DIY Front End 2022

[Cinco]

I used the JFE2140 they work very well.
Post #895

I've forgotten how to link to a post so that link is broken .

 

[Cinco]

I started with +12dB (which is R3 & R4 = 40kohm) on my MoFo. I like to socket things until I settle on a permanent value,
When I'm happy with the value, I remove the socket then solder in permanently.

BTW, these are my own PCBs with Texas Instruments JFE2140 as the long tailed pair. Can also use LSK389 SOIC or TO-71.

I got a little impatient waiting for boards to be stocked in The Store.


View attachment 1186813

 

[adrianrw]

Thank you very much @Ben Mah and @jt23.

I've rewired as described and noticed I forgot to short R13. Here is an updated wiring plan.

 

[sov]

For singel ended input make jumper between G and -
Edit:
And shouldn’t you take signal out from (out) and ground?

 

[Ben Mah]

Andrian, Your diagram looks correct.

sov, With an unipolar V+ power supply, R10 is jumpered and V- becomes ground. VG is not ground. One half of the power supply voltage would be present at VG.

 

[sov]

Of course, sorry for my fault and thank you for fast correction.

 

[STOXX]

What are the capacitor board spacings?

Cheers & happy Canadian Thanksgiving.

 

[Ben Mah]

I do not have a board to measure but Nelson wrote that the board is 1.7" x 3" with mounting holes spaced at 1.575".

With those dimensions you can scale the spacings from the picture.

And Happy Thanksgiving to you too.

 

[STOXX]

Okey dokey...
7mm
10mm
15mm
ish

 

[Monk55]

5 mm for C4,5
7.3, 10, 14.7mm for C1-3

 

[von Ah]

Proof of concept works! I built and added R0 boards to my TDV. Stock FE2022 with kit transistors. 10x gain. Power supply is a mere +28VDC. Sounds quite nice.

Now I gotta figure out how to securely attach them to the chassis.

After this success, I’m going to get fancy with the R1 kit I have. That one will get either a bunch of K170s, a double bunch of K209s on adapter PCBs, or some K369s I have stashed away. Those boards will go in my BOO OS build.

Thanks again, Nelson!

 

[Zen Mod]

Boo is for Sissies

 

[von Ah]

Boo is for Halloween 🎃. I have it in the main rig for the season.

For this TDV, I affixed the FE boards and now have hum. Is it likely that the noisiness is due to routing the DC power lines around the inductors, or due to proximity with mains input?

I’m owning up to my greenhorn status.

 

[von Ah]

My use here is single supply, single ended input. Is it advised to make a CL60 connection from V- to chassis earth?

 

[Zen Mod]

always; whatever rail called GND, connect it to chassis in some way, more or less elaborate

doesn't matter how much unlikely, that's what keeping you alive if primary of Donut goes bonkers to secondary

and, as free l(o)unch, darn thing most likely is going to hum less

 

[von Ah]

Heck yeah! CL60 earth worked a charm! No more buzz. Turn-on transient also gone.

Thank you, ZM! All back to a silent background.

 

[von Ah]

Next level futzing: I made a dual JFET. I have a small tape of ~100 K209GRs to play with.

 

[STOXX]

I made a dual JFET.

Well, that's kinda neat. Cool.

 

[MJPAudio]

It's not done yet.....

Nelson did you ever get around and publish the balanced out version of this? Thanks!

 

[juanitox]

when i try to run it with LTspice with a single power supply it does'nt work with the V- to Ground any idea ?