Should the R and L RCA center pin have the same resistance?

[Nehan]

Greetings.

I get 95k in the right RCA (red) and 94.1 in the left (white).

 

[Grainger49]

You are reading the slight differences in the full range of the stereo pot.  It is inconsequential.  If you had a stepped attenuator using discrete resistors they would probably not be the same but might be a little closer.

 

[Nehan]

So I won't notice a difference in the sound (volume) between both channels?

Thanks you for the quick answer.

 

[Grainger49]

Right, at that resistance it takes much more to make the center image off to the right or left.

However... there is always exceptions.  I find many recordings off center.  It isn't the system, it is the recordings.

 

[Nehan]

Thanks you very much sir.

In the TRS jack check, the voltage never drops to 0. Instead, it fluctuates between 0.00 and 0.07. Is it ok o it have to be always 0.0?

 

[Paul Birkeland]

Thanks you very much sir.

In the TRS jack check, the voltage never drops to 0. Instead, it fluctuates between 0.00 and 0.07. Is it ok o it have to be always 0.0?

That's certainly close enough to call it 0.

 

[Nehan]

That's certainly close enough to call it 0.

Thanks you for the clarification.

 

[Nehan]

Hi there.

After install the speed ball, the voltage at the TRS check goes up to almost 20v. quickly, and then drop to 0.0v -0 .07v. Are those 20v. a problem or are not that high to be dangerous for the headphones?

 

[Paul Birkeland]

That's normal.

-PB

 

[Nehan]

I should read before asking. I'm sorry. I "fixed" it with this: http://bottlehead.com/smf/index.php?topic=2946.0.

I am very happy to have my amp finished. Thanks everybody for the help!

By the way, a little background noise at music silences is normal in a tube amp, right?

 

[Paul Birkeland]

By the way, a little background noise at music silences is normal in a tube amp, right?

Hmm, tell us about your headphones and audio source?

A poorly soldered 220uF/250V capacitor can lead to an amp with perfect voltages and perfect functionality, but noisy at the same time.

The Crack, with the volume control turned all the way up, will make some noise into most headphones.  Of course, if you played music into the amplifier with the level control up this far, it would be unlistenably loud (which is why the noise is there in the first place).

-PB

 

[Nehan]

The path is PC > ODAC RCA > Crack > Sennheiser HD600.

Is better to have the PC volume at max, and the crack volume low?

I'll try resoldering the 4 caps.

 

[Doc B]

Yes, you want the source level as high as it can be, as that helps improve the signal to noise ratio of the overall system.

 

[Nehan]

After resolder the caps, I was checking the voltage and something exploded. What I have to do?

Edit: I checked the pin 1 and 2, and the values were better than before (1 = 80v., 2 = 170v.), but in the pin3 something exploded. I don't know if I touched something else.

 

[Doc B]

When you say exploded do you mean you saw a spark? That would be from touching the probe from a live terminal to another terminal, or ground. If the voltages are OK and it sounds OK no harm was done.

 

[Nehan]

I saw a spark and I heard a sound like a small firecracker.

 

[Nehan]

You are right. Checking the voltages now, everything is ok. The noise is still there though.

 

[Doc B]

Does the noise go up and down with the volume control? Does it stay the same as the volume control goes up and down? Is it a buzzy sound? Have you checked the other threads about this kind of thing for suggestions for possible solutions?

 

[Nehan]

The noise go up and down with the volume control, and when the volume control is set to 0, there aren't noise.
Indeed I have checked other threads.
I'm not sure if it's a buzzy sound. Is like a pink noise.
I don't think that I have a problem with RF at RCA because there are <50cm long and have a great insulation.
My apartment doesn't have ground and, generally, I have an old and bad electrical installation. Maybe is it?

 

[fullheadofnothing]

If the noise is altered by the volume control, that means that it is not a problem with the circuit. Either it is insufficient isolation of the wires that go from the jacks to the potentiometer (i.e. poor braiding, or locating the wires too close to the circuit), or it is related to your interconnects or source component.