F3 Builders Thread

[ed linssen]

LU1014s

Last day for order a board set (or more , without LUs)!

Hi there!
Has someone on this forum a couple of th LU1014s left for me?
Would be very pleased...

Were can I find a decent 'build' manual or thread for the F3 on the web?
Thanks for help.
Ed

 

[carsten.witt]

Hi Ed,

keep your fingers crossed for the LUs.
The BOM was shown as teaser in GB thread ... it will extended in a few days ... need more time.

Please take a look: BOM

 

[badrisuper]

Hi

Is F3 a good match for Tannoy HPD 315 or Yamaha NS500M?

Thanks
Badri M

 

[JeffYoung]

Singled-ended amps with low damping factors are often a good match with full-range drivers, which might point to the Tannoy. But I've never heard either speaker.

 

[Zen Mod]

Hi

Is F3 a good match for Tannoy HPD 315 or Yamaha NS500M?

Thanks
Badri M

it is good match for 12" Tann , but not the best

missing little power and little control too

F3 is match from heaven for crazy 8" drivers ......

 

[carsten.witt]

Hi all,

from the GB (https://www.diyaudio.com/forums/group-buys/339780-watt-f3-please-eu.html#post5840497) are only two sets of pcbs left, if interest please contact me.

 

[manniraj]

Sent you a PM.

 

[manniraj]

Looking for some genuine LU1014D FETs as I am planning to pick up the last set of group buy boards from Carsten. Seems to be difficult to get them and I hope NP can provide me couple of them for my build and F3 should pair well with my 8" Audio Nirvana drivers which are fairly sensitive 🙂

Thanks

 

[carsten.witt]

Last board set is free again.

 

[Johnny Canuck]

Has anyone tried an F3 build with 2SK1530 rather than IRFP240/240R? The Harris parts have become very scarce recently.

 

[Dennis Hui]

You can use vishay irfp240. No need for Harris ones.

 

[JeffYoung]

Yeah, the Lovoltech is in the driver's seat. The 240s are just a c-multiplier, a CCS, and a cascode, none of which are critical.

That being said, last I checked NJSemi had Harris IRFP240Rs. Ask for Ron.

Cheers,
Jeff.

 

[indra1]

N channel IRFP are good, you do not need Harris.

 

[Johnny Canuck]

Wow, thanks for your replies!
Glad I had the LU1014’s (from one of NP’s frequent giveaways - thanks Nelson!)

 

[lordvader]

Bit of a bump on this thread, but anyway 🙂
One of the channels of my f3 amp fails pretty much instantly. To make attempted repair easier, I've taken the amp apart. This separates it from bulky psu.

Can I test a single F3 channel with a 50V (maybe even just 30V) bench supply, linear or switching supply? Will make my life easier!
I really just need to identify the failing component - possibly a short somewhere ...

 

[2 picoDumbs]

Yes

 

[JeffYoung]

FWIW, I always test each channel on a bench supply first. That way you can slowly run up the voltage and see what kind of current it's drawing....

 

[lordvader]

I actually had the amp running for a few years, then I think a drip of water caused a channel to fail. Have another amp, so the F3 was sitting idle.

Was about to sell it for parts, but then thought I'll take a crack at repairing it. Might pop back here every now and then for advice, as I've got no idea what the failing part is!

 

[lordvader]

Quick update on the testing. I tested each channel with a bench supply, and all seems normal...

At 46V, each is drawing 1.6A. 1VAC in and about 4.6VAC out.

The only difference is that on power up, one channel draws 0 amp, then slowly ramps up to 1.6V, the other immediately jumps to 2A, then slowly comes down to 1.6A.

Could this surge trip my fuses? Each channel has a 1.25A slow blow (I think). Oh, and I'm on 240VAC. Dual mono supply.

 

[Zen Mod]

what's VA of Donuts , and size of cap bank?

T1A25 is sounding too low , so give us data