Sound with volume on 0

[soje]

Noob question:

I've thrown together a simplified version of #124 on my test bench to get an idea of the sound of these amps. As such, I haven't spent to much focus on layout. Given this, the amp doesn't hiss or buzz too much.

However, with the volume knob on 0, there's still (faint) guitar sound thru the amp.

If I ground the output of the 2. stage (after the cap) the amp is silent. If i ground the grid of the second stage the sound is lowered, but still there, and a bit distorted.

Is this normal?

Does that sound come thru the HT?


Regards
Soje

[Structo]

Could just be the pot. Did you use a 1M pot?

Maybe it isn't a full 1meg when at 0.

[ayan]

Noob question:

I've thrown together a simplified version of #124 on my test bench to get an idea of the sound of these amps. As such, I haven't spent to much focus on layout. Given this, the amp doesn't hiss or buzz too much.

However, with the volume knob on 0, there's still (faint) guitar sound thru the amp.

If I ground the output of the 2. stage (after the cap) the amp is silent. If i ground the grid of the second stage the sound is lowered, but still there, and a bit distorted.

Is this normal?

Does that sound come thru the HT?


Regards
Soje

Try a different tube there and the problem (not quite a problem ,actually) will most likely go away.

Gil

[soje]

I don't think it can have anything to do with the volume pot. As described, there's still sound thru the amp, when I ground the grid of the second stage.

This noise may not be a problem when the volume is turned up, but when the OD is switched on, the noise is quite quite high. I'm wondering if this has any negative impact on the overall sound.

Besides, how does ther sound get to the PI, when the grid of the second stage is grounded?

Regards.
Soje

[ayan]

Besides, how does ther sound get to the PI, when the grid of the second stage is grounded?

Regards.
Soje

Did you try a different tube in there? Sometimes there is internal grid-plate coupling.

Gil

['67_Plexi]

Noob question:

I've thrown together a simplified version of #124 on my test bench to get an idea of the sound of these amps. As such, I haven't spent to much focus on layout. Given this, the amp doesn't hiss or buzz too much.

However, with the volume knob on 0, there's still (faint) guitar sound thru the amp.

If I ground the output of the 2. stage (after the cap) the amp is silent. If i ground the grid of the second stage the sound is lowered, but still there, and a bit distorted.

Is this normal?

Does that sound come thru the HT?


Regards
Soje

Try a different tube there and the problem (not quite a problem ,actually) will most likely go away.

Gil

+1

[soje]

Yes, I tried several actually. The "problem" consisted thru all of them :-/

I'm pussled as to how the sound is able to pass thru, when the grid is grounded.

As it is, I don't think the 2. stage is actually amplifying the sound/noise, but merely "picking it up". Otherwise, it shouldn't disapear when the output cap is grounded.

Would it be possible it was picked up thru either the plate or cathode circuitry?

....or is it just something tubes do,and I'm just complaining


Regards
Soje

[llemtt]

When you say 2. stage (aka V1b) grid grounded do you mean just after the grid stopper resistor? right at the tube socket?

How do you "ground" it?

teo

[jaysg]

I'm pussled as to how the sound is able to pass thru, when the grid is grounded.

A wire with current flowing (no matter how small) is an antenna. Antennae can transmit and receive. Sometimes a straight wire between two points is the worst solution. Look for high voltage points (off of plates) to transmit.