Mr C,
i'd use 240s on top and 9140s down below.
My last 2 amputee projects had complementary vert. mosfets PP output stages, JAM's Mosfet A40 and Mr Greg Ball's GB50d, both run in full Class A.
On both, switching from IRFP9240 to the lower voltage capable 9140 was a major improvement.
I think it's a darn shame for the F4 to breathe on 9240s.
Now, where are the bigguns ?
(i is an oddball, at some point it gets easier to live with)
i'd use 240s on top and 9140s down below.
My last 2 amputee projects had complementary vert. mosfets PP output stages, JAM's Mosfet A40 and Mr Greg Ball's GB50d, both run in full Class A.
On both, switching from IRFP9240 to the lower voltage capable 9140 was a major improvement.
I think it's a darn shame for the F4 to breathe on 9240s.
Now, where are the bigguns ?
(i is an oddball, at some point it gets easier to live with)
I just had an amazing experience. I live in a town of 2000 people in Vermont. Our local hardware store/lumber yard is also a Radio Shack. I walked in there at 5 pm on a Saturday night and was able to walk out with a fist full of the appropriate resistors to make my F-4's match the updated schematic.
It is amazing to me that I was able to do that. Well, back to the man cave as my wife calls it. I have my own room too. 16' X 32'. Unfinished, but concrete walls and floor are the beginnings of a killer listening room. I do have my system set up in it presently and the size and layout of the room make it better than I've had before. I'm afraid that if I waited to do my F4 until it was done, I would never finish it.
It is amazing to me that I was able to do that. Well, back to the man cave as my wife calls it. I have my own room too. 16' X 32'. Unfinished, but concrete walls and floor are the beginnings of a killer listening room. I do have my system set up in it presently and the size and layout of the room make it better than I've had before. I'm afraid that if I waited to do my F4 until it was done, I would never finish it.
16 x 32....
You could build one heck of a bass horn in one end of that bad boy!
I'm so sick of cluttering up the great-room that I absolutely must finish my hobby room before starting any other project. Now that winter's approaching, I know that if I begin the F4, there will be no stopping..... like ahh....what hobby room?
Congrats with locating those resistors on short notice.
You could build one heck of a bass horn in one end of that bad boy!
I'm so sick of cluttering up the great-room that I absolutely must finish my hobby room before starting any other project. Now that winter's approaching, I know that if I begin the F4, there will be no stopping..... like ahh....what hobby room?
Congrats with locating those resistors on short notice.
carpenter said:
benefit is in certainly better symmetry between upper and lower part of signal , when amp leaves portion where it works in A class .
setting offset isn't even slightly easier to set , in case of super duper everything matched .....
but- for real benefit - matching of lower and upper part of amp must be dynamic, not static ............ so - just forget about it ..........
So, the new parts are in and the story is the same. 155 mV max bias with no DC offset. I'm stumped, but not giving up. The mosfest I am using were matched by Peter Daniel. Now unless I somehow shuffled them, I think they should be ok.
Winter is coming..... Ha!! We've had snow twice. We actually had snow and then the last of the trees in our yard dropped the leaves. I spent part of today raking frozen wet leaves.
I am going to work on walls before that bass horn, yet I may end up there someday.
Winter is coming..... Ha!! We've had snow twice. We actually had snow and then the last of the trees in our yard dropped the leaves. I spent part of today raking frozen wet leaves.
I am going to work on walls before that bass horn, yet I may end up there someday.
I'm another of the winter F4 Improvement Society. Also rebuilding to a new system, F4 based. I DO have an advantage as my F4's have been operational- I just need to strip them down and rebuild them to be reliable. Then I have actually just ordered a kit for a Pumpkin pre. Finally a balanced Twisted Pear DAC and my old Baszilla's ....and time for a break - I hope before winter is over....
Banned
Joined 2002