F4 power amplifier

[iperv]

I mean the Cin, not the reservoir caps.

Attached is the BA pushpull output stage, the same design as F4 but without the buffer.

If the input is 5K, why 440u or 1Ku at Cin?

Edit: I'm a bit obsessed with the input capacitors... ;-)

 

[Zen Mod]

input node is just conveniently connected between these two caps (they having a role which I told you); it can be just one cap, but then you must use dedicated coupling cap - see M2 for example of that

2 caps in BA are "just" C part of additional RC filtering of rails

 

[iperv]

Thank you Zenmod, understood.
I think they (or it) have to be of very good quality.
I don't like very much bipolar caps at the input, but this is a different case.

 

[william2001]

My boards are populated with Elna Silmic 2's, and no bypass. I don't have much to complain about with it. Granted, I did not do any "cap rolling".

 

[Zen Mod]

Thank you Zenmod, understood.
I think they (or it) have to be of very good quality.
I don't like very much bipolar caps at the input, but this is a different case.

been there, done that , zillion times ....... changing things I'm not understanding, just to feel smart

it is good - if leads to more efforts invested in learning

but, don't fret - I'm still changing things I don't understand

 

[moe29]

was this ever done?

"I think I'll also take this circuit and add a voltage gain front end to it for a subsequent product."

maybe the first First Watt Integrated Amp?

 

[Zen Mod]

BA3 is not that?

 

[cal3713]

was this ever done?

"I think I'll also take this circuit and add a voltage gain front end to it for a subsequent product."

maybe the first First Watt Integrated Amp?

Here's a link to the gain stage ZM is referring to: Burning Amplifier Gain Stage for BA-3 – diyAudio Store

 

[moe29]

BA3 is not that?

Sorry, i was being lazy... and losing memory?!

 

[Variac]

BA-2 also. Nelson’s Burning Amp idea was was to have various front ends driving a “follower’ output stage, ie basically an F-4. Now I’m forgetting, I assume there was a BA-1 front end also…

 

[william2001]

BA-1 / BA-2 shared the same IPS/VAS, single ended vs push pull OS there.

 

[Variac]

And now he’s up to something similar with the VFET amps! , encouraging various front end designs….

 

[6L6]

"I think I'll also take this circuit and add a voltage gain front end to it for a subsequent product."

Yes. BA-3.

 

[Gyuri]

I'm in a process to gathering parts for Sy's Impasse preamp.

 

[dabochkarev]

Yes. BA-3.

I have made F4 with ba3 front end in one cabinet, but with separate input and output RCAs. So, i can use F4 with internal BA3FE, using external RCA links, or with external preamp.

 

[Ground point 9]

I have made F4 with ba3 front end in one cabinet, but with separate input and output RCAs. So, i can use F4 with internal BA3FE, using external RCA links, or with external preamp.

How do you switch between the two?

Can you post a photo?

 

[dabochkarev]

Back panel consist of:
1. Pre (ba3) input RCA
2. Pre(ba3) output RCA
3. F4 input RCA

So you can connect source to 1, then connect 2-3 with RCA-RCA link and use internal ba3 front end, or connect your external preamp or dac directly to 3.
Now i'm far from home. Pics will be later.

 

[Ground point 9]

Back panel consist of:
1. Pre (ba3) input RCA
2. Pre(ba3) output RCA
3. F4 input RCA

So you can connect...

Ah, much like the ol' NADs. Understood!

 

[Variac]

I'm in a process to gathering parts for Sy's Impasse preamp.

As I constantly mention, I have an Impasse with paralleled F-4s (which is what SY designed them for) Fantastic!

 

[soldersmoker]

I have a basic audio question, since I have an F4 connected to a tube preamp that delivers slightly higher-than-average gain, but nowhere near Sy's or Zen Mod's designs.

Is there a qualitative difference in the sound if the F4 is not being driven with a full 35 p-p of input voltage, or is it just a wire with gain that is quieter, not subjectively worse-sounding? I guess I'm wondering if the harmonics have differing relative outputs to each other, based on the voltages driving the amp, say a higher proportion of 2nd to 3rd or the reverse. And maybe other stuff.

Meanwhile, I'll be building an Aleph J to temporarily replace the F4's guts in my 4U amp. I'm curious if providing, say 5V peaks, sounds worse (anemic in some sense, maybe?) than 14V peaks, or if it doesn't make a lick of difference. I imagine speaker sensitivity might have some role in how it sounds, too.

I apologize for sounding gooey, but my curiosity demands answers!