The diyAudio Firstwatt F6

[2 picoDumbs]

Depends on what you want to achieve.

 

[6L6]

Try C2 connected as shown in the 6 Moons transcript first, IIRC, you should just be able to tie on end of the cap to a leg of the mosfet, that's not all that frankenstieny of a PCB hack.

See what you think, and then try it the other way.

 

[Zen Mod]

dilema-including MOSFET source resistors in AC path or not , solved by Papa's post

Can someone clear something up for me? There's talk about where c2 connections.

Where does the negative leg of C2 go- to the Source of the mosfet, like in the first post schem or after R2, closer to negative voltage? There store boards are like the schematic.

http://www.diyaudio.com/forums/pass-labs/258613-diyaudio-firstwatt-f6-17.html#post4371378

http://www.diyaudio.com/forums/pass-labs/289328-me-my-new-f6.html#post4670139

 

[wdecho]

For the electronic challenged solder slingers as myself I think I understand what is being said now about placement of the C2 capacitors. I believe Papa is saying that the resistors are there for the Fairchild transistors stability and not there to tailor the sound. If you want to tailor the sound you move the negative leads of C2 to the other side of the R1 and R2 resistors. I do wonder why one resistor is .56 and the other .47 ohms unless in the circuit one output mosfet drifts more than the other. I personal like more 2nd harmonic and use a tube preamplifier with my F6 that has generous amounts of 2nd harmonic so placement of the cap is of no consequence to myself. If you are using a "clean" pre you may want to move the leads and introduce some 2nd harmonic.

At the BAF presentation on the F6 with the power jfets the R1 and R2 resistors tailor the sound.

 

[Zen Mod]

For the electronic challenged solder slingers as myself I think I understand what is being said now about placement of the C2 capacitors. I believe Papa is saying that the resistors are there for the Fairchild transistors stability and not there to tailor the sound. If you want to tailor the sound you move the negative leads of C2 to the other side of the R1 and R2 resistors. I do wonder why one resistor is .56 and the other .47 ohms unless in the circuit one output mosfet drifts more than the other. I personal like more 2nd harmonic and use a tube preamplifier with my F6 that has generous amounts of 2nd harmonic so placement of the cap is of no consequence to myself. If you are using a "clean" pre you may want to move the leads and introduce some 2nd harmonic.

At the BAF presentation on the F6 with the power jfets the R1 and R2 resistors tailor the sound.

just change Fairchild to mosfet , and you got it right

 

[wdecho]

I was going to include corrections would be appreciated.



Quote from Nelson:

(The Fairchilds in the F5 have a bigger temperature coefficient, so they
drift more with temperature than the IR N channel parts.

Also, you can use higher values for the Source resistors on the F6 if you want,
as they are not seen in the AC performance, only the DC.)

The first paragraph explains why the difference in resistor values in the F5 and I am sure the reason for the different values in the F6 R1 and R2 resistors is much the same. Careful reading of what Papa is saying explains everything.

 

[vdi_nenna]

just change Fairchild to mosfet , and you got it right

Btw- the jfet F6 BAF degeneration schematic shows C2 before the resistor. Looking at it, I was unsure. Perhaps they are Fairchild mosfets.

Ok. I'm using IR.

Thx

Vince

 

[aspringv]

Hi there all,
Does anyone have a part created in eagle of the Jensen transformer? I've a PCB design I'm planning and it'd speed things up to not re invent the wheel.

Thanks all!

 

[2 picoDumbs]

If you don't have any luck I will certainly borrow your reinvented wheel.

 

[aspringv]

Noted! Never constructed a part in eagle before so I guarantee nothing in terms of a quality end result

 

[Sangram]

I've often placed wire pads of appropriate diameter and bore on the pin locations, and a bounding box on the dimensions layer. This is a little simpler than Eagle parts and more intuitive.

Of course you have to convert everything to mils first, but that's relatively easy.

 

[drewburn]

This may be a question that has been asked before, if so, sorry
.
Has anyone compared this F6 amp with Zens, mine is the original vers with choke power supply.

I'm interested in comparative sound quality. I know the F6 is more powerful

 

[vdi_nenna]

I had owned the Zen with 2 amp bias and choke filter.
I can say without doubt that the F6 mosfet and F6 jfet are in another league.

From the power, sound stage, tonal quality, high end extention, the F6 dominates over the Zen.

Not saying the Zen sucks. Just saying it's no contest by comparison.

Vince

 

[6L6]

These amps are just different expositions of musical awesomeness, comparing them is like walking into a garage full of Ferraris and trying to decide which the the most red Italian sports car.


That said...

The biggest single difference between the Zen and the F6 is power and damping, which will make it sound very different. (And the F6 will sound 'better' to most people's ears.)

 

[vdi_nenna]

By the way, the mini aleph was a nice step above the zen.

Now the Zen 9 could hold its own. It has a sweet quality.
Very nice.

 

[6L6]

The Zen 9 is basically an F3.

And vice-versa.

 

[2 picoDumbs]

Zen V 4 is bloody nice too.

 

[Zen Mod]

every Zen is good

 

[plasnu]

As far as I understand, those Papa's amps are the brainchildren of the post modern philosophy, so there is no better or worse.

 

[poseidonsvoice]

These amps are just different expositions of musical awesomeness, comparing them is like walking into a garage full of Ferraris and trying to decide which the the most red Italian sports car.


That said...

The biggest single difference between the Zen and the F6 is power and damping, which will make it sound very different. (And the F6 will sound 'better' to most people's ears.)

Well said. And let me express a word of thanks for all your hard work in documenting the Pass builds. The F6 is one of them that I am plan on building...

Anand.