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Thread: Electromagnetic output from pickups

  1. #1
    Americana in France? Daniel Nestlerode's Avatar
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    Default Electromagnetic output from pickups

    I'm about to ask a couple really geeky questions.

    I play both electric guitar and electric mandolin, and being somewhat less than independently wealthy I have just a few amps. So I run both my Esquire and my JBovier EMC-5 through the same set of pedals and the the same 15w tube amp (an Ampeg Jet II J-12T).

    What I have noticed is that effects react more strongly to my Esquire than they do to my EMC-5. The tremolo on the amp, the octave pedal, the compressor/preamp, etc all are noticeably stronger when using guitar signal versus mandolin signal.

    (Oddly, overall volume is not noticeably different, though I am sure there is a difference.)

    Question is... Why is this the case? Is it simply a matter arc length in the string as it passes the pickup's field, or are there other factors?

    Another question is... Would a preamp in the mandolin bring it up to the guitar's output level without adding that .meh. solid state tone?

    My goal would be to run both the Esquire and the EMC-5 through the exact same rig and be able to count on the same level of effect.

    Comments? Anyone? Anyone? ....Beuhler?


    Daniel

  2. #2

    Default Re: Electromagnetic output from pickups

    I haven't heard of this issue before. Put a capo on the 12th fret of the esquire and see what happens. My initial thought was that it had something to do with the overall impedance of the instrument which includes the pickup and the pots.

  3. #3
    Registered User John Bertotti's Avatar
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    Default Re: Electromagnetic output from pickups

    My first thoughts are string type/composition and, pickup type and or construction. For example, are they steel strings on both, round wound or flat, etc. Pickups are the typical guitar style with pole pieces or bars what type of magnets or does one use a piezo bridge type of pup, or the glued in discs some use. Next, the pedals themselves some will work great with guitars but other instruments forget it while others will work great with multiple instruments. And cables make sure you try with the same cable for both.
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    Registered User Pete Braccio's Avatar
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    Default Re: Electromagnetic output from pickups

    It could be lots of things: type of pickups, impedance (how hot) of pickups, types of pots, capacitors, wiring, etc.

    To solve it, I would put a boost pedal as the first pedal for the Mando.

  5. #5

    Default Re: Electromagnetic output from pickups

    First and foremost, what is the input impedance of the first pedal in your chain. The pickup in your mandolin is likely to be a piezo. They need at least a 1 meg ohm input impedance. It is imperative to have a full, non ice picky tone. Regular magnetic pickups are a different animal, so right off you have an impedance mismatch. You can solve this with a DI or a preamp designed for acoustic instruments.

    You can't go direct to your amp. Same scenario. It was built with magnetic pickups in mind.

    Which leads me to the next bit of bad news, guitar amps are designed to work in a very defined frequency range. From the tone control to the speakers, they are all about midrange. They cut both highs and lows. A bass amp is actually a better bet because they usually have a tweeter to capture overtones in the high frequency ranges. My acoustic amplifier, a Carvin AG 300, is actually a repurposed bass amp. They just designed a new front end. The cab was a three way and it had a 300 watt power amp already.

    So back to your problem. First you need to deal with the impedance mismatch so you get what your mandolin pickup has to offer. The second problem is the need for a full frequency speaker cabinet. An acoustic amplifier or a small powered PA speaker is the ticket. I use an inexpensive (easy for me to say) under $200 Behringer 8" powered cab for a monitor, and it filled a good sized room in a pinch.

    So, low to high:

    Passive DI with a 1 meg ohm input impedance ( be sure of this, keys and digital drums use DIs that don't have this, so check the specks.

    Acoustic pre from less than $100 to how much you got in the bank, rich guy.

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    Registered User jefflester's Avatar
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    Default Re: Electromagnetic output from pickups

    Quote Originally Posted by Br1ck View Post
    First and foremost, what is the input impedance of the first pedal in your chain. The pickup in your mandolin is likely to be a piezo.
    A good informative post, but your assumption right of the bat is incorrect. He told us what model the mandolin is (JBovier EMC-5) and it's clearly an electric mandolin with magnetic pickups:
    Click image for larger version. 

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    Registered User John Bertotti's Avatar
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    Default Re: Electromagnetic output from pickups

    Do you have a buffer? That will certainly help with any impedance mismatch and a lot of people already have one. If one of your pedals is a boss it probably already is buffered Try it on its own then add pedals one at a time and see where the issue is, if possible leave the buffer first and if you happen to have two leave one at the end, if possible. the impression that everything has to be true bypass is phooey IMHO. I'm not going into why I think this if you are really interested you can search the net for it. I find it was a great marketing term to make some extra cash for pedal companies. Don't get me wrong I have more true bypass then I do buffered pedals but being buffered doesn't mean it is a dud of a pedal, the whole rest of the circuit has as much or more to do with that.
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    Registered User jefflester's Avatar
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    Default Re: Electromagnetic output from pickups

    What Pete and John said. Particularly John's suggestion about trying one pedal at a time, trying to pinpoint.

    As far as a clean boost for the mando vs the guitar without going out and buying one just to try. Assuming you have an overdrive pedal you could experiment with that as a clean boost, gain low and output high. On for the EMC-5, off for the Esquire to see what kind of an affect that has.

  9. #9

    Default Re: Electromagnetic output from pickups

    I don't expect a mandolin pickup to sound the same as a guitar pickup but that Bovier should have a pretty hot pickup. I had a similar complaint from a customer with his pedal chain. I had wired in a three way switch which had an out of phase setting which was wreaking havoc on the signal . I changed to a coil tapping switch and it went away. It clearly was the ground but I don't know if the issue was truly with the instrument, the pedal chain or mixing board. It worked perfectly in my shop and through several amps at a local music store. It was odd because I have used that wiring setup on 30-40 mandolins without complaint. I would look at the ground through the whole system.

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    Americana in France? Daniel Nestlerode's Avatar
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    Default Re: Electromagnetic output from pickups

    Hello all, and thanks very much for your replies!

    I thought a few photos might be helpful

    Click image for larger version. 

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    Pedal board signal going right to left.
    Boss TU-12H tuner, Mooer octave pedal, Origin Effects SlideRig (dual chain compression/amplifiers), Boss SD-1, Boss BF-3. All are getting power from the onboard power supply 9v non-discrete.
    I use the first channel of the Slide Rig to add some smoothness to the tone. Second channel is a clean boost for lead. The Octave pedal gets some time on one song in the set, and the other two are merely toys at this point. But Like I said, ALL the effects are more responsive to the Tele/Esquire than the EMC-5 (I have not experimented with the Arrow in this regard yet.)

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    Emandos: JBovier on the left Arrow G5 on the right

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    E-series Squier Telecaster currently wired as an Esquire despite the neck pick-up and an Ampeg Jet II 1x12 15w amp with tremolo.

    I use the same cables for all three instruments and generally don't change settings when I swap them. I like short tun cables whenever possible. Though I sometimes use a 20' instrument cable between the amp and pedal board when necessary.

    The Tele/Esquire is currently running D'Addario 10s and both the JBovier and the Arrow have 56, 42, 24, 16, 11 Ernie Ball Super Slinky ball end electric guitar strings.

    I don't think the Mooer is buffered.

    I wonder if taking a voltage meter to the instruments while they are being played would yeild and useful informaiton?

    Daniel
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    Registered User Tom Wright's Avatar
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    Default Re: Electromagnetic output from pickups

    My mandos with the Ryder stacked singles ate noticeably less output than a guitar. But i think the difference is twofold — the higher pitch range is not where the effects show up best, and (in my experience) emando is prone to a narrower sound, plenty of fundamental and not much in overtones, because the pitch is higher to begin with so there isn’t much “room” in the tone for interesting harmonics those effects can work on. Put another way, the waveform is probably closer to a sine wave than is the guitar’s waveform.

    That is the main reason I prefer the single coil tone for mandolin. I have one 10-string that has a Ryder side-by-side humbucker for the bridge pickup and even on a mandolin it is lacking in those high partials.

    To compare your instruments’ responses you should play notes in the same range, and with treble rolled off some on the guitar. I’m sure your pedals and cables are fine.
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    Default Re: Electromagnetic output from pickups

    One thing to remember the output of the pickup is due to the vibration of the string. The guitar has much less tension and much more vibration/wobble over the pickup than the mandolin. You may want to put the pickup on the mandolin closer to the strings than the guitar to get more signal.
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    Default Re: Electromagnetic output from pickups

    Quote Originally Posted by jefflester View Post
    A good informative post, but your assumption right of the bat is incorrect. He told us what model the mandolin is (JBovier EMC-5) and it's clearly an electric mandolin with magnetic pickups:
    Click image for larger version. 

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    Default Re: Electromagnetic output from pickups

    In the picture that's shown of your model mandolin, it appears that you have P-Bass pickups. I've used these often for mandolas and octave mandolins. There is however no firm fast rules concerning how hot they are. Typically these pickup are single-coil and provide a humbucker configuration when used in the traditional installation on a bass guitar. That said, they are almost always installed as a pair of single coils in-series RWRP on a bass and generally have a total impedance of 10 or 11K. With your three-way switch, there's little chance that your mandolin can be wired with the pickups in series when you're in the middle position so when you have both pickups selected, the total pickup impedance might be more like 2.5K. Not saying that this is the issue but it might be. I'm gonna guess that the problem mentioned is less so when you have only one pickup selected??? This would be even more likely if you have a stacked noiseless pickup on your esquire.

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    Americana in France? Daniel Nestlerode's Avatar
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    Default Re: Electromagnetic output from pickups

    Wrenchbender,
    Thanks for that. The pickups are Designed by Jeff Cowherd and called JB-53s. But they are wired as you suggest. I'll check to see if there's a difference between single coil and humbucking settings.

    Tom Wright,
    Your assessment rings true. I do actually like using the octave pedal (it can go 2 octaves in each direction) with the mandolin on a very subtle setting because it adds a bit of sparkle. So we're looking at possibly another reason someone could be designing amps and effects for emandos! (I wish someone would!)

    Thanks again ALL!
    I have some ideas to follow up now!

    Daniel

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    Default Re: Electromagnetic output from pickups

    are you plugging both instruments into an A/B like the Morley A/B/Y or the Fender clone? I've heard those can be both tone and volume killers. In other forums people suggest either a Radial switcher box or Tone Bone (2 insrument preamp) or ... swapping out the cables by hand

    You could try a clean boost on the JBovier, I like TC electronics sparks, both the 4 knob and 1 knob versoiins, the 1 knobber is around $30 on ebay or guitarcenter used.
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    Default Re: Electromagnetic output from pickups

    Just had a thought.

    As one ages, the hearing above 17kHz disappears. I think the threshold age for that is about 40. I wonder if the gear is working perfectly and I just can't hear it because the pitch range in the overtones is too high!

    That would be funny.


    Daniel

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    Default Re: Electromagnetic output from pickups

    Pardon? Speak up a bit!

    Nice idea, but I'd be surprised if a guitar amp speaker did much at 17kHz
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    gary nava; luthier GarY Nava's Avatar
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    Default Re: Electromagnetic output from pickups

    Having recently completed two electric mandolins, one with a 360mm scale and an octave version with a 546mm scale and exactly the same pick-ups, amp etc. I think that all things being equal it’s down to string length. My octave certainly had more output. The short length of the string’s vibrating arc and the current it would generate in the pick-up’s magnetic field was something that led me to use “hot” high output pick-ups on my e-mandos.
    Cheers Gary

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    Default Re: Electromagnetic output from pickups

    Quote Originally Posted by derbex View Post
    Pardon? Speak up a bit!

    Nice idea, but I'd be surprised if a guitar amp speaker did much at 17kHz
    Yep, they typically have a peak at around 2K for the old Fender Jensen speakers, between 2.5K and 3K for Celestion, dropping after 4K and gone by 6K.

    Id say the answer to the difference between guitar and emando is a second pedal or two in the chain. Signal losses are trivial and that way the settings could be appropriate to each instrument. I get fine results from guitar-optimized pedals but Im not switching back and forth.

    Any pedal that reacts to input level would act differently, for example an overdrive pedal needs the gain set much higher for the mandolin. An envelope follower also will act differently, and pitch shifters might also. Chorus and delay would not show any real difference, although the narrower frequency range of high-pitched strings through a humbucker will probably seem less chorused than the richer harmonics of a Telecaster.

    Perhaps just have an extra EQ pedal which can add signal level while thinning out the high midrange by cutting a little 800 Hz. That yields a fuller tone with less ear-rattling hard midrange. The Boss pedal has substantial gain if needed.
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    Registered User John Bertotti's Avatar
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    Default Re: Electromagnetic output from pickups

    Does anyone think a powered PA might be a better device to play the mandolin through? Honestly just curious, not trying to rile anyone up. I play my Martin000-18 with K&K through a QSC and should I ever get my A electrified I will probably use it as well. To me, it sounds good.
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    Default Re: Electromagnetic output from pickups

    Any PA would have the provision to reproduce highs, while guitar amps don't. I would think any powered speaker or speaker with provisions for highs would be much better for mandolin.
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    Registered User Tom Wright's Avatar
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    Default Re: Electromagnetic output from pickups

    Quote Originally Posted by pops1 View Post
    Any PA would have the provision to reproduce highs, while guitar amps don't. I would think any powered speaker or speaker with provisions for highs would be much better for mandolin.
    An electric mandolin with humbuckers has pretty much zip for information above 6K or so. It’s functionally an electric guitar, not an acoustic mandolin. I personally prefer woofers to guitar speakers — they have the same range, up to maybe 6K Hz, fewer coloring resonances, a bit more hi-fi in tone. (Also the only high-power small cones are woofers.)

    Given that the goal here is a good electric tone, overdriving tubes and or speakers, extended high frequency response is actually not desirable.
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    Default Re: Electromagnetic output from pickups

    Quote Originally Posted by Tom Wright View Post
    An electric mandolin with humbuckers has pretty much zip for information above 6K or so. It’s functionally an electric guitar, not an acoustic mandolin. I personally prefer woofers to guitar speakers — they have the same range, up to maybe 6K Hz, fewer coloring resonances, a bit more hi-fi in tone. (Also the only high-power small cones are woofers.)

    Given that the goal here is a good electric tone, overdriving tubes and or speakers, extended high frequency response is actually not desirable.
    I agree Tom, but I think the A he is talking about is an Oldwave oval.
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  29. #25
    Registered User Tom Wright's Avatar
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    Default Re: Electromagnetic output from pickups

    Quote Originally Posted by pops1 View Post
    I agree Tom, but I think the A he is talking about is an Oldwave oval.
    Indeed, I missed that you were responding to that. I agree, monitors are good speakers for acoustic, given you probably would benefit from some tone shaping via preamp.
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