Is this transformer OK to be use with the FirstWatt F1-F4 amplifier?
Plitron, Product ID: 077014201
300VA Power Transformer
Output: 2 X 18VAC @ 8.33A
Plitron, Product ID: 077014201
300VA Power Transformer
Output: 2 X 18VAC @ 8.33A
For the input FET's 2SK370 and 2SJ108, what is the best type to use
GR: 2.6-6.5ma, BL: 6-12ma or V: 10-20ma?
Thanks...
SB
GR: 2.6-6.5ma, BL: 6-12ma or V: 10-20ma?
Thanks...
SB
Algar_emi said:For the input FET's 2SK370 and 2SJ108, what is the best type to use
GR: 2.6-6.5ma, BL: 6-12ma or V: 10-20ma?
Thanks...
SB
BL
On the F2 schematic, there is a L1 choke just before R23-R26.
What was its value?
No reply for the transfo rating, any comments?
What was its value?
No reply for the transfo rating, any comments?
Algar_emi said:On the F2 schematic, there is a L1 choke just before R23-R26.
What was its value?
No reply for the transfo rating, any comments?
that L Papa drew as self inductance of WWnd resistors ;
that xformer will have ~ 25V unloaded per leg ;
can you compare that with power consumptions and used voltage in each of F amps?
What do you mean Zen Mod? The schematic is referring to 18V secondary.
can you compare that with power consumptions and used voltage in each of F amps?
Algar_emi said:What do you mean Zen Mod? The schematic is referring to 18V secondary.
OK there it is :
stereo F1 need +24V at 200VA
stereo F2 need +24V at 150VA
stereo F3 need +46V at 200VA
stereo F4 need +/- 24V at 160VA
so - your xformer is just enough for each of them .
So I got these results:
Power Needed:
stereo F1 need +24V at 200VA = 4A per channel = Plitron 057014201, 160VA, 2X18V, 4.44A
stereo F2 need +24V at 150VA =3.2A per channel= Plitron 047014201, 120VA, 2X18V, 3.33A
stereo F3 need +46V at 200VA =2.2A per channel= Plitron 057014201, 160VA, 2X18V, 4.44A
stereo F4 need +/-24V at 160VA = 3A per channel = Plitron 047014201, 120VA, 2X18V, 3.33A
Power Needed:
stereo F1 need +24V at 200VA = 4A per channel = Plitron 057014201, 160VA, 2X18V, 4.44A
stereo F2 need +24V at 150VA =3.2A per channel= Plitron 047014201, 120VA, 2X18V, 3.33A
stereo F3 need +46V at 200VA =2.2A per channel= Plitron 057014201, 160VA, 2X18V, 4.44A
stereo F4 need +/-24V at 160VA = 3A per channel = Plitron 047014201, 120VA, 2X18V, 3.33A
well here it is.....damned if it didn't work straight out of the box...I've been running it for about an hour being fed by my creative zen and it sounds good through the cheapo test(£4each) speakers...cold bias was no prob and dc set to zero no prob
can only get the fets to about 38degs so far...I think I was being over cautious by spreading them out on the sink..mmmmm
can only get the fets to about 38degs so far...I think I was being over cautious by spreading them out on the sink..mmmmm
Attachments
Algar_emi said:So I got these results:
Power Needed:
stereo F1 need +24V at 200VA = 4A per channel = Plitron 057014201, 160VA, 2X18V, 4.44A
stereo F2 need +24V at 150VA =3.2A per channel= Plitron 047014201, 120VA, 2X18V, 3.33A
stereo F3 need +46V at 200VA =2.2A per channel= Plitron 057014201, 160VA, 2X18V, 4.44A
stereo F4 need +/-24V at 160VA = 3A per channel = Plitron 047014201, 120VA, 2X18V, 3.33A
nope ; maybe I wasn't clear - sorry .
check that again ;
what I wrote are Voltages and power consumptions ;
you must increase wattages of xformer at least for 50% , looking at my post ........... even better - double wattage .
so :
stereo F1 +24V at 200VA - xformer min 300VA
stereo F2 +24V at 150VA xformer min 225VA
stereo F3 +46V at 200VA xformer min 300VA
stereo F4 +/- 24V at 160VA xformer min 240VA
vitalstates said:well here it is.....damned if it didn't work straight out of the box...I've been running it for about an hour being fed by my creative zen and it sounds good through the cheapo test(£4each) speakers...cold bias was no prob and dc set to zero no prob
can only get the fets to about 38degs so far...I think I was being over cautious by spreading them out on the sink..mmmmm
😉
seems that you can squeeze two F4s on those heatsinks
Zen Mod said:
😉
seems that you can squeeze two F4s on those heatsinks
Naah, it seems like he can bias his fets at 400mA per device 😀
Magura 🙂
Member
Joined 2002
Algar_emi said:Is this transformer OK to be use with the FirstWatt F1-F4 amplifier?
Plitron, Product ID: 077014201
300VA Power Transformer
Output: 2 X 18VAC @ 8.33A
Here ya go,
http://www.plitron.com/shopping/shopexd.asp?id=162
http://www.diyaudio.com/forums/showthread.php?s=&threadid=104773&perpage=50&pagenumber=1
First thoughts on the F4...
I took it to a local meet of valve heads yesterday(Daniel in the lions den)...
The general concensus was that it was a bit clinical and sharp but in fairness the damned thing wouldn't warm up....sooooo
I upped the bias to 250mv and it got hot pdq....Without exception in about 10 minutes everybody was tapping their feet and all agreed it took on another personality, far more liquid and dare I say it ..far more valve like.
during the conversation somebody was swapping out a black gate from one of the amps and I casually asked its value.......
tee hee the F4 was put together for less than the price of 1 cap.......
I love it already and its only done about 20 hours..future looks rosy
Thanks Nelson
Regards
Ed
I took it to a local meet of valve heads yesterday(Daniel in the lions den)...
The general concensus was that it was a bit clinical and sharp but in fairness the damned thing wouldn't warm up....sooooo
I upped the bias to 250mv and it got hot pdq....Without exception in about 10 minutes everybody was tapping their feet and all agreed it took on another personality, far more liquid and dare I say it ..far more valve like.
during the conversation somebody was swapping out a black gate from one of the amps and I casually asked its value.......
tee hee the F4 was put together for less than the price of 1 cap.......
I love it already and its only done about 20 hours..future looks rosy
Thanks Nelson
Regards
Ed
vitalstates said:
I upped the bias to 250mv and it got hot pdq....Without exception in about 10 minutes everybody was tapping their feet and all agreed it took on another personality, far more liquid and dare I say it ..far more valve like.
If you got the heatsink for it, you would get even more of what you obviously like by upping the bias even further. Another way to get the same result, but with less power and heatsink is to simply disconnect 1 FET from each bank and give them like 400mA each (or more if you have the heatsink for it). The upper limit for the devices is well over 3A each.
Magura 🙂
Wow, excellent report, and wonderful suggestions... so, with a hefty water cooled heatsink, I could up the bias from 200 mA to what value?
Magura suggests that each power fet can handle 3 amps. Forgive my ignorance, but with 6 power fets, is that a combined total of 18 amps, or does the fact that it's push/pull make it 9 amps continuous. At any rate, that's a lot of transformer and one huge power supply!😀
Magura suggests that each power fet can handle 3 amps. Forgive my ignorance, but with 6 power fets, is that a combined total of 18 amps, or does the fact that it's push/pull make it 9 amps continuous. At any rate, that's a lot of transformer and one huge power supply!😀
carpenter said:Wow, excellent report, and wonderful suggestions... so, with a hefty water cooled heatsink, I could up the bias from 200 mA to what value?
Magura suggests that each power fet can handle 3 amps. Forgive my ignorance, but with 6 power fets, is that a combined total of 18 amps, or does the fact that it's push/pull make it 9 amps continuous. At any rate, that's a lot of transformer and one huge power supply!😀

ya can't be serious ....... off course that that's 3A through each pair ;
that reminds me on one of my brilliant attempts when I tried to connect AC/DC feedback to LTP via xformer ........ which already have driver role
complicated to describe without picture , but believe me - that was brilliant idea !

Hey Ed,
Are you running single-ended inputs, or running as a balanced pair monoblock? I'm curious how this affects the sonics.
Are you running single-ended inputs, or running as a balanced pair monoblock? I'm curious how this affects the sonics.
Zen Mod said:
ya can't be serious ....... off course that that's 3A through each pair ;
Naah, that's per device

Magura 🙂
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