Hi all,
Just in the interest of trying something a bit different, any reason I can't sub a C2m1000170din for the IRF parts?. I've no particular reason to do so other than for fun and for experimentation. I see no reason why not, but I don't understand the reasoning behind the values for degeneration of the FET's and if that should be changed for the different parts.
Just in the interest of trying something a bit different, any reason I can't sub a C2m1000170din for the IRF parts?. I've no particular reason to do so other than for fun and for experimentation. I see no reason why not, but I don't understand the reasoning behind the values for degeneration of the FET's and if that should be changed for the different parts.
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thats a cool idea 🙂
in addition to the zen-masters comments ,
you'll also probably want to make sure you have enough voltage in the bias circuits to be able to supply about 7-8volts to the gates - see the datasheet curves - this looks like a purdy high threshold device. Maybe subbing 9 volt zeners for Z1 and 2 will do nicely.
Remeber to tell us what you find ....
in addition to the zen-masters comments ,
you'll also probably want to make sure you have enough voltage in the bias circuits to be able to supply about 7-8volts to the gates - see the datasheet curves - this looks like a purdy high threshold device. Maybe subbing 9 volt zeners for Z1 and 2 will do nicely.
Remeber to tell us what you find ....
Can do!
...whoa, scratch that until I find someone local who supplies these parts. The price locally at element 14 is twice as much. I'd better get googling 🙂
...whoa, scratch that until I find someone local who supplies these parts. The price locally at element 14 is twice as much. I'd better get googling 🙂
Just checked Spencer's web page and he is no longer offering the matched J74/K170 sets as of March 15th, so now what???
Diyaudio shop to the rescue:
http://www.diyaudio.com/forums/pass-labs/258022-ba-3-preamp-build-guide-14.html#post4274592
Contact Linear Systems and get a bunch of jfets. Matching is not hard. Just need some alligator clips, a meter with ammeter and a new 9v battery. Try to get jfets from the same lot, if possible. More likely to get good matches.
Sim issues
Hey all, anyone a SPICE guru? I've simmed the F6 with the Cree part as well as the trusty IRF part's and I appear to be simming whatever the opposite of an amplifier is... Ie I've got less voltage swing at the terminals than went in!
If anyone has some input I'd appreciate it.
...Actually, should I start a new thread or append this to the SIC fet thread or the original f6 thread? Please let me know 😀
Hey all, anyone a SPICE guru? I've simmed the F6 with the Cree part as well as the trusty IRF part's and I appear to be simming whatever the opposite of an amplifier is... Ie I've got less voltage swing at the terminals than went in!
If anyone has some input I'd appreciate it.
...Actually, should I start a new thread or append this to the SIC fet thread or the original f6 thread? Please let me know 😀
Attachments
Cheers ZM; I'll get back to you in about 6000 reply's. It does read like you guys had a lot of fun on that thread, however I wish there was a way to get the forum search to return a result on attachment filenames...
<edit> and I'm a donkey - the values I had for the inductance of the Jensen was way to low, and I've now solved that problem, although I've just thrown a number in as opposed to thrown the correct number in. Anyway, all good and back to work with the Sim!
<edit> and I'm a donkey - the values I had for the inductance of the Jensen was way to low, and I've now solved that problem, although I've just thrown a number in as opposed to thrown the correct number in. Anyway, all good and back to work with the Sim!
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Me had another idea. What about using Jfet after transformer to bias mosfet. Then you have more gain, mor DF, and more
Interesting possibilities.? Still can use local as well as overall feedback.
Interesting possibilities.? Still can use local as well as overall feedback.
Oddly enough, no. My thought was, adding that second device brings a lot of new options to the table, among them, some interesting feedback points. You also can switch the secondary windings and have non inverted phase. DF should do better as there is more feedback available, although not a ton. I would maybe even consider cascading the driver Jfet, just to improve conditions the transformer sees. Dunno. It's a thought that has been appearing from the shadows of my mind, on occasion. Not simple, but possibly interesting. Still my faves amp, and still like SS better🙂
PCB for the diyAudio store are on order. The build guide is currently in-progress.
To begin, there will be a limited release (25 sets) of PCB only. Later on, once the transformers are made, there will be a set of Jensen transformers+PCB available.
It's doubtful that the Jensen transformers will be available by themselves in the diyAudio store. (The margins are just too narrow to make it work.) Jensen can take orders from individuals, so if you want transformers alone, buy from them. 🙂
To begin, there will be a limited release (25 sets) of PCB only. Later on, once the transformers are made, there will be a set of Jensen transformers+PCB available.
It's doubtful that the Jensen transformers will be available by themselves in the diyAudio store. (The margins are just too narrow to make it work.) Jensen can take orders from individuals, so if you want transformers alone, buy from them. 🙂