Re: shorted MOSFETs
I don't see why this would be a problem? I do it all the time. It's hard to put them under extreme pressure with a #6 screw? And I'm not aware of this thermal compound becoming electrically conductive under these circumstances... You may be refering to the e-poxy like compound they have. That would only be a problem if your thinking of removing them. But, I guess you are
lgreen said:
I don't see why this would be a problem? I do it all the time. It's hard to put them under extreme pressure with a #6 screw? And I'm not aware of this thermal compound becoming electrically conductive under these circumstances... You may be refering to the e-poxy like compound they have. That would only be a problem if your thinking of removing them. But, I guess you are
Re: shorted MOSFETs
I wouldn't think this would be a problem either. Personally, I use Arctic Silver for CPUs because of it's thicker consistency, but not for semiconductors though. But I don't think it makes a huge difference with either one so why chance it.
Oh and regular white Thermalcote is rated for higher temperature if it makes any difference.
There's no substitute for the right heatsinks. I don't think you're going to make up for undersized heatsinks with some esoteric grease.
lgreen said:
I wouldn't think this would be a problem either. Personally, I use Arctic Silver for CPUs because of it's thicker consistency, but not for semiconductors though. But I don't think it makes a huge difference with either one so why chance it.
Oh and regular white Thermalcote is rated for higher temperature if it makes any difference.
There's no substitute for the right heatsinks. I don't think you're going to make up for undersized heatsinks with some esoteric grease.
Re: Re: shorted MOSFETs
There is a screw plus a copper bar with 4 screws that pushes each set of 3 transistors down. So we are gettning a lot of force. But if that's not the problem I will figure it out next go around.
Anyway, what say you on
Question #1
Question #2
??
flg said:
There is a screw plus a copper bar with 4 screws that pushes each set of 3 transistors down. So we are gettning a lot of force. But if that's not the problem I will figure it out next go around.
Anyway, what say you on
Question #1
Question #2
??
Re: Re: Re: shorted MOSFETs
I'm not familiar with the design totally off the top of my head but 4 banks of 3?... Sounds like at a minimum you need to mach a bank of 3. Possibly 2 banks on the same side (top or bottom), 6 total
I would say: do not re-use silpads...
Sounds like a better way to apply force evenly but, torqueing to spec is always a good idea. Nelson often points out the torque Pass Labs uses(on 1 screw with a washer) on their product but, I don't remeber off the top of my head. Maybe you want to buy a torque screwdriver???
😀
lgreen said:
I'm not familiar with the design totally off the top of my head but 4 banks of 3?... Sounds like at a minimum you need to mach a bank of 3. Possibly 2 banks on the same side (top or bottom), 6 total
lgreen said:
I would say: do not re-use silpads...
lgreen said:
Sounds like a better way to apply force evenly but, torqueing to spec is always a good idea. Nelson often points out the torque Pass Labs uses(on 1 screw with a washer) on their product but, I don't remeber off the top of my head. Maybe you want to buy a torque screwdriver???
😀
Igreen
Important to match Q2, Q11 so these should go on the same heatsink.
Q1 and q10 not so important
Important to match Q2, Q11 so these should go on the same heatsink.
Q1 and q10 not so important
audiodan said:
OK, so the plan will be to buy 3 new unmatched fets and use them for Q10. the other 3 sets are already matched, and I will put the Q2, Q11 banks on the same heatsink.
If this seems wrong let me know.
audiodan said:
Well that's the question right? Do I need to match Q1/Q10 too. You say no then yes. What is your position?
Are you guys serious or just fooling around to kill time ?
Why would anyone want to match the current sources and output stages on opposite sides of a balanced amp that employs feedback to set the gain, and has trimpots to adjust the output DC level.
That's similar to matching four gasturbine engines for exact identical fuel efficiency to use on a 747, and then modulating the fuel supply of each individual engine to obtain identical thrusts.
Why would anyone want to match the current sources and output stages on opposite sides of a balanced amp that employs feedback to set the gain, and has trimpots to adjust the output DC level.
That's similar to matching four gasturbine engines for exact identical fuel efficiency to use on a 747, and then modulating the fuel supply of each individual engine to obtain identical thrusts.
With an X amp, the distortion and noise which is identical in phase
and amplitude on the two halves cancels and does not have to be
removed by feedback. The presumption is that careful matching will
improve that effect.
😎
and amplitude on the two halves cancels and does not have to be
removed by feedback. The presumption is that careful matching will
improve that effect.
😎
Papa - just a quickie .....
am I wrong ( or I am wrong ) - present XA amp output stages are F4 sans input jfets ?
(OK , also sans two electrolyt caps
)
am I wrong ( or I am wrong ) - present XA amp output stages are F4 sans input jfets ?
(OK , also sans two electrolyt caps
)
The TL431 is a nice part. When you are biasing an amplifier using a
Vgs or Vbe multiplier, the bias voltage not only depends on the temperature
but also on the current run through the bias transistor, and you will find
that varying. If you make the bias voltage generator independent of these
two parameters, then it's easy to compensate the bias (or not) with a
thermistor in a circuit with an arbitrary coefficient.
😎
Vgs or Vbe multiplier, the bias voltage not only depends on the temperature
but also on the current run through the bias transistor, and you will find
that varying. If you make the bias voltage generator independent of these
two parameters, then it's easy to compensate the bias (or not) with a
thermistor in a circuit with an arbitrary coefficient.
😎
Nelson Pass said:
I have slight impression that you asked high res pictures on 6moon ....... just another way to please spoiled kids
😎
just thinkin' .... and looking at 6moons XA.5 pictures ..... ( what else - I certainly can't just go and build Cheff's great UP UGS amp ) ......
I'm gonna major ROFLMAO ........ in this yore days of prestigious exotic fifi gadgets , Papa is sending signal (in XA.5 amps ) through two 220uF , on each side .......
and these amps are judged as finest money can buy ......
hehe , another explanation why Papa is always smiling on funny pictures ...... fooling audiophools again , and making things in pure engineering way , again ..........
am I right , or I'm right ...... ?
I'm gonna major ROFLMAO ........ in this yore days of prestigious exotic fifi gadgets , Papa is sending signal (in XA.5 amps ) through two 220uF , on each side .......
and these amps are judged as finest money can buy ......
hehe , another explanation why Papa is always smiling on funny pictures ...... fooling audiophools again , and making things in pure engineering way , again ..........
am I right , or I'm right ...... ?
Nelson Pass said:
well , I wasn't sure are they caps across bias network , but I must wrote something to call elephant from the bush .....
(humor/engineering part wasn't part of elephant call )
now you gave me more to think
hi all
any one have some of these baords they want to part with
i would prefer built if possible
regards sheafer
any one have some of these baords they want to part with
i would prefer built if possible
regards sheafer