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Post subject: Anyone seen the insides of the expression pedal?
Posted: Thu Jan 08, 2015 10:38 am
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Has anyone opened one up? Some are nothing more than a pot and a few components and the control circuits are all in the amp, or i'm thinking in this case the 4 button footswitch. reason i ask is i don't want one, i just want to be able to step on a button footswitch and have a slight volume boost. If i knew what the guts of the pedal were i could determine whether i could figure out how to build what i want. I'm a tech so no need to school me on that idea. But i need to know if it's nothing more than a pot and a few basic components that controls a circuit inside the 4 button or amp. If thats the case i'd buy one so i could figure it out then sell the pedal once i've figured it out and built a switch. Don't wanna go to the trouble of buying one and losing $ by selling it unless i have an idea of whether it's possible, hence this post and question.


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Post subject: Re: Anyone seen the insides of the expression pedal?
Posted: Thu Jan 08, 2015 12:08 pm
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The EXP-1 expression pedal is not just a simple analogue potentiometer. The pedal sends digital control signals to the amp. The logic to use those signals is inside the amp (rather than in the EXP-1 or the MS-4 4-button footswitch; one can use the EXP-1 on its own without the MS-4).

Note the logic in the EXP-1 also includes circuitry to "pass through" the digital signals to/from the MS-4 as well, so that you can 'daisy chain' both items to connect to one amp.

In short: no, not an easy thing to make from scratch. Even if you could reverse-engineer the circuitry, it would probably cost more in parts and time to assemble than just buying the real thing.


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Post subject: Re: Anyone seen the insides of the expression pedal?
Posted: Thu Jan 08, 2015 1:14 pm
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Thanks. Disappointing but good to know. I'll have to figure out a better way to accomplish this, tho i may be out of ideas.


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Post subject: Re: Anyone seen the insides of the expression pedal?
Posted: Thu Jan 08, 2015 2:54 pm
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Quote:
figure out how to build what I want ... I'll have to figure out a better way to accomplish this ... i just want to be able to step on a button footswitch and have a slight volume boost

You could look instead at building your own MS-2 (rather than MS-4 or EXP-1) - if you really prefer building your own rather than buying. The MS-2 works as a simpler analogue pedal, and lets you switch presets or turn effects on/off within a preset. So you could setup two presets (or one preset with an effect on and off) to get your 'normal' and 'boost' tones.

I've documented the internal workings of the MS-2 on this forum; search for posts by me containing the word "resistance" and you'll find it.


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Post subject: Re: Anyone seen the insides of the expression pedal?
Posted: Thu Jan 08, 2015 7:26 pm
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By ms2 you mean the 2 button footswitch? i have that and have the 4 button. But i don't want to do t by switching identical patches aside from slightly different volume levels. Of course that was the first thing tried but w/o going into the several reasons why it doesn't work for me, the delay is more than enough. yes, it's slight, but it isn't usable that way for me plus there are other reasons. I even built a box with a pot and a switch to bypass it that works in the loop. Affects the tone negatively tho. I have no other ideas up my sleeve.


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Post subject: Re: Anyone seen the insides of the expression pedal?
Posted: Fri Jan 09, 2015 1:33 am
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Although I can fully understand what you are trying to achieve. The EXP-1 is a relatively inexpensive item, is well built and to put quite simply works.

May be obvious but the only other option would be to put a clean boost in the FX loop something like a MXR Micro Amp. I have one of those and can atest to these working however I decided chaining the MS-4 to the EXP-1 was a simpler set up in a gig situation than having to deal with another two cables into the FX loop.

As already mention although desirable the cost of producing something with a one switch volume boost is prohibitive.


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Post subject: Re: Anyone seen the insides of the expression pedal?
Posted: Fri Jan 09, 2015 2:02 am
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oczad wrote:
By ms2 you mean the 2 button footswitch? i have that and have the 4 button. But i don't want to do t by switching identical patches aside from slightly different volume levels. Of course that was the first thing tried but w/o going into the several reasons why it doesn't work for me, the delay is more than enough. yes, it's slight, but it isn't usable that way for me plus there are other reasons. I even built a box with a pot and a switch to bypass it that works in the loop. Affects the tone negatively tho. I have no other ideas up my sleeve.


I guess I'm confused but if you have the 4-button switch and all you want to do it slightly boost your volume, why wouldn't you just apply something like the ranger boost stomp to the preset using the stomp button on the 4-button switch. Isn't that exactly what you're wanting to do?

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Post subject: Re: Anyone seen the insides of the expression pedal?
Posted: Fri Jan 09, 2015 3:10 am
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Quote:
i don't want to do t by switching identical patches aside from slightly different volume levels ... doesn't work for me, the delay is more than enough

Then as I suggested above, and dunedindragon also suggested, you can do it by turning an effect on and off within a single preset. This doesn't have any delay (or, a delay so short it doesn't matter - I just tried it on my amp to be sure). For example, add a stomp effect (eg overdrive or compressor) with 'clean' settings (so as not to change the tone) but with its level set to boost the signal slightly. Then, with the MS-2 footswitch or the MS-4 in "mode 3" you can do exactly what you said in your original post: "I just want to be able to step on a button footswitch and have a slight volume boost"

If you're already using the stomp effect in the preset, you can also pretty much achieve this with judicious use of a 'mod' effect. For example, you can set the phaser effect to give a clean sound and use its level control just to give a volume boost to the signal.

However, if your preset is already maxed-out with effects, then this approach isn't going to work, and I'd second 81LesPaul's suggestion to do this with a proper boost pedal in the fx-loop (or between the guitar and amp input, depending where in the signal chain you want the boost).

I note you say you've already tried this with a home-made boost switch but it "affects the tone negatively." This shouldn't happen with a proper clean boost pedal. A "box with a pot and a switch" is not a clean boost pedal - from your description it doesn't sound like you have circuitry in there to match the input and output impedance of the amp's fx loop, nor to ensure a 'flat' response across the whole frequency spectrum, etc. A pot and a switch may serve as an approximation, but a proper clean boost pedal (ie that controls the signal amplitude without changing its tone at all) is somewhat more complex.

Quote:
I have no other ideas up my sleeve.

You actually have quite a few options. One of these should achieve what you want perfectly (unless there's some other aspect to this you haven't explained yet?):

- Do this with the amp's own footswitches (MS-2, MS-4), in one of two ways: either by changing preset (with yes an unfortunate tiny delay), or turning an effect on/off within a preset (as long as there is a spare effect slot in the preset to use for this)

- Do this with the EXP-1 in volume mode*. You'll have to buy one of these (rather than make one). As 81LesPaul says, this isn't particularly expensive and is a perfect way to achieve what you want. It won't affect the tone at all (as it's a digital control signal to the DSP in the amp, not an analogue pedal taking the audio signal).

- Build or buy a proper analogue volume boost pedal and put it in the fx-loop or between the guitar and amp. Such a pedal is versatile (you can use it in other setups, not just your Mustang) but will always have a (very slight) effect on your tone (compared to using the EXP-1), as it is affecting the analogue audio signal.

- Control your volume boost with the guitar's own volume control (which is the way many successful musicians used to do it before all this new-fangled technology came along!)

- Do it "on the cheap" with a home-made approximation of a boost pedal, and accept that the tone will be affected. Nothing wrong with that, but it's a compromise and up to each person to decide if it's the right compromise for them.

Personally, I'd do it either with a boost effect in the preset, controlled by one of the footswitch (MS-2, MS-4) buttons, or with the EXP-1 in volume mode.

The one thing you can't easily do (which I think is what you were originally thinking) is have an on/off switch that mimics the heel/toe positions of the EXP-1 (well, you can, by separating the EXP-1's volume/expression switch from the main unit so you can press it independently, and setting fixed values for its 'volume' and 'expression' modes as your two volume settings, but you still need to have the EXP-1 too for this to work, in which case you may as well just use the EXP-1 as intended). But there are enough other options instead that I'm sure you'll find a way to achieve what you want.

* - you can also use the EXP-1 in expression mode, set to control the 'level' of one of the effects in the preset (or in fact pretty much any parameter of the amp model or any effect in the preset), which will allow you to place the volume control at different places in the signal chain and thus control the volume/boost in different ways.


Last edited by scott-uk on Fri Jan 09, 2015 4:24 am, edited 1 time in total.

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Post subject: Re: Anyone seen the insides of the expression pedal?
Posted: Fri Jan 09, 2015 4:18 am
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One further thing. Re-reading your posts, it sounds as though you're happy to buy an EXP-1, but have some objection to using it to control volume, preferring instead a simple on/off switch to flip between two pre-configured volume levels?

So I wondered if your objection to using the EXP-1 is a worry that, being a pedal rather than a switch, it would be difficult (particularly in a live setting) to move the pedal to exactly the right position for each of your desired volume levels?

If that is your concern, then it is easily solved. You can configure the volume range over which the pedal operates. So if (for example) you want your boost volume to be 100% and your normal volume to be 80%, you can set the those values for the pedal's toe and heel positions.

Then simply push the pedal all the way back to its heel position and you have your 'normal' 80% volume; push the pedal forward to its toe position and you get your 100% 'boost' volume. No danger of setting the volume too high or low, or not adjusting it far enough: you just always move it all the way from heel to toe and back again.

Plus, if you're then further concerned that when you push the pedal to the toe position you might accidentally push too far and press the mode-change button, there are ways to solve that too.


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Post subject: Re: Anyone seen the insides of the expression pedal?
Posted: Fri Jan 09, 2015 5:19 am
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Quote:
an on/off switch that mimics the heel/toe positions of the EXP-1 ... by separating the EXP-1's volume/expression switch from the main unit so you can press it independently, and setting fixed values for its 'volume' and 'expression' modes as your two volume settings

For completeness, and my own interest, I just did this. (Well, I didn't dismantle my EXP-1, but I configured it (CTRL-E window in FUSE) to use the EXP-1's volume/expression button as an on/off volume boost*, without needing to use the pivoting pedal itself).

This does exactly what the OP wants: "i just want to be able to step on a button footswitch and have a slight volume boost"

It doesn't require the MS-2 or MS-4. It doesn't require any other boost pedals (commercial or homemade) in the fx-loop etc. It doesn't require any additional presets. It doesn't use-up any of the effect slots in the preset. It doesn't have any delay.

What it does require is that you buy (and keep, and have connected to the amp) an EXP-1 pedal. You just don't use it as a pedal, you use it solely for its mode-change button - which you can remove from the EXP-1 and mount as a separate 'stomp' switch (or replace with a more rugged switch if required).

This is the closest I can come to the complete goal and intent of the OP's request. If buying (and keeping) an EXP-1 is not acceptable to the OP, then we're back to any one of the other solutions.

* There are lots of ways to do this, depending what else you have in the preset and what sort of boost you want. Here's one example:
- Amp model "British 60s"
- Amp model Master Volume (nb not the Mustang Master Volume!) set to eg 50% (5.5)
- EXP-1 Volume Mode set to "Off" (not essential, but if you don't want to use the pedal safest to turn it off)
- EXP-1 Expression Mode Behaviour set to "AMPLIFIER"
- EXP-1 (Expression Mode) Parameter set to "MASTER"
- EXP-1 (Expression Mode) Heel and Toe positions both set to "100%" (or whatever boost value is wanted)
- EXP-1 "Reset parameter to preset value when switching to Volume Mode" must be ticked


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Post subject: Re: Anyone seen the insides of the expression pedal?
Posted: Fri Jan 09, 2015 8:44 am
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Thanks for taking the time to write all this ! Thats the closest thing so far, tho i do have to know whats in the pedal. If the guts are small enough to fit in a box thats not too bix that would be nice. Or if i can copy the circuit onto a smaller board assuming there are no proprietary parts. In fact, the smaller the better because i plan on gutting the footswitches and mounting the circuitry of both the 2 and 4 buttons in one box with only the switches i use coming out and one would be a volume button. So theres going to be a lot of room taken up and it's already going to be rather big so size is a consideration.

However, i'm at a bit of a loss as to what exactly you are saying because when you say turn the volume mode to off, i don't get that. I am somehow missing what exactly is happening. Can you explain it w/o the pedal? In other words, if i were to go from the patche's current volume to 5% more manually with the amp settings, what would i be doing that the pedal is doing in your example. I take it NOT turning the preset's volume up 5% because you said set volume mode to off. See what i'm asking?

EDIT: hmmm...are you saying volume mode to off and PRESET volume mode on? So that there are 2 different volume modes, one being a global master?

scott-uk wrote:
Quote:
an on/off switch that mimics the heel/toe positions of the EXP-1 ... by separating the EXP-1's volume/expression switch from the main unit so you can press it independently, and setting fixed values for its 'volume' and 'expression' modes as your two volume settings

For completeness, and my own interest, I just did this. (Well, I didn't dismantle my EXP-1, but I configured it (CTRL-E window in FUSE) to use the EXP-1's volume/expression button as an on/off volume boost*, without needing to use the pivoting pedal itself).

This does exactly what the OP wants: "i just want to be able to step on a button footswitch and have a slight volume boost"

It doesn't require the MS-2 or MS-4. It doesn't require any other boost pedals (commercial or homemade) in the fx-loop etc. It doesn't require any additional presets. It doesn't use-up any of the effect slots in the preset. It doesn't have any delay.

What it does require is that you buy (and keep, and have connected to the amp) an EXP-1 pedal. You just don't use it as a pedal, you use it solely for its mode-change button - which you can remove from the EXP-1 and mount as a separate 'stomp' switch (or replace with a more rugged switch if required).

This is the closest I can come to the complete goal and intent of the OP's request. If buying (and keeping) an EXP-1 is not acceptable to the OP, then we're back to any one of the other solutions.

* There are lots of ways to do this, depending what else you have in the preset and what sort of boost you want. Here's one example:
- Amp model "British 60s"
- Amp model Master Volume (nb not the Mustang Master Volume!) set to eg 50% (5.5)
- EXP-1 Volume Mode set to "Off" (not essential, but if you don't want to use the pedal safest to turn it off)
- EXP-1 Expression Mode Behaviour set to "AMPLIFIER"
- EXP-1 (Expression Mode) Parameter set to "MASTER"
- EXP-1 (Expression Mode) Heel and Toe positions both set to "100%" (or whatever boost value is wanted)
- EXP-1 "Reset parameter to preset value when switching to Volume Mode" must be ticked


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Post subject: Re: Anyone seen the insides of the expression pedal?
Posted: Fri Jan 09, 2015 9:33 am
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Quote:
If the guts are small enough to fit in a box

Someone has posted pictures of the inside of an EXP-1 on this forum before. You'll have to search for them, but from memory, the circuitry is a lot smaller than the overall size of the pedal, so I suppose yes it could be re-housed in a smaller box. Personally, that seems a waste to me, losing the use of the pedal, but each to their own. All I was envisaging was re-housing the mode-change switch in a separate box alongside the EXP-1 if you want to control that separately - although you don't even have to do that, just keeping the pedal in its toe position and tapping it (like the 'paddle' stomp buttons on Boss effects boxes) does the same job.

Quote:
i plan on gutting the footswitches and mounting the circuitry of both the 2 and 4 buttons in one box with only the switches i use coming out and one would be a volume button

Again, seems a lot of unnecessary work - the MS-2 and MS-4 are already pretty compact and robust units. But again, each to their own.

Quote:
i'm at a bit of a loss as to what exactly you are saying

Presumably because, not yet having an EXP-1, you've never seen how it works in practice. Once you have one, it's all pretty simple if you just follow the instructions I gave. But to try and explain further:

I suggested turning the volume mode of the pedal off, because you don't want a volume pedal, although you could leave it on and use the pedal too if you wanted.

What you principally want is a two-way switch. The settings I provide give you exactly that, by changing the pedal mode. With these settings, when the pedal is in "volume" mode, it's doing nothing: you're just getting the preset settings you've configured (or as above it could be a conventional volume pedal if you want that too). So this is the switch position for normal playing.

When you want your boost, press the button to put the pedal into Expression mode ; the amp then picks-up the "expression" settings you've applied to the pedal, as listed in my previous post. In fact, these could be anything you like - you could use it to turn a tremolo on/off for example. In your case, you want it for a volume boost. So I just picked a convenient volume parameter (the Master volume of the modelled amp) and set that in the pedal settings to a higher value than in the preset. I made the heel and toe values the same so that, whatever the pedal position, you get the same volume boost, which is what you wanted.

You're right, this is nothing to do with the Preset volume. It's the same as turning the modelled amp's Master volume up (nb not the Mustang's Master volume knob). You can find this parameter on the second page of the amp settings on the amp's LCD screen, or in the Advanced amp settings in FUSE. You don't have to use the modelled Master control, you could pick anything else that does the job; it was just the first and most convenient one I found for the purposes of an example.

Quote:
are you saying volume mode to off and PRESET volume mode on? So that there are 2 different volume modes, one being a global master?

Err no, I'm not sure what you're thinking there but you're on the wrong track. Does the above explanation make it clearer?


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Post subject: Re: Anyone seen the insides of the expression pedal?
Posted: Fri Jan 09, 2015 12:15 pm
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Quote:
Someone has posted pictures of the inside of an EXP-1 on this forum before. You'll have to search for them


Fantastic, i will do a search. Thanks.

Quote:
Again, seems a lot of unnecessary work - the MS-2 and MS-4 are already pretty compact and robust units. But again, each to their own.


Yes, it is. But to explain fully the reasons why i want to do this in enough detail to make you say "ahh, i see" i'd have to waste a lot of time typing and it's not important to the discussion of how rather than why.

Quote:
Err no, I'm not sure what you're thinking there but you're on the wrong track. Does the above explanation make it clearer?


i would except for one thing. If it doesn't control the preset or GLOBAL master, but as you said the "master", only a few amps have a master. So are you saying that with the ex pedal you basically have an unseen master for all models ?


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Post subject: Re: Anyone seen the insides of the expression pedal?
Posted: Fri Jan 09, 2015 1:31 pm
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Quote:
only a few amps have a master. So are you saying that with the ex pedal you basically have an unseen master for all models ?

No. This doesn't magically create unseen extra parameters, it's just using parameters that already exist. If the amp model doesn't have a master, then you pick some other parameter to use instead. I just used that as one example, for one amp model. As I keep saying, you can pick any parameter you want, for any effect in the preset. There's bound to be a volume/level in there somewhere you can use.

If for some reason you really can't find a suitable parameter, then you can just set the "expression" mode to control (preset) volume directly. Then you just set "volume" and "expression" mode volumes to be two different values and switch between them (as in previous post, for each mode set heel and toe to the same values).

I really think at this point you should just buy an EXP-1 and play with it. Your questions now are mainly just lack of knowledge of how the pedal, and its configuration settings, work. The best way to fix that is to get one and use it.


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Post subject: Re: Anyone seen the insides of the expression pedal?
Posted: Fri Jan 09, 2015 1:54 pm
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Well, yeah, but at almost $100 I'm a bit hesitant. I have a drawer full of pickups and other gear i wish i'd been more hesitant about.


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