F5 V3

[flamethrower1]

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]

You mean P3? See page 7 in the article.

 

[Dennis Hui]

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

Dennis

 

[McQuaide]

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

 

[flamethrower1]

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]

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]

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,
Ulf

 

[flamethrower1]

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

 

[McQuaide]

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


https://www.diyaudio.com/forums/pas...fier-illustrated-build-guide.html#post3973246

 

[flamethrower1]

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

 

[flamethrower1]

After doing some more digging, I found a couple of people saying the snubbers are not needed unless you have a way of measuring the ringing from the diode board.
I also found this for a quick order BOM from Digikey, Digi-Key - Fast Add.
No idea where it came from.
Anyway, they are calling out 27000UF caps.
I am also beginning to think that not using the diode board and going with monolithic bridges might make things a lot easier

 

[SRMcGee]

Flamethrower1:

You would be better off with a larger transformer for each F5T V3 mono-block. I’m using 1kw toroids and they are terrific. Get at least 600 VA; 800 VA would be better.

If you’re planning on using eight 27,000 uF caps in each chassis, you’re on target. I thought 160,000 uF, as proposed in NP’s F5T article, was a bit anemic.

Regards,
Scott

 

[brian92fs]

SRMcCee - I believe you’re describing a PSU for a F5 Turbo build. He mentions a 18-0-18 transformer which suggests a “regular” F5 at 24V

 

[flamethrower1]

SRM, thanks for your advise.
I have the regular F5 V3 boards.
I guess all I am trying to achieve at this point is a DIY AMP that is very clean.
My musical preferences tend to be clean and concise rather than loud.
The board build is well documented it seems, not so much with the power supply.
Would help if I could do a search on this sight,I type in F5 or DIY PSU for a search and get no matches found

 

[Dennis Hui]

This should help with the PSU:

diyAudio Power Supply Circuit Board v3 illustrated build guide

 

[flamethrower1]

ha, I looked at that thread I do not know how many times and finally see that my answer was right in front of me.
Now to find the caps, looked at Digikey and Mouser and they both show zero Qtys on 22000

 

[flamethrower1]

Well at least audio grade anyway

 

[Ben Mah]

Nothing wrong with these caps for power supplies:

B41252A5229M000 EPCOS / TDK | Mouser Canada

SLP223M025H5P3 Cornell Dubilier - CDE | Mouser Canada

The CDE cap is rated for 3000 hours at 105 C, and the price is right (Canadian dollars shown, so even better in US dollars).

I use these caps in my amps and I think most people do too.

https://www.mouser.ca/ProductDetail...=sGAEpiMZZMvwFf0viD3Y3ROGmxq83YAGBYJdx9Vlp74=

if 35V cap preferred. I have used 25V caps in my FW supplies with 18V transformer secondaries with no issues so far.

 

[flamethrower1]

I thank you Ben Mah for your help and assistance, appreciated

 

[rhthatcher]

You're going to need higher voltage than 18 on your transformer. I'm going to be building F5 V3's for a friend soon when all of his parts arrive. I have the chassis, boards, transformers, and a few other odds and ends in my car that I picked up yesterday.

He ordered one Antek AN-6435 per monoblock. You could kick it up to 800VA or more, too. I'll test both on my quasimodo / oscilloscope to size the snubber resistors. Maybe I can knock that out this afternoon. My experience is that the snubber values are pretty consistent across the same mfr and model number. I'll post the values here when done.


You're going to need higher voltage rated caps in the PSU with the higher voltage rails. He's going with 22000uF 63V Digikey: 565-4899-ND



If you haven't bought Mosfets yet, I'll be matching a ton of them for my buddy's amp, and kitting up more pairs and quads for others. I'll be posting them here as that happens. I expect that will happen sometime in the month of September depending on when he orders his last batch of parts.