in usual/common Papamp , pretty much everything is on same temperature ......... in other words - in 10C window
so , just clamp them to main hs
so , just clamp them to main hs
yes. i had a look at the diode data sheet. and the differece is marginal.
so there is no point in using external heatsinks.
as long as one is not going to push the bias to the limit🙂
so there is no point in using external heatsinks.
as long as one is not going to push the bias to the limit🙂
same goal for every iteration ......... keep those heatsinks at 55C , max .....
no brainer .......... then .
no brainer .......... then .
Heatsink or no heatsink is solved or irrlelevant..... Just make sure you got an adequate heatsink. Here is my question. PLease explain this statement and how it relates to the ouput power of the amp.
"The result is that the amplifier can now deliver 38 amp peaks"
First statement seems to suggest a cheat for more pure Class A, but the second seems to slip into the A/B category. Funny that he has addressed this very topic in another article, but equally funny that he has chosen to take his Pass amps in the dircection of more true Class A power.
"What if you remove the Source resistance altogether?
First off, you get the 44 amps. In addition, with Fets you get an output stage
that will deliver more Class A power at a given bias figure due to the square
law character of the Fets."First off, you get the 44 amps. In addition, with Fets you get an output stage
that will deliver more Class A power at a given bias figure due to the square
"The result is that the amplifier can now deliver 38 amp peaks"
First statement seems to suggest a cheat for more pure Class A, but the second seems to slip into the A/B category. Funny that he has addressed this very topic in another article, but equally funny that he has chosen to take his Pass amps in the dircection of more true Class A power.
So Class A is still Class A and diodes just allow full acces to given fets abilities, even if it is of a hybrid nature. Funny, all this talk of power, I was uncomfortable listening to single pair version😀. Of course i do not have proper multiway speaker and lsiten to silly FR stuff with woofers.
1.6, but not mine.
1.6, but not mine.
Last edited:
buzz
context is very important .
just because of disregarding that , every F5T thread is at least 65% nothing more than noise
Papa was talking there about more class A in heavy (low ohmic) load
edit :
if one is not in need for hefty Turbo cojones , it's insane to build it
I don't recollect hearing about these diodes being used in any Pass main line product. But then they haven't been including the "Fun Hardware Facts" section in the manuals for a long time. So who knows.
That being said the diode idea is particularly clever and is a real plus for smaller amps that need the ability to produce extreme current peaks.
Graeme
That being said the diode idea is particularly clever and is a real plus for smaller amps that need the ability to produce extreme current peaks.
Graeme
yup
that's the very jewel of F5T article/project
everything else is "just" upping [voltage/bias/number of outputs] tutorial
that's the very jewel of F5T article/project
everything else is "just" upping [voltage/bias/number of outputs] tutorial
Last edited:
On the MUR3020W datasheet, the Vf axis is linear, but the vertical axis is logarithmic scale.
10-15 degrees doesn't make a significant difference in Vf, so mounting the diodes on one heatsink or the other doesn't make the diodes kick in a lot sooner.
But a 15 degree jump in diode die temperature does make a difference current wise.
Take the example of my previous post : 40C or 50C diode temperature means ~0.865A or 1.25A diode current at a Vf of 0.6
One MOSFET would do ~2A drain current, the other nearly 2.5A
10C temperature difference between one location of a heatsink and another isn't that round the bend.
(e.g. EUVL's heatsink measurements in the latest LinearAudio fagazine)
Agreed.
And there's nothing wrong with upping voltage/bias/number of outputs. In fact, it's one of my favorite things to do!
Graeme
Absolutely. I am not in need of the power, but just trying to help with the parameters for those that are, since i have the amp built and can test and talk. Too much talking, sure. Whats that among friends? Diode heat discussion was roundabout way of introducing the importantce of adequate sink. Don't want anyone to underestimate what 4 pairs of oututs @1A with 32V rails will do to a heatsink. Normal amps are sensitive to proper sinking, but in this one, even more so, as we have added another variable that introduces possible instablilty directly related to temperature. It is of great help when you, Andrew, Jacco, FLG and others chime in to help as many of us are just wading in with much less experience. To that i have a
Still sounds fair to me.
I can buy disc spring washers by the piece if i drive up to a Fabory store, nearest to my place is 15 minutes by car.
If i order them online from Fabory, i'd have to buy a hundred minimum, plus mailing cost, company account.
For Belleville washers in the US, you likely need a similar fastener supplier, local, they're not run off the mill parts a general hardware store will have.
(Fabory e.g. has stores only in Grand Rapids and Houston)
trivia : Jean Francois Belleville in France patented these washers +150 years ago
Never seena thermostat on the line in a PSU before, so I wa wandering if this was an acceptable one.
LM26CIM5-SPA/NOPB National Semiconductor | LM26CIM5-SPACT-ND | DigiKey
Is this a secondary safety measure for overall temperature n case?
LM26CIM5-SPA/NOPB National Semiconductor | LM26CIM5-SPACT-ND | DigiKey
Is this a secondary safety measure for overall temperature n case?
