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Old 19th January 2011, 10:58 AM   #1391
cviller is offline cviller  Denmark
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Hi Serge,

I know it is tempting to add decoupling, but Nelson Pass actually tells us not to do it. If you do it, the amp will be more at risk of oscillating.
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Old 19th January 2011, 11:03 AM   #1392
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Nelson Pass actually tells us not to do it

I have the good answer

Thanks
Serge
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Old 19th January 2011, 04:54 PM   #1393
h_a is offline h_a  Europe
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Quote:
I know it is tempting to add decoupling, but Nelson Pass actually tells us not to do it. If you do it, the amp will be more at risk of oscillating.
Do you have by chance any link to that?

As these do not directly affect stability margin I would be curious for the reasons.

Hannes
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Old 19th January 2011, 06:25 PM   #1394
cviller is offline cviller  Denmark
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He has mentioned it many time in the f5 monster thread, but here is an example:
F5 power amplifier

I believe the problem is that you will create an LC oscillator by the supply interacting with the signal gnd on the amp board.
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Old 20th January 2011, 09:00 AM   #1395
h_a is offline h_a  Europe
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Thanks for the link, interesting, might be due to the current feedback design (huge bandwidth) and/or board layout.

Hannes
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Old 23rd January 2011, 10:02 AM   #1396
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Is a new batch of V2 coming ? I did a stereo F5 using V1, and I want to do another one to have balanced monoblocks. If you are doing a new batch of the V2, I am going to wait to get the boards for the second one.

Thanks,

Davide
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Old 23rd January 2011, 10:05 AM   #1397
cviller is offline cviller  Denmark
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The next batch will be in the diyAudio store (DiyAudio PCB Bank) - but it normally takes quite a while for boards to be ordered and produced. I think the boards will be ready late spring.
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Old 24th January 2011, 07:20 PM   #1398
viki_v2 is offline viki_v2  India
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Guys i need pcb files of f5 for etching , Please help
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Old 31st January 2011, 03:29 PM   #1399
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Thinking about changes, there are things that could be useful, although they can be accommodate in other ways, like:

1) Extra pads to parallel a second resistor to the mosfet source resistors (R11 R12)
2) pads to add the extra resistor for EUVL degeneration trick
3) pads to allow the connection of two boards together for balanced
4) pads to parallel a second resistor to R1 R2

I understand it's not a big deal to do all the optimization with the actual design, and if it's complicated just forget it, but I think they would make a very versatile board, potentially capable of the monster F5 parallel+balanced.

D.
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Old 31st January 2011, 05:13 PM   #1400
lhquam is offline lhquam  United States
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While you are adding pads, consider pads for a 6 pin header for bias adjustment connections to a ribbon cable.

I learned the hard way, that it is possible to accidentally short something and smoke an amplifier while making probe connections during bias adjustments. To prevent this in the future, I directly soldered 6 wires of a CAT5 cable to my cviller boards, using 1k resistors in series with the connections to prevent possible problems. The cables connect to a 2 pole x 6 position rotary switch. The 2 outputs of the switch connect to a multimeter for adjusting bias. The CAT5 pairs connect to each end of R11, R12, and output/gnd. Everything other than gnd was isolated with a 1k resistor. I will post pictures if you like.
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