F5 power amplifier

alexw88 said:
Can someone please help with my 2 questions?

1. For the thermistor, should I use PTC or NTC?

2. I plan to use the CLC type of supply filtering, is that enough? or I must use active regulation to get good THD/noise performance?

Thanks!

I got both questions answered by reading the May issue of AudioXpress in the library! The F5 article is very well written and it is especially useful for the "caveman" like me. It has very detailed description about the circuit design and building hints. :)
 
Good for you, i've also got one of those libraries at hand that have goodies on the shelf before my mailman takes his monthly break from therapy classes. (H, even after three Q of a Y monitoring THIS lot i'm still going strong with my self-controll therapy.)

But you're still welcome to read the first 10 pages of this thread with a fine-toothed comb :clown:
 
steenoe said:
You totally missed the point, either purposedly or not. I acknowledge what you brought to these people. I even have your very amp playing for the second year! I did not critisize you specifically, I even said it was not personal. I never critisized anyone for not answering newb questions!! I did critisize the way some of the members does so, though!! I stand by that, anytime......


Okay...it's official...I'm confused.


Grey
 
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Joined 2006
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Nice drawing twitchie

My background is NOT in electronics, but I've got a problem with idle hands. That mixed with spending far too much time on the internet and enough recklessness to try most anything at least once
Mine is not either. Idle hands are a dangerous thing. Consume money and time. My method is to remember to breathe and walk away from it, when your frustrated and not sure. Wait a while, then research, then ask the right questions. It's really the journey for me, then the music. (although being a tinkerer is a problem, the system won't stay still.)

I started building tube amp stuff from kits 10 years ago. I started truly understanding circuits slowly, and still have questions.

Building a crossover schematic for me was a good place to start.
If you get this circuit working that is great. If there is a mistake, a few more holes and wires will cure it

Again many namaste's to NP. Reading some of his advice is far better than just following instructions on a kit. His writings allow you to actually know what's happening, and he speaks in common sense terms. Is helpful, and beg to say available. Some of with father issues. :bawling: truly appreciate that. And I find that almost all of you are helpful. I am always learning.
 
Twitchie -- you might want to move the IRFP240 and TH2, reversing their positions -- this will allow you a shorter path to the gate of the IRFP240 -- if the gate-stopper resistor value is "high" (10x the value specified) then it would be problematic. Sometimes I just solder the gate-stopper resistor directly to the gate pin.
 
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Just an observation...

The board doesn't have mounting holes yet.

I feel that if you were to mounting the FETs to the heatsink without fixing the board to the heatsink, you might leave yourself open to a vibrating PCB. I only say this because there are no mounting holes at all. Please ignore this if you are drilling them later.


BTW- Nice board!

V~
 
twitchie said:

I'm just not looking forward to the next part - drilling holes.

With any luck ( and wife + 2-year old permitting), I may just have this thing stuffed and singing before summer's over :D

Thank you Nelson Pass for your immeasurable contributions to this hobby! :cheers:


Drilling PCB's is a walk in the park.

I would not change anything, but simply just stuff the boards, and see IF any problem at all should arise, but I doubt it should cause you trouble.


Magura :)
 
Formerly "jh6you". R.I.P.
Joined 2006
GRollins said:
One of the most valuable things you can do when you're laying out a PCB is to put it down and come back to it the next day. Better still, two or three days later. You'll see all kinds of things that can be done better. Sometimes you even catch mistakes.



As I am seldom satisfied with my own PCB work, I do approach in
different way. I darw all paths on the paper with pencil and check
them wether all are going to right directions and branches.
And, if I am sure of that, I just make the PCB and finish all at the same
time. I do not want to cry over my ever-ugly PCB works...
But, the impovement is possible for the second try... third try...
 
Hey Twitchie,

I've been studying your board layout and you've done a fine job, but I found a little error in the feedback loop. R1 and R2 should be 10 ohms, not 10K, and should probably be 3W also.

I'm still looking but nothing else jumps out at me right now.

Also, on the traces around the 240, it would be better to locate R14 much closer to the gate pin and pass the source trace under it.

Keep it up, you're lookin good.

Bill
 
Babowana said:




As I am seldom satisfied with my own PCB work, I do approach in
different way. I darw all paths on the paper with pencil and check
them wether all are going to right directions and branches.
And, if I am sure of that, I just make the PCB and finish all at the same
time. I do not want to cry over my ever-ugly PCB works...
But, the impovement is possible for the second try... third try...


Once the music starts where's UGLY then???

Twitchie..no need to make the 10ohm resistors 3w. The rest should work just fine. If you do it again consider allowing for choices on the source resistors..I for one have LOTS of Dale 5watters. Also slightly larger pads on the smaller traces aids in solder flow. Good job for the first try.