2 P90's - pick up height and other general questions

heatmiser

heatmiser

mr. green christmas
Hi,

I have a 1968 Gibson SG Special with 2 P90's and there's some basic things I'd like to ask that I've never really understood. I was reading antichef's thread below and I guess this is pretty similar, but somewhat different issue. I think I understand far less than he about the inner workings of guitars, so if anyone can explain in really high-level, general terminology that might help me.

1) What's the deal with Pick Up height? Is it simply that raising them increases volume and lowering does the opposite, or is it more complicated than that? Are there general rules about PU height that I should know? I've raised and lowered them over the years, never really knowing what I was doing, and the differences were subtle enough that I never really could predict the results of height changes.

2) What is the relationship between the two PUs? I have a 3-way selector switch, plus a volume and tone knob for each PU. I understand that I can play through one, or the other, or both combined depending on the position of the switch. How does the PU height of each impact the sound when combined?

3) It has varied over the years in terms of perceived output from each PU, and I struggle to get it to a state where all 3 settings are comparable in volume so that I can switch on the fly without a huge gain or drop in loudness. Currently, the bridge PU is quite loud, with plenty of hum. The neck PU is slightly less loud with slightly less hum. When combined, there is a noticeable drop in volume with much less hum. At one time, I had it so the volume drop was less noticeable, and the middle setting had a nice sort of honky, mid-rangey tone to it. Now, in addition to the volume drop, that distinctive tone is lessened and it sounds more "normal"?

Any thoughts and/or general advice on how I should set these to play together better? Thanks.
 
No knowledge for you, but I just wanted to say that I'm jealous of that guitar. I suppose the P90s are original? If you ever have the back open, it would be cool to know whether they appear to be wired out of phase (electrically speaking) - like the black wire goes to the center pole on one pot, and the white on the other pot (assuming you have black and white wires, and two volume pots - I suppose the same could be true with both pickups going to one pot)

If you've raised and lowered them a lot, your experience is probably like mine - closer isn't necessarily better, even if it's stronger. It never occurred to me until the other thread that their relative heights could be affecting the mixed signal sound, but that makes total sense.
 
P90s are single coil so they are inherently more likely to hum.

A humbucker uses two coils which can be used to cancel out the hum, hence the name humbucker.
So when you play both p'ups together, depending on how it's wired you make essentially a big huge humbucker with it's coils separated which is why you're getting much less hum in the middle position.
Often on strats you can overcome a bad hum by using two p'ups at once.

As for the volume loss ..... that's because of phase cancellations between the two p'ups much like phase cancellations between two mics on an acoustic or a speaker. Since some of the sound is being cancelled by the out of phaseness that means there is less sound and thus less volume.
That's a very simplified explanation but suffices for discussing this.

As for pickup height ..... higher is closer to the strings so equals more volume ..... too high can actually pull on the strings (magnets in the p'up)
and cause tuning issues. It's more common on a strat type p'up where the poles are themselves the magnets as opposed to a P90 where the poles are simply screws passing on the magnetism of a bar magnet they pass thru or rest upon.

As for settings for you P90s, I don't have measurements for you although I bet there's some primers on it on the net but I'd just experiment 'till I got it where I liked it and make a note. Different people are gonna want and hear different things so I think it's gonna be hard to simply look up some measurements and use that.

Personally, except on strats, I tend to get all my p'ups as high as they'll go without hitting the strings when I'm fretting it on the last fret.
 
The pickup height can have a pretty big impact. Close to the strings is gonna be a hotter, stronger signal. It's usually gonna be more bassy too. It's going to "hit" the amp harder. Lower to the body is going to lower the signal. It's usually going to brighten up a little bit. It's going to "clean" the sound some. The standard height on an SG has the bridge p/u pretty close to the strings and the neck sits relatively low. You can of course change it to however you like it. On a side note, I saw a video one time of I believe IIRC it was Gary Moore ripping on something with I think was P-90s as he was giving an interview. He was talking and noodling away at the same time. He then said something like "hang on a second" and he whipped out a tiny screwdriver and adjusted one single pole piece like 1/4 turn. Then he started up again as was satisfied. Lol.
 
antichef said:
No knowledge for you, but I just wanted to say that I'm jealous of that guitar. I suppose the P90s are original? If you ever have the back open, it would be cool to know whether they appear to be wired out of phase (electrically speaking) - like the black wire goes to the center pole on one pot, and the white on the other pot (assuming you have black and white wires, and two volume pots - I suppose the same could be true with both pickups going to one pot)

If you've raised and lowered them a lot, your experience is probably like mine - closer isn't necessarily better, even if it's stronger. It never occurred to me until the other thread that their relative heights could be affecting the mixed signal sound, but that makes total sense.
Click to expand...

Yeah. I love the guitar but I haven't maintained it like I probably should. So far as I know it's all original except the knobs were gold speed knobs when I got it. I've since put on newer gibson witch hat knobs which look so much better, but not nearly like the '60's ones. The hardware kinda sucks though...(like all specials?). The bridge has fixed ridges in place of moving saddles, so intonation adjustments are pretty hard. The tuning pegs are in line and the gear ratios seem awful to me. In line tuning pegs always just seemed like a sign of cheapness to me, but who knows?

I just feel like adjusting the PU height does have a big affect on the combined PU sound as that's all I've ever adjusted on this thing and it sounds way different now than it used to. I suppose there could be other explanations though...
 
Lt. Bob - thanks for that plain explanation. I knew some of that, but some I did not.

I didn't expect hard and fast rules about PU height and will experiment more paying closer attention to how it affects volume and tone in each of the 3 positions.

I guess what I'm wondering is, given the phase cancellation stuff you mentioned, could playing around with the 2 individual PU heights change the phase relationship between the two and therefore affect the tone drastically when they're combined, or are those two things not too related to one another?
 
Does your SG have two or four knobs? If you have individual volume knobs you can blend more or less of each pickup when they're both on.
 
Greg_L said:
The pickup height can have a pretty big impact. Close to the strings is gonna be a hotter, stronger signal. It's usually gonna be more bassy too. It's going to "hit" the amp harder. Lower to the body is going to lower the signal. It's usually going to brighten up a little bit. It's going to "clean" the sound some. The standard height on an SG has the bridge p/u pretty close to the strings and the neck sits relatively low. You can of course change it to however you like it. On a side note, I saw a video one time of I believe IIRC it was Gary Moore ripping on something with I think was P-90s as he was giving an interview. He was talking and noodling away at the same time. He then said something like "hang on a second" and he whipped out a tiny screwdriver and adjusted one single pole piece like 1/4 turn. Then he started up again as was satisfied. Lol.
Click to expand...

Cool. Thanks Greg. So in your opinion, PU height affects tone in addition to volume....

If so, maybe I need to raise that bridge PU, as I get feedback lately that my tones are too thin or harsh or whatever...perhaps raising it will give me a beefier, warmer tone? I know there are many other factors, but...I think I want a heftier, more aggressive tone than I'm getting, in addition to trying to get the levels on all 3 PU settings closer to one another in volume.

I'm not supposed to mess with the screws lined up (much like poles) on the PU itself, am I?
 
Greg_L said:
Does your SG have two or four knobs? If you have individual volume knobs you can blend more or less of each pickup when they're both on.
Click to expand...

One volume knob for each PU.

However I had it set up before (wish I could go back!), with both volume knobs @ 10, the middle position had this cool, unusual mid-rangey kind of honky tone to it, but I noticed then that if I backed of the bridge PU volume ever so slightly, it lapsed back into a much quieter, cleaner, sort of "normal" tone.

Currently (after many random adjustments (why oh why?)), my starting point in the middle position with both knobs at 10 is the normal, quieter tone that I don't like so much...
 
heatmiser said:
Cool. Thanks Greg. So in your opinion, PU height affects tone in addition to volume....

If so, maybe I need to raise that bridge PU, as I get feedback lately that my tones are too thin or harsh or whatever...perhaps raising it will give me a beefier, warmer tone? I know there are many other factors, but...I think I want a heftier, more aggressive tone than I'm getting, in addition to trying to get the levels on all 3 PU settings closer to one another in volume.
Click to expand...
Well P-90s aren't the raunchiest pickups around, so you're limited. But yeah, putting them closer to the strings will "mean" the sound up some. For example, on that Hallmark Mosrite clone I just got, the pickups are pretty similar in construction to P-90s, but they're super hot. Hot! They kick out the jams. I dropped the bridge p/u height about 3/16" and it tidied things up quite a bit.

I'm not supposed to mess with the screws lined up (much like poles) on the PU itself, am I?
Click to expand...

You can, but that's some real fine tuning stuff. I'd advise against it unless you just really want to. Count your turns so you can go back to normal if things get screwy.
 
Understood. I'm not thinking I'll get your LP>Marshall tones, nor is that necessarily what I'm going for most times, but it's subtle differences, you know? I just feel like fairly recently, I used to get complimented on the sounds coming from that thing, but there's been a trend of "shrill, thin, etc" feedback lately that has me looking for answers...

I will stay away from those screws! I really don't know what I'm doing and so things could get screwy in a hurry!
 
heatmiser said:
[ I guess what I'm wondering is, given the phase cancellation stuff you mentioned, could playing around with the 2 individual PU heights change the phase relationship between the two and therefore affect the tone drastically when they're combined, or are those two things not too related to one another?
Click to expand...
yes it can make a large difference.
I think the mic analogy is a good one since we all have some understanding of that issue.
Say you've got two mics not in great phase .... will it make a difference in the final sound if you increase the level of one mic as opposed to the other? Of course.

So let's say you have the bridge a lot higher than the neck ....... that means you'll have less cancellations of the freqs that dominate the neck p'ups response and which will give you one sorta sound.
OTOH let's say you have the neck p'up way high and the bridge down ..... the bridge will now impact the sound less and so you'll have a cancellation that's been changed also since the neck p'up will be 'hotter' so it will overcome some of those freq/cancellations while the bridge p'ups response if less and so you'll have less cancellations of the freqs that dominate it's response.

Once again, I'm sure there are some inaccuracies in my prediction of what gets cancelled but the general idea is applicable.

Boiled down ..... yeah ... the relative heights of the p'ups can and will produce a different final output from the combined sound of the two if you change their respective heights.
 
The mic comparison is where I was starting from, so it's very helpful for me. In the DAW, I've been able to rescue tracks by "adjusting" the phase on one using a plugin and bringing the whole package together in a way that sounds good.

I suppose when you think about the screws on the pickups, you're almost talking about a crude graphic EQ on each one. So if the phase coupling is punching some holes in particular frequencies but not others (as is the case with me, I think), maybe you could remedy that by adjusting screws that sit roughly in the frequency ranges that are getting hit hardest. Of course, you could royally screw things up, too.
 
heatmiser said:
I'm not supposed to mess with the screws lined up (much like poles) on the PU itself, am I?
Click to expand...
that would be more for adjusting the output levels of individual strings. So if you have a B string that seems too loud or soft compared to the other strings you can fine tune that string only by adjusting the pole pieces.
That's why on classic strat p'ups the pole heights are different. It's their decision as to which strings need a little more or less in order to have the same volume.

antichef said:
I suppose when you think about the screws on the pickups, you're almost talking about a crude graphic EQ on each one. So if the phase coupling is punching some holes in particular frequencies but not others (as is the case with me, I think), maybe you could remedy that by adjusting screws that sit roughly in the frequency ranges that are getting hit hardest. .
Click to expand...

ummmmm ..... maybe .... I hadn't thought of that ....... but they're really mostly for individual string volume adjustment.
 
Lt. Bob said:
ummmmm ..... maybe .... I hadn't thought of that ....... but they're really mostly for individual string volume adjustment.
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Yes - hence the crudeness - sort of using the frequencies of the string (which change when you fret it, and also exist in other mixes on other strings when you fret them) as a proxy for an EQ band. Actually this sounds like a terrible idea now that I spell it out.
 
Thanks again Bob - your analogy makes sense. I guess with mics you can move them around so much more than PUs that I wasn't sure it had too much impact in that sense.

Based on what you and Greg have said...it sounds like I want the bridge PU higher and maybe the neck PU lower (at least tone-wise)...still so hard to get all 3 positions somewhat close in volume while capturing the kind of tone you want. It used to just "work" years ago, but then some ill-advised fiddling and now I can't seem to get back to that old set-up!
 
antichef said:
Yes - hence the crudeness - sort of using the frequencies of the string (which change when you fret it, and also exist in other mixes on other strings when you fret them) as a proxy for an EQ band. Actually this sounds like a terrible idea now that I spell it out.
Click to expand...
welllll ....... it actually sounds like an interesting idea with some merit regarding the issues you're trying to address.
It might very well make a difference but I would worry that you'd be fine tuning the freq response of the two p'ups together at the cost of ending up with unequal volumes of the individual strings.
 
Lt. Bob said:
that would be more for adjusting the output levels of individual strings. So if you have a B string that seems too loud or soft compared to the other strings you can fine tune that string only by adjusting the pole pieces.
That's why on classic strat p'ups the pole heights are different. It's their decision as to which strings need a little more or less in order to have the same volume.
Click to expand...

Cool. There have been times where the B string seemed too quiet and the G string too loud, etc. I guess if I'm still encountering that, I could raise the screw under the B string slightly and lower the one under the G, but not sure I trust myself!
 
antichef said:
Yes - hence the crudeness - sort of using the frequencies of the string (which change when you fret it, and also exist in other mixes on other strings when you fret them) as a proxy for an EQ band. Actually this sounds like a terrible idea now that I spell it out.
Click to expand...

I figured that was what you meant...kind of made sense to me when you first mentioned it, but I don't know that I'd be that adventurous to try it...
 
heatmiser said:
Cool. There have been times where the B string seemed too quiet and the G string too loud, etc. I guess if I'm still encountering that, I could raise the screw under the B string slightly and lower the one under the G, but not sure I trust myself!
Click to expand...
as gregL said .... simply count the number of turns and you can always go back to exactly where it was
 
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