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flamethrower1 7th August 2019 12:35 PM

F5 V3
Just ordered the boards to build this amp.
Doing research on initial set up, I have found all the answers I need on setting bias thanks to all of the great info posted by others, thanks.
I can not however find anything on adjusting the center pot.
Can anybody point me in the right direction.
Please forgive me if this sounds like a noob question,this is my first amplifier build.

Thanks, Greg

nr12 7th August 2019 01:26 PM

You mean P3? See page 7 in the article.

Dennis Hui 7th August 2019 01:33 PM

One really should have some way of measuring distortion to adjust P3. If not,
I recommend just leaving it at the midpoint position.

This thread should give you idea of what P3 adjustment is about.

Adjusting P3 - a video


McQuaide 7th August 2019 04:21 PM

You can just omit P3 unless you are going to use a distortion analyzer.

flamethrower1 8th August 2019 12:12 AM

I appreciate the guidance from you guys, thanks.
Nr12, what article are you referring to.
I have been doing a lot of research and reading and have not found a reference to adjusting P3.
Maybe I missed something

BluesTM 8th August 2019 04:19 AM

I thought P3 was like used for AC balance. If you didn't have a distortion analyzer could you use a scope to get a balanced signal at the output?

nr12 8th August 2019 04:50 AM

Hi flamethrower1,

I refer to Nelsons article about the F5 Turbo. The basis of all threads. You should have read it in the beginning.

Best regards,

flamethrower1 8th August 2019 01:28 PM

Yeah, I actually did read that article some time ago and read it again last night.

McQuaide 9th August 2019 07:43 PM

Here's 6L6's video about P3 adjustment on a BA-3.

flamethrower1 17th August 2019 11:00 PM

I have all my parts ordered for the F5 boards.
Getting ready to order the parts for the DIY PSU.
I am planning on using the Antek 4218 transformer.
I have seen other posts that recommend going to 15K CAPS VS the 10K, anyone have some real life experience between the two?
Also, the input snubber and resistor combo, here is what I have found
Antek 400VA, 18v

Cx 10nF
Cs 150nF
Rs 18.3Ω

Antek AS-4218 with Cx=10nf Cs=150nf and Rs=6-10Ω. I'm using 7Ω in my actual circuit

Antek AS-4218, 400VA, dual 18V secondaries, dual full wave bridges:
(Attributed to another DIYer who requested to not use his name.)

Cx = 3.3nf
Cs = 470nf
Rs = 16.9 ohms

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