F5 power amplifier

thanh1973 said:
They are some seriously large caps you have!!!!
What improvement (ie audible) do expect to hear by using these?


what audible difference one can expect , having serious 50 to 80uF block caps , as bypass ?

:clown:

increasing speed of PSU can't harm , and difference is easily detected in whole frequency spectrum
 

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How will a film cap change an electrolytic
I dont see that to happen
It will only have influence at frequencies where the film cap is effective
Which is higher frequencies

Coherence will suffer
I wont exchange coherence with enhanced top
Every component with "impressive" effect always just seem to bother me, and are only annoying when listening
So now I just avoid such

In worst case you may even have ressonance/ringing
At least it sounds that way to me

btw, somewhere I have seen a technical explanation why not to do "snubbers" and "bleeders", which would be kind of the same thing to me
 
Re: F5 enclosure

kimarin said:
This italien site has som nice enclosure's http://www.modushop.biz

I wonder if anyone think this cabinett can be used to the F5?

http://www.modushop.biz/ecommerce/cat079_l2.php?n=1
(scroll down to P 400 mm) size: W 450 mm, D 400 mm & H 120 mm.



It might be ok, maybe depending on room temperature
Well, it ought to work ok fore 25watt
Hard to say without specs on heatsink mounted

But 4U better and 5U the best 😉

Its the height you really need
Should I buy a 300mm heatsink it would be no less than 150mm height, and 200mm preferred
But maybe a bit over the top, and might not be needed really

A Fisher 300x200mm heatsink would cost 50EUR each
So modushop prices seem good
I take it they are delivered as shown, with heatsinks
 
F5 enclosure

Thanks for the reply. I think I'll go up a unit ( 4U) 🙂 One thing I don't understand tho is why R5-8 is 3W? Is there realy that big current running through those resistors? I hoped i could use my 0.6w metal film's here. If not I have 1ohm 2W metal film's that I could parallel in 4 each channel.
 
Re: F5 enclosure

kimarin said:


One thing I don't understand tho is why R5-8 is 3W?



I believe . . . one reason among others is . . . when we adjust P1 and P2 without connecting the output load, the R5-8 act as a load taking care of the potential high load current. And, this is why I also recommend to use R1 and R2 of at least 0.5W . . .

I hope I have read Papa's consideration correctly . . .


🙂
 
Nelson Pass said:

Alternatively, you can increase the value of the Source resistors to 1 ohms,
and increase the value of the feedback resistors from 2 X 100 ohms and 10
ohms to 1 X 100 ohms and 22 ohms.

I am somewhat curious about that modified feedback mechanism. Do I have this right? Merely 1x 100 ohms? Not 2x 200 ohms "so as to share the dissipation"?