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Old 10th February 2013, 11:36 AM   #1291
kroyin is offline kroyin  India
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Option 1--8 irfp240 mosfets each being fed 1 A supplied by 16V rails
Option 2 -- 4 irfp150 mosfets each being fed 2 A supplied by 16V rails (ZM just squashed this :-))

I'll try both.

The funniest part is that i'm currently ravaging the AJ, one channel with 1 pair (1A each @ 24V), the other channel 2 pairs (1A each @ 24V), i hear no difference, guess my 8 ohm spk's are real 7~8 ohm (not current hungry) (or) my headphones have shorted :-) :-)

Lets just stay on F5T :-) :-)
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Last edited by kroyin; 10th February 2013 at 11:48 AM.
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Old 10th February 2013, 02:12 PM   #1292
a.wayne is offline a.wayne  United States
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Difficult to hear differences without a proper setup ...
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Old 10th February 2013, 02:16 PM   #1293
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by kroyin View Post
Pics of my utilitarian F5 V2 monoblocks. Biased @ 320mV with ~8mV offset. Haven't had the chance to play with P3

Boards from indian group buy DIY: Pass F5 turbo v2 initiated - Page 18

Mosfet (perfectly matched) & diodes from Buzz

300VA, 8x15K caps per channel. Heatsinks are 500mm long with 125 mm width (not optimum config, but was cheap and handles the heat very well)

F5 vanilla didnt work for me, Aleph J set the bar pretty high, F5T V2 sailed over the bar (by a few centimeters :-)).
I would add another 300va transformer to maximize your output stage and for best sonics , a single 300va is way too small ..
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Old 10th February 2013, 02:36 PM   #1294
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Here is retry of distortion measurement of my F5T. Slightly adjusted for higher 2k to 3k. THis gave the widest and best overall soundstage.
Attached Files
File Type: pdf F5T V2.pdf (122.2 KB, 105 views)
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Old 10th February 2013, 02:43 PM   #1295
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Originally Posted by a.wayne View Post
I would add another 300va transformer to maximize your output stage and for best sonics , a single 300va is way too small ..
I think he is using 2X300Va transformers.One 300VA/channel.

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Sachin
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Old 10th February 2013, 03:18 PM   #1296
dazed2 is offline dazed2  Canada
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Quote:
Originally Posted by buzzforb View Post
Here is retry of distortion measurement of my F5T. Slightly adjusted for higher 2k to 3k. THis gave the widest and best overall soundstage.
Buzz,
maybe a stupid question, but is the blue line 2nd order distortion? is there no 3rd order distortion at all? Or am I reading the graph completely wrong?
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Old 10th February 2013, 03:26 PM   #1297
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THe blue line is the soundcard in loop back. Red is the amp. Look at the bottom of the graph for the frequency for the distortion. It was tested at 1k, so you see a spike there. Then 2k and 3k, falling in pretty good relation. Have a tiny bit of 5k, which i dont like, but unsure of how to get rid of it.
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Old 11th February 2013, 02:08 AM   #1298
Lo_Tse is offline Lo_Tse  Canada
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Quote:
Originally Posted by buzzforb View Post
Here is retry of distortion measurement of my F5T. Slightly adjusted for higher 2k to 3k. THis gave the widest and best overall soundstage.
The peak at 2KHz is below -90 dB and the signal at 3KHz is below -100 db (there is a trace at 4Khz but it is below -120db). This is pretty good.

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Old 11th February 2013, 02:31 AM   #1299
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Yes. I could drop the 2k alltogether and lower k3, butbi dont like the sound as much
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Old 11th February 2013, 05:21 PM   #1300
Marra is offline Marra  United Kingdom
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I fired up my F5T V2 this afternoon and one channel was adjustable as req'd but the other one would'nt go above .32V before the trimmer started clicking.I know I need to increase the value of R5/6 but wondered is there a resistor value to use and is it worth changing them on both boards?

Ignore this I found the answer in #971.Thanks Audiosan

Last edited by Marra; 11th February 2013 at 05:39 PM.
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