.
The "F4" or the "Aleph-X" ?
Mr. Nelson Pass.
I'm very curious, which would you prefer driving a pair of B&W Matrix 801 S2's.
The "F4" or the "Aleph-X" ?
Nelson Pass said:
ok-that means pair of F4 on a pair of 989 ?
puzzle is -takin' 989 pair home
or takin F4's home ?
Zen Mod said:puzzle is -takin' 989 pair home
or takin F4's home ?
Both, probably.
Leave them all there or take them all home, probably . . .
Nelson Pass said:
aah the singing mattresses i call them. The housing of the new ones ,the 2905, are significant different from the old one's they are nice.
A question for they who have build a F4 already; what is the degree celcius per watt of your heatsinks ?. Have done some time with the pcb cad program but I need to know if the heatsinks that i have in mind are large enough.
Jaac TheMaster said:
I don't know what rating you need, but the amount of current is the same as in aleph30, but you'll have 6 volts less rail to rail.
I have mounted my f4 in a temporary box (I'll put it in a different one when I finish my preamp). The heatsinks are 36x7x18cm, but the fins are horizontal, thus making the air flow resistance too high. You can't boil an egg on them, but after a couple of hours, I cannot hold my hand on the heatsinks for more than a few seconds.
Attachments
What do you think about DC protection and soft start circuit integrated on PCB? This amplifier is quite powerful 😉
veteran said:
The usual NTC is enough for softstart of the toroids, and there is no need to do tricks to avoid thumps, they have been removed by papa! 🙂
I have placed the fuse and NTC on a small scrap board to the left of the psu board.
It might be a good idea to have some speaker protection in case of transistor failure, if you have expensive speakers, but the circuit feels rock solid as it is.
I have almost the entire BOM for F4s, well, almost. The concern is that the input JFETs are nearly impossible to obtain in my country. I do have a bunch of BF244, BF256, 2N5461, 2N5486, a couple of 2N5459s and J111s and nothing else. Which of these can I use to get the F4 idea off the ground.
Any offers of JFETs on payment would be appreciated.
Any thoughts/offers?
Thanks Nelson, thanks all!!
Any offers of JFETs on payment would be appreciated.
Any thoughts/offers?
Thanks Nelson, thanks all!!
Further to Sam's question,
In my case I have two posiblities
J74/K170
or
J103/K246
Both on the BL flavor
Maybe the answer to which is best for the aplication is burried some place on the thread but cant find it.
In my case I have two posiblities
J74/K170
or
J103/K246
Both on the BL flavor
Maybe the answer to which is best for the aplication is burried some place on the thread but cant find it.
OK, I searched, but I haven't seen a reference to what a reasonable VA rating would be for a single transformer to feed both channels of the F4 ....
Variac said:
Papa have that in his white paper about PS-es
dissipation for both channels multiplied with ,say, 3 .........
for start
Variac said:
I use a 300 VA. This would be a continuous VA rating, and
you see various ratings for continuous vs short term and of course
this has to be taken with ambient temperature, frequency, and
power factor. When in doubt, Plitron.
😎