DIY Front End 2022

[Mark Johnson]

Some people prefer to eliminate one or more AC coupling capacitors from the signal path; dual rail power supplies are one way to implement this.

Keep in mind, though, that the complete amplifier contains a "back end" as well as a "front end", and there are more than one FirstWatt back ends which contain AC coupling capacitors. Even with dual rail power supplies.

_

 

[simon dart]

Thanks @Mark Johnson The F4 is my intended application. So I could omit the FE output coupling cap with split supplies? Making sure the DC offset on the output was reasonably low so as not to stress the input FETs of the F4 of course.

 

[Joschl]

Yes you can 🙂 Provided that your FE alone is okay in the DC department. Then you treat the F4 with the FE together as a unit and tune it to good DC behaviour.

 

[BRN]

Ben,

Thank you for making the power supply boards available. I just finished the installation in my FE22 and it is working great.

It is had to beat the FE22 as a preamp. On top of the rack that is so easily it is to build.

Thank you Mr. Pass for sharing this with us.

 

[Ben Mah]

BRN, you're welcome.

I agree, it is a great preamp, thanks to Nelson!

 

[manniraj]

Here is my FE2022 line stage with 20db gain and thanks to @6L6 for his excellent representation of what resistor values to choose for different gains. I finished mine using VRDN psu set to +/-24vdc. Powering this preamp with the LU1014 amp and sounds excellent so far. Once again thanks to Nelson to share yet another outstanding line stage for us 🙂

 

[Aleph5]

Nice chassis. What volume pot/board is that?

 

[manniraj]

It’s a alps 10ka pot soldered to a small pcb -
https://a.aliexpress.com/_mLOgXcE
Even store has a nice pcb

 

[poseidonsvoice]

Very nice @manniraj !

I particularly like the purple colored spacer underneath your FE2022 boards 😉 !!

Best,
Anand.

 

[manniraj]

Thanks Anand that’s what I could find to isolate the pcbs from the chassis as was eager to test the preamp out and I wasn’t disappointed at all. It’s now on to my main setup and makes my XA25 to sing and dance 👍

 

[Simrol]

Hi, I've got something wrong, the sound is dark and a lot of bass, very withdrawn and low, uses 42v, is it too low. Or have I connected something wrong

 

[Ben Mah]

Is C6 0.22uF? If it is, it is way too large. Remove it and listen again.

 

[Simrol]

Thanks for the reply, yes it's 0.22, will try to remove it tomorrow, see what happens, it's starting to get a bit late here in Norway

 

[Simrol]

super thanks for the help Ben Mah, now it plays beautifully, 😀

 

[manniraj]

Nelson suggested to use either a 33pf or a 100pf but what difference does it make if you exclude this cap? Right now I am using a 33pf.

 

[Mark Johnson]

Are you referring to the oscillation prevention capacitor C6? Do you hope to get oscillation, by discarding its antidote?

_

 

[Nelson Pass]

Actually I did not encounter a need for the cap as presented, but as with the offset pot and
PNP emitter resistor I wanted to make allowance for the potential of needing it.

 

[manniraj]

Are you referring to the oscillation prevention capacitor C6? Do you hope to get oscillation, by discarding its antidote?

_

Yes thats the one C6 and I think I hope not to get any oscillation but as NP replied I guess I can omit and try to see the difference.

Thanks

 

[Ben Mah]

My DIY FE 2022 is the original PCB which has no accommodation for C6. It seems to be working fine with no issues. I enjoy listening to it every day. 🙂

 

[gary s]

Mine is the original as well, and is just about the best FE I have ever had in my system. It is not going anywhere anytime soon. No C6 in sight.