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Feedback question

Discussion in 'Amps, Mics & Pickups [DB]' started by bigmags14, Mar 4, 2016.


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  1. bigmags14

    bigmags14

    Jul 22, 2014
    Hey guys, I play jazz upright bass in a 18 piece big band at school. I have a plywood bass, an upton bass rev solo pickup, and a markbass players school amp. The pickup is basically a piece of wood that fits in the bridge wing. Yesterday on the wooden stage, I was getting horrible feedback even if I was 6 to 8 feet in front of the amp. I turned the gain down and everything and it just wouldn't stop. I took it to a practice room on a tile floor and it was fine and sounded great. I could be right next to it and no feedback. I need to figure this out, I know there are other posts on feedback but what is it about a stage that could make it do that?
     
  2. sevenyearsdown

    sevenyearsdown Supporting Member

    Jan 29, 2008
    Sanborn, NY
    Try getting the amp up off the floor.
     
    old spice likes this.
  3. samson3382

    samson3382

    Apr 26, 2009
    Boise, Idaho
    A preamp with a phase reverse might be useful. I have the fishman platinum pro bass EQ.
     
    old spice likes this.
  4. bigmags14

    bigmags14

    Jul 22, 2014
    I put it on a chair and it is much quieter and I lost a lot of the low end
     
  5. Decoupling the bass itself from the floor could be an alternative.
    Put the endpin back in and place the bass on a big cushion or pillow for instance? :)
     
  6. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC

    Apr 17, 2004
    Yes! In addition to the other techniques advised to provide isolation, a pre-amp with polarity inversion and a high-pass filter (HPF) is one of the best tools you can have in your bass-amplification arsenal. The wisest money you can spend in that regard would be on one of these. I recommend the Series 2.
     
  7. I don't know in which bridge wing you have your pickup, the bass side gives a lot more fundamental than the treble side.

    But the most important point is where is the cab output directed to? It should not directly blow to back of top. It might help if you are an isolation between cab and bass, so pug it on the right side behind you, put it on a chair and if possible angled upwards. Direct the cab to the ribs of the bass or to the front if you position it more to the right.

    If you are not very experienced with double bass amplification, the bridge mounted pickups deliver much stronger low frequencies than the bass radiates acoustically, so it is common practice (for experienced players) to turn down the bass EQ for a more natural sound.
    If you want that much low energy, better take a bass guitar.

    Anyway, high energy low frequencies make a sound muddy, some music styles call for that,but not a big band.
     
    drurb likes this.
  8. B String

    B String Supporting Member

    Apr 11, 2002
    Los Angeles
    I don't mean to give conflicting info, but most wing pickups (Underwood, BP - 100, Shadow, FullCircle, etc) actually give more highs and mids, although it helps to have a 10meg ohm buffer pre. I've also had luthiers tell me that a good upright bass will naturally put out fairly low frequencies. (mid forties) Why not try amplify the full range of the bass. Also, I wouldn't try to push a big band with a single 8 or 10in speaker. (That's just me)
    I would ask.... What kind of Markbass amp is the OP using? Has it got a 15in speaker, or something smaller? Where are the tone controls set? Also...The Rev solo pickup is VERY picky about how it sits in the wing in relation to tone.
     
  9. bigmags14

    bigmags14

    Jul 22, 2014
    I am using the Markbass CMD JB players school combo amp.It has a single 15 inch speaker. My eq on the amp is flat, i raise the VLE filter to about 9 o clock and the VPF filter to about 8 o'clock usually. Gain usually around 10 or 11 o'clock and then master volume wherever i need it depending on where I'm playing. On the stage usually around 1 o'clock. I also have a little piece of balsa wood under the pickup so it fits better, if that changes anything.
     
  10. B String

    B String Supporting Member

    Apr 11, 2002
    Los Angeles
    15"s can be tricky with upright basses. See what happens if you move the pickup around a little.
     
    Mike Law likes this.
  11. A 15" can indeed be problematic, specially without a high pass filter, so you might want to get an HPFpre for that.
    I hate to play through a Markbass amp because of the VLE and VPF filters. They can kill the sound if set wrongly. I think somebody posted working settings for these filters somewhere here on Talkbass. Use the search function and read through the results.

    You need a second player or at least someone with a trained ear. Play acoustically and with the amp, let the 2nd person explain how the sound differs, change the EQ and try again until the amlified and acoustic sound are similar. If you have a second player change positions and listen, give the second player instructions what to change and how much. If you are satisfied don't forget to write down your settings. That can easily take an hour and you might want some rest for your ears in between.
     
  12. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC

    Apr 17, 2004
    Let's restrict this to the Rev Solo. Like many other bridge-wing pickups, the Rev Solo will happily transduce infrasonics. I began a long discussion of their effects here years ago. It's the primary reason to employ a HPF.

    Well, okay, but I've pushed one with a single Wizzy 12" especially when using the Ehrlund EAP because it transduces so well the temporal attack/decay. That's another story, though. IMO, a DB amplified with a big rig in a big band is a bit of sonic heresy.:) Remember all of our "ancestors" who pushed big bands with no amplification. The Rev Solo is finicky about proper placement. There is, however, a sweet spot. Once you find it, you mark it and that's it. I found that it's almost binary. You either have it right or you don't.

    That's not because they are 15"s, per se. Rather it's a function of how many cabs with 15"s are voiced. The diameter doesn't determine the tonal balance.

    Nice, but as I'm sure you'll agree, the sound that you want when the band starts up may not be the one that most closely matches the acoustic character of the bass when played in the quiet. Most of us make adjustments (e.g., a bit of a boost in the upper midrange and highs) so that the bass cuts through the "mix."

    I agree about those type of gimmicky tone-shaping filters. If the entire rig can't be replaced, then best to hang a pre-amp with good tone-shaping options at the input. Seems that there is sufficient tone-shaping on the Markbass besides the two "filters." I suggest that you simply don't use those.
     
    Last edited: Mar 5, 2016
    Povl Carstensen likes this.
  13. bigmags14

    bigmags14

    Jul 22, 2014
    So is the hpf pre a certain brand? I found a website online for them and it looks like there is only an email address to buy them. I sent him An email. Any other recommendations for a preamp?
     
    Last edited: Mar 5, 2016
  14. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC

    Apr 17, 2004
    If you don't need a pre-amp with tone controls, then this is the place to go. Francis Deck is one of us and he builds the devices on the side. We all call it the Fdeck HPF/pre. :) Francis will get back to you. Just order a Series 2 via the web order form. You'll be happy you did! Now, after you place the order, you can search the threads here and find out why so many here swear by the Fdeck HPF/pre.
     
  15. Eric Hochberg

    Eric Hochberg

    Jul 7, 2004
    Chicago
    Drurb already posted this HPF-Pre, updated Sept. 30, 2014 - hpftechllc
     
  16. This was not meant off a final sound but to come closer to a double bass sound than a bass guitar sound. If it doesn't cut through, you need to change that, but then you have a better starting point than a heavy bass bass guitar-like sound.
    And with two people investing time to find things out there is a better learning effect.

    BTW, probably not the OPs amp but the MiniMark only has volume, VPF and VLE. I once needed to use one in a session with a different instrument and had no idea how to change the sound for the better. And the second thing is, what is neutral, if you don't know the neutral setting, there are more knobs with unknown functions to fight with. Might be OK if you own one, but not if you need to use other peoples Markbass amps.
     
  17. B String

    B String Supporting Member

    Apr 11, 2002
    Los Angeles
     
  18. Feeds back on wooden stage. Does not on tiled floor. Sounds like energy feeding back through the end pin.

    Try a piece of rubber / flat tennis ball / etc. under the end pin. Even trying a different spot on the stage could make a big difference.

    Plus what ^they^ all said.... of course.

    Steve
     
  19. bigmags14

    bigmags14

    Jul 22, 2014
    so a little update:

    I appreciate all the responses and I gained a lot of great info. My problems seems to now be my pickup, I was getting Barely any sound out of it this morning. I was turned like almost all the way up and it was just so much softer than it should have been. So I ended up driving to upton bass (they make the rev solo) because I live nearby and they tried refurbishing it but no matter what they couldn't get a good sound out of it and they even tried multiple rev solos. When he pressed down on it it would be loud but then it would be really soft. I ended up just buying a realist pickup to put on there because I had a gig and that's where I'm at now. He even did some work to my bridge because my adjusters were all the way down and it was pitched backwards a little I guess. So I wasn't having any feedback problems with this new pickup and I like it so far...
     
    Mike Law likes this.
  20. bigmags14

    bigmags14

    Jul 22, 2014
    I do have a rubber piece screwed on to the end pin threads, maybe it could have been where I was standing
     

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