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Thread: Preamp Question

  1. #1
    Bob Ayers Ranger Bob's Avatar
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    Default Preamp Question

    I’m looking for a preamp that will work with more than one type of pickup. My guitar has an LR Baggs Element active. Mandolin has a Barbera saddle transducer, passive. And I have a Myers microphone pickup to use for my octave (Feather). Any suggestions? Thanks

  2. #2

    Default Re: Preamp Question

    Hi Bob,

    Sounds like you need a pre-amp with sufficient headroom and boost to cover your passive and active options.

    We've tried working out a workflow during the lockdown period. For recording, the noise signal can be troubling. The Audient series preamp for recording work fluidly without colouring too much. I'm got a clip somewhere using it although I've only taken up the mandocello during lockdown and not sure I'm enjoying it as much as I thought!

    Otherwise if you're looking for a preamp to perform, the Art Tube MP series are incredible value and offer that huge headroom and phantom if you need it. They ae not so portable and require mains power. It does have a proper XLR connection. For plug and play portability, the Fishman Platinum series pre-amp is quick to assemble and easier to use across all your equipment.

    Kind regards

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    Default Re: Preamp Question

    Im a neophyte when it comes to amplification, but Ive used the LR Baggs Venue DI with good results on guitar (LR Baggs M1) and mando (Rigel CT-110 with internal piezo, not sure of the brand). New the Venue is around 300. They do make more basic models but Ive not played them. Red Eye and Fishman typically get good reviews on here as well. Well get kinda loud from time to time in our praise band (with drums, keys, electric guitar), but certainly not bar or concert loud, FWIW. Others with way more experience than myself will chime in

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  6. #4
    Bob Ayers Ranger Bob's Avatar
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    Default Re: Preamp Question

    Yeah. I saw a Baggs Venue this morning in the Cafe' classified. Was going to snap it up when I finished golf which of course was too late. I snoozed. I losed.

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    coprolite mandroid's Avatar
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    Question Re: Preamp Question

    Do You Understand the Impedance matching requirements of various sources the preamp must synchronize with ?
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    Bob Ayers Ranger Bob's Avatar
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    Default Re: Preamp Question

    Probably not. I guess that's why I asked the question.

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    coprolite mandroid's Avatar
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    Default Re: Preamp Question

    Read up on the manuals of your various pickups .. I can't do that for you.

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  10. #8
    Bob Ayers Ranger Bob's Avatar
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    Default Re: Preamp Question

    Don't really recall asking you to do anything......especially for me. Oh, and they were listed.

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    Registered User Tom Wright's Avatar
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    Default Re: Preamp Question

    The impedance issue is overblown in my experience. In the 70s we plugged our Barcus-Berry violin pickups straight into the Twin Reverb. The feared "quack" is mainly the pickup reproducing what the violin or mandolin can't acoustically, which is the low treble/upper midrange. This band is not reproduced by the top plate, so when it is strong from a pickup it sounds unnatural (because it is).

    The main difference from impedance matching will be overall high/low balance, with richer low end in a proper very-high impedance input. But for natural tone the challenge is in the midrange. No contact pickup is a microphone--that is, it doesn't naturally reproduce the sound heard through the air.

    Under-saddle pickups are typically too strong in the 1000 Hz range, snd benefit from a large, narrow cut there. To get the Gibson F5 sound you want a boost around 250-300 Hz.

    For contact with the top, like K$K, similar midrange shaping is needed, with possibly a bit of treble boost (~3K) along with likely a cut at about 600 Hz.

    Mainly, expect to apply substantial tone shaping for a pickup, in any amp.
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  15. #11

    Default Re: Preamp Question

    I guess we didn't get a complete "use case" description from the OP, but is the assumption that this is a live situation? It seems like the chance of anybody coming up with a single preamp with even 2, let alone 3, separate inputs, i.e., designed for different instruments, and not a mic+pickup, is unlikely, unless it's part of an acoustic amp/pa, and even then, more than two is unlikely, so then you'd be looking at, what, an A/B box (or A/B/C?) in front of a preamp? Then, if you don't want to be fiddling with tiny knobs when you switch instruments, you'd need a preamp that supports presets - something I honestly am surprised I couldn't find - at least with EQ settings, though here we'd probably like a preamp that has impedance, and EQ/feedback controls in the presets, too

    Maybe a product will come along, but it seems like a pretty small niche has been carved out, when a small pedal board with dedicated pres feeding into that A/B/C switch is going to be where I'd go.
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    coprolite mandroid's Avatar
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    Default Re: Preamp Question

    lots of Piezo pickups have megaohm impedances , the nature of that signal source ..

    magnetic ones and the output of onboard preamps (your 9v battery powered ones) is much lower..
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  17. #13
    Registered User Mandobart's Avatar
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    Default Re: Preamp Question

    Quote Originally Posted by Tom Wright View Post
    The impedance issue is overblown in my experience. In the 70s we plugged our Barcus-Berry violin pickups straight into the Twin Reverb. The feared "quack" is mainly the pickup reproducing what the violin or mandolin can't acoustically, which is the low treble/upper midrange. This band is not reproduced by the top plate, so when it is strong from a pickup it sounds unnatural (because it is).

    The main difference from impedance matching will be overall high/low balance, with richer low end in a proper very-high impedance input. But for natural tone the challenge is in the midrange. No contact pickup is a microphone--that is, it doesn't naturally reproduce the sound heard through the air.

    Under-saddle pickups are typically too strong in the 1000 Hz range, snd benefit from a large, narrow cut there. To get the Gibson F5 sound you want a boost around 250-300 Hz.
    Not entirely accurate. I spent several years active duty in the USN as an electronics technician. I had lots of training on and experience with radar, radio and reactor plant control systems.

    Years later I studied system dynamics as part of my BSME from the University of Washington. There is an irrefutable fact that whenever an unmatched interface occurs in any system, there is loss and distortion when transferring energy across that interface. The high impedance is inherent to piezoelectric pickups. A preamp does way more than boost a signal. It is there primarily for impedance matching. Some preamps (RedEye for example) actually attenuate the signal from the pickup.

    A matched impedance at the instrument pickup to amplifying device interface is required regardless of the type or brand of pickup used. Most of us are more influenced by the marketing from various mfrs trying to tell you their product is better, than by their technical people trying to tell you how it really works. But most readers/players are non-technical lay people and more interested in and influenced by marketing than by boring technical facts.

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  19. #14
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    Default Re: Preamp Question

    Bart is right, I never understood the term 'pre amp' for an impedance matching device.
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    Default Re: Preamp Question

    Quote Originally Posted by pops1 View Post
    Bart is right, I never understood the term 'pre amp' for an impedance matching device.
    That’s also probably down to marketing guff. Who wants to buy an “impedance matching device”? Also, most of them do more than match impedance. They vary the levels - so they are an amplifier of sorts - and they include equalisation (tone controls).

    The only true piezo impedance matching device I remember came as an add on to the pickups produced by Barcus Berry back in the 1970s. They were sold as a pre-amp. Anxious to find out what was in one, I borrowed one from a local music shop overnight and carefully opened it. It contained little more than a battery and a single field effect transistor - effectively a FET buffer.

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