Let's talk end-of-chain volume circuits...
- Thread starter The Gator
- Start date
Changing R8 to decrease the gain of the final stage (Q3)would also help.
The majority of the tone in regards to Q3 is the shear amount of gain going into Q3, not what's coming out of Q3(with the exception of how hard it's hitting the input of the amp, which will change tone in any form of attenuation).
Lift the leg of R8 that goes to ground, run clip and wire from it to a pot and add some resistance in series and tune it by ear.
Or, go through your 2n3904 stash and find one with a low hfe. Look for one near or below 100. Did you document the hfe of the 2n3904 you used in Q3 by chance?
The majority of the tone in regards to Q3 is the shear amount of gain going into Q3, not what's coming out of Q3(with the exception of how hard it's hitting the input of the amp, which will change tone in any form of attenuation).
Lift the leg of R8 that goes to ground, run clip and wire from it to a pot and add some resistance in series and tune it by ear.
Or, go through your 2n3904 stash and find one with a low hfe. Look for one near or below 100. Did you document the hfe of the 2n3904 you used in Q3 by chance?
cdwillis
Well-known member
I was under the impression that the issue isn't just the loud output volume, it's that the actual tone of the effect doesn't sound good unless it's loud. Reducing the overall volume output so the knob can be turned higher would solve that. Using a different taper would not because it would just change the position of the wiper on the pot so you'd still have to turn it up to sound good. I probably misunderstood.
Laundryroom David
Keyboard Cowboy 🤠
Sounds like you needed Jerry’s Pot back when it was available.
Effector 13 Jerry's Pot
Effector 13 Jerry’s Pot passive volume control. Nothing fancy, just a switchable volume attenuation for Jerry Garcia. Very rare. (Used)
caskmusic.ca
Laundryroom David
Keyboard Cowboy 🤠
How I understood as well.
Dropping Q3 ouput, by bias or replacement, seems like the simplest fix.
In turn, I'm not certain it's the town of the circuit that's changing when the level knob is turned down but instead the pot interacting with devices downstream.
That CR filter is a low cut at 30 hz. RC would change/sweep when the pot it turned, but a CR shouldn't.
There is no shunt resistor in this circuit, so the output impedance is directly correlated to the pot, correct?
If so. The pot will alter tone regardless of what else is done to drop the output. Except, maybe, if it's run into a buffer.
jesuscrisp
Well-known member
Actually, I would suspect the filter acts as low pass with the volume knob changing the filter cutoff frequency, that 51K resistor acting as a "stopping" resistor. If you consider how a voltage divider works, you always have series resistance in the signal path after all, except when it's cranked.
The Gator
Well-known member
I apologize for being confusing.
Here is where I'm at now:
I really just want to bring the overall volume down on this circuit as it goes from unity to melt you're preamp in your Vibrolux. That being said, I love that sound!!!
My 2n3904s are all in the 350 to 375 Hfe range. I tried putting a transistor in with 120 hfe at Q3 and it did not lower the volume hardly at all and did not sound the same.
I changed to a different taper and that definitely let's you turn it up farther before you smell the amp cookin...lol. (jk)
However, not gonna be enough for what I want.
I put a 100K resistor between the pot lug 3 and the rest of the circuit. That brought it down considerably and still sounds awesome.
Gonna try a few more things tonight.
Sorry if this seems unnecessary to you.
By all means don't do it to your circuit. It is not necessary. Just turn yours down.
I modify most of the things I build. That's just me.
I will say every time I build/modify a circuit I learn something and I have fun.
Every time I post a question on this forum I learn as well.
Thank you for everyone's input.
Here is where I'm at now:
I really just want to bring the overall volume down on this circuit as it goes from unity to melt you're preamp in your Vibrolux. That being said, I love that sound!!!
My 2n3904s are all in the 350 to 375 Hfe range. I tried putting a transistor in with 120 hfe at Q3 and it did not lower the volume hardly at all and did not sound the same.
I changed to a different taper and that definitely let's you turn it up farther before you smell the amp cookin...lol. (jk)
However, not gonna be enough for what I want.
I put a 100K resistor between the pot lug 3 and the rest of the circuit. That brought it down considerably and still sounds awesome.
Gonna try a few more things tonight.
Sorry if this seems unnecessary to you.
By all means don't do it to your circuit. It is not necessary. Just turn yours down.
I modify most of the things I build. That's just me.
I will say every time I build/modify a circuit I learn something and I have fun.
Every time I post a question on this forum I learn as well.
Thank you for everyone's input.
