Big Ugly Mod help..

[FireBall]

Ok, I finally got all my parts to do UnklMickey's Big Ugly mod. I want to try something a little different with this, if possible, so I am calling on the GN guru's to help me...

I normally don't use a tone control, but I have two potentiometers in my guitar, the second was previously used for a second volume. What I want to do is add a mini boost amp that is mixed in using the available potentiometer, similar to what Charvel did with the model 4 guitar. I am using a mini boost circuit now, but it is wired in as a pre-amp for the entire guitar. I like the pre-amp, but it is a bit much for the humbucker, but sounds great with the singles and the split pickups, the mini boost has some headroom with it, but I would like to be able to roll the pot off to make the pickups passive, then add the boost in.. (this is what my charvel does). I would like to do this all with UnklMickey mod.


What do you think, is this possible? Did I describe what I want clearly... <---- not good at that... If I can't do this and have to use a tone, thats ok also.

summing it up... ;D The Big Ugly with a volume and a second potentiometer to mix in the mini-boost active circuit from passive to active.

btw... if anyone wants to draw a diagram, I am using dimarzio pickups... fastrack 1 thats 4 conductor and tone zone that is also a 4 conductor pickup.


Here is a crude drawing of the preamp:



I believe I have it labeled correctly, I'm not good at this as you can tell, I'm better at following instructions... ;D

[FireBall]

What is the "momentary N.C." on the Big Ugly wiring diagram? Is this the "Blast" button?

[sumgai]

fireball,

What is the "momentary N.C." on the Big Ugly wiring diagram? Is this the "Blast" button?

Yes. It temporarily lifts the ground from the volume pot, which in effect takes the volume pot completely out of the circuit.

The thinking here is, a volume pot is actually a divider - when turned away from minimum resistance at one end or the other, there are two paths for the signal to follow. By the use of a "blast" switch, one of those paths is momentarily removed, thus all of the signal is sent along the single remaining path. Even if the resistance in that remaining path is significant, it won't be very noticible - the signal going out the jack will pretty much be as loud as if the control were at 10 (or 11, or.....).

That's why you want to carefully plan on where you're gonna put it, and whether it's momentary (spring-loaded) or regular.

HTH


in re: your request:

Let's recap here........ Are you asking if it's possible to put a pre-amp into the circuit between the volume control and the output jack? And further, that it can be made to "fade" between passive and active, with a second volume control? Is that what you're wanting here?



sumgai

[FireBall]

Thank you for the reply...

sumgai said:

in re: your request:

Let's recap here........ Are you asking if it's possible to put a pre-amp into the circuit between the volume control and the output jack? And further, that it can be made to "fade" between passive and active, with a second volume control? Is that what you're wanting here?

Yeah, sort of.... ;D

I guess I am asking for help in two folds here...

Can I do the big ugly without a tone control... but with a mix (fade) potentiometer for the preamp...

I want a single volume for the entire guitar, and a mix (fade) control for the preamp (if possible). I know the preamp can be wired with a push/pull to activate/deactivate the preamp from active to passive. I would like to do this with a potentiometer so to mix in the amount of boost or none at all.

All this using the Big Ugly wiring design that Runewalker pointed me to when I first joined the board. I already had the active preamp ordered when I found you guys and installed it a couple weeks ago as a preamp for the entire guitar, but I can't control it except for just rolling off the volume. My Charvel Model 4 has a preamp boost that can be controlled with a potentiometer in addition to a volume for the entire guitar....I basically was trying to copy that setup wired with the big ugly design.

Do I need a the "blast" thingy for the Big Ugly diagram? I wasn't planning on using it.... that is the reason for that particular 2nd question.

Here are my parts to date:

Two push/pull pots DPDT.... 500k
Two push/pull pots DPDT.... 25k (for the active)
(I bought two of each push/pull pots, I only planned on using the two needed to pull this off...)
5 way superswitch
Cap for tone (if I need to go with a tone setup)
Two 500k pots that are currently installed in the guitar
A bottle of Ibuprofen...

Sorry for buggin you guys..

[sumgai]

fireball,

Nope, no buggin' goin' on 'round these parts.


The ointmented fly in your big picture is this: if you feed the signal to both the pre-amp and the output jack at the same time, and then you hook the preamp output to that same jack, you've just tied the preamp output back to the input - in most parts of the world, we call that a short circuit! I'm sure you'll agree that this would be a Class A screw-up, right? Which explains why there's nearly always a switch, to select either the straight or the amp'ed output - the preamp input and output are always isolated from each other.

I can think of a few ways to get around this, but they're involved, and parts intensive (meaning, the wallet's gonna take another hit). I'd rather avoid that, if possible. So I got to thinking that if Charvel did something special, it'd be nice to know just what they did. But when I googled for the Charvel Model 4 (and the 6, same thing), I got bupkis in the way of diagrams. Do you have one, or know where one might be?


Almost forgot..... the blast switch is a feature, not a requirement. Simply hook a wire across where it would be, and all will operate as advertised.




sumgai

[FireBall]

Hello again...

This is the only information I could find on the Model 4 electronics and it doesn't tell very much... I do know that they have the volume pot soldered to the mid boost board and the mixing pot is wired to the board.




My brother drew up this diagram for just adding a mixing volume, but I don't know how to read it, and he lives 300 miles away... so we haven't tried it since I'm only good at the red wire goes here and the blue one goes here type wiring diagrams... ;D

[JohnH]

I cant see any sensible way of doing this active/passive blending. The first diagram does not have passive/active mixing, just a variable active boost to the mids. Id suggest wiring it up like that. The second diagram, as Sumgai suspected, gives nasty feedback around the amp, and heavy loading on the pups in passive mode - so not recomended.

The best active/passive control is just a switch - two poles to switch the input and output, and a third if you want to cut the power as well when in passive mode. Even then, in passive mode, the onboard volume control would not be working, so it would be full output only

cheers

John

[FireBall]

I understand what you are saying.

Would you review this edit to the Big Ugly diagram that I did... I changed the pickup wiring color codes from seymour duncan to dimarzio colors. I plan to just wire up the Big Ugly and scrap the preamp on this guitar.

Again, all I changed on the diagram is the wiring colors for the pickups, I didn't update the version number, hope I didn't offend by updating the diagram from seymour duncans to dimarzio, if so I apologize in advance. I just need a visual reference to help me wire. Please check to see if I made the correct changes.

[FireBall]

Anybody have a chance to check and see if I made the correct changes to reflect Dimarzio pickup color codes? If they are correct, this could be added to the thread of the original to go with the Seymour Duncan layout.


Thanks,
FireBall

[sumgai]

fireball,

Nope, sorry, I'm not the DiMarzio guy around here. Don't worry, someone will get to it in a moment or so......

I do note that you've left the "blast" switch in the circuit. A bit of white-out will cure that deficiency.

And your brother's mix control was correct, if one condition is met - the output of the pre-amp must be out-of-phase with the input, or there will be howling feedback. If that condition is met, then the pre-amp will have to work quite hard to overcome the low resistance (50KΩ isn't very much here), which then portends that the battery life will be pretty short. Personally, I wouldn't do it ...... unless the girl at the 9volt battery store was very easy on the eyes! ;D

Final comment: The circuit you showed from the Model 4 doesn't answer my particular questions. It's a hookup diagram, made for users who don't want all the nitty-gritty details, they just want to wire the thing into their guitars, and start playing. It's great for that, clear enough for anyone to do the job without questions or head-scratching. But for us electronics whizzes, it's lacking all the design theory, leaving us to scratch our heads.

As you've noted, it's probably a good thing to let it go for now, and make sure everything else is working as desired. Fortunately, this is modular in concept, so it can be added at a later date, without wrecking anything you've already done.

HTH


sumgai

[FireBall]

sumgai said:

I do note that you've left the "blast" switch in the circuit. A bit of white-out will cure that deficiency.

Thanks sumgai! I left that in because I remember you saying to just omit that switch and just wire without it.

sumgai said:

And your brother's mix control was correct, if one condition is met - the output of the pre-amp must be out-of-phase with the input, or there will be howling feedback. If that condition is met, then the pre-amp will have to work quite hard to overcome the low resistance (50KΩ isn't very much here), which then portends that the battery life will be pretty short. Personally, I wouldn't do it ...... unless the girl at the 9volt battery store was very easy on the eyes!

My brother drew that diagram for me basically over the phone, I gave him the wiring diagram from the pre-amp and told him what I was looking for. The pre-amp diagram suggested 50k potentiometers, thats why he had the 50k? in the diagram. He actually owns a Charvel Model 6, but has been playing a Parker Fly for a few years now... I wish he would give the Model 6 ;D which is basically a neck-through 24 fret version of my model 4 thats in pieces.

sumgai said:

Final comment: The circuit you showed from the Model 4 doesn't answer my particular questions. It's a hookup diagram, made for users who don't want all the nitty-gritty details, they just want to wire the thing into their guitars, and start playing. It's great for that, clear enough for anyone to do the job without questions or head-scratching. But for us electronics whizzes, it's lacking all the design theory, leaving us to scratch our heads.

I have searched several hours for a diagram for the Model 4/6, and all I could get from searching was people wanting diagrams also, and the simple one that I posted. I keep a watch on eBay for them, but when they show up they really seem to go for some $$.



I hope to work on the new diagram this weekend, I can't wait to try it out.... I just hope I don't shut down the power grid in my neighborhood with my old soldering iron!!!

[FireBall]

Ok, got "The BIG Ugly" wired up yesterday. I went ahead and wired the Dimarzio wiring that I posted (I went ahead with the unverified version and took a chance). The only problem I had was not verifing the super switch with the ergonomics of my guitar. I wired everything but the pickups outside the body, but when I tried to install the switch, it wouldn't fit... it needed to be reversed... sad part is that I new this before I started, but I guess I measured only 9 times so I had to go back and rewire.

The conclusion...

Well I need a GPS system to find my way around all the different sounds! Everything seems to work great, although I miss the pre-amp for the over the top gain, I like all the variations I am getting. After a few weeks, I may stick the pre-amp back in. One thing is true that Runewalker had warned me about was not having much audible difference in the front pickup since it is a Fast Track 1 dual blade single coil when splitting the coils. It basically just gets less volume but almost the same tone. I really like some of the switching between the front and back..some really smooth tones. All in all, I'm happy...

Fireball