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F4 power amplifier
F4 power amplifier
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Old 26th June 2019, 07:36 AM   #4451
sov is offline sov  Sweden
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I'll try
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Old 26th June 2019, 05:50 PM   #4452
cal3713 is offline cal3713
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Originally Posted by sov View Post
I'll try
Please report back when you do...
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Old 26th June 2019, 06:43 PM   #4453
BigE is offline BigE  Canada
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How long would be minimum rail length be before requiring such bypass caps? I mean what is min distance from PS cap bank to output boards that could use the motor start cap?
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Old 26th June 2019, 09:15 PM   #4454
Zen Mod is offline Zen Mod  Serbia
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F4 power amplifier
why bother thinking ?

they're cheap .... just put them in
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Old 20th July 2019, 09:02 PM   #4455
sov is offline sov  Sweden
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Just finished the F4 and I am VERY pleased with the sound. Running F4 with B1 Korg and Cornwall speakers (105dB). Compared with M2, Tea-bag style, in above setting the sound becomes more clear, tight and still very easy for the ears. Now I can use the volume knob better. F4 sounds very nice at lowest volume and still could rearrange furniture with highest.

The M2 had a 400VA transformer and the F4 has a dual mono PSU with 2x400VA and Pass general PSU.

Bias is set to 295mV. The build guide says half the trafo-VA but I guessed since I have dual mono PSU heat sinks they sets the threshold. Heat sinks gets to 47C, (117F). Heat sinks is 5u 300.

@cal3713, I have not compared without the Ducati motor-run 40uF caps but the sound is addictive so I guess and hope they are doing their job. ZM’s recommendation is at least 50uF(!)

Don’t look at R8. You did, didn’t you? What is a k more or less among friends?
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Last edited by sov; 20th July 2019 at 09:05 PM.
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Old 20th July 2019, 09:22 PM   #4456
Zen Mod is offline Zen Mod  Serbia
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F4 power amplifier
Biiiiiiiiiig washers!!

Fugly!



(hope you didn't forgot split washers where needed)
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Old 20th July 2019, 09:37 PM   #4457
sov is offline sov  Sweden
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Thx!
Spit washers almost everywhere, especially on mosfets. Thought that big washers could even the pressure.
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Old 21st July 2019, 03:00 AM   #4458
anatech is offline anatech  Canada
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F4 power amplifier
Hi sov,
I think those fender washers are a brilliant idea! It sure beats putting a string of accurate holes in a bar of metal. I may just take your idea for some of my projects. Good thinking.

-Chris
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Old 27th July 2019, 05:25 PM   #4459
Andrzej Sochon is offline Andrzej Sochon  Poland
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Quote:
Originally Posted by Zen Mod View Post
...if you have a place in case , connect 50uF motor-run caps as bypass for final caps in filter section , that usually brings some speed and freshness...
Additionally try to use fast recovery rectifying diodes instead of typical rectifying blocks.
Also on the F4 input, use THIN wires (eg twisted two wires drawn from LAN twisted pairs) instead of shielded wires.
You may discover more details, speed and freshness too...

Last edited by Andrzej Sochon; 27th July 2019 at 05:32 PM.
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Old 27th July 2019, 05:46 PM   #4460
cal3713 is offline cal3713
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Finally bought some 50uF motor caps to add to my power supply. Do they need to be installed upright, or can I lay them on their sides? The latter gets the wires a little closer to where they need to go in my case...

Quote:
Originally Posted by Andrzej Sochon View Post
Additionally try to use fast recovery rectifying diodes instead of typical rectifying blocks.
Also on the F4 input, use THIN wires (eg twisted two wires drawn from LAN twisted pairs) instead of shielded wires.
You may discover more details, speed and freshness too...
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