A guide to building the Pass F4 amplifier

[2 picoDumbs]

That looks like a good match for the F4

 

[myleftear]

If on the metal, that’s the Vgs, which is the actual measurement. Still, don’t separate the trios.

And to answer the next question, the Vgs of the N channel will almost never match the Vgs of the P channel, and they don’t need to for proper operation.

Tank again, 6L6
Here's what I've got. I'm very confident this will come true

 

[Zen Mod]

that's one decimal place too much, if you ask me

me being lazy, of course

 

[myleftear]

that's one decimal place too much, if you ask me

me being lazy, of course

Well...

 

[6L6]

Matches to within one mV. Wow. That’s a nice set.

 

[myleftear]

the other set matches by just a mere 6 mV and 1 mV.
That's diyaudiostore...

 

[2 picoDumbs]

I've noticed Vishay are producing tighter matching parts compared with 8 years ago.

 

[Zen Mod]

or you're slower in matching, so they're bored of waiting ......... better to line up instead of waiting operator's decision

 

[2 picoDumbs]

Good to see they are thinking of me.

Hahahaha

 

[myleftear]

Good to see they are thinking of me.

Hahahaha

They may have been thinking of you—but they stopped waiting for _me_ [emoji23][emoji56]

 

[Alan Cohen]

Q: I'm ordering parts for the PSU. I'm confused about values for input snubber capacitors and resistors.

 

[6L6]

They have to be trimmed to your transformer.

 

[Alan Cohen]

I'll be using this: https://www.antekinc.com/content/AN-5220.pdf

 

[6L6]

Look through the “Quasimodo results thread” (It’s named something like that) and see if anybody has used that transformer.

 

[Alan Cohen]

I did a search for 5220 and didn't see anything.

 

[2 picoDumbs]

Well they're not something you absolutely need so it's something you could work out later.
I don't use snubbers.

 

[chede]

I've noticed Vishay are producing tighter matching parts compared with 8 years ago.

I just built an F4, matching the MOSFETs myself for that.

Bought one tube (25 pcs.) of each, Vishay IRFP240 & '9240.

Did match all FETs at 25V and 500 mA.

Out of my tube of '240s, I got three Triplets within +/- 1 mV. And another two Triplets within +/- 3 mV. And then, two more pairs within 1 mV.

Of the 25 pcs. of '9240s, I got one Octet within +/- 2 mV, or two Triplets within +/- 1 mV and a perfect pair ... also, there's one more Triplet within 1 mV, and two more perfect pairs ...

Spread between highest and lowest Vgs was about 9 mV for both the '240s and '9240s, respectively.
And the '240s and '9240s were less 10 mV apart from each other in Vgs.

So, if you buy a complete tube of each from a reputable distributor, you could actually just pick your MOSFETs randomly from the tube and be done with it ...

Therefore, I have to second pico, and I'm happy with Vishay's production tolerances

Regards, Claas

 

[2 picoDumbs]

Yeah that's what I've been getting which is way better than pre 2010.

 

[cal3713]

Damn, I missed a click or something and haven't been getting email updates for my f4 threads. Missed out on some action, but have been putting a good 3 hrs a night onto my F4s. Just bought a high gain dht pre-amp based on the eml 20a-m... excited to hear the f4s driven by a new circuit (current pre uses 6sn7s). Glad to see more people making the right choice and building these wonderful amplifiers.

 

[Alan Cohen]

While I'm waiting on the cabinet, I got the amp boards stuffed.

I'm missing R22. Somehow overlooked it when ordering. I checked my stash of 1/2W resistors and don't have a 750R. I love paying $10 for $.40 worth of parts! I'll wait to see what else I missed.

I received the Antek 5220 500CVA transformer. The dang thing weighs over 10#.

I'm a little confused on the PSU. I'll start and post when I get stuck.