DIY Front End 2022

[lolo6990]

Thank you very much!
Planned to do the same, also putting the filter like AmyAlice or the simpler one!

 

[meurich10]

How balanced does the power supply need to be? I built a +/- 27 vdc supply using 3x 9.1 volt zeners and fets and it ended up +0.3 volts higher on the positive side. I think I could change some zeners to get it closer but I don't want to if this is good enough.

Also....What current draw should I expect?

 

[Ben Mah]

The current draw is approximately 12mA per channel: https://www.diyaudio.com/community/threads/diy-front-end-2022.394339/post-7231380

The slight voltage imbalance shouldn't be an issue.

 

[MARCUS SOLOMON]

Hi
Last time I used FE2022 +/-24V with my F5T V3 I found huge DC OFFSET at the output when played it quite loud (over 30W) then I shorted DC blocking (3.3uF) at the output of FE2022 to solve this problem, Why I got DC from typical FE2022 ?

Thank you.

 

[e_fortier]

When your output power is below 30W, is your DC offset lower ?
Which version do you have, the one where R6 is replaced by P1 (1kohm) ? Use P1 to adjust your DC offset.

 

[MARCUS SOLOMON]

When it played lower than 30W its offset is only 10mVDC. I used latest version of FE2022 with 1K trim pot and also trimmed it to 0VDC at the output of TR (in front of output cap)

 

[Zer0Sense]

Can you guys tell if I can use this as mic pre for SM7B? I have a tube preamp with 2 channels with phanthom power (REDD .47).
How to commutate theese correctly from preamp XLR with 48V and mic output? What connect where.
On the board I see In+, in-, v+, v-, grnd, out. I plan to use 2 boards in same enclosure for both channels. SK170BL pair on each board.
Thank you

 

[Nelson Pass]

When it played lower than 30W its offset is only 10mVDC. I used latest version of FE2022 with 1K trim pot and also trimmed it to 0VDC at the output of TR (in front of output cap)

I can't help but think that it's the result of clipping, which is not perfectly symmetric.

 

[ghitus]

Hi guys, just to be sure of what to do, if I want to measure DC offset, should I short the board input?

Thank you,
Gaetano.

 

[Stanislav]

It will definitely not hurt.
Good idea always to short the input unless measuring gain, freq. response, etc.

 

[peter19500]

I need an advice. Do you think it would improve the sound with the Musician Pegasus r2r dac? I use unbalanced outputs to the final amplifier. According to the reviews, asymmetrical outputs on Pegasus (as well as similar dacs) are sloppy.

 

[e_fortier]

Hi

I have just finished my FE2022 and wanted to share some pics, the enclosure was build by one of my friend on this forum. This preamp plays great, thanks a lot Mr Pass 👍
The big 4 pole switch if to select from a gain of 4x or 10x.

 

[peppennino]

Wow, what a preamp! 😍
Rhanks, Papa!!!

 

[cubicincher]

Hello peppennino,

so simple and so good! Enjoy the sound!
Nelson Pass gave us another beautiful toy.
Cheers
Dirk

 

[simon dart]

Here's my build with Clarity Cap CSAs and super regs from the DiyAudio store. I didn't post a picture of the outside, it's a black box 😊 sounds so very good on gain duty for my F4!

 

[ronnieponsones]

I made 4 kits Aca 1.8 monoblocks and Acp+ preamp and Aca mini. What are the expectations driving the amps using the front end 2022? I read they are good for F4 amps because of the gain. Appreciate comments and direction as I ordered the 20usd FE kit.

 

[lolo6990]

whatever you want to add, it goes either in front of Black Box, or after Black Box

so, in short - No.

Volume pot goes in front of Black Box
main reason - R1 is defining part of circuit, gain wise and impedance wise; R3 also being important ........... and - in case of resorting to single rail arrangement, there is substantial DC potential across R3

Hi.

Volume pot is being suggested in front of the Front End.
But it is also mentioned that addition like volume pot could go before or after the Front End board.

If i want to keep the inputs as XLR / balanced until it leaves the Front End, can i put a volume pot (Alps RK27 10k) after the Front End without any adverse effect ?
Idea is to have "XLR/balanced inputs" -> "Front End" -> "Volume Pot" -> "Ship of Theseus" in 1 box.
[But if there are incompatibilities mentionned, that would be "RCA/unbalanced inputs" -> "Front End" -> "Volume Pot" -> "Ship of Theseus" in 1 box]

 

[Zen Mod]

why placing vol pot after gain stage ?

proper place for volpot is before gain stage, which is also acting as buffer for volpot output impedance

if your goal is to save money, instead of using bal volpot in front of gain stage, so you can use normal stereo volpot after the gain stage, logic is no good, reasons explained above

and also you get gain stage not working in full scream mode, if getting full voltage from sources

 

[peter19500]

Can I use it as a quality converter with minimal gain from balanced to unbalanced?

 

[lolo6990]

@Zen Mod
Thanks for the answer.
I didn't knew balanced vol pot existed...when i searched around for balanced volume control, i mostly found solution based on opamp and integrated circuit. I will search better
And if i don't find, i will then forget XLR/Balanced and go RCA/Balanced -> Vol Pot -> Front End -> Ampl.
(sorry, did a bad copy/paste in the original post. I should have inverted the position of the vol pot...but then you helped with your explaination. thanks for that)
Regards