Yes, the "R" in the rCRCRC can be used to adjust the voltage available at the last capacitor, if there is constant current draw on that supply rail.
The F5 does not have constant current draw when processing a signal.
If you make the last C very large you can compensate to some extent for the effect of variable current draw on the supply rail.
The balanced F5 or F5x do have constant current draw, but only while operating in ClassA output mode. A current transient that demands speaker current to be higher than the ClassA limit will increase the current draw on the supply rail and the capacitor voltage will sag significantly.
The F5 does not have constant current draw when processing a signal.
If you make the last C very large you can compensate to some extent for the effect of variable current draw on the supply rail.
The balanced F5 or F5x do have constant current draw, but only while operating in ClassA output mode. A current transient that demands speaker current to be higher than the ClassA limit will increase the current draw on the supply rail and the capacitor voltage will sag significantly.
So, i'm doing a standard stereo F5, and after having your guys input, it sounds like i might be able to make it work. but the real question is, will i be able to reduce it enough, to keep the amplifier a live?
Andrew, do you know the proper formula, to calculate how to drop voltage? and roughly estimate what my final voltage will be without and resistors? so that we can tell obviously how much to reduce it?
EUVL, What are my options for reglators?
And again thank you guys for thew help, i'm pretty fresh to this stuff!
And i want to give my apologies to 6l6, i didnt want to turn your thread into a power supply guide! i only asked because this was a good spot that obviously people are dealing with F5's! is there a chance that you have any further progress? i'm excited to see how your amp is going!
Andrew, do you know the proper formula, to calculate how to drop voltage? and roughly estimate what my final voltage will be without and resistors? so that we can tell obviously how much to reduce it?
EUVL, What are my options for reglators?
And again thank you guys for thew help, i'm pretty fresh to this stuff!
And i want to give my apologies to 6l6, i didnt want to turn your thread into a power supply guide! i only asked because this was a good spot that obviously people are dealing with F5's! is there a chance that you have any further progress? i'm excited to see how your amp is going!
Sorry 6L6, I forgot this was your thread to describe your build.
Crazy,
go back to the original F5 thread or start a new one for your self.
However, I suspect a team of us could be typing away for weeks (continuously) to bring you up to speed.
Simply asking about Ohm's law tells us that your electrical knowledge is lacking.
Crazy,
go back to the original F5 thread or start a new one for your self.
However, I suspect a team of us could be typing away for weeks (continuously) to bring you up to speed.
Simply asking about Ohm's law tells us that your electrical knowledge is lacking.
I would just order the appropriate transformer, if that one isnt returnable, just set it aside for a later project. Dont know who you got it from, but Antek is a good source for economical transformers.
I used 2 of his 300VA 18 + 18 in a dual mono setup. My build I'm beginning now will use a single transformer, Antek, 500VA 18 + 18. If regulators were necessary, Mr Pass would have utilized them. Just build the basic amp for starters. This is an excellent thread to watch for pointers
Good luck,
Russellc
So after doing a little math, assuming the gain in voltage is a constant ratio, switching from AC to DC, I will be at roughly 29.3V without any resistors. So say we drop 6 volts, with a 1.3 amp bias, I would need 12 .38 ohm resistors, or could I reduce that down to 3 1ohm resistors, and have a little larger voltage drop... right? Assuming I'm still at 1.3 amps bias
As Unfortunate as it is, yes. my electrical knowledge is lacking, heavily. And i'll go search around, and find all the necessary formulas, and similar things, so i can hopefully do most of the number figuring i need. and take notes for sure! If i cant figure something out, i'll ask the experts.
And i probably will just set the 24V aside for another project, and order the proper one.
you dont need to know very much, or how to calculate anything
its all in the F5 manual, in every detail
even a supply schematic clearly showing 18Vac trafo
To save you some time. The first one you want to know as Andrew mentioned is V=IR.
Start your own thread and I am sure many people will help you out.
Last week was some discussion about tapping the mounting holes for the power transistors - some people do have a tough time with it and sometimes leave a raised edge, holes at wrong angles, wrong position because of broken taps, etc, etc - most of us have been there, done that, ...
There are quite a few "Transistor Mounting Spring Clips" & "Transistor Clamp Bars" readily available that'll take much of the drama out of the whole mounting exercise, particularly useful if you remove the transistors more than once - also, pressure is applied directly onto the centre of the back of the transistor, a good thing - basically, retail versions of the common mounting bar/bracket idea.
I find them very useful, perhaps other's may also ......
There are quite a few "Transistor Mounting Spring Clips" & "Transistor Clamp Bars" readily available that'll take much of the drama out of the whole mounting exercise, particularly useful if you remove the transistors more than once - also, pressure is applied directly onto the centre of the back of the transistor, a good thing - basically, retail versions of the common mounting bar/bracket idea.
I find them very useful, perhaps other's may also ......
Even though I don't need to know very much, I would really like to know how everything in an amp works. I'm working my way there but still need more! And thanks everyone.
Hows the amp coming 6l6?
So that's what this thread is about... The amp PCB for the 2nd channel has been stuffed, but other than that, I haven't done anything since the last post with photos.
I am going skiing for a week+ starting Monday, so you will not see any updates from me until a few days into March. Unless something bizarre happens tomorrow and plans fall through, I will not have any time to work on it at all.
Stay tuned in, this project will be completely documented as it gets completed.
Question about silpads
Hi,
I have built 2 F5 and 2 Aleph J so far in order to run some of my speakers in active configs. In my experience, F5 has been the easiest to build if one were to build the stock design of Mr. Pass.
I have also used mica washers and goop (heatsink paste) for heatsinking the outputs. But it is quite difficult to manage with mica and goop if you are replacing the outputs or do some changes with other output variants such as Toshibas.
I have bought a bunch of silpads, but wasn't happy with the heat transfer compared to goop. Do I need to use goop with silpads too? How about keratherm? Do they need goop as well?
Cheers.
Hi,
I have built 2 F5 and 2 Aleph J so far in order to run some of my speakers in active configs. In my experience, F5 has been the easiest to build if one were to build the stock design of Mr. Pass.
I have also used mica washers and goop (heatsink paste) for heatsinking the outputs. But it is quite difficult to manage with mica and goop if you are replacing the outputs or do some changes with other output variants such as Toshibas.
I have bought a bunch of silpads, but wasn't happy with the heat transfer compared to goop. Do I need to use goop with silpads too? How about keratherm? Do they need goop as well?
Cheers.
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My understanding is no. I know that for sure about sil pads, and that's what I've been told about keratherm. Someone can verify this?
Russellc
if the insulator is soft or squiggy then it is almost certainly designed to fill in all the scratches in the heatsink and the active device. No goop needed to fill the scratches a second time.
Many of these "dry" type need heat to make them "flow". This will happen at first warm up. second operation may turn out to run slightly cooler, i.e. heatsink slightly hotter due to better transfer of heat through the "prepared" insulator.
Hard insulators, like mica, metal oxides, Kapton do not fill the scratches. These need goop to exclude air from the interfaces.
If Kapton is treated on one side with a flowable goop then the bare side will still need goop.
Many of these "dry" type need heat to make them "flow". This will happen at first warm up. second operation may turn out to run slightly cooler, i.e. heatsink slightly hotter due to better transfer of heat through the "prepared" insulator.
Hard insulators, like mica, metal oxides, Kapton do not fill the scratches. These need goop to exclude air from the interfaces.
If Kapton is treated on one side with a flowable goop then the bare side will still need goop.
http://www.diyaudio.com/forums/pass-labs/37262-mica-goop-2.html#post1032023
And Keratherm is not based on two-phase wax, so no need to heat to flow.
I have written an article for Jan Didden's Linear Audio on thermal design of Class A amplifiers, for those who want to understand and then onto design their own. Probably out in the second half of the year, as far as I know. There is a detailed comparison of all commonly available insulator types. The simple conclusion is that Keratherm is still the best solution to-date that money can buy (off the shelf).
Patrick
And Keratherm is not based on two-phase wax, so no need to heat to flow.
I have written an article for Jan Didden's Linear Audio on thermal design of Class A amplifiers, for those who want to understand and then onto design their own. Probably out in the second half of the year, as far as I know. There is a detailed comparison of all commonly available insulator types. The simple conclusion is that Keratherm is still the best solution to-date that money can buy (off the shelf).
Patrick
I used a very simple method, all by hand. It was my first attempt at working with aluminum, and my first attempt at tapping drilled holes. I very carefully used a hand held drill and used a little oil designed (or at least sold as such)
for tapping. Tapped the holes, 4-40 and 10-32 with an inexpensive hand held tap. Then removed the "edge" by using a bit designed to make cone shaped holes so screw heads of that shape can fit flush. I didnt cut a cone shaped hole, just used it to remove the raised edge, and it worked perfectly!
There are a lot of more precise methods I'm sure, but this worked for me with minimal tools.
Russellc