Help on building an active bass signal attenuator

[ilcaccillo]

Hello,
I have 3 bass guitars that I use live but one of the basses has a much louder output than the other 2.
I already adjusted the pickups height but its not enough, its a passive bass.

I would like to build a simple pedal active buffered pedal so I can use it to attenuate this bass signal in the songs it will be used. I preffer to do this than use a booster for the other 2 pedals.

Could you please give me some advices on the type of circuit to use for this porpuse and point me in the right direction?

I was thinking in using an opamp with JFet inputs, so it has an high impedance input.
I just dont dont if I should use the opamp in less than unit gain or use the opamp in unity gain and have some passive attenuation after that (volume Pot). Maybe I need another buffer after the pot.

Please let me know what do you think

Thank you so much
Regards

IL

[fryingpan]

Probably a simple emitter/source follower is enough, with a volume pot after it. Attenuating the volume would increase output impedance but it shouldn't be an issue as capacitances in play would be negligible (as opposed to a direct guitar/bass signal). You could also attenuate the signal at the input with a pot if you use a BJT device (and you'd keep the low output impedance of the emitter follower).

[Phoenix]

Here's how I've done it before (I had a customer with a very similar problem).

[EBK]

Forgive me if I'm not understanding the situation correctly, but does the too-loud bass have a volume knob?

[fryingpan]

To be fair, attenuating the bass from its volume pot will cause some tone loss. And it is/can be fiddly.

[ilcaccillo]

To be fair, attenuating the bass from its volume pot will cause some tone loss. And it is/can be fiddly.

Yes definitely.

what I'm looking to achieve is having the unit in a pedal format, having it buffered and with the least amount of Tone loss possible.
I might even do it with a rotary switch instead of a pot so that the setting stays fixed gig after gig.

Thanks

[ilcaccillo]

Here's how I've done it before (I had a customer with a very similar problem).

Thank you so much Phoenix, I will try out your circuit.

[EBK]

I can tell that you are excited about building something, so this is the last I'll say on this topic before getting out of the way:
You could also achieve your goal with one resistor and one capacitor by a simple rewiring of your bass.

[ilcaccillo]

I can tell that you are excited about building something, so this is the last I'll say on this topic before getting out of the way:
You could also achieve your goal with one resistor and one capacitor by a simple rewiring of your bass.

No,
My Goal is to build an active attenuator pedal. That was clearly stated in the first post.

I don't know why you posted or are still posting in this thread

[DIY Bass]

With my basses I only use 2 at a time, not three.  I have a (commercial) pedal that takes 2 inputs and switches between them.  Each input has a separate volume, so you can really accurately match the volumes.  It might be too complicated, but I can see a three input device with selectable input and volume for each input would be a very cool solution for you - although also a more complicated one.

[ilcaccillo]

With my basses I only use 2 at a time, not three.  I have a (commercial) pedal that takes 2 inputs and switches between them.  Each input has a separate volume, so you can really accurately match the volumes.  It might be too complicated, but I can see a three input device with selectable input and volume for each input would be a very cool solution for you - although also a more complicated one.

Hi DIY Bass, thanks for your input. What pedal do you have? it would be nice to study that circuit

The 2 seperate inputs are nice, and flexible in a lot of situations.

In this case I just use the same Jack cable for all the basses (same input) and I just want to have to press 1 pedal (to attenuate the signal) when I use the third bass.
And I would like to build the unit myself.

Thank you so much

[DIY Bass]

The one I have is the Behringer AB100

[GibsonGM]

I don't know why you posted or are still posting in this thread

Because he was trying to help make the solution to your problem easier for you, and this is generally a 'toss your thoughts in' sort of place where everyone is invited to comment in any way they may think is beneficial.   Other forums are often more rude, and you may be more used to them?
Sorry you took offense to that.

[ilcaccillo]

The one I have is the Behringer AB100

Pretty usefull box,
thanks for sharing

[ilcaccillo]

Because he was trying to help make the solution to your problem easier for you, and this is generally a 'toss your thoughts in' sort of place where everyone is invited to comment in any way they may think is beneficial.   Other forums are often more rude, and you may be more used to them?
Sorry you took offense to that.

Your post and 2 more posts in this thread have no use or relation to whats been asked in my first post, I guess some people have a lot free time and preffer to spend that time jaackaassing others people threads instead of helping.

You are free to continue doing that at your will,
but I preffer to ask you politely to just post if you want to help a fellow member building an Active/Buffer Attenuator circuit to use as a pedal for his Bass.

[duck_arse]

Because he was trying to help make the solution to your problem easier for you, and this is generally a 'toss your thoughts in' sort of place where everyone is invited to comment in any way they may think is beneficial.   Other forums are often more rude, and you may be more used to them?
Sorry you took offense to that.

Your post and 2 more posts in this thread have no use or relation to whats been asked in my first post, I guess some people have a lot free time and preffer to spend that time jaackaassing others people threads instead of helping.

You are free to continue doing that at your will,
but I preffer to ask you politely to just post if you want to help a fellow member building an Active/Buffer Attenuator circuit to use as a pedal for his Bass.

yeah, Gibson, only post if'n yer gonna help.

[samhay]

Before this thread goes to hell in a handbasket, can I offer a suggestion?

OP - If you are determined to make an active bass signal attenuator, can I suggest you consider making instead an active bass signal attenuator and booster?

If you use a similar design to that Phoenix posted, you could add a little gain to the second stage so that you can both cut and boost the signal. This would make the effect more versatile at the expense of a couple of resistors and a capacitor.

[GibsonGM]

But, but...you're not helping, Duck!! How dare you??

[Danich_ivanov]

Alright, here's what i would do.

First thing i would try is to take a simpliest buffer from Amz website and add a volume control after it, play around with caps, perhaps even try a cap across the volume pot, and see if it does the job without messing around with the tone too much, if it works, great. As a bonus, instead of using a standard 3pdt wiring, i would wire up a switch for a volume pot, so that other instruments could also benefit from the buffer.

If the result is not satisfying enough, and you want to go a little more crazy, you can build a preamp, something along the lines of "Activator 2" with a volume pot after it. You could also add a buffer, if you want, add a separate switch for it (just in case), and switch preamp on/off for volume cut, while, again, leaving the buffer for other instruments. Or instead, simply add a switch for a volume, just like in the first example, but instead of a buffer, other instruments would benefit from the preamp.

But the reality of it is that simple volume pot with a cap across (treble bleed mod), should do the trick just fine (just saying).

[GGBB]

But the reality of it is that simple volume pot with a cap across (treble bleed mod), should do the trick just fine (just saying).

Although a treble bleed cap does avoid treble loss, it involves a change of tone - however slight. I'm guessing the OP is trying to avoid that - which is why he's asking specifically about an active attenuator, and has already rejected a previous suggestion to go passive.