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Old 29th January 2013, 06:19 AM   #1191
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by AudioSan View Post
lots of outputs. yes. but no one have that amount of bias VS rail voltage
5.52A bias makes it good for over 480W class A power at 8ohm. but it is voltage limited at around 50W at 8ohm with +/-32V rails.
Quote:
Originally Posted by a.wayne View Post
San,

Can you explain how you are calculating the power from 32v rails ...?
Quote:
Originally Posted by AudioSan View Post
+/-32V rails give you about 29V P-P on the output.
29*29/4ohm=210W peak or 105W Rms.

for class A power:
3.6A*2=7.2A peak.
7.2*7.2*4ohm=207W peak or 103W Rms.
Audiosan, would you like to re-write that and try to get it right this time?
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Old 29th January 2013, 09:08 AM   #1192
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Here we go again.
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Old 29th January 2013, 09:46 AM   #1193
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Quote:
Originally Posted by AndrewT View Post
Audiosan, would you like to re-write that and try to get it right this time?
it is already right.
you do not have to calculate Rms factor first. if that's what your thinking of.

29*29/4/2=105W

29*0.707=20.5V
20.5*20.5/4=105W

same goes for bias.

Last edited by AudioSan; 29th January 2013 at 09:54 AM.
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Old 29th January 2013, 12:47 PM   #1194
AndrewT is offline AndrewT  Scotland
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why do you need to be told again and yet still insist it is right?
You have mixed up Vac V rms, Vpk and Vpp
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Old 29th January 2013, 05:36 PM   #1195
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Quote:
Originally Posted by AndrewT View Post
why do you need to be told again and yet still insist it is right?
You have mixed up Vac V rms, Vpk and Vpp
so what you say is, that one dont get this output from that rail voltage?

then it seams that you have to inform Nelson that his power calculations has been wrong all this years, as my numbers match his numbers.
from the F5turbo article:

The F5 TURBO V1
Increasing the power supply voltage is the obvious way to get more power out
of an F5. You can simply raise the supply rails to +/-32 Volts and get 50
watts into 8 ohms right away without other modification. 24 V AC secondaries
on the power transformer will do it. Don't forget to use higher voltage power
supply capacitors. Probably you should also upgrade R9 through R12 to 5
watt resistors. Depending on your heat sinking, you will probably want to
adjust the bias so that the power transistors don't run too hot.

Here you see the F5 without the limiters and with an additional set of output
devices. With adequate heat sinking, you can bias them to 1 amp each, for a
total of 2 amps, which will operate the circuit Class A well above 100 watts
peak into 8 ohms. You probably take the bias to 3 amps with enough sink.
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Old 30th January 2013, 01:34 AM   #1196
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Hi Guys,
I decided to look throught my transistors and see if the theory that a small copper part is not tinned near the body of a gen-u-wine part, well I have got parts from all over the globe,
Check the pic and see if you see what I saw,I will put them on the curve tester and see how they look.
Regards,
NS
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Old 30th January 2013, 01:46 AM   #1197
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On eBay, there are multiple sellers offering 2sk117gr with Idss of 14mA
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Old 30th January 2013, 01:50 AM   #1198
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nosmoke. the pic is to smal to study. but i can't remember to have seen any copper at the end of the legs on spencer's J-fets. and they are the real deal. maybe it can be seen with a HD pic.
let us know how the testing goes.
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Old 30th January 2013, 01:50 AM   #1199
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Quote:
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On eBay, there are multiple sellers offering 2sk117gr with Idss of 14mA
well. thats a no brainer
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Old 30th January 2013, 01:54 AM   #1200
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Look on Ebay. Apparently not.
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