See, I told you the list wasn't 100%.
Those of you who go the Bipolars will have the option of IRF250's.
Those of you without the transformers you need may have the
option of getting something else, depending on what I have.
Or maybe not...
😎
Those of you who go the Bipolars will have the option of IRF250's.
Those of you without the transformers you need may have the
option of getting something else, depending on what I have.
Or maybe not...
😎
Nelson Pass said:See, I told you the list wasn't 100%.
Those of you who go the Bipolars will have the option of IRF250's.
Those of you without the transformers you need may have the
option of getting something else, depending on what I have.
Or maybe not...
😎
What kind of Bipolar experiments did you do ?
I thought you were devoted to Mosfets.
Well, amp number 26 has the IRF244 / IRF9240 complimentary pairs, and since they have felt tip marks like "439 ... 394" times 4 pairs per side, I will assume they have been matched electronically after assembly to the resistors on the boards ... so I would hate to "destroy" the boards by removal simply to install my own projects. I suppose someone should have these and I would be more than happy to exchange these heat sinks with mounted and matched boards and MOSFETs <for> heat sinks without any boards or transistors installed ... any takers? 
Nelson: I would like to obtain a transformer of about 600 VA capable of producing DC rail voltages of about +80/0/-80 VDC (yes, w/center tap) and hopefully you have such and will let me buy one. I insist that I pay for this ...
Nelson: I would like to obtain a transformer of about 600 VA capable of producing DC rail voltages of about +80/0/-80 VDC (yes, w/center tap) and hopefully you have such and will let me buy one. I insist that I pay for this ...
Yes, it would be a shame to undo the matching. It would help to know if in fact the resistors were taken into account. I get the idea that they aren't. Either way, couldn't you just unbolt the boards, not the entire side panel?
The transistor leads go through the side panel into the output board, so no separating the board from the heat sink without unsoldering all of the transistors.Variac said:
Besides, the side panel is easy to remove. The whole chassis can easily be disassembled into individual panels. It's going to be super easy to work with.
" ... no separating the board from the heat sink without unsoldering all of the transistors. ..."
" ... The whole chassis can easily be disassembled into individual panels. It's going to be super easy to work with. ..."
Same, same with the MOSFETs ...
" ... The whole chassis can easily be disassembled into individual panels. It's going to be super easy to work with. ..."
Same, same with the MOSFETs ...
preiter said:
Yup. I'd take advantage of the way they're assembled to make the two 5-channel amps with different topologies.
- Eric
hitsware said:
I believe you'll find that Nelson is devoted to what works.
Add to that the P-ch gain-shelving quirk that seems to be spreading (like an infectious disease) and you could easily imagine a motive for using bipolars. That said, Nelson is in a position to buy and stockpile large quantities of parts so he may be able to coast for a while if he so chooses.
I've been eyeing bipolars for a while, though I've yet to do much in that direction. Too busy.
Grey
hitsware said:
In the dark-of-night kinds of experiments, Muuuuuhahahahahaha...
FastEddy said:
Sorry, all I have is the 1.5 to 2 KVA stuff, no 600 VA.
😎
More to come shortly.
MOSFET Questions
Hi Everybody,
I've been talking to FastEddy about swapping him my MJ bipolar heatsink assemblies for his IRF244/9240s.
The good news is that the swap would leave me with two comp MOSFET amps that I would run in "mono balanced operation" per the F4 manual. The trouble is that I would want the two to be identical but one would has IRF240/9240s and the other would has IRF244/9240s.
Nelson tells me that the 240s are nearly identical to the 244s with exception of the 240 having slightly fatter pins in a non-standard TO-3 package.
I wonder if they sound the same or close enough for practical purposes? Any thoughts or experiences with this?
To further complicate matters, Nelson has IRF250s on hand. If the 240/244 thing doesn't work out, would I then substitute the 250s for the 24Xs using the existing 9240's as their P-channel counterparts? Or would I need to find another P-channel part? Or would I need to use all 250s to create single-ended amps? That ceases to be an F4, doesn't it, or am I missing something?
If the neither of the 250 options work out, I could always go back to the 240. I know I can get them but getting them matched is another matter.
Some guidance would be very helpful.
Thanks.
k
Hi Everybody,
I've been talking to FastEddy about swapping him my MJ bipolar heatsink assemblies for his IRF244/9240s.
The good news is that the swap would leave me with two comp MOSFET amps that I would run in "mono balanced operation" per the F4 manual. The trouble is that I would want the two to be identical but one would has IRF240/9240s and the other would has IRF244/9240s.
Nelson tells me that the 240s are nearly identical to the 244s with exception of the 240 having slightly fatter pins in a non-standard TO-3 package.
I wonder if they sound the same or close enough for practical purposes? Any thoughts or experiences with this?
To further complicate matters, Nelson has IRF250s on hand. If the 240/244 thing doesn't work out, would I then substitute the 250s for the 24Xs using the existing 9240's as their P-channel counterparts? Or would I need to find another P-channel part? Or would I need to use all 250s to create single-ended amps? That ceases to be an F4, doesn't it, or am I missing something?
If the neither of the 250 options work out, I could always go back to the 240. I know I can get them but getting them matched is another matter.
Some guidance would be very helpful.
Thanks.
k
" ... the 240s are nearly identical to the 244s with exception of the 240 having slightly fatter pins in a non-standard TO-3 package. ..."
?? My '244's are all in TO-204 cans ?? ... so close to a TO-3 type that you couldn't tell 'em apart in the dark. : http://www.datasheetcatalog.org/datasheets/90/283511_DS.pdf
?? My '244's are all in TO-204 cans ?? ... so close to a TO-3 type that you couldn't tell 'em apart in the dark. : http://www.datasheetcatalog.org/datasheets/90/283511_DS.pdf
Nelson,
Doesn't seem any of the first watt designs use more than two output pairs. What experiments were you going to do with these amps with six pairs?
- Eric
Doesn't seem any of the first watt designs use more than two output pairs. What experiments were you going to do with these amps with six pairs?
- Eric
Let me join this party.
In order to make this great, I would like to offer holes drilling and tapping to all the people that will do this project on original Nelson chassis, and that are in need of help with metal work. There are not to many holes that you most likely will need, but if you need I will be happy to do it for you. Like I explained, this is just for people from this group with Nelson's cases. These cases are so gorgeous that it will be sad not to do it well.
In order to make this great, I would like to offer holes drilling and tapping to all the people that will do this project on original Nelson chassis, and that are in need of help with metal work. There are not to many holes that you most likely will need, but if you need I will be happy to do it for you. Like I explained, this is just for people from this group with Nelson's cases. These cases are so gorgeous that it will be sad not to do it well.
Well, I suspect by their size that they were used as mules for Pass Labs, not First Watt. Interesting that Nelson's "shop tools" are our treasures!
FastEddy--
I have a whole bunch of 12 - 1/4 pieces of heatsink!!!!!!!
more than I can ever use, or will ever have time to build into amps. Semi-complete chasis would sure make it much more likely that I will get to build amps.....
I haven't read all the posts posted since I read your post--have they been spoken for yet?
JJ
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