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Old 25th January 2011, 05:33 PM   #10111
labjr is offline labjr  United States
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Reminds me of that scene in Caddyshack.

"I want a hamburger, no a cheeseburger. I want a hotdog. I want a milkshake. I want potato sala--You'll get nothing and like it!"
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Old 25th January 2011, 06:14 PM   #10112
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by viki_v2 View Post

very sorry for annoying you guys,
I got some helping ans here so kept on asking.

keep up the good work
Bye

It would have been of great help.

the point is, it will be a complete mess if we go too much off topic

members come to F5 thread to debate F5, and not something completely different

ask your questions in appropriate threads, and you will get proper answers

wish you luck



moderation
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Old 25th January 2011, 07:03 PM   #10113
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Quote:
Originally Posted by viki_v2 View Post
very sorry for annoying you guys,
I got some helping ans here so kept on asking.

keep up the good work
Bye

It would have been of great help.
Hi viki,
please, run away from A class amps, go to AB, f.E:
Project 101 - High Power, High Fidelity MOSFET power amplifier
It's a very good amp, not expensive and not hard to build!

& for fun!
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Old 25th January 2011, 08:02 PM   #10114
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So, P1 & P2 should be set a minimal setting before powering up the F5?

I think I may have a cold solder joint, can't seem to get thing out of one of my P2 pots.
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Old 25th January 2011, 08:40 PM   #10115
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Read this:
Your F5 blew up, now what do you do?
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Old 26th January 2011, 12:09 AM   #10116
alazira is offline alazira  United States
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Quote:
Originally Posted by Nikon1975 View Post
Now this is clear, what about the matching story? I understood that the 5 ohm give an asymmetry to the circuit to compensate the difference of the devices. Then, how to choose them ?

Thanks,

D.
Hi,
If you are planning on doing the 5ohm degeneration trick you need:
1) N-P matched mosfets for each channel.
2) 2SJ74 with an Idss about 1mA more than 2SK170
3) either add 5ohm resistor between the 2SJ74 source pin and the feedback node, or replace R with 15ohm and feedback of 75ohm.

All three steps are required.
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Old 26th January 2011, 05:37 AM   #10117
EUVL is offline EUVL  Europe
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> All three steps are required.

Only if you want perfect even harmonics cancellation.
And the cancellation works for single ended F5 just as well.


Patrick
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Old 26th January 2011, 08:54 AM   #10118
Marra is offline Marra  United Kingdom
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I'm using Caddock MP930 resistors for the .47R and 50R feedback will 25C/W clip on sinks be big enough?

Marra
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Old 26th January 2011, 01:43 PM   #10119
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Maybe this is a silly question but...

All the cool guys with nice equipment make the tuning looking at the distortion at 1W. Now my USB scope, has a dynamic range that is limited to -90/-100dB. Good for tube amps, but with the F5 all the harmonics are buried. Can I do the tuning at 10 W ?

Thanks,

D.
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Old 26th January 2011, 02:54 PM   #10120
AndrewT is offline AndrewT  Scotland
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use Cordell's distortion magnifier.
If that is not sufficient then consider a higher test frequency and/or a higher test voltage and/or a lower test load impedance.

If you still can't see it in any of the IMD tests then you probably can't hear it either.
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regards Andrew T.

Last edited by AndrewT; 26th January 2011 at 02:56 PM.
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