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Fearful 12/6 "farting" issues.. driving me mad

Discussion in 'Amps and Cabs [BG]' started by mrmakas, May 16, 2018 at 5:10 PM.


  1. popgadget

    popgadget Supporting Member Commercial User

    Sep 4, 2005
    Eastern, PA USA
    Authorized Greenboy Designs Builder, Scabbey Road
    How much clearance do you have between the grill and the woofer?
    The woofers have more excursion that you might think and make ugly noises when they hit the grill. Try it with the grill removed to eliminate that as a possible cause.
     
  2. Nickweissmusic

    Nickweissmusic Knows all intervals from one Fred, to Juan octave Commercial User

    Jan 26, 2014
    San Diego, CA
    I teach lessons and perform live music in and around San Diego CA. Sometimes I even make money doing it!
    And yes, it could also be a sealing issue, although don’t use pl glue around the speaker itself, unless you like unnecessary ugly messes, that is. There are gaskets and tapes for that. Speaking of tape, I have to tape over the unused jacks on my beloved bag end, or they whistle from the air movement!

    I still think the problem is expecting more thump than the cab can deliver.
     
    Last edited: May 17, 2018 at 2:11 PM
  3. Lonnybass

    Lonnybass Supporting Member

    Jul 19, 2000
    San Diego
    Endorsing Artist: Pedulla Basses
    The majority of distorting is the result of something loose in the crossover or wiring. Anything not zip tied, hot glued and stapled down is going to result in some nasty distortion sounds coming through the drivers, in particular the mid.

    Do not underestimate the amount of over-engineering that needs to go into the electrical joints and cabling integrity. These cabinets can move massive amounts of air but can also shake looks all but the most secure connections.
     
    Matthijs likes this.
  4. briandavismurph

    briandavismurph

    Jul 1, 2013
    I am following this thread out of interest for my own recently acquired empty Bag End S12. I am planting a Kappa 3012LF in it next week and hoping for a good stack pairing with my 35 year old Bag End S15 with Bag End OEM woofer powering it with GK MB500.
     
    BadExample likes this.
  5. I can only express my feeling about bag end cabs in Tagalog: Ito ang masarap!
     
    Nickweissmusic and spankdaplank like this.
  6. briandavismurph

    briandavismurph

    Jul 1, 2013
    sorry I do not speak your language
     
    BadExample likes this.
  7. briandavismurph

    briandavismurph

    Jul 1, 2013
    actually I speak too soon, Google Translator says "It's Delicious" I suppose that makes some sense.
     
    BadExample likes this.
  8. That's pretty close!

    It can also describe a feeling as much as a flavor or taste.

    Pinakamasrap!
     
    ctmullins likes this.
  9. somebrains

    somebrains

    Feb 7, 2017
    ang mga pangit na babae ay humahagap ng malakas
     
    spankdaplank likes this.
  10. chris_b

    chris_b

    Jun 2, 2007
    That's just showing off!
     
    mmbongo likes this.
  11. GMC

    GMC

    Jan 1, 2006
    Walmer
    Well...your Eminence driver is one of the most common modern 12" currently used for bass. It's unlikely to be that driver unless you are spanking it with a silly amount of wattage. It's not a high powered PA speaker, it's a 450w RMS. Have you tried the mid driver on it's own? I'm wondering if it's blown? The Eminence Alpha 6 is only a 100w driver and the tweeter handles even less wattage.

    I'm kind of wondering what your SPL intentions are? The 3012LF should be good for about 121db @ 450w with an f3 of around 50hz (very good). With a pair of them 127db at 900w is achievable. But it's not a 2kw high power, low sensitivity PA driver. The 3012LF can usually do more with 100w than many PA speakers can do with 600w.

    The Alpha 6 mid driver is only good for about 114 db. So while it's a full range audio cab, it's not a full range cab in terms of it's SPL across the frequency range. The tweeter (looks like an APT80) is good for 118db @35w. So it's in the ball park of the bass 12" driver. I'm just not so sure the mid driver can keep up with the rest of the cab.

    I've often looked at the Greenboy three way designs with curiosity. The Tweeter choice has quite a high starting frequency, I've often wondered if this is why it's a three way design. There are better tweeters out there that start at a much lower frequency and could make a better 2 ways design. Ciesta make a 200w tweeter that sounds better and could work in a 1K cross over. A 2 way design would be lighter (less drivers and a less complicated cross over) but a lot of the audio detail is being handed to tweeter...so a really clear and quality unit is required.
     
  12. Sparkl

    Sparkl

    Apr 23, 2011
    Europe
    I am reading this topic and I find it hard to believe some people justifying the farting sound to be a part of a cabs character.

    Without “fart” pedals or tube amps or preamp gain knobs cranked all the way up this is not what classifies as a clean sound let alone on a cab the likes of fearful/fearless which is supposed to be voiced relatively flat and uses powerful speakers.

    It could be the crossover, do double check if you got all the wiring right and inspect if you actually didn’t happen to come across a disfunctional crossover. Next step would be to check for any leaks.

    I am not a technician myself but have visited many shops who deal in cab repairs and they mostly tend to check the cabs through a frequency generator to isolate frequencies and deal with them hertz by hertz.
     
    Spacecase likes this.
  13. DukeLeJeune

    DukeLeJeune rational romantic mystic cynical idealist Supporting Member Commercial User

    Nov 24, 2008
    Princeton, Texas
    Owner & designer, AudioKinesis; Auth. mfg, Big E (Home Audio only)
    You gotta seal the mid-chamber airtight, and that includes the hole that the wire passes through. The woofer can pump the mid if you don't. As Passinwind (resident fartout expert) said, even a small leak can have big audible consequences.

    Also a mistake in the crossover construction could be allowing low-frequency energy to get through to the mid.
     
    blip, Arjank, monsterthompson and 4 others like this.
  14. ficelles

    ficelles

    Feb 28, 2010
    Devon, England
    That isn't "underpowering". That is driving the amp too hard, causing it to distort. If the cab itself were distorting, it would distort more with a higher powered amp.
     
  15. jnewmark

    jnewmark Just wanna play the groove. Supporting Member

    Aug 31, 2006
    Stax 1966
    Play guitar.
    Yeah, and since he farted out a 15/6, BEFORE he had the 12/6/1, I think he's asking too much from a 350 watt amp.
     
    carl h., Passinwind, Jim Carr and 3 others like this.
  16. 10cc

    10cc

    Oct 28, 2013
    Pushing the amp too hard. It was barely on. Amp was set flat, gain was at eleven and master at ten o'clock.
     
  17. Wow! Thanks for all the input every one!

    This is my plan of action:

    1. Remove drivers and all hardware
    2. (re-)Seal all corners just to be sure and reattach hardware and cables whilst sealing and attaching them to walls. (i realised my cables alone might be causing the havoc flopping agains the chasis. I have build cabs before, but this time somehow was in hurry to test the mid, so this probably the cause)
    3. Test it.
    4. If the problem remains i will take the crossover under proper inspection and test it without the woofer with a sig gen. I built it myself (point to point on a piece of super thin plywood) but the parts were from a kit supplied here in Finland specifically for the Fearful 12/6. I also inspected the values of the cross over and they matched the diagram.

    Other thoughts on the matter:

    Could mid driver polarity cause this? I would expect comb filtering etc but not this. :)

    @GMC I was wondering about the max SPL of the alphalite6 as well, but i figured that Greenboy most likely did his job rather well when designing it :) I guess (or rather hope :p ) there just isn't that much mid material coming from a bass so the 114db would suffice?

    The farting jokes do crack me up :roflmao: honorable mention to @Passinwind on this one :D:bassist:


    Thank you all so much! i will keep you posted. Unfortunately this thing called work keeps me from the more important things in life such as building this cab tonight, but tomorrow i will most def be doing those 4 steps.

    :cigar:
     
  18. backin82

    backin82 Jack of a Few Trades Supporting Member

    Sep 9, 2009
    Oklahoma City, OK
    Having built a 15/6 and tried it in many different venues and spaces with many different heads and several basses, my vote is for this post exactly. I started a thread or two on here trying to work out similar issues to the OP, and eventually just arrived at the idea that I don't like flat response cabs. My attempts to make it sound like most other normal cabs was like trying to fit a square peg into a round hole.

    I went a different direction, and I've been much happier with my sound since.
     
    Nickweissmusic likes this.
  19. BK bassist

    BK bassist "Apollo's Ghost" Gold Supporting Member

    Apr 20, 2017
    Brooklyn, NY
    OP, there are a few authorized Fearless builders who are pretty active here on TB ... Maybe you want to reach out them for some advice. Depending on where you live, you might be too far away from one of those guys. I’m sure they’d be happy to help you with some advice or at least answer some questions about build specs.

    I just picked up a Fearless 215 from Paul at Scabbey Road studios in Pennsylvania and its a monster cab with beautiful articulated sound. I run a P bass through it Usijgba Subway D800+ head and a Tech21 dUg Pinnick pedal pushing crazy lows and the cabinet took all the low end beautifully without farting out.

    I’m pretty sure one of the authorized Fearless builders will jump in on this thread shortly and hopefully offer you some advice.

    Good luck brother ...


    82FCBFB1-6867-4BB7-A107-8E5056B538CC.
     
    Dave Hill likes this.
  20. seamonkey

    seamonkey

    Aug 6, 2004
    If you have a recording interface, take a DI of the bass, and a mic'd cab track at the same time. Or use a sine wave synth in the daw and sweep the frequencies. In the daw you can invert one signal, phase align (nudge a track a couple of milliseconds) then mix them back together. This ends up emphasizing just the difference and can make it easier to hear what is actually going on.
     
    BK bassist likes this.