SOLVED Nobelium Preamp/DI Issues

[danwojaz]

Hey,

I built a nobelium a few weeks ago and It appeared to work, but while playing through it, the low E string Distorts/ farts out when played hard. When I heard this, I unplugged the jack from the input and a loud squeal came from the speakers. I am using a one spot for power supply with 9v 1700ma.

The Bass, Treble and Volume can adjust the frequency of the squeal.

I have replaced the tubes with new tubes and still have the same issue. The sound comes out of the 1/4" output and the DI output.

 

[danwojaz]

I was wondering what you should be reading in this section ?

 

[vigilante398]

I was wondering what you should be reading in this section ? View attachment 70992

That's before the rectifier, so you should just be seeing AC there. If you're measuring voltage there with a multimeter it won't look like much.

 

[vigilante398]

Does the squeal also occur when something is plugged into the input?

 

[danwojaz]

It only happens, when everything is unplugged. I have gone through making sure nothing is going to ground that shouldnt, I am wondering if I have a bad filter capacitor like C6 since the tone controls impact the squeal frequency.. If I cant figure it out, Ill probably just order another board and order all of the parts from Tayda instead of mouser.

When plugged in, the noise goes away, but when the volume is turned up on a passive bass guitar, it almost sounds like a slight fuzz when you hit it will too much volume. Its not quite a fuzz, but thats the best way I can describe it.

 

[danwojaz]

Here in the video you can hear how there is something going on in the low end, and then i disconnect the bass from the input there is a noise.

 

[chris.knudson]

Can you post some photos?

 

[danwojaz]

 

[danwojaz]

The 1M I took out

 

[danwojaz]

 

[vigilante398]

If one LED is lighting up and the other isn't, it's a pretty good sign you have continuity issues on your tube daughter board connections, and that's one of the most common issues I see with C2C builds in general. Check all the solder joints on both sides of all the pins, make sure you have enough solder but not too much on each one, make sure there are no cold solder joints and also no joints that were heated so much the solder pad lifted off the board (I've seen it a couple times now).

If you're comfortable CAREFULLY checking voltages, probe the cathode of the UF4007 and let me know what voltage you're getting. If everything is working but the sound is off, that can also point to a low plate voltage

 

[danwojaz]

@vigilante398 the led is because I accidentally had flashing LEDs

 

[hooper]

Looks like you've got ECC83's in there. That will certainly provide much more gain than the 12AU7's (ECC82) that would be stock.

 

[danwojaz]

@hooper well this is much better, still gets a high pitch noise out of the 1/4 inch output when nothing is plugged in. I will probably just replace the capacitors to see if I can get rid of it

 

[hooper]

That high pitched noise is probably heterodyning. What are you using to power it?
Since the noise only happens with nothing plugged into the input, I'd probably just replace the input jack with a shorting jack (switchcraft 12a, or 112a) with the switch lug tied to ground.
On my board, I haven't experienced that noise, because there's always something plugged into the input. The first pedal in my chain has a shorting input, so it's dead quiet, til I plug in and start flailing about.

 

[danwojaz]

@hooper could you try unplugging the input and see if you get noise? I tried using a one spot 9v and it has enough current, I tried my strymon power supply, mono power supply, and a dc power generator.

That high pitched noise is probably heterodyning. What are you using to power it?
Since the noise only happens with nothing plugged into the input, I'd probably just replace the input jack with a shorting jack (switchcraft 12a, or 112a) with the switch lug tied to ground.
On my board, I haven't experienced that noise, because there's always something plugged into the input. The first pedal in my chain has a shorting input, so it's dead quiet, til I plug in and start flailing about.Could you try in plugging the input and see if you get noise?