maxkracht wrote: ↑Mon Aug 21, 2023 2:21 pm
Apologies if I sounded rude, just trying to make sure we are all on the same page. I don't have formal education related to electronics either, and we are all here to learn. The word gain is often used to mean volume or simply distortion. You were correct in describing a more technical meaning of the word, how much voltage comes out of a tube vs how much came into the tube, being largely related to how it is biased.
You don't have to worry about my answer anymore.
You asked what gain means to me, and since I don't think I can give you a good answer, so I was tell you my level of electrical knowledge.
maxkracht wrote: ↑Mon Aug 21, 2023 2:21 pm
Changing the ratio of the two resistors after the gain knob should be very noticeable, it is another fixed volume control after your variable volume control, but If you have the "unboost" set with the 100k/1n to ground, changing the 500k resistor to 1M doesn't make a difference, because the 500k was effectively not there to begin with. 100k is the path of least resistance. Remove the 100k from circuit, and try changing the voltage divider again and you should hear the difference. If you don't, I'm guessing there is something else in circuit that you aren't seeing.
I installed it because there was no reason not to install a boost circuit, but in fact, this circuit is considered to be in a default state when the boost circuit is not engaged, and the tone when the boost circuit is engaged is not very satisfactory. So to be honest, I do not use this because I did not like this well.
Therefore, even when the test of switching the 500K grid leak was attempted, this "unboost" was not set.
But still, nothing changed. I also thought that it was not normal that there was no change, but maybe there was a build error that I didn't know about, so I'll have to take a look again and put the switch back on and test it.
In fact, the 500K Grid Leak resistor of the second stage of Ecstasy is expected to be installed for switching I think.
If you look at the overall circuit diagram of the amplifier in the first post of this thread I posted, you can see that the corresponding position is switched for Plexi mode.
When viewed as a single channel, the gain pot already plays the role of Grid Leak, but when switching channels or modes, DC flow is blocked with the switch disconnected, which can cause serious popping noise or switching delay. To prevent this, signal It seems to have additionally attached a grid leak that is always connected even in a disconnected state.
I don't use the plexi mode as a foot-switchable "channel" like the original amp, but as a "mode" of the dirty channel, so I think it's okay to omit the 500K despite a little inconvenience.
When considering only the sound aspect without considering convenience factors such as switching, it is considered that the gain pot is already playing the role of grid leak, and the grid leak is doubled(parallel).
I would like to ask a question for a moment here.
The configuration of the road to the second stage after passing the first coupling cap is like this,
voltage_div.jpg
In the case of most amplifiers, additional Grid Leak is rarely installed with the gain pot installed.
In the case of the ecstasy circuit, assuming that the gain pot is set to the maximum, it seems to be the same form as applying a grid leak of about 330K in parallel with a 500K pot +500K gird stopper resistor and a 500K grid leak.
Is this guess of mine correct?
If this is correct, when the gain pot is changed to 1M, a 1000K pot +500K grid stopper and a 500K grid leak are installed in parallel, eventually resulting in a grid leak of about 375K.
If so, I think that changing the gain pot from 500K to 1M actually doesn't make a big difference.
So, if you are not going to remove 500K Grid Leak, if you change the gain pot to 1M, I think that changing the Grid Leak to about 1M will have an appropriate effect.
Howt do you think about it? Please let me know if there are any problems with my guesses.
From the same point of view, I think that the reason why no change was felt when switching the 500K grid leak was because of the small difference between 500K + 500K and 500K in parallel = 330K vs 500K + 500K and 1M in parallel = 500K .
It was not even tested with the gain pot set to the maximum, so the difference may have been felt less. How do you think about it?
Actually, there are only a few parts to try, and I think it's a situation where I can try and feel it myself, but I feel sorry that I can't try it freely because of the complicated build structure.
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