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Double Big Twin. Move to the wings?

Discussion in 'Amps, Mics & Pickups [DB]' started by Eilif, Jul 2, 2012.

  1. Eilif

    Eilif Holding it down in K-Town. Supporting Member

    Oct 1, 2001
    I've got one of these babies on my upright, paired with a basic 2 band K&K preamp.


    I've had it for years and I've never been completely happy with it. Now that I'm playing Klesmer and Folk music, I'm even less happy with the tone and amount of string noise I get from it. I prefer the sound of a SM57 wrapped in a towel and stuffed behind the tailpiece.

    What I was wondering was, could I take the tranducers, sandwich two of them on either side of a piece of cork and stick a pair in each wing? Sort of like the pic below of a bassmax (which reportedly has less string noise), but with with a sandwich in each wing.


    I realize there may be phase issues, but if I did try this, which way should I orient each tranducer?
  2. This should actually work, to some degree.

    Per wing, you'd not want to sandwich flat side against flat side; both would have the flat side down. Otherwise you're just having the two pickups in each wing cancel each other out.

    However, I'd question whether you really need two pickups in each wing if you move to the wings. Might be better to cannibalize the pickup (cut off two of the pickup "arms", solder them to another jack for another pickup).
  3. There's one more option -- you can try an out-of-phase arrangement, where in one wing you put the flat side up, and in the other wing the flat side down.

    That trick is usually used with bridge-foot pickups, but if you're using cork no reason not to try it both ways.

    You just don't want _both_ pickups on _one_ wing to be of opposite orientation, if you choose to keep all the pickup elements.
  4. chet814


    Feb 18, 2008
    Los Angeles Area
    FWIW re Double Big Twin being not acceptable: I have mine mounted on my '61 Kay bridge running through a Markbass F1 and Markbass New York 121 (12"). The F1 head (300W @ 8ohms) is plenty powerful and versatile (dial in perfect tone via VLE/VPF controls), and the 121 is inherently boomy, which makes up for the tinny and stringy tone of the Double Big Twin, and I'm very happy with the setup. Although, this pickup setup does sound "thin" through other rigs (GK, Phil Jones, AI, etc.). So, I've concluded that one's amp/speaker pairing with this pick up matters a lot...
  5. Eilif

    Eilif Holding it down in K-Town. Supporting Member

    Oct 1, 2001
    Thanks for the advice guys. I'd stopped checking after a couple days, but I really appreciate the input and directions.

    I'll try kozmiak's ideas and see what happens.

    Chet 814. Thanks for the advice also. Unfortunately I'm stuck with my current rig, and many places I've got to go through the house anyway, so fine-control over my rig is non-existant right now. I did help my father pick out a markbass rig last year. Maybe I should head over there and call in a favor....
  6. Turning a bridge wing pickup sensor upside down does NOT change the phase! These are pressure sensors and the pressure to the sensor does not change in this case.

    Turning it upside down might change the sound of the pickup (if the sensor is not centered in the sandwich).
  7. doublehorn


    Feb 7, 2014
    Rossland, BC
    This is a pretty old thread, but I have a few thoughts about K&K Double Big Twin placement and preamp selection that might be useful, in case anyone is still interested. I'll start by saying my DBT just came in this week, but I've spent hours and hours fiddling with every possible placement on the bridge, preamp impedance matching, and blending with another piezo pickup, a little something like this:
    1. I started by placing the DBT transducers in the bone stock positions, a few millimeters down the bridge, directly under each string according to the instructions. Seemed logical enough, but the sound that produced was distant, pretty mid-rangy, and not particularly pleasant. Sounded like someone playing my bass in the bathroom next door.
    2. I tried a bunch of other placements using 4 tiny spring clamps to temporarily place the transducers on the bridge, and even the tailpiece just for kicks (that sounded awful, BTW). As a general observation, the sound seemed more pleasing the closer the transducers could be to the top edge of the bridge. In fact, the best sound came from placing two transducers on the downward facing side of the bridge between the E & A and the D & G strings as close as possible to the edge of the bridge, then the other two on the upward facing side of the bridge in the same locations. So two pairs directly facing each other on opposite sides of the bridge, kind of BP-100 style. Not at all conventional placement, but produces a very pleasing tone. The problem with this though is that two of the tiny lead wires need to be fished through the holes in the bridge and would rub against it causing some scratchy sounds. Without that problem, I probably would have gone with this placement. It was the best tone of all the placements I tried.
    3. A close second, and the final placement that I've now committed to with glue, was to place three transducers between the strings right at the top edge of the bridge with the 4th tucked out to the E side edge of the bridge as close as possible to its neighbor. See the image. This produces a nice, stringy, woody tone with lots of transient detail and bass, but very little of that distant, mid-rangy sound others have complained about.
    I'm guessing proximity to the top edge of the bridge produces good sound because it maximizes the quantity of short wavelength, higher frequency information that makes it to the transducers rather than being absorbed by the wood of the bridge. Dunno. An acoustical engineer would have a better answer for that.

    Anyway, the DBT on its own sounds pretty good set up this way, but blended in roughly equal proportion with a Gage Lifeline for some depth and deep warmth, the sound is as close to a mic as I've heard from piezo contact pickups so far. Both resist feedback very well, so far I've made it to 101dB without feeding back. I'm blending both through a 2 channel Tonebone PZ Pre set to 10Mo impedance on both channels, which really sounds quite a bit better than through the 1Mo inputs on my Clarus head. The one thing I wish the Tonebone did was to be able to flip the polarity of each channel individually. There _might_ be a subtle phase problem going on with this blending, might not. Can't quite tell, but it still sounds pretty darn good.

    All in all, I like the sound of the Lifeline and I like the sound of the DBT. Together, they're excellent.

    Attached Files:

    .:Aidan:. and Ben B like this.
  8. If you need to fiddle the cables through the bridge cuts, use foam around the cables where they go through the cuts. Same principle as with the Full Circle foam inserts.
  9. doublehorn


    Feb 7, 2014
    Rossland, BC
    Right, so several months into this pickup configuration with the Double Big Twin on the top of the bridge blended with the Gage Lifeline in the bridge adjuster position, here are my conclusions. I love this setup. It's about the best live amplified sound I've been able to produce. It's really hard to tell, but there is a very small phasing differential because of the locations of the pickups relative to the vibration source that makes them sound a touch muddy together if uncorrected. I'm blending the two pickups through a Radial Engineering JDV MKV which has a phase delay controller precisely for this kind of setup, but the amount of delay I'm introducing in the Lifeline circuit is so small that it's really only possible to hear the difference this makes through some good headphones. Live in a loud room, whether the delay circuit is on or not makes no appreciable difference, but at the very least, the JDV is a high quality preamp with 2x 10MO inputs that can be blended, and it allows me to control the blend but still only offer FOH one unified signal from the upright, so it's not a total loss.

    If I had it to do all over again on a limited budget, I'd skip the Lifeline altogether and just go with the DBT on the top of the bridge through a good quality, high impedance preamp (>10MO) with a DI out. If quick setup and teardown is a mission parameter for a gig, this is exactly what I do and it also sounds very good. FWIW.
    .:Aidan:. likes this.
  10. doublehorn


    Feb 7, 2014
    Rossland, BC
    OK, on the off chance anyone is still watching this thread, here's a little update that I feel is worth sharing. I've had a chance to fiddle with the Radial JDV a little bit and have settled on some settings that really work well for live sound, even stupid loud. Here's the complete setup:
    1. Cheap Chinese plywood bass, regular adjustable maple bridge
    2. K&K Double Big Twin glued in the slightly unconventional manner documented above
    3. Gage Lifeline in the E side bridge foot, traditional placement
    4. Radial Engineering JDV with phase control circuit <-- this is the key!
      • A & B inputs blended, obviously
      • DBT -> B input, 10 MΩ impedance setting, level @ max, HPF @ 11:00ish
      • Lifeline -> A input, 10MΩ impedance setting, level @ 2:00ish, HPF hard over on 5Hz
      • Phaser circuit engaged and rolled to 12:00, phase switch @ 0*

    I've tried a bunch of variations, but the above is definitely the sweet spot. Crystal clear live sound with all the rich caramel lows of the Lifeline @ full frequency spectrum, blended with some nice string detail and woody mids from the DBT high passed as described above, probably 80Hz if I had to guess. **The key element in all this is the phase control circuit on the JDV, which aligns the phases of the two pickups, exactly as advertised.

    Without proper phase alignment, the sound is thin, honky and quite unpleasant. To test this phase alignment hypothesis, I also ran the same two pickups blended into a Radial Tonebone PZ Pre that I know makes every other instrument sparkle, and it sounded like absolute garbage when that preamp normally produces lovely tone in everything it touches. Also ran the JDV with the phase circuit off and that too sounds pretty bad. Turn on the phase circuit and bam, as if by magic, all the electronics disappear and you're suddenly just hearing the natural sound of the bass at amplified volumes. In fact, when I finally nailed the settings, I thought something had gone wrong with the gear until I realized it was just playing my bass back to me verbatim. All this works exceedingly well at very, very loud performance volumes. Loud enough to vibrate the E and the A strings on their own if I don't hold them during bars of rest. It really simplifies monitoring when the sound is nice and clear like this. No more wondering about intonation.

    Some would, uncharitably, call the money I've spent on this setup foolish and they might well be right. Pickups and JDV are approaching C$1000 with taxes, but if you care about your live sound, maybe you'll see the value in all this. I don't know any double bass players who are unconditionally thrilled with their amplified sound. Most seem resigned to just live with whatever amplification system they have and overcome bad tone with sheer musicianship. It's no secret that double bass is really hard to amplify live, but this the closest thing to perfect that I've seen.

    FWIW - DG.
  11. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator

    Oct 19, 2000
    Louisville, KY
    The JDV is a really interesting looking device. Can you explain what the "Drag" control does? Is it sweepable variable impedance?

  12. My guess is that's the phase control adjustment pot.
  13. I rather think the phase control is the right one called "phaser" going from zero to 180 degrees.
  14. bassfran


    Mar 1, 2012
    Endorsing artist: Lakland basses
    From their web site product description;

    The design begins with 100% discrete electronics and a unique class-A circuit with zero phase-cancelling negative feedback front-end. This is augmented with Drag™ control load correction that lets you optimize the impedance that is being applied to the pickup along with extra rail voltage for an abundance of headroom. The result is virtually zero harmonic, phase and cross-point distortion resulting in the most natural rendering without coloration or artifact of any type.
  15. LOL! I really look stupid now! It was so obvious!
    I made your day I guess!
  16. doublehorn


    Feb 7, 2014
    Rossland, BC
    Ya dudes, I'm probably not the best guy to ask about the variable drag circuit. I did fiddle with it using a few basses out of curiosity, specifically an old passive Jazz, an 18V active Ibanez, my piezo upright of course and even a K&K bridge plate passive pickup in an acoustic bass guitar and I found that it didn't do much in the in between settings of the sweep. The active instruments sounded the same everywhere within the sweep and the passive & piezo instruments all liked the 10MΩ better than anything in the range of the drag sweep. Dunno. The magic is in the phase circuit which is definitely the pot on the far right.

    There are a couple (inconsequential) design decisions that baffle me about the JDV though. Like the big radiused handle on the top. Not sure what that's for. Maybe for attaching to your fist in case of an unscheduled bar fight. And the assembly of cords and transformers required to power this unit is also quite clumsy, although the power cord clicks satisfyingly into the JDV like an XLR and won't budge at all during a show, so that's good I guess. There is a mic input that can be supplied with phantom power, I suppose for those dual pickup systems that have a little bullet mic, but it's 1/4" instead of XLR, so I guess you'd need a special adapter for that? Not sure.

    Aside from those puzzling things, the JDV does exactly what I wanted it to and produces results that are so much better than I had expected. This is a pretty specialized topic, but I hope this information helps someone out there.
    Chris Fitzgerald likes this.
  17. doublehorn


    Feb 7, 2014
    Rossland, BC
    Here's an interesting and useful update for anyone who might still be watching this thread, especially you Chris Fitz. My little AI Ten2Ex / Clarus head combo, while wonderful to schlep around, has been struggling with louder stage volumes a little bit, so I've acquired a Barefaced Two10, which definitely has more punch down low at the higher SPL. It's also voiced quite a bit darker than the AI 2x10, enough so that my JDV trick outlined above was sounding a bit muddy through the JDV > Clarus head > Barefaced 2x10. I also wanted more amplification power and fewer preamp sections in the signal chain, so I've now swapped out the entire rig so it looks like this:
    • Same bass, same pickups (**I'm only using the Gage Lifeline now, see below)
    • JDV (with drag circuit, which I'm now using Chris), connected via the balanced XLR out to....
    • Crown XLS1000, unadorned 1100W power amp, no preamp section at all
    • Barefaced Two10
    **Here's where it gets interesting: the JDV is now the only preamp in the signal chain, no more Clarus with 1MΩ inputs, just the Crown power amp. I've recently become interested in the topic of pickup loading and input impedance. Interested enough to experiment with the drag circuit on the JDV, and it turns out the input impedance witnessed by the passive piezo pickups makes a huge difference to the tones that come out at the speaker. Conventional wisdom says that a passive piezo should go into the highest possible impedance input, but I'm finding the 10MΩ piezo booster on the JDV makes the Lifeline sound pretty tubby and dark, which seems to be its nature, but is manageable with some EQ intervention. Buuuut, with the piezo booster off and Drag Circuit engaged, the Lifeline sheds all of that dark, tubby character and takes on a lovely, organic and woody timbre that is quite pleasant and very lifelike. Radial says the range of the Drag Circuit is 22kΩ - 500kΩ, but for the signal chain I have in place, the sweet spot is with the Drag about a quarter turn from the bottom. Hard to say what that impedance figure is exactly, but maybe 100kΩ? With the +20dB JDV output line booster engaged, this makes the Lifeline produce a strong, balanced, woody sound with none of the brittle finger and string noise, none of the dark, boomy thwacky attack sounds, just a lovely, musical mid range with some authentic growl that I didn't know the Lifeline was even capable of producing, and just enough bottom to sit below the mix and just a touch of string noise. This is totally contrary to everything I've read about the input impedance passive piezo pickups like. It's worth noting that this only works with this specific signal chain. If I plunk the AI Clarus back in with the 1MΩ mic inputs behind the JDV, all that dark tubbiness returns. I'm sure someone out there knows why that is.

    Anyway, the significant information in this update is about changing the input impedance seen by a passive piezo pickup using the Drag circuit on the JDV in a way that shouldn't work on paper, but it does. Makes the Lifeline sound fabulous. FWIW.
  18. The sound of a bridge pickup has too much laws compared to the acoustically radiated sound of a DB. A high input impedance passes these intense lows as vibration ally present at the pickup position. Turning down the bass EQ helps to get rid of them.
    A lower input impedance does more or less the same, but the amount depends on the amplitude. A higher amplitude will deform the electrical output waveform, also called distortion.
    So if you dial in your sound with low to medium volume it might not work well with higher volume (besides that the higher volume delivers too intense bass frequencies again and needs a further reduced bass EQ again).
    A high input impedance delivers the signal up distorted, but it might not be the signal you would like to hear unchanged out of the speaker.

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