F2 Initial Listening Impressions

[apassgear]

So Nelson couldn't resist to give it all

Now seriously, I greatly appreciate Nelson for sharing so much with us.

Well, so here you are fellas, the whole enchilada

 

[Circlomanen]

That's correct; originally it was set at 15 ohms as per Nelson tips.

Wouldnt it be beneficial to connect that 15 ohm resistor from powersupply rail down to the drain of Q1 ???

 

[Nelson Pass]

It would allow any power supply noise to bleed into the
circuit. Also, being that the F2 is cap coupled on the output,
running it after the cap to ground assures that the DC on
the output is at ground - the resistor bleeds off the capacitor
charge if there is no resistive component to the load or if there
is no load. This prevents surprises if you are connecting the
speaker to an amplifier which is already switched on.

 

[audionut]

It looks like from Apassgear's schematic that one could build an f2 on the old Zen boards...just change the values of some of the components....Is that right???

 

[steenoe]

That would be more or less correct🙂 Take a look at this initial schematic, based on the ZenV1 boards from Pass himself.
Except for the regulator, thats pretty much it. A few values has to be corrected as per Apassgears schematic. Otherwise I think it is perfectly do-able. As a sidenote I might add that the regulator propably isn't to find in the original F2. But thats just speculations on my account😉
My intention was to modify the Zenv1, but now I am going for Apassgears nice boards.

Steen😎

http://www.diyaudio.com/forums/showthread.php?postid=669358#post669358

 

[KT]

It looks like from Apassgear's schematic that one could build an f2 on the old Zen boards...just change the values of some of the components....Is that right???

That would be more or less correct🙂 Take a look at this initial schematic, based on the ZenV1 boards from Pass himself.

Awesome!

I was looking to sell my v.1 boards, but now I think I'll keep them.

Best,
KT

 

[steenoe]

I was looking to sell my v.1 boards, but now I think I'll keep them.

KT, if you want to play with current source amps and fullrangers, that would be the easy way to do it🙂
Considering the bit of hum from the ZenV1 into the speakers, you might want to consider some additional PSU filtering, though😉

Steen🙂

 

[rebojorge]

I also want a piece of the action!!

After that I will have a great excuse to build some high efficiency full rangers.

Gracias Tony.

 

[steenoe]

I also want a piece of the action!!

Rebojorge, you are more than wellcome😀 😀
I know about those darn Fullrangers too, they are a bit tempting, arent they😉

Steen😎

 

[rebojorge]

Yes they are tempting.... I just finished my first amp and speakers.... (well not finished but they are up and running)... and can`t wait to get to the next proyect. I don´t want to go off topic here so I will post some pics and details soon on a different thread

 

[Nelson Pass]

I know about those darn Fullrangers too, they are a bit tempting, arent they

Very tempting

 

[rebojorge]

Specially if you have a little spare room for the Kleinhorn

 

[apassgear]

Well, I'm back after a house change... I still have my hands full with this but the nice side of it is that now I have a dedicated room for electronics, not the kitchen table, ejem...

Nice to see you rebojorge jumping to this wagon.

Steenoe, how far are you from finishing the F2?

 

[steenoe]

Steenoe, how far are you from finishing the F2?

I might be able to finish the amp within a week or so. I will have to finish the speakers also, though. I have a pair of Corals without boxes. I am not sure the F2 will like my ProAc 2.5 clones very much.

Steen 🙂

I have a dedicated room for electronics, not the kitchen table, ejem...

Thats nice, its a pain to clear the kitchen table every at suppertime isn't it😀 They claim NP does it though, with all the First Watt's, beeing kitchen table project's😀

 

[Variac]

He confessed that they aren't reallllly made on the kitchen table, but they are mostly made by his hands..

 

[acaudio]

Very tempting

Yes!

I´m infected too. I built in the past days a F1 clone and now I´m owner of a pair Fostex FE206E. It´s crazy how good these sounds. The tweeter is disabled, it´s just a test setup, but it sounds so already much better as my previous system.

Adam

 

[audio3000]

I run my FR125 on a 2 x 4 ft open baffle with off-center location. The amp is similar to apassgear's posted circuit. The major differences are some component values and I use LM317 as regulator. Only one watt at 1% THD. I was inspired by Nelson's Zen amps to design it.

They sound very nice, very open, good mid and like in a concert hall but lacking bass. I am very willing to trade bass for good mids and highs..🙂 At least at the present moment. The bass has to be fixed but I prefer to enjoy them now.

I ran the FR inside a BR box before, but didn't like it. The box was not optimized. It's just a handy old big speaker box happened to be in my basement. They sounds too forward and aggressive. Needed a tube amp to correct the situation. But with OB, the 1W amp sounds closed to my tube amp. The FET amp is more detail and the tube amp gives out sweeter mids.

 

[Vix]

Hi,

I was thinking about building an F2, but then Mr. Pass published the ZEN V8, and then….

I started scratching my head and wondering if the F2 can be improved a bit and use a cascade “trick” from the Zen V8. I added a buffer as well. You may argue about the choice of mosfets. Those drawn are the ones that I have handy, so you can put your favorite ones.

So there is a schematic. I called it F 2.5. Heheh....Please have a look and see if it should work. I am not sure about the 470 K resistor (marked red). Is it necessary or the circuit can do without that one? Will only P2 be sufficient for setting the proper voltages? (Then P1 could be a fixed resistor 220 K).

Sorry for a bad hand drawing…

Regards,

Vix

 

[Vix]

Hi

I feel disapointed🙁

I know that the circuit I posted yesterday may seem silly, but I really needed an advice. I do understand some electronic concepts, but some are not so clear to me, that's why I asked a question.

Still, I got an impression that my post was disregarded. Or maybe wasn't read by those who could offer an advice. Don't get me wrong, I don't want to offend anyone, I am thankful for this forum and the shared knowledge.

It would be nice if some of you could find the time to have a look at the schematic and tell me if there's something wrong...

Thanks,

Vix

 

[steenoe]

Hi Vix
Dont be put out by this🙂 Its easy to overlook something like this,
especially if you dont follow this particular thread.
The circuit you made looks pretty interesting. I am sure someone will take a look at it😉

Steen.