What do you think of this...?

[mrbrown49]

LINK

 

 

Anybody hear of these before? Do they work?

[mbarn3065]

It looks like it is just a potentiometer in a box! It would do the same thing as a master volume. You would only get pre-amp tube distortion, not power tube distortion. A volume pedal in a fx loop would be the same thing. If your amp already has a master volume you don't need another one. And if you don't have a master volume on your amp, you probably will not have a fx loop, so it would be useless!

[hal9000]

For amps that don't have an overall master and an FX loop, this kind of product can be useful. If you're handy with a soldering iron and have a few bucks, you can make one according to the schematic below:

 

 

Any (25k - 50 kOhm) CTS or Alpha pot will do the trick there. The total cost will be about $7.

[rememberduane]

Originally posted by hal9000 For amps that don't have an overall master and an FX loop, this kind of product can be useful. If you're handy with a soldering iron and have a few bucks, you can make one according to the schematic below: Any (25k - 50 kOhm) CTS or Alpha pot will do the trick there. The total cost will be about $7.

 

Is that basically a PPIMV for NMV amps that have FX loops?

[hal9000]

 

Originally posted by rememberduane Is that basically a PPIMV for NMV amps that have FX loops?

Generally, an FX loop is after the preamp, but before the phase inverter, so it's not a PPIMV. However, it's a real easy way to add a master volume to an amp.

 

Since my Mesa F-100 doesn't have an overall master, I built a box like the schematic to have more control. The F-series preamp sounds better with its channel masters high and overall level low, rather than the other way around.

 

The final version of the box was actually for a solo boost where the pot was switched in by a relay so I could use a remote latching footswitch. Solo boost was then true bypass. That works great.

[rememberduane]

 

Originally posted by hal9000 Generally, an FX loop is after the preamp, but before the phase inverter, so it's not a PPIMV. However, it's a real easy way to add a master volume to an amp. Since my Mesa F-100 doesn't have an overall master, I built a box like the schematic to have more control. The F-series preamp sounds better with its channel masters high and overall level low, rather than the other way around. The final version of the box was actually for a solo boost where the pot was switched in by a relay so I could use a remote latching footswitch. Solo boost was then true bypass. That works great.

 

 

Ahh, good stuff. Glad to see some real great stuff on the forum today, in light of all that's happening.

 

Hrm -- think one could attach a rocker switch to that design and basically make a volume pedal? Is that all a volume pedal is?

[hal9000]

Originally posted by rememberduane Ahh, good stuff. Glad to see some real great stuff on the forum today, in light of all that's happening. Hrm -- think one could attach a rocker switch to that design and basically make a volume pedal? Is that all a volume pedal is?

Thanks. Yes, that's all a volume pedal is, but generally they use a high impedance pot (250 or 500 kOhm) since it's connected between a guitar and amplifier. FX loops are generally much lower impedance which is why the pot I used is 25 kOhm.

 

If you wanted to make a footswitchable box for a solo boost, you could just wire the pot through a DPDT panel mount switch from Carling like this (316-PP):

 

 

Of course, that would take some long lines from your FX loop, but the box is totally passive.

[rememberduane]

Originally posted by hal9000 Thanks. Yes, that's all a volume pedal is, but generally they use a high impedance pot (250 or 500 kOhm) since it's connected between a guitar and amplifier. FX loops are generally much lower impedance which is why the pot I used is 25 kOhm. If you wanted to make a footswitchable box for a solo boost, you could just wire the pot through a DPDT panel mount switch from Carling like this (316-PP): Of course, that would take some long lines from your FX loop, but the box is totally passive.

 

Yeah -- cable runs do tend to mess with the tone/response though. I don't actually own an amp with an FX loop right now, and don't plan on it, but it's cool to know anyway.

 

Hopefully somebody who needs it will see these posts!

[hal9000]

Originally posted by rememberduane Yeah -- cable runs do tend to mess with the tone/response though. I don't actually own an amp with an FX loop right now, and don't plan on it, but it's cool to know anyway. Hopefully somebody who needs it will see these posts!

Yup, i don't like long cable runs either, which is why I made mine remotely switchable. The FX loop lines are only about 6 inches if the box is on top of my amp. There is a switching line that runs to my playing position, but it's only to switch the relay so there is no audio degredation.

[rememberduane]

 

Originally posted by hal9000 Yup, i don't like long cable runs either, which is why I made mine remotely switchable. The FX loop lines are only about 6 inches if the box is on top of my amp. There is a switching line that runs to my playing position, but it's only to switch the relay so there is no audio degredation.

 

 

Very cool, never tried that. I'll definitely have to look into it. Very very cool idea.

[SkidMarx]

Originally posted by hal9000 For amps that don't have an overall master and an FX loop, this kind of product can be useful. If you're handy with a soldering iron and have a few bucks, you can make one according to the schematic below: Any (25k - 50 kOhm) CTS or Alpha pot will do the trick there. The total cost will be about $7.

 

is this looking from the top down or bottom up? Important so the pot isn't wired backwards.

[hal9000]

Originally posted by SkidMarx is this looking from the top down or bottom up? Important so the pot isn't wired backwards.

I didn't mark it so people could choose whichever direction they felt best. Everybody has their own way of determining what makes sense. So, if anyone builds the box and it works "Backwards" for them, they just have to flip the outer two lines and it's "Correct."

[mrbrown49]

Thanks for the replys guys. Thats what i suspected. I actually wired something out last night to see whats its effects were and it wasn't very favorable with my amp. As you indicated in your discussion, it just limited the master gain and all the gain came from the preamp stage. I guess I better bite the bullet and get a power brake for this amp to drive the drive tubes harder at bedroom volume.

 

Thanks again!