Q-tron (plus) volume pot

[joepius]

Hello y'all,

Is there anyone out there who has attempted the following:

installing a volume pot on an Electro Harmonix Q-tron (plus, or not) - they are notorious for volume boosts when engaged, at least mine is. I'd like to add a pot so I can taper down on that boost but I have no idea to wire which wire where & how & whatnot! Anyone?

[Blitz Krieg]

is there a boost switch on that one?

[antonis]

Just before your Output jack and the bypass switch there is a resistive voltage divider (Ok.. this is for output impedance but we can ignore this scope for simplicity..)

The values are 150R & 2M2 wich means that we - practically - have no signal loss (2200000/2200150 -> 0.99993182283)

The hard way is to "predict" how much you want to lower your output (in % term) and then replace the 150R resistor with another of aproppriate value ..

An easier way is to replace the 150R resistor with a pot wired as variable resistor (or just a trimmer inside the enclosure) and tweak it to your need..

The easiest way is to just wire an external pot with the first lug connected to the ring of the output jack and the middle lug to the tip of the jack..
(you may leave the third lug "open" or wire it to the middle lug)

[joepius]

is there a boost switch on that one?

Hi Blitz - yes, there is a boost switch on this one.

[joepius]

The easiest way is to just wire an external pot with the first lug connected to the ring of the output jack and the middle lug to the tip of the jack..
(you may leave the third lug "open" or wire it to the middle lug)

Hi Antonis, thanks so much for your reply!

What value pot would I need for this operation? Does it need to be audio, or linear? Cheers!

[joepius]

The easiest way is to just wire an external pot with the first lug connected to the ring of the output jack and the middle lug to the tip of the jack..
(you may leave the third lug "open" or wire it to the middle lug)

Hi Antonis, thanks so much for your reply!

What value pot would I need for this operation? Does it need to be audio, or linear? Cheers!

Answering half my own question: obviously this requires an audio pot

As for value, I am still searching. Anyone? Cheers!

[PRR]

> obviously this requires an audio pot

If you only need a small reduction, Linear is probably what you want.

Try it. If you end up always working down around "1", then you want Audio taper.

The pot on the output, in guitar-chain work, may generally be 10K or 100K, 50K is often excellent.

[antonis]

What value pot would I need for this operation? Does it need to be audio, or linear? Cheers!

As you see, PRR is as fast as lightning..!!!

(if you find a 47k pot, it's just fine..)

[joepius]

This time I was slow as snot ~ thanks Antonis, PRR, and the others! Will attempt to install the pot some time soon.

[joepius]

Y'all - imo the best way to go about adding a volume control to the Q-tron(+) is by building a true bypass box with a volume attenuator in it. I've tried wiring a volume pot directly to the Q-tron's OUT, and - obviously - this affected my overall volume when the Q-tron was switched off. Haha! n00b

[joepius]

To whom it may concern:

wire a 10k linear pot between the Q-tron's CIRCUIT OUT and footswitch's designated lug that hooks up the circuit out wire. This way, the volume pot won't affect your volume (or tone!) when the whole thing is bypassed. I'm getting smarter every day! 

[aron]

Great. In general I would have used a trim pot inside so there would be no drilling. In any case, cool!

[joepius]

[joepius]

Great. In general I would have used a trim pot inside so there would be no drilling. In any case, cool!

Drilling is a means to an end, for me; I don't mind that. Be careful removing the circuit from the casing, however; it's a real snug fit. The way I went about it was to first loosen one side of the connector jacks, then the other, then flip the whole thing out.

I mentioned in the other post that I've used a linear pot for the volume function; I eventually ended up settling for a 10K audio pot, after trying several values, both linear and audio.