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Old 9th August 2011, 03:23 AM   #10851
sangram is offline sangram  India
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Similar thing happened to me once when the lead connecting one of the power transistors worked loose. A huge, momentary pop. Later figured that even if one output goes bust and the other is fully conducting, offset is maintained close to zero. The speaker does see close to rail voltage at the instant of the fault, but only for a half second.
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Old 9th August 2011, 06:30 AM   #10852
vtr is offline vtr  Switzerland
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results

with resoldering the resistor (i use to 220 style power resistor for feedback, but couldn´t fit it in the pcb holes so i did solder it to -lötnägel- in german no idea if soldering nails is a correct translation so maybe i did some bad solder work and the fault was only the bad contact-because when i turned the amp of the resistor was outside of the amp...)

but the amp was fine. nothing blown so maybe all was my bad craftmanship?

i tested then the current limit circuit and found that it limits the current perfect down to 2 ohms, with 1 ohm it starts to oszillate when cutting of-is this a behavior of the irfp240/9240 or the circuit itself?

an additional result of my testing was that my transformer or the filter choke induces hum to my speakers even when not connected to the speaker itself, these l´s have quite some magnetic pickup in the filter network of the speaker
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Old 10th August 2011, 08:12 PM   #10853
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Default dc offset

I'm attempting to bias one of my channels again.

I'm seeing 0v at the speaker binding posts (dc offsets) - - maybe I'll have to adjust my meter.

I know I should be approaching zero as R11 + R12 get inline - but to start with 0v?
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Old 10th August 2011, 09:09 PM   #10854
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Quote:
Originally Posted by cyclecamper View Post
Perhaps for targetting human perception and processing an amp with higher basic distortion figures may actually be not just plesant but more "accurate" where it matters to human hearing.
Easy enough to explore this with the F5. Just adjust P3 to get out of the
2nd harmonic null and take a listen.

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Old 10th August 2011, 09:27 PM   #10855
flg is offline flg  United States
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P3?
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"It was the perfect high end audio product: Exotic, inefficient, expensive, unavailable, and toxic." N.P.
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Old 11th August 2011, 12:08 AM   #10856
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Hasn't this been around?

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File Type: jpg F5 R1 SCH.jpg (362.6 KB, 1600 views)
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Old 11th August 2011, 01:44 AM   #10857
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Quote:
Originally Posted by Nelson Pass View Post
Hasn't this been around?

Uhhh, nope.

On the boards I had burned for myself I provisioned using alternative source resistors which effects the same result.
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Old 11th August 2011, 05:21 AM   #10858
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Silly me.

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Old 11th August 2011, 07:13 AM   #10859
vtr is offline vtr  Switzerland
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Default is it worth upgrading Mr Nelson?

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Originally Posted by Nelson Pass View Post
Hasn't this been around?


i see the different thermistor arrangement and some k2 balancing circuit-maybe only to implement the p3 as a easy fix?

thanks
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Old 11th August 2011, 12:07 PM   #10860
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Just when one had read the manual at least 76 times and mastered every single and and if
Papa came along with a new thing.


Is going to take me at least a week to understand the P fortunatley I am a bit beter with numbers and the 3 should only take a few days.

Magic
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