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EMG 81 internal preamp clipping

JustinBourdeau

New here
As a follow up to a thread I saw today about EMG preamp clipping, I decided to test it out on my guitars at home.

The internal preamp in the EMG 81 is absolutely, positively clipping like crazy. Both my guitars with 81s suffer the same problem. The clipping is so loud with my Dean ML... Disgusting. Two sets of EMGs are now up for sale.


I'm heading out to a Skeletonwitch show right now so if y'all want sound clips, I'll post them later on or tomorrow.

If you have active pickups, test your guitar's DI output to determine if you have the problem too.
 

Hysteria

Regular
Would be interesting to see how the 'X' series (that nobody seems to use...must get a set!) fares. I know they are still 9V (as standard) but I think the pre-amp has been modified.

That said, wouldn't an alternative be to move the pickups further from the strings. I've never found it a problem before myself but I try not to twat the strings like I'm going to kill them :p Seriously, though, moving them back might help and it's not like we need active pickups for driving amps into OD these days...or ever in the last 30 odd years really.

Also, I wonder what the benefit of the 18V mod is when you follow it with a 9V pedal? Doesn't this just move the clipping?

And if we're going for anything other than a super-clean tone, does it really make any difference?
 
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S

Soultrash

Guest
ever tried the EMG's without any battery at all?
i did this once and could not really complain asbout the tone, at least in a high gain context.
the only downside is the very low output, however you can compensate on this easily using the axe fx.
 

JustinBourdeau

New here
Not an EMG user, but a Google will quickly tell you that all EMGs clip internally. It's not a fault. Some folk are less sensitive to it.

Lots of folk like to use two batteries for 18v to increase the headroom of the emg preamp. This seems to resolve the clipping.

http://www.metalireland.com/community/viewtopic.php?f=12&t=38734
18v mod isn't needed. It's just a matter of lowering the pickup height until the clipping goes away. It's as simple as that. I've resolved the clipping issue completely.
 

JustinBourdeau

New here
ever tried the EMG's without any battery at all?
i did this once and could not really complain asbout the tone, at least in a high gain context.
the only downside is the very low output, however you can compensate on this easily using the axe fx.
I gave it a try and it sounded really bad. I jacked the input to 100% and it was still horrendous. I just lowered the pickup height until the clipping went away. The EMG set now has a much more dynamic and responsive tone. I recommend you do this with yours.
 

JustinBourdeau

New here
Where did you learn about clipping? How was measurement conducted to show the actual signal vs. the clipped signal?

I am curious about clipping because if the op-amp can go rail-to-rail it should be able to cover almost everything except slamming big chords....
It's really not that complicated. If EMG is advertising that their op-amps can run rail-to-rail, they are flat out lying. EMGs set too close to the strings will clip like crazy. Ignore the people saying you need to put them as close to the string as possible. That's wrong. Use your DI signal as a reference, raise or lower your pickups according to the waveform. If there is no clipping, raise your pickups until you see it clip and then back them off just enough so they don't clip anymore. If you are already clipping, lower them until they aren't clipping any more.
 

JustinBourdeau

New here
Would be interesting to see how the 'X' series (that nobody seems to use...must get a set!) fares. I know they are still 9V (as standard) but I think the pre-amp has been modified.

That said, wouldn't an alternative be to move the pickups further from the strings. I've never found it a problem before myself but I try not to twat the strings like I'm going to kill them :p Seriously, though, moving them back might help and it's not like we need active pickups for driving amps into OD these days...or ever in the last 30 odd years really.

Also, I wonder what the benefit of the 18V mod is when you follow it with a 9V pedal? Doesn't this just move the clipping?

And if we're going for anything other than a super-clean tone, does it really make any difference?
You were right. I lowered the pickups, using the DI signal as a reference, until the clipping went away. The pickups are performing much, much better now. More dynamics, fuller sound, natural tone.
 

vangrieg

Forum Addict
Ignore the people saying you need to put them as close to the string as possible. That's wrong. Use your DI signal as a reference, raise or lower your pickups according to the waveform. If there is no clipping, raise your pickups until you see it clip and then back them off just enough so they don't clip anymore. If you are already clipping, lower them until they aren't clipping any more.
But lowering pickups also alters their tone. Many people prefer clipping. Or don't mind it. Or even like it.
 

Rex

Legend!
D...what is the point of an EMG, a somewhat hot pickup made by means of an opamp compensating for an intentionally weak magnet (that doesn't have a lot of string pull)? If so, why is it one of the main choices for metal guitars?
A strong, steady signal that's pretty much unaffected by amp impedance or knob settings. Or they like how it sounds.

That, and the big reason that guitarists use one thing over another: they look around, see what other guitarists are saying and doing, and copy that. :)
 

vangrieg

Forum Addict
Do you have any data sheets in mind that give ideas of typical outputs?
No, I've never seen meaningful authoritative data about it. Actually, if you think about it, it's not that easy to get. What is typical output? You can measure peaks all right, but passive pickups do not clip, so what's a peak? If you put a bridge pickup on a Jackson, it'll be closer to the neck and thus output will be higher than on most other guitars. It'll also depend on your technique a lot. With actives it's easier because their characteristics are largely defined by the preamp. DiMarzio publish some output data, but it's impossible to compare because it's some RMS measurement apparently, not at all obvious how it was made.

Anyway, it's rather easy to see in practice.


If you're right, what is the point of an EMG, a somewhat hot pickup made by means of an opamp compensating for an intentionally weak magnet (that doesn't have a lot of string pull)? If so, why is it one of the main choices for metal guitars?
There are several things. First, passive humbuckers may have higher peak transient output, but the average level will be lower. Second, active pickups compress, they are easier to play somewhat, more predictable in terms of output, less dependant on technique. Third, they are less noisy, have low output impedance, have fewer problems with long cable runs. Fourth, they are more wideband, with less pronounced resonant peaks, which may be a good or bad thing depending on what you expect, but it's a feature. Fifth, lower transient output makes them easier to record into cheaper interfaces. Sixth, they can clip internally.

So, the point is tone and convenience.
 

vangrieg

Forum Addict
I don't recall seeing anything compression-related... perhaps I can find it again.
It's not like they have built-in compressors inside, the preamp just cuts off loud transient peaks while boosting the overall level.
 

steadystate

Fractal Fanatic
It's really not that complicated. If EMG is advertising that their op-amps can run rail-to-rail, they are flat out lying. EMGs set too close to the strings will clip like crazy. Ignore the people saying you need to put them as close to the string as possible. That's wrong. Use your DI signal as a reference, raise or lower your pickups according to the waveform. If there is no clipping, raise your pickups until you see it clip and then back them off just enough so they don't clip anymore. If you are already clipping, lower them until they aren't clipping any more.
EMG has adjusted the gain such that you can run the preamp rail to rail by setting the proper pickup height. They cannot possibly set the gain to accomodate every player's style and strings given one per-determined pickup height. The X series has slightly less gain. I have an X. I use very light strings and have a light touch, so my pickup is practically touching the strings with no clipping. Almost, but not quite, which tells me they designed it correctly.
 

vangrieg

Forum Addict
So here's some information from someone who makes custom pickups:

Active pickups do clip, that's part of the deal. This is especially true for EMGs that have some awfully crappy op amp and the circuitry is implemented to overcome related problems. So, to begin with, there's a diode that drops some voltage from the battery, it's 8.7 even with the freshest one, less than 8 in reality. Then because of how the circuit is implemented the rail to rail voltage is actually half that, about 4 volts. Less in with most batteries. The pickup itself is somewhat similar to a PAF, so it's relatively high output. Medium output humbuckers can generate up to 8-10 volts peak to peak. Easily more than 4 (we're talking about transient peaks, not average level, of course). The absolute maximum an EMG pickup can generate is a bit less than 4.5 volts peak to peak. And that's with a lot of clipping. Also of note, the waves arent symmetric, so half waves clip as well even though the overall peak yo peak voltage may be fine. Doubling the voltage can alleviate the problem somewhat, but it doesn't double the headroom because the op amp gain is fixed and the coils generate what they generate - so basically, the 18 volt mod is to ensure there's more than 9.

In terms of clipping, SD actives use much better components and their circuit is better designed, so they can output up to 6 volts and clip much less. Also, because they use a better op amp, they don't have to do tricks like EMG's low cut filter to cut excessive noise. This filter, made of very cheap components, introduces quite a lot of distortion.

Please don't shoot the messenger (me), I'm just saying what I learned and I'm unable to verify this information myself.
 

mr_fender

Fractal Fanatic
Think you missed a decimal point there. Medium passive pickup output is closer to 0.8 to 1.0 volts peak not 8 to 10 volts. For 10 volts, the pickup coil and magnets would be the size of a car battery.
 

vangrieg

Forum Addict
Think you missed a decimal point there.
No, I most certainly didn't. Think about it this way - Axe front input takes 16 dBu, and for especially hot pickups the rear input takes up to 20 dBu. That's about 14 and 21 volts peak to peak, respectively.

Alternatively, if they truly had 1 volt peaks, sound cards with 0 dBu headroom would do just fine. Yet try to strum hard into a +6 dBu input, you'll clip it. And that's about 4.5 volts peak to peak.

And no, to generate that voltage a pickup doesn't have to be huge. Huge is for power, and we're talking about very little power since guitar pickups properly generate output into high impedance inputs with tiny current.
 
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mr_fender

Fractal Fanatic
Ah, peak to peak. I was thinking more like RMS in my head for some reason. Max peak to peak makes a bit more sense.
 

vangrieg

Forum Addict
RMS in my head for some reason. Max peak to peak makes a bit more sense.
It is somewhat frustrating that there is no standard way to measure output, and when there IS data, it's next to impossible to compare pickups made by different manufacturers because you never know what it means. But maybe it's not even possible in a meaningful way for passive pickups, I don't know. It's just hard to say what to mean by "peak output" in their case, there are so many variables - where it is positioned, what string gauge, how hard one strums, how many strings at once etc. After all, there's nothing that limits them - inductance and magnet power sort of do, but I don't think that they do it in a hard way. With active pickups it's easier - the preamp acts as a limiter, and output just can't get any higher than the preamp spec. But even then it's hard to say what they mean when they throw in some numbers without any explanations.
 
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