I would love to match mosfets with everyone, but I didn't grab any at BAF. 
Perhaps I will visit the local surplus places this week. Next Sunday would work better for me, but please do not plan around me.
best regards,
psz.
Perhaps I will visit the local surplus places this week. Next Sunday would work better for me, but please do not plan around me.
best regards,
psz.
Another thing to consider is that those that convert their complimentary outputs to single ended will have 6 matched 240's per side to use.
If that isn't enough and they need to go to the 250's then the 240's may become avaialble. I assume people won't hoard them.
Seems like there will be enough to go around. Certainly if you remove output devices from a case you should desolder them carefully from the circuit board so that both can be reused..
If that isn't enough and they need to go to the 250's then the 240's may become avaialble. I assume people won't hoard them.
Seems like there will be enough to go around. Certainly if you remove output devices from a case you should desolder them carefully from the circuit board so that both can be reused..
Variac said:
This will easy to achieve, because the plate is quite thick, and only
the tips of the leads protrude from the pc board.
😎
Ok, this "making up my mind" is tough!
luckily, I am in no real hurry, although some here are.
Here is a question to Nelson or Zennie or whoever:
Nelson originally mentioned making F4's out of the amps because it is a more straightforward proposition. Some here want as simple a project as possible. I am very much enjoying my F4 clones that I recently rebuilt and completed. They are a very worthy project for your Burning Amps and sound great!
So, my brother has some extra transformers with dual 25 volt outputs which should give about -/+33 volt rails, right? And the Burning Amp chassis have 6 pairs of devices per side, twice what a regular F4 has.
So, would this combo, 33V and twice as many output devices work out for a kick-butt F4? I guess we don't want to cook the JFETS, but clearly there are ways around this. What sort of power output would it have?
Mark
luckily, I am in no real hurry, although some here are.
Here is a question to Nelson or Zennie or whoever:
Nelson originally mentioned making F4's out of the amps because it is a more straightforward proposition. Some here want as simple a project as possible. I am very much enjoying my F4 clones that I recently rebuilt and completed. They are a very worthy project for your Burning Amps and sound great!
So, my brother has some extra transformers with dual 25 volt outputs which should give about -/+33 volt rails, right? And the Burning Amp chassis have 6 pairs of devices per side, twice what a regular F4 has.
So, would this combo, 33V and twice as many output devices work out for a kick-butt F4? I guess we don't want to cook the JFETS, but clearly there are ways around this. What sort of power output would it have?
Mark
Variac said:
who is Nelson ?
to be on safe side - you need cascoding these little critters on input ...... and maybe even paralleling another pair ......
certainly most convenient way is to use 2SK389+2SJ109 on input
I'm pretty sure that Papa will answer to your questions faster than that "Nelson" guy ........
I played around with adding some surface area to the existing heat sinks in anticipation of getting more than 30W from my smaller chassis No. 34 (4 transistor pairs/ side) and came up with this straightforward addition.
My Big Question: What's the most single-ended performance I can reasonably squeeze from my bag of IRF250 and my smaller chassis and pcb?
My Big Question: What's the most single-ended performance I can reasonably squeeze from my bag of IRF250 and my smaller chassis and pcb?
Attachments
Tosh,
I don't see how a lot of heat is going to be able to be transferred to the tubular heatsinks The contact points betweem them and the existing tubes is going to be very small. I think it would be a lot better to use square tubing in a similar waybolted to the existing sinks, with sink grease .
I don't see how a lot of heat is going to be able to be transferred to the tubular heatsinks The contact points betweem them and the existing tubes is going to be very small. I think it would be a lot better to use square tubing in a similar waybolted to the existing sinks, with sink grease .
Variac: If I went the tubular route I would expect to mill a ~1/4 inch flat on each tube to increase the mounting area. (The tubes are shown as 1.25 inch diameter.) I first thought about rectangular tubes (especially as they would be much easier to work with), but figured they 'cover up' or rob a lot of existing area where they mount. I am definitely open to ideas!
Here's a look from above with the cover transparent.
Here's a look from above with the cover transparent.
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Matching Party
I definitely want to join you guys for the matching party. Please keep me in mind. I'm in SF proper.
k
I definitely want to join you guys for the matching party. Please keep me in mind. I'm in SF proper.
k
It was a little bit of softening the lines as well as preparing for max heat dissipation, as I'd like to get at least 30W out of it. But mostly playing with adding visual interest with minimum effort.
" ... I'd like to get at least 30W out of it. ..."
... talking like you need 30 watts of heat dissipation (?) ... The sinks are already mighty healthy. I'm installing 400 watt industrial strength MOSFET modules under powered by ~ 25% = ~ 300 watts expected each side ... since all my other amps don't even get warm to the touch with smaller sinks, I figured these standard aluminum channels to be plenty ...
BUT then again I don't really know how Pass Labs' hardware / designs work exactly or how much is enough or too much.
... talking like you need 30 watts of heat dissipation (?) ... The sinks are already mighty healthy. I'm installing 400 watt industrial strength MOSFET modules under powered by ~ 25% = ~ 300 watts expected each side ... since all my other amps don't even get warm to the touch with smaller sinks, I figured these standard aluminum channels to be plenty ...
BUT then again I don't really know how Pass Labs' hardware / designs work exactly or how much is enough or too much.
Mr. Fast,
Single ended class A is unbelievably hot running if Tosh is planning to go in that directuon. More heatsinks allow more bias - a very good thing. But I think I would build the thing first, then see if more is needed..
Tosh,
As far as robbing existing area, I think that you will really want that common area to transfer the heat- after all they aren't one piece-bolted together isn't as efficient as if they were.. then again, what do I know other than the above..
Single ended class A is unbelievably hot running if Tosh is planning to go in that directuon. More heatsinks allow more bias - a very good thing. But I think I would build the thing first, then see if more is needed..
Tosh,
As far as robbing existing area, I think that you will really want that common area to transfer the heat- after all they aren't one piece-bolted together isn't as efficient as if they were.. then again, what do I know other than the above..
Vladimir suggests Dec 6th or 7th for a matching party at his place. Will that work for you all?
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