Volume Stabilizer

GiovannyS10 · September 21, 2015, 12:31:19 AM

Hello everyone!

There is some times i made a Chorus Little Angel, is a very good project! And i decide use it on my pedalboard. The problem was it have much gain of volume when activated. But now i have a very boring problem. My pedal work right, but i like to use chorus with distortion with the distortion before chorus. But because the pedal have so much gain, when the dist are activate with the chorus, the volume increases uncontrollably, is deafening. For solve it i put a trimpot for control the volume of pedal. Worked very right and i enjoyed so much my dist + chorus. But the new problem is: The chorus continue increases gain, but on the dist it increase much gain (high volume) same when the dist are on the low volume, and on the clean guitar almost you hear the sound(veeeery low volume). I want a circuit to stabilize it. Independent of dist turned on or i using clean guitar i want the output volume of chorus be the same. How a make it?
When i use the chorus before the distortion this problem dont exist, but not is the same. Is very boring use chorus before the distortion.

Thanks for all. And for solve any questions here is the circuit i used.

hymenoptera · September 21, 2015, 09:08:26 AM

The circuit that evens out levels would be a compressor, but I'm not sure that's the solution you're looking for. I think what you need is a way to adjust the output of one or more of your pedals, and you mentioned already using a "trim pot" to do so, but I'm still not sure what exactly the problem is..

Can you post a video of the problem?

GibsonGM · September 21, 2015, 09:28:04 AM

What do others think about lowering the value of R15 (?), the opamp feedback resistor, so as to bring the level down a bit? That could be make into a trimmer.

OR, we could simply add a volume pot to the output (trimmer also), allowing G. to dial in the ideal output level...this is assuming you want the output volume of the chorus to be at one level.

The 'problems' you describe seem to be more related to the interaction of the chorus & following distortion..it could be pretty complicated to have each sound good on its own, but then match them together for an "ideal" sound. I would be more likely to make a SECOND distortion for use without the chorus, and then put the chorus & dist. in ONE box, so they are set up and easily operate together!! One switch to activate them both. Sort of like "Framptortion".

samhay · September 21, 2015, 09:29:00 AM

The Little Angle chorus should be unity gain - i.e. it does not have gain.
I think there is something wrong with your build.

hymenoptera · September 21, 2015, 10:05:47 AM

Good point, samhay. I wonder if there has been any resistor substitutions...?

GiovannyS10 · September 21, 2015, 03:54:14 PM

Hello guys, i will post a video... When i said, the problem is with the increase of volume. I can regulate its on trimmer (trimpot), but when i use pedal alone the sound is very low, and when i use with distortion is very high, i want to regulate only the sound with dist. I dont change the project. I think to create a decibels regulator. So with a example, on the input we have 50db and i regulate the output to max 60db i will have a 50db out, because 50 db is into the limit (60 db). But if we have 70db on input we will have 60db on out, the circuit will decrease the volume, understand? Is this my idea, but i am open for new. Soon i will post a video, now i will finish a delay.

samhay · September 21, 2015, 05:09:41 PM

What is the distortion?

GiovannyS10 · September 21, 2015, 08:40:16 PM

I am using a Smash drive with this pedal.

GiovannyS10 · September 21, 2015, 08:52:13 PM

I recorder this video for you see.

The same riff on the sequence: Dist + Chorus (See the high sound), Only distortion, Clean sound, Only Chorus. See, the dist are on the same volume than clean sound, but furthermore the chorus are high on the dist and very low on the clean. And i already using the trimmer to regulate the sound, otherwise you are deaf. If i take off the trimmer the clean sound with the chorus return to be high, and the chorus + dist comes to be deafening.
And see it too. Here is on a music, feel the boost on the chorus.

But the boost is not the principal problem and yes the decrease of volume when i use clean sound. When the volume is good for clean, is so high for dist, when volume is good to dist is so low to clean... ¬¬ Damn

idy · September 21, 2015, 09:15:49 PM

That is weird, the chorus does not boost a direct guitar but does boost the distortion pedal...
The chorus seems to act normally, but the distortion pedal gets louder when it "sees" the chorus.

Smash Drive is LM386 based? What is interacting? Is the Smash Drive homemade also? Which version/schematic?
Have you tried this experiment with another distortion pedal instead? With a buffer (or booster set to unity) in between?

GiovannyS10 · September 21, 2015, 09:19:22 PM

Hello idy!

I know, is very weird. Yes, SmashDrive is based on LM386 and i make the original schematic present on this forum. I cant try with another pedal, because i dont have another pedal :/

This is the layout i used:

And i forget the dist on the minimus on this video (because this the driver sound are weird), now is normal, and the sound have more gain when chorus is turned on.

idy · September 22, 2015, 12:45:25 AM

There are lots of versions of Smash Drive. Yours has a tone stack but no volume control. The tone stack is "naked" in that it has no "gain recovery" or buffering after it.

A simple "emitter follower" buffer of JFet "source follower" is a good thing to have around and easier to build than the other two pedals you made. Breadboard one and try?

What kind of amplifier are you using? Maybe it interacts badly with the smash drive?... A pedal like this with no volume control would usually be much louder than the guitar straight into the amp.

GiovannyS10 · September 22, 2015, 08:58:05 PM

Hi Idy! Im sorry, i forget to say you, i modified my pedal. Only 2 things. I get off the Low control and put a Volume control to replace. Only. I have volume control. And i am dont using no one amplifier. Only guitar > Pedals > PC. I think i will put a SPDT switch to select "normal mod" and "dist mod" on my chorus pedal, it is good for control... What do you think? Is dont what i want, but is something.

MrStab · September 23, 2015, 01:02:52 AM

Quote from: GiovannyS10 on September 22, 2015, 08:58:05 PMI get off the Low control and put a Volume control to replace.

Do you mean you put a Volume control in the same place as the Bass/Low control? Or did you remove Bass, and put Volume after? A drawing of how you connected that area could be useful

MrStab · September 23, 2015, 01:30:52 AM

if you removed Bass, then Treble has no path to ground, and Mid would not work properly, either. There's also less loading from the tone stack than what the circuit expects.

(...i may have misunderstood, sorry if so!)

GiovannyS10 · September 23, 2015, 02:30:59 PM

Hahahaha! No sir, its wrong. I removed the bass pot and connected the terminals...
See it:

Very better, no?
Hahaha!

samhay · September 23, 2015, 04:34:25 PM

^Only guitar > Pedals > PC.

The input impedance of your PC sound card is probably very low (maybe 10k) by guitar amp standards. This will seriously load down the Smash Drive, which has quite high output impedance, resulting in relatively low output level.
The Chorus has quite high input impedance - 470k - and low output impedance - about 5k. It is acting as a buffer.

To fix this problem, I would build a simple always-on op-amp or FET buffer to put at the end of your signal chain before the PC.

hymenoptera · September 24, 2015, 10:22:16 AM

I think samhay nailed it. I bet this setup behaves entirely different going into a guitar amp. Might even solve the volume issues. The buffer at end of chain will likely fix everything right up, even going into the computer sound card.

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Volume Stabilizer