Being a newbie, I have taken to ohming out the connection between heatsink and device. It has saved me at least once.
Hi all,
I am trying to put together a Mouser order and have a few queries, i would appreciate if anybody can help with the following.
-2SK170/2SJ74 and 2SK370/2SJ108 FETs are obsolete, can anybody recommend any suppliers or substitutes for these parts?
-Resistor Values, the DIYAudio BOM and Schematic has some different values from the original FirstWatt F4 Schematic. I remember reading something about the 10R being preferred, anything to this or just run with the DIY BOM?
R3,R4 = 22R vs 10R
R8 = 22.1K vs 27.4K
R10 - R15 = 100R vs 150R
Thanks,
Mark
I am trying to put together a Mouser order and have a few queries, i would appreciate if anybody can help with the following.
-2SK170/2SJ74 and 2SK370/2SJ108 FETs are obsolete, can anybody recommend any suppliers or substitutes for these parts?
-Resistor Values, the DIYAudio BOM and Schematic has some different values from the original FirstWatt F4 Schematic. I remember reading something about the 10R being preferred, anything to this or just run with the DIY BOM?
R3,R4 = 22R vs 10R
R8 = 22.1K vs 27.4K
R10 - R15 = 100R vs 150R
Thanks,
Mark
Please begin at the begining of this thread, most things are explained very very well.
About the 2sk170 and 2sJ74 you can buy the new equivalents from the DIY audio store or seek out a seller of vintage parts such as FETaudio.
Cheers!
About the 2sk170 and 2sJ74 you can buy the new equivalents from the DIY audio store or seek out a seller of vintage parts such as FETaudio.
Cheers!
Just gone through the entire thread again and not seeing anything to do with the schematic differences?
I seen the LSJ74 and LSK170 in the store but wasnt 100% if they were direct replacments, and besides i dont want to buy eight of them @$47 when i only need two of each. Sent a message to FETAudio to see if they can help..
Cheers,
Mark
Hey guys, all things being equal, which will be better at driving 4 ohms speaker? An F4 or an F5 Turbo V2?
Hi Mark,
There is an exchange in the main F4 thread regarding the differences starting here:
http://www.diyaudio.com/forums/pass-labs/97540-f4-power-amplifier-416.html#post4042488
Cheers,
Dennis
Thanks Dennis, i must have missed that part when skimming through the thread. I have ordered both sets of resistors so i'll go with the First Watt schematic values, just seems odd the DIYAudio schematic hasn't been corrected.
To save others the time searching in the future i got some matched sets of the 2SK170/2SJ74 FETs from here Store FET Audio | Hi-End Audio Projects
And the main IRFP240 & IRFP9240's from h_a here http://www.diyaudio.com/forums/swap...fets-your-f1-f4-f5-aleph-j-6.html#post2853398 Hannes can also supply the K170/J74 and TL431's as a complete set.
Thanks for the help folks..
Hello Guys,
a quick question: I am putting together the PSU for an F4, diyAudio Store PSU, and I am getting 25.4 and -25.7 volts out without the amp boards connected. Is this ok for an F4? If it is too high, what do I need to do to get it down? down to how much?
Thank you for you time.
p.
a quick question: I am putting together the PSU for an F4, diyAudio Store PSU, and I am getting 25.4 and -25.7 volts out without the amp boards connected. Is this ok for an F4? If it is too high, what do I need to do to get it down? down to how much?
Thank you for you time.
p.
It will drop to 22.5-23.0V once you connect a load to it. Unloaded, it's measuring perfectly. 🙂
You are awesome 6L6! I am moving slowly but I'm getting there. The more I do, the more interesting it gets. To see those red leds light up with no smoke was... priceless!
Thank you again, all the best.
p.
Thank you again, all the best.
p.
Lots of folks wisely suggest it's impossible to tell without more information. I'll venture from the nature and phrasing of the question you'd be happier with the F5v2. I'm doing that kind of driving (KEF 104/2s) with an F5v2 right now. I'm very happy with the combination.
I'm also building an F4 so at some date in the future I may be able to speak more directly to you question at least regarding driving this one kind of 4 Ohm speaker.
cheers!
Lots of folks wisely suggest it's impossible to tell without more information. I'll venture from the nature and phrasing of the question you'd be happier with the F5v2. I'm doing that kind of driving (KEF 104/2s) with an F5v2 right now. I'm very happy with the combination.
I'm also building an F4 so at some date in the future I may be able to speak more directly to you question at least regarding driving this one kind of 4 Ohm speaker.
Hi jdg, thks for your respond. I had considered the F5V2 as well as the F4 & BA-2/3. I decided to go with the BA-3 with +/- 24v rails as suggested by Zen Mod & 6L6 for my 4 ohm speakers. I'm sure the F5V2 will be something special, but the BA-3's no feeback design intrigue me, so BA-3 it is. The F4 is also very special as well, & it's so versatile in it's implementation in the audio chain, I'm sure you will be delight by it. Heck, any FW amp is special!
Big transformers can be had on ebay. How about 1kva for 65usd? Thats what I paid. EI core, not toroid.
Hi all and thanks 6L6 for great explanations. I have two F4 to build, got most of the parts except PSUs, will use DIYAudio when store will be back.
Questions :
1/ 400VA Trafos I ordered have one primary winding 230v. Is it okay or is it better to stick with the 2x115 ?
2/ is it okay then to place the thermistors in serie with one side of the winding. I guess yes but would prefer to know while I can change my order.
Thanks a lot
Jean-Louis
Questions :
1/ 400VA Trafos I ordered have one primary winding 230v. Is it okay or is it better to stick with the 2x115 ?
2/ is it okay then to place the thermistors in serie with one side of the winding. I guess yes but would prefer to know while I can change my order.
Thanks a lot
Jean-Louis