DIY Front End 2022

[Sadface]

OK thanks. That makes sense.
Also upon closer inspection, the rolloff is only 1db.

Best not trouble myself trying to fix things not broken.

 

[william2001]

Ya I wouldn't sweat a teeny tiny bit of rolloff like that graph in the article. That's like tenths of a db there in your area of concern..

Another quick thing.. C1 is really optional if you can be certain that anything feeding this circuit does not have DC on it. A greenhorn might be better off leaving it in place as a safety blanket. If a source has DC offset, the individual that designed it should be drawn and quartered because that's not acceptable in my world.

 

[Sadface]

I intend to make a new pcb with the psu integrated to fit a particular chassis.

If regulators were placed right beside the fe2022, could the rc network on the supply rails be skipped or are they an important part of the circuit?

 

[william2001]

You can skip the RC on the rails. But I think capacitance on the output of the regs is still recommended.

Somehow the store FE '22 boards get by without compensation caps. Be sure you check for stability on your new pcb, it may oscillate with a different, less optimized layout.

 

[Sadface]

I ordered the kit from the store so I will be very carefully studying the layout.

Does anybody know what the current consumption is per board with a standard implementation?

 

[Dennis Hui]

See Papa's post #20: https://www.diyaudio.com/community/threads/diy-front-end-2022.394339/#post-7231380

 

[Sadface]

Thanks.
So 3mA + 9mA = circa 12mA

Do r11 and r12 have an important function?

They look to me like bleeder resistors for c4/c5?
Assuming say 20vdc power supply rails then they would add another 2 mA.

So conservative 15mA seems realistic?

 

[Ben Mah]

15mA is a good ball park number. The actual number may be a bit higher or a bit lower.

R11 and R12 form a voltage divider for the unipolar power supply option, to equally divide the voltage between the two capacitors. It is not needed if the power supply is bipolar, although it can be left in place.

 

[Sadface]

OK thanks.

With a regulated bipolar supply.
Could the value of c4/c5 be reduced to something like 100uf like one might typically see with supply rail decoupling?

 

[ml48]

I have wired the pre as balanced input,single output and with a 36v single supply.I am getting a slightly variable static sound at all times that increases with volume control. It is on both channels. Is this transistors failing? Appreciate any suggestions to cure this problem.

 

[Ben Mah]

Does it work - does it play music? Or does it only output static?

Have you double checked component placements, wiring, and solder joints? Bad solder joints can result in noise.

Post some clear, focused pictures. Include shots of the overall construction and closeups.

 

[Zen Mod]

naah

it's so not interesting when there are pictures ......

 

[Ben Mah]

You know you want to see some pictures!

 

[Sadface]

Just an academic question as I have a parts kit from the store.

Would the circuit work properly if one were to buy a bunch of J113 from mouser and throw them into the circuit with no matching?

Higher distortion?

 

[Mark Johnson]

Try the experiment!