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Fdeck and GB Shuttle 3.0

Discussion in 'Amps, Mics & Pickups [DB]' started by BrandonL, Jan 13, 2020.

  1. BrandonL

    BrandonL Supporting Member

    Sep 20, 2018
    Boise, ID
    As an amplification neophyte I have an HPF question. The background is that I'll soon get my hands on a GB Shuttle 3.0 combo (for DB with Realist copper p/u). From what I can tell, an HPF like the Fdeck is commonly used by folks for this set-up. Impedance for the amp is 500 K-Ohm I think.

    My questions are:
    - do I have this right so far (about the fdeck rec)?
    - if so, should the HPF plug in before the amp input or as an "effects loop?" (see pic), or does it not matter?

    Feel free to educate me on anything else I might be missing here...

    GB shuttle .png
  2. Ric Vice

    Ric Vice Supporting Member

    Jul 2, 2005
    Olivette, Missouri
    If you don't plug the FDeck into the front end of the amplifier, so that it's Pickup>FDeck>and Genz Benz. You will not get the 10 Meg Ohm load that the FDeck HPF/Buffer Preamp provides. 500 K is to low for piezo pickups.

    So, you will only get the 500K that the preamp section of the Genz Benz provides. You will still be able to use it as a Hight Pass Filter and Phase Reverse. You could plug into the HPF in the effects loop you'll likely be past

    the EQ section.
    Zbysek, BrandonL and Wasnex like this.
  3. bherman

    bherman Supporting Member

    Apr 30, 2009
    Grand Junction, CO
    easiest way to do it (and most effective in my experience) is plug your bass into the fdeck, than the fedeck into the amp. You can just sit it on top of the amp if you like, and use a short cable to connect it to the amp. Easiest way is to use 9v batteries, unless you have a 9v power adapter and don't mind having something else to plug into.
  4. BrandonL

    BrandonL Supporting Member

    Sep 20, 2018
    Boise, ID
    Got it. So:
    Pick-up > FDeck > amp

    Thanks ya'll!
  5. Ric Vice

    Ric Vice Supporting Member

    Jul 2, 2005
    Olivette, Missouri
  6. JeffKissell

    JeffKissell Supporting Member

    Nov 21, 2004
    Soquel, CA
    Don't be afraid to try the FDeck in the effects loop though... when I had a GB Shuttle 6, one of my piezo pickups (APTflex) sounded best straight into the amp with the FDeck in the effects loop. FWIW, all of the bridge wing style pickups wanted the FDeck in line before the amp.
    The final proof is if it sounds how YOU want it to.
    Dr. Love and BrandonL like this.
  7. Dr. Love

    Dr. Love Supporting Member

    Nov 5, 2008
    Lubbock, TX
    You can try both ways, but I'm willing to bet one will sound much better and it will be immediately apparent. I personally run: bass, fdeck, tuner pedal, then to the amp/di/pa/whatever else is making it loud.
    Zbysek likes this.
  8. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    To followup on Jeff's comment: Piezo pickups are affected by the load impedance and the difference between say 500K, 1M, 5M and 10M can be quite audible with most pickups. Usually the higher the input impedance the more lows and less highs. Depending on the bass, the pickup and your personal taste, the ideal impedance for you might be different than for someone else.

    Just the other day I was using a borrowed Demeter amp with 1M input impedance at a rehearsal. I tried it with and without my fDeck (10M), just to hear the difference. At first, I thought straight into the amp sounded really good (all tube preamp, nice)...then I plugged the fDeck in and the heft increased dramatically, not something that could be compensated for with the amp EQ. However it wasn't that the Demeter by itself sounded bad. I've also had this experience with GK amps...1M input impedance plus a high mid EQ band that sits right where you want it to control the nasal aspect of most pickups makes them very DB friendly, but adding the fDeck still gives more heft to the sound.

    There are a few boxes out there that allow the user to dial in the input impedance to your taste if you're anal enough about your sound. My personal experience is that anything between 1M and 10M works well for me,
    Zbysek and Ric Vice like this.
  9. Zbysek


    Mar 23, 2017
    Czech Republic
  10. Zbysek


    Mar 23, 2017
    Czech Republic
    That's a great choice, IMHO. I use GB Shuttle for my (electric) upright. It works great!
  11. basss

    basss Supporting Member

    Aug 27, 2001
    I didn't find a buffering preamp to make much of a difference with the shuttle. My piezos sound good straight into the amp.
    powerbass likes this.
  12. Ric Vice

    Ric Vice Supporting Member

    Jul 2, 2005
    Olivette, Missouri
    Weirdly enough using the Headway EDB-2 the 5 Meg Ohm setting sounds better with the Realist, Upton Rev Solo, Planet Wing, and even the Ehrlund EAP.
  13. powerbass


    Nov 2, 2006
    western MA
    I agree, I have the Fdeck Pre but like straight into the 3.0
  14. Ric Vice

    Ric Vice Supporting Member

    Jul 2, 2005
    Olivette, Missouri
    Thing is the Shuttle’s have FET’s in the
    Preamp which warm up the sound. I had the same issues with the FDeck and my Walter Woods amps the HPF works just fine but the Woods actually sounded better plugging directly into the Channel input.
  15. BrandonL

    BrandonL Supporting Member

    Sep 20, 2018
    Boise, ID
    What is this FET you speak of??
  16. Ric Vice

    Ric Vice Supporting Member

    Jul 2, 2005
    Olivette, Missouri
    Feild Effect Transistors, Headway uses them, so did Walter Woods, and Grace Designs.
  17. The field effect transistor has a very high input impedance (the impedance is so high that a resistor is needed to lower it to the useful value for a certain application) so very few electrons need to go in and out which is good for piezos. It is mainly a current amplifier (same voltage but more electrons can be delivered to the next stage.

    Bipolar transistors have a lot lower input impedance and won’t work well directly connected to a piezo.

    There are also OpAmps with a FET input stage like the one in the HPFpre version 3. They are also commonly used in mixing consoles.

    Also an FET is more similar to a tube than to a bipolar transistor.

    The highest input impedances have MOS-FETs. But they are very sensitive to static electricity and can be damaged just by touching the gate connector (more modern ones have some safety built-in).
    Povl Carstensen and Ric Vice like this.

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