Paul Marossy

Ok, just got the rest of the parts from SB today!

But I'm beening banging my head on the wall trying to get a decent dang PCB transfer!

I also noticed that when I transfer it to the PCB, its backwards from the diagram, so I take it I need to rotate it around?

-Stormy

Not sure what you mean exactly. The copper is on the the bottom side of the PCB, so the layout will look like a mirror image when you transfer it to the PCB. Does that help?

One problem I can see is that your feedback resistor is really small, so it will have very little gain. I would try something like a 220K instead and see what that gets you.

And the other thing that you have to take into consideration is the impedance of the headphones that you plan on using.

These pages might help point you in the right direction with designing a headphone amplifier circuit:

http://www.headwize.com/projects/opamp_prj.htm

http://www.headwize.com/projects/cmoy2_prj.htm

Like I said earlier, there's a half a second of charging period, where the zenor charges up to the voltage its set to. Zener diode will pull as much current it needs to charge to its break down point

No, I think you are confused on the zener's mode of operation. If you give a 5 volt zener 3 volts, you will get 3 volts max. I do not think there is a way to get 5 volts.

+1 on confused.

Hmm... not sure why it would be humming then.

Maybe when installed in an Ibanez those wires need to be switched around? I put a DiMarzio FRED in one of my Ibanez guitars once and I had to try a lot of different things before it worked as it should - without being out of phase and wired like a humbucker. I took it out of that guitar, though, so I can't look at how I wired it.

EDIT: I found a wiring diagram that I made for my Ibanez a long time ago. It's not exactly how it ended up being wired, but from my notes on it it at least tells me that when I connected it per DiMarzio's instructions, it was not a true humbucker. When I first wired it, it was actually two pickups wired in parallel. I had to wire it differently than the DiMarzio instructions. I'm pretty sure that the black & white wires where not connected together when I finally got it working as it should work.

Did you install them per this document?

http://www.dimarzio.com//media/diagrams/virtual_vintage2.pdf

How many wires does your pickup have? And how did you connect them to your pickup switch?

It appears to me from looking at this diagram, http://www.dimarzio.com//media/diagrams/virtual_vintage2.pdf , that you have a red, green, white, black and bare wire. Did you wire it per this wiring diagram?

All I can think of is that you must have somehow defeated the humbucking feature of the pickup because it shouldn't be humming.

Perhaps what is happening is that the middle pickup is quiet (how does it sound with the middle only if that is a selection?)...but the selector is splitting the HB's. Likely it was set up to be HB'ing with one of the HB's split and the middle pickup (like a strat in 2 and 4 position)...now that you have got a noiseless (which is also an HB) you will have lost that effect when split and the others may be making noise if that makes sense.

Otherwise, if your VV SC has 4 conductor wiring, you may have connected it wrong so it is only operating on one coil.

Yeah, what Pete says makes sense. But then why would it hum in position 3? It shouldn't be doing that if this were the case. Weird...

Hi Paul,

The Dimarzio Virtual Vintage 54 Pro is a stack HB/noiseless PU so there should be very minimal/no hum at all. I have a Strat with the same pickups(3 VV54Ps)and it is quiet.

Ah, so that would be unusual to have a hum then, wouldn't it? I guess I should have looked at the topic title a little closer.

OK, so how many wires does it have then? If it's more than two, maybe it's not connected properly for use in your Ibanez. On the Fender "Hot Noiseless" pickups I put in one of my guitars there is only two wires, so if they are out of phase, you just reverse the wires. But I didn't have a problem with hum at all.

Is it a brand new pickup? Maybe it is faulty or something.

Two notes: the soldering on the pot isn't the prettiest ever, but it holds up on continuity check, second you can see the copper foil removed underneath the volume pot. After the above discussion I guess I should put it back.

If all of your ground wires are soldered to the back of the volume pot and the volume pot doesn't have continuity with the the shielding, then that could be a large part of your problem with noise right there.

Hi,

I have an Ibanez S470 with 2 Dimarzio D' Activator Necks and a Virtual Vintage 54 Pro in the middle. The middle PU hums in the 2,3,& 4 positions. I checked both coils with a meter and they are OK. Then I pulled the PU to check connections and no problems. I noticed a ground lug screwed to the body inside the middle PU cavity so I taped it and also the bottom of the PU. No change. Could this ground lug be causing some line interference or something? I'm thinking about moving the ground lug but I'm not sure that is the problem and don't know where to relocate it.

It sounds like it's not wired properly/conventionally. I believe that you should have a split humbucker at positions 2 & 4 and single coil in position 3, which is where you would expect to hear some amount of hum. That's how my S470FM is wired, anyway.

Thanks Paul! My house isn't that big so my amp is about a meter from my computer. Never gives me much trouble though, even with single coils provided I don't stand directly next to it. They're also at different angles.

About the antenna thing: I posted a link to an article on that on the previous page of this thread.

PUs I'm using are 2 stock MiMs and a texas special in the bridge. The most important thing for me right now is to KNOW which is the correct way to go:

Option 1: audio circuit completely seperate from shield, shield being connected to ground

Option 2: audio circuit makes contact with shield through the casing of the volume pot and the shield is at one point connected to the bridge

Option 3: something different (brainfart: what would happen if I left the shield ungrounded? My guess is that should work

If I know which one of these is correct, then I can start troubleshouting convergently, instead of having to run every test twice or thrice.

What you want to end up with when you are all done is to have all grounds connected together in one place, otherwise known as "star grounding". The pot bodies and switch bodies should be connected to the shielding, and the shielding should be connected to ground. Having the shielding not connected to ground will not do much for you. Ideally, all of the pickup cavities and the control cavity should have continuity between them and ground. That way, you get a Farady Cage.

After all of that is accomplished, your pickups will still be the weak link. But you will have done everything humanly possible to quiet everything from extraneous noise.

Additional note: the instrument is NOT stringed yet (but I don't see how that would make any difference).

When tapping the PUs with a screw driver you hear pops as expected.

When I lift the pickguard off the problem remains the same.

If I would attach the ground wire from the bridge to the pot, instead of to the bottom of the cavity the audio circuit would be grounded again and the guitar would be playable I guess. But that would leave the shield ungrounded.

EDIT: I connected the pot casing to the shield again and got something different: it is less noisy (but far from silent) then when not connecting pot to shield. Noise still goes away when touching metallic parts. When not touching you have a noise level with a constant 'tick' sound: about every 0.5 second your hear a 'tick' through the amp.

That would seem to confirm what I read once somewhere about the pot bodies acting like antennas if they are not grounded. On the ticking sound, it sounds like it is picking up some kind of digital pulse from something nearby. I bet if you go to another room that ticking noise will go away. I've even had my wrist watch coming thru pickups before when working on a guitar and it makes kind of a pulsing noise, too.

By the way, when you are conducting your tests, what else is in the room with you? Computer monitors (CRT), flourescent lights, wall warts, transformers, fan motors and stuff like that nearby your guitar will make just about any guitar hum no matter how well it is shielded, and especially if your pickups are pointed at those sources of EMI.

And what kind of pickups are you using? I built a guitar once with a cheap pickguard/pickup combo and it hummed A LOT, and I shielded the heck out of the ENTIRE control cavity and the pickup cavities, too. The problem did not go away until I got better pickups to put in the guitar. By its very nature, any single coil pickup is going to be very susceptible to EMI, but even more so the really cheap ones.

Just throwing out some more ideas...

You can easily get ground loops in power supply grounds where several devices are sharing a common ground, or if you connect the inputs of two different amplifiers together thru a common ground.

While I have star grounded at least one tube amplifier and it made a very noticeable difference, in an electric guitar, I do not consider that to be ground loop territory. Personally, I do not see it happening in a guitar. The weak link in a guitar is the pickups and no amount of sheilding and star grounding is going to fix cheap pickups that are just flat out noisy and like to pick up any noise around them (ask me how I know). Shielding does help to a point, but it will only do so much. The shielding does help to shunt EMI & RFI to ground, though, that's the purpose of it. But then you have metal strings that act like a big antenna, and that's part of the reason why the bridge is also grounded.

Here's a page that might be a good read for you. While based on tube amp design, the same principles apply to any audio circuit. http://www.geofex.com/Article_Folders/lead...n_tube_amps.htm

This is a good page on shielding a guitar: http://www.guitarnuts.com/wiring/shielding/shield3.php

The guage of wire I use isn't 22. I don't know what it is, but its bigger. I figured bigger = faster transfer, so I just went for the biggest and most flexable balance I could. I want to say its either 20 or 16 or something like that... I got it like 9 or 10 years ago.

Bigger wire doesn't equal "faster transfer". The gage of wire used in an electronic device should be a balance between durability and having the proper voltage rating. Electrons travel just as fast down a 10 gage wire as they do a 22 gage wire... but a 22 gage wire will fry if it trys to handle the same amount of current as a 10 gage wire could have on it. The other thing to think about is multi-strand wire vs. solid core wire. Solid core wire breaks pretty easily, so it's not something that you would want to use in anything but the most stable of environments.

My personal favorite, although a bit expensive, is multi-strand 22 gage silver coated teflon wire. I use it in the stompboxes I build. It's durable, solders really well and the insulation doesn't melt when you're soldering.

Should I worry about noise with no shielding?

You should always shield the control cavity and cover for it. You might get some noise if you don't shield it.

There is not enough energy available from the string via pickups to drive the circuits that you need.

That's essentially what I was trying to say.

Capacitors in parallel are additive. All I see them doing is bleeding a large part of your signal to ground. Kind of like having a very large cap on a tone control.

A secondarily, how is a 5V zener diode ever going to ever do anything in a circuit that will not see more than 2V PTP for an instant?

The caps held sustain while the one of the zener models is effectively a battery. In this circuit the zener diode draws more and more current to boost the circuit to that 10v mark in this case. While it may be that you wont need the 10v always there it is simply to force the circuit to have a supply for the op-amp.

yeah, but the "breakdown voltage" of a 5V zener diode is 5V. Where is that circuit ever going to see 5V from passive guitar pickups that only output an instantaneous max. of of 2V PTP?

You need to have it built because I think your circuit simulator in this case is not a reflection of the real world.

to the left of the circuit looks very interesting, but i'm lost, looking at everything east of those diodes (that could be attributed to a sloppy schematic, or the fact that I don't know what the 4 plugs are on an oscilloscope). I guess my first question is, why so many capacitors? They are all in parallel, so can't you just figure the equivalent capacitance and use one big cap?

The number of caps is to make sure that all the frequencies are taken out and moved to a near flat line voltage. Caps in parallel add and the fact that when the signal is removed the caps discharge slower and allows for time to pick the next note, rather than having an instantaneous discharge would could harm the op-amp or other components. But the real answer is having one small cap would not cut out the low frequencies and in fact would block them from having a proper charge. The zener diodes are their to help the caps sustain that voltage for when the signal dips below the negative line.

Basically the number of caps are their to act as a sustaining tool

Capacitors in parallel are additive. All I see them doing is bleeding a large part of your signal to ground. Kind of like having a very large cap on a tone control.

A secondarily, how is a 5V zener diode ever going to ever do anything in a circuit that will not see more than 2V PTP for an instant?

Two reasons for the pickup to die:

Problems from bad installation (jank the hookup cable hard enough and you will get problems, and that is just one way of creating problems)

Environmental issues (Anyone know what sweat can do corrosion wise?)

I've seen quite a few dead pickups and the most common problem is damage during installation. That is often an easy fix. Sort out the problem and replace the hookup cable and you're fine. Don't be too scared to open up the pickup. Be gentle and careful and take notes (or pics) of what you are doing and you will be fine. If you cannot find the problem and the pickup arn't under warranty: send it to someone to do a partial or complete rewind.

I thought about sweat maybe being a possibility, but only because of a Seymour Duncan factory video I watched not too long ago where they mention something about it.

Probably a short like he said. The coil wire is contacting itself somewhere...giving only a fraction of the resistance and output.

That'd have to be a factory defect though. I'm surprised it's just now cropping up. Maybe the wax was the only thing keeping it from shorting and over time the vibrations worked it into contacting another wire. Who knows.

Well, I guess your explanation seems plausible. It's still kind of a freak thing, though.

Who knows, if you contact DiMarzio about it, they might tell you to send it to them and they'll send you a new one if it proves to be a factory defect. Only one way to find out...

The weird thing to me about all of this is that I have to ask how did this happen in the first place? I've never heard of a pickup just going bad before. It's usually due to broken wires in the electronics cavity, bad pickup selector switches, that sort of thing...

I think you will find that in the real world you are not getting nice constant sine wave signals out of signals, excessive times to charge up those caps and then farting when the supply falling below as the signal decays...there seem to be quite a few fundamental flaws and what you appear to be getting from a sine wave is effectively a squarewave een in an ideal world with a very simple signal and constant form and with both pickups feeding it. Reality is simply not like that...massive changes between a big low chord and a high single not, huge changes as the frequencies increase...and you are working with AC signals and the caps will pass most of this rather than store them.

In the end that is a lot of electronics stuffing up the signal, all of which will rob from the actual output to the guitar and take from the "tone" and all apparently to avoid a battery...I still fail to see the point other than to avoid a battery, but you are adding so much stuff in there anyway you would need the kind of space in the guitar that a battery would take anyway as far as I can see.

Sorry if I sound too negative, but there comes a time to solder up an experiment and see what really happens.

Still...good to think about such things...you're not the first...and perhaps you may come up with some ideas from it that might well be worth pursuing more...

pete

Interesting idea. But, I have to agree with Pete on all points. If you build it, I think the real world end result will be completely different from what you are simulating. It would be an interesting experiment in any case.

The other thing is that it will have massive distortion according to your oscilloscope screenshot. Those sine waves have been practically turned into square waves. It seems to me that it will sound a lot like a very muddy sounding Fuzz Face type circuit with a low output.

Not to mention that any passive circuitry you put on the output of passive pickups is going to load them down because they are high impedance devices. You will lose output power and clarity, especially in the higher frequencies. You'll be fighting the inductance of the pickups, which can be two to four HENRIES; and the impedance of an inductor actually goes up with frequency.

Trying to operate a circuit using only the voltages generated by the pickups themselves doesn't really fly, either. Really hot output humbuckers only put out around 1V or maybe 2V peak to peak before rapidly tapering off. I don't see how a full wave rectifier is going to do anything. Yeah, in a sense, your pickups are a source of AC but it's not going to work like you think. If you full wave rectify your guitar signal, all the bottom halves would be flipped over so they're identical to the top halves. There are two peaks/valleys where there was only one, so you would hear an octave up, not a louder signal. And then, it's not a pure sine wave, so you also get the harmonic series of the rectification, plus the cross-products of any multiple frequencies that were there. And there are also some losses, so some amplification is now required to make up for the those losses or to boost the signal.

An audio transformer, unless it is a really good one, will also load down the pickups and add more inductance. It will not make the signal any louder, either. They are used for impedance matching or isolation, not to boost a signal.

Which leaves you with an active circuit to boost the output without killing your high end. Something like the tried and true FET buffer/booster works, and presents a high impedance to passive guitar pickups.

I want to see a schematic...

O.o Definitely want to see a schematic for this. Either I don't know enough about electronics to understand how you could do this or you're full of it.

I have to also agree...

I actually just saw a reference to this project at the http://www.diystompboxes.com forum, where I am also a member.

I must say, this is one cool project. I like the concept and the execution of it. And the handiwork is excellent in all regards, as well as the innovative built from scratch ideas. And I think the double layered case is also a brilliant idea.

Bravo!

so, i guess what youre all saying is, don't be a boutique pedal designer? or at least, dont go to college for it.

seems like whats gonna end up happening is i'm gonna get an awesome degree in who knows what, and maybe end up going do something relatively unrelated to that degree?

Life has no guarantees. I know people with two different degrees, and they are doing something completely different from their degrees by their own choice. Or people I know that have engineering degrees and can't find any work because of this "recession" we are in, so they are detailing cars or working at a tire place.

And then you have people like me that don't have degrees, or any college at all, but worked their way up from the bottom and make more (or used to before they became unemployed) money than most P.E.s do on a national average. Practical experience can take you pretty far, but the challenge is selling yourself when you don't have a degree or a stamp. Like I said, life has no guarantees, and a college degree is in the same category AFAIAC.