HS-3 noise/hum problem

[Deleted]

Hello, i have a partscaster build demoed here :

and here :

It has an HS-3/Generic SC/HS-3 configuration which i really like.
Yesterday i was experimenting with extreme distortion sounds (+ boost + wah wah) and found out that the bridge HS-3 hums a hell lot more than the neck HS-3. I was worried about the wiring so i started comparing my other guitars/pups with the same distortion settings (EMG 81, EMG 60, Dimarzio Super Distortion, Dimarzio Fast Track 1, Fast Track 2). What i figured out, i sort the noiseless pups from the least noise (most noise-free) down to the most noisy as :
1) HS-3 neck (no hum, no noise even under those extreme distortion + boost + wah wah)
2) Fast Track 1 (minimal hum, almost no noise)
3) Fast Track 2 (average hum, bearable)
4) EMG 81, EMG 60 (excess hum)
5) Super Distortion (even a little more hum)
6) HS-3 bridge (equal or a little more to SD and EMG)

I am puzzled here, the fact that Super Distortion and EMGs behave this way, is an indication that my wiring is on the "OK" side.
OTOH, the fact that there is such a huge difference between bridge and neck HS-3 is an indication that something went wrong in the process.
I bought both HS-3 used.
One of my HS-3 (bridge the humming one) looks like :


The other HS-3 (neck the non-humming one) looks quite different, has a bare ground wire so i assume it is from older version and looks like as presented here : tomoweb.blog59.fc2.com/blog-entry-1587.html


Should i assume this is ok? or should i go and open the pickguard to check the wiring?

Thanx!

[newey]

GD-

Comparing noise levels across two different guitar platforms isn't going to tell much, as there are simply too many other variables.

The HS-3 with the bare ground wire is, I suspect, a newer rather than an older version. Newer pickups are more likely to have a shield wire. The shield wire is simply grounding the baseplate/frame of the pickup, it is not connected to the windings.

If the noisy HS-3 has a metal baseplate, you can run a shield wire from that to ground, see if that makes a difference. It may or may not matter. With high distortion settings, all bets are off when it comes to predicting noise levels . .

Is the guitar shielded?

[Deleted]

Hi newey Thanx.
The guitar is semi-shielded : i have coated all the pups/control cavity with conductive paint, back in 2011 when i joined the nuts.
But the new pickguard only has shielding on the control side, and does not come in full metal to metal contact with the conductive coat underneath. This is something i will definitely have to enhance/improve, maybe by aluminum tape as i have done in the past.
Now both of the two HS-3 (which are installed in the same said guitar) have a chassis/ground wire. One is covered with plastic, and one is bare/naked metal. I suspect the bare one is the oldest design.

Maybe some wiring/soldering went cold? I gotta inspect this, but family is back and party is over... it could take me weeks before i re-open the guitar... (having other priorities in the house etc...)

[Deleted]

A very good (IMHO) answer i got from the dimarzioforum.com.

I take the liberty to re-produce it here :

By RayBarbeeMusic

On pickups with 4 conductors plus a bare ground wire, that ground is for the baseplate, or in the case of a noiseless single, probably the shield around the coil. In theory that gives a greater level of noise reduction. In practice they must have decided at some point it was un-necessary, or just not necessary enough to justify the cost, because they quit doing it.

In any case, with a 250k pot and a .047uf cap, which is really quite large in an electronic sense and not well isolated from the circuit by a 250k resistance, you have high end being shunted to ground. A fair amount of what we hear as noise or hum is the overtones of a 60 cycle fundamental. If you send the upper parts of those overtones to ground, you'll perceive less hum. My guess is that is exactly what is going on.

For instance, when I design a high gain tube preamp, I'll typically use a plate bypass cap on the last stage to shunt unpleasant high harmonics to ground through the power section (not the same aurally or in terms of feel as using a cap to ground directly off the audio path, but electronically very similar). A by product of that vs. amps that don't do it is that the amp seems much more quiet since a lot of those 'buzz' overtones are being sent to ground with the harsh upper harmonics of the preamp signal. I've even seen some, well lets say 'more prone to euphamism' designers, call this a noise reduction circuit. That is just a by product of what it's purpose is.

In any case, I'd bet that if you disconnect the tone from your neck pickup, it will hum in a similar manner to the bridge .

If not, then I'd suspect a cold solder joint, lack of shielding in the cavity, etc, to be the culprit. Make sure your solder joints are well flowed and clean, that you clean any oxidization off the two parts you are soldering before soldering, and shield your control cavity if noise is still an issue.

As for difference in DCR readings, I wouldn't read much into it. The wire used to wind pickups has variation in it, 21-23k is a lot of turns even of very thin wire, there will be enough variance in the wire size over that length to account for that difference.

[newey]

GD-

He's right about the DCR reading variances. But I'm not buying his theory about the tone cap being the culprit. At "10" on the tone pot, the cap is effectively out of the circuit and can't be contributing anything to the situation. Also, if the tone cap were responsible, you would notice a variation in the level of hum as you turned the control down. I've never experienced that, and I'm betting you don't either.

.047 caps and 250K pots are quite commonly used in the world of guitars, and if this were the case, by now we'd all know about this effect. The writer's analogy to noise reduction in an active (amp) circuit is a stretch, as he himself notes.

I'd continue looking for a cold joint, that's the more likely culprit.

[Deleted]

Sept 13, 2013 4:50:18 GMT -5 newey said:

GD-

He's right about the DCR reading variances. But I'm not buying his theory about the tone cap being the culprit. At "10" on the tone pot, the cap is effectively out of the circuit and can't be contributing anything to the situation. Also, if the tone cap were responsible, you would notice a variation in the level of hum as you turned the control down. I've never experienced that, and I'm betting you don't either.

.047 caps and 250K pots are quite commonly used in the world of guitars, and if this were the case, by now we'd all know about this effect. The writer's analogy to noise reduction in an active (amp) circuit is a stretch, as he himself notes.

I'd continue looking for a cold joint, that's the more likely culprit.

Ok, but aren't 250 KOhm tone pots famous for letting some of the highs escape to ground (as opposed to 500 KOhm pots), and therefore being the pots of choice for strats (as a way to darken the sound of strats being considered "thin" by "nature")?

Now about ".047 caps and 250K pots being quite commonly used in the world of guitars, and if this were the case, by now we'd all know about this effect", i doubt anyone has tried this under a heavily noisy context. Boost: 10, Gain: 10, + additional boost, + wah wah, + the noise reduction setting to 1 or 0. I forgot to say all this is generated within Boss ME-25, with custom settings.
With "off the shelf" distortion, even heavy, the difference in noise between the two HS-3's is barely noticeable. I have to make it extreme, and eliminate any noise reduction system, in order to make the effect noticeable.

Now if it was a cold joint, the only culprit would be the chassis/baseplate ground. Not the signal hot or signal ground. Cold joint in any of the signal wires would result into poor sound best case or no sound at all, average case, right. But if it was the chassis ground, then it would have no that huge of effect, since i hear that newer designs lack this additional chassis ground wire.

Puzzled as to what this might be... Another issue is that almost *all* pups in the house are more noisy than this particular new HS-3 which i got from a (very fine and fantastic greek virtuoso) fellow guitarist just 2 weeks ago. Could that new pup be "that" good?

Anyways, experimentation will shed some light, i hope soon. Thanx for your thoughts, i will have them in mind.

[newey]

Ok, but aren't 250 KOhm tone pots famous for letting some of the highs escape to ground (as opposed to 500 KOhm pots), and therefore being the pots of choice for strats (as a way to darken the sound of strats being considered "thin" by "nature")?

No pot is perfectly manufactured, and there are variances as with any component. But with the the knob turned to "10", highs (or lows, for that matter)aren't "escaping to ground". The reason that 250K pots are preferred for SC-equipped guitars is the overall resistive load on the circuit, as compared to a higher value pot.

The overall resistance of the circuit is what matters here, not just tone pots. Strats use 250K volume pots as well, and increasing the value of either pot(or both)will make the sound brighter (or "thin", if you prefer). This effect has nothing to do with shunting anything to ground.

i hear that newer designs lack this additional chassis ground wire.

Manufacturers have generally been adding shield wires to pickups over the last 50 years, not subtracting them. There is a cost to adding the wire, and no one would do so if they thought it was unnecessary. The fact that people now use more high gain and distortion is a big part of the reason these wires were added.

You yourself said earlier:

both of the two HS-3 (which are installed in the same said guitar) have a chassis/ground wire. One is covered with plastic, and one is bare/naked metal. I suspect the bare one is the oldest design.

I suspect you're right, and that all these pups still have a chassis ground, whether bare or not makes no difference. They probably went to using an insulated wire because, from a manufacturing standpoint, it means one less type of wire to stock. There can be significant savings in not having to order, warehouse or inventory added types of parts, even if the insulated stuff is a bit more expensive to purchase.

[Deleted]

Just a report on this, regarding EMG 81/60 noise. Opened up the ibby tonight and noticed the bridge ground wire connected to the casing of the volume pot. (This is against EMG's instructions, but cannot know yet if this contributes to noise). Will try tomorrow removing it.

Also, just figured out the stock shielding of Ibanez ARZ800 is a joke. Hardly any connectivity in the supposedly "carbon paint" "shielded" control cavity. And the supposed aluminum foil which covers the cavity cover is hardly conductive. ;(

[Deleted]

Un-soldered the bridge grounding from the volume pot (which took me about 15 mins, it was SO STRONGLY soldered i could not melt it). The hum was still there (maybe a little better). Not as much as a plain unshielded SC, but still there. Then i switched to the neck pup, isolating the bridge pup from the rest of the circuit and just connected the guitar cable to the pins of the bridge pup (with another cable into the jack, in order for the pups to operate at full voltage). The hum was almost identical. So its the pups. Old design. Dimarzio fast track 2, of equal output had almost zero noise under the exact same conditions. (guitars side by side). And this Aria strat with the fast tracks has absolutely zero shielding work. Even Seymour Duncan LiveWires classics had considerably less hum than the EMGs. LiveWire Metal had almost the same hum, but we are talking about a pup with double the output of the EMGs.

[newey]

So its the pups.

I'd try a proper shielding job before anything else. Even some HBs need the help . . .

[Deleted]

Oct 13, 2013 22:04:52 GMT -5 newey said:

So its the pups.

I'd try a proper shielding job before anything else. Even some HBs need the help . . .

That's exactly what i must do. However having other passives with zero cavity shielding work but also with minimal hum put me into thoughts about the EMGs.