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Convince me NOT to build a $20 mid box

Discussion in 'Amps and Cabs [BG]' started by gil_mor, Sep 17, 2019.

  1. gil_mor


    Apr 24, 2006
    Talent, OR
    Here’s my situation:

    For larger shows, I use my 1X15+2X10 and have no issues.
    For smaller shows / tighter stages I need to do a single trip from the car. So one cab only.

    The issue is that I my ears aren’t located on my knees and it’s hard to get the definition I crave.

    My proposed solution is this:
    A tiny dedicated mid box, placed strategically (on a mic stand?) and aimed at my ears. I get the tone I need. FOH doesn’t need to worry about my stage level.
    Small, cheap, light solution.

    I’m thinking this speaker:
    "GRS 5SBM-8 5" Sealed Back Midrange" from www.parts-express.com!

    With this crossover:
    "Parts Express 800 Hz High Pass 8 Ohm Crossover" from www.parts-express.com!

    Ok, why is this a bad idea?
    DJ Bebop and N4860 like this.
  2. lz4005


    Oct 22, 2013
    What amp are you proposing to use? That speaker is only 35w.

    Are you talking about using that in addition to your normal amp and single cab that's too low to the ground to hear? Why not use an amp stand or a milk crate?
  3. MattZilla


    Jun 26, 2013
    Angled amp stands are like $50 if you buy them or like $15 for steel angle bar, hardware and black primer paint.
  4. Wasnex


    Dec 25, 2011

    I have used a pair of Galaxy HotSpots on mic stands in the manner you describe. They helped a little with clarity and articulation in the high mids. I also had an Eden D210XLT directly behind me.

    The HotSpots would have been totally worthless without the Eden, as they did not have a sufficient low frequency response. I found my listening experience was best if I took the time to adjust the spacing of all the speakers so the sound from all three speakers arrived at my ears at the same time. This would allow me to create the sensation of being engulfed in the sound. But if I stepped out of the sweet spot, the ghost image collapsed and the quality of the sound was degraded due to comb filtering.

    So if you think you will be able to gig, with just a mid range cross over at 800hz and the backwash coming back from the PA, I think you will find this doesn't work very well.
    Rip Van Dan, pellomoco14 and gil_mor like this.
  5. gil_mor


    Apr 24, 2006
    Talent, OR
    I'm using my Markbass F1 (350 at 8ohm) I figured the actual wattage from the cross over will be pretty low. No?

    I think this would be more compact than an amp stand, and probably safer as far as things getting knocked out. My 1X15 is pretty mid shy anyway so although i'm sure the stand would help, it won't create something that's missing.

    That being said, I should look into a stand regardless .
  6. gil_mor


    Apr 24, 2006
    Talent, OR
    That's actually very interesting. It's neat that you did it. What model of Hotspots did you use?
    I was going to use my 115 and the mid range, I agree the backwash from the PA will not work .
  7. Wasnex


    Dec 25, 2011
    The sensitivity of the driver is only 89dB. Compare that to the sensitivity of your 15". If they are drastically different, then the mid will need to be a lot closer to your ear than the 15" to make up for the difference in SPL. If you hear the same frequency from both drivers and they arrive at different times, you get the phasing and comb filtering I mentioned in the last post. You may still find it useful and it's only $20. But I would not have high expectations.

    I think you will get better results by elevating the cab and tilting it to aim the mids at your ears.
  8. GmanJeff


    May 16, 2008
    Vienna, VA
    Go direct, leave the amp and speakers at home, and use IEMs with your bass in your personal mix.
  9. Wasnex


    Dec 25, 2011

    I had the original HotSpots with volume controls. The model was HSVC. I believe the current mode, HS4, uses the same drivers and tuning, but it's not available with a volume control. The HS7 is available with volume control and is slightly larger, but I haven't tried this model. I don't think either will balance well with your speaker off the output of your bass amp.

    My bass rig was an Ashley MX508 rack mixer and a QSC US series power amp, so I was running a stereo rig. The monitor mix from FOH was routed through the MX508 so I could control the level and balance it with my bass's signal in the HotSpots. The D210XLT got bass only. During the show, I would use the volume controls on the HotSpots as needed rather than adjusting the level on the board.

    The HotSpots are not high fidelity, but they actually cut through pretty well for vocals. The helped a little with bass, but most of what I could hear coming from them was mids. They sounded disjointed and out of context if I did not take time to work out time alignment between the HotSpots and the D210XLT. Running an HPF inline with the HotSpots would probably have been a huge improvements, but I did this was a long time ago, before HPF pedals were a thing.
    gil_mor likes this.
  10. gil_mor


    Apr 24, 2006
    Talent, OR
    Cool setup. Probably more tweaking than I'd have patience to do though.
  11. gil_mor


    Apr 24, 2006
    Talent, OR
  12. BogeyBass


    Sep 14, 2010
    the sealed back mids are notorious for not sounding very good.

    i have recommended them before, and if done right they are " okish" and that is really the trick is doing it right to somewhat " hide" how good they dont really sound lol.

    on paper the sensitivity is actually somewhat high. in reality it is still a 5" or 6" with rather poor sensitivity being forced to survive in a tiny steel cavity so sensitivity and response peaks is ridiculous. dont believe me take a normal 5" or 6" mid. shove it in a tiny tiny tin can and let me know how it sounds.

    being in such a tiny space the impedance curve also becomes very weird and a pain in the butt to design a crossover for. likewise looking at the impedance curve and understanding the bandwith. you need to cross them over very very high. and that is really all they do is a little bit above 700 to 800hz ironically is the same spot the impedance curve becomes friendly to even start crossover design. likewise SPL is not very high until they really bark under somewhat higher power. you can use very simple 1st order or 2 nd order filters with normal mids. sealed back needs a steep 18dB 3 rd order filter crossed over high. the steep filter and high crossover. is what " hides" how ugly they can get if done otherwise

    you want a good mid box you need to get decent sensitivity using better mid drivers that can be crossed over lower and sound better. usually a pair would work. 5" or 6" pair in a somewhat small but much larger box. likewise nice response if lightly stuffed or lined with poly fiber

    or just use a single 8" designed to be a mid driver. without the expectations of people trying to get alot of " bass" from a 8" and just using a mid that can be crossed over lower. say instead of a horrid sealed back 700 to 800 hz. and the usual fart factor of 300 to 500hz from a 5"/6" pair.
    a 8" on a simple 100hz high pass does fine.

    or just use a 12" on high pass or use a " wedge" or monitor type driver which is a 12" designed to go in a very very small box pointed up at a angle. kinda like a.....monitor. the efficiency and power handling of a relatively low cost 12" will destroy and 8" or 5" or 6" sealed back. and yes a monitor on the floor pointed up to you by the microphone stand is great. many many stages utilize things called a monitor. you can make one buy one bring one etc etc and it works
    DrMole, Chickenwheels and gil_mor like this.
  13. five7

    five7 Supporting Member

    Dec 5, 2009
    amp stand cost me $20, works well
    superheavyfunk and Chickenwheels like this.
  14. Wasnex


    Dec 25, 2011
    Also the rack was way too heavy for a low volume gig. It was my touring rig that was transported in the back of a commercial box truck with a lift gate. For local gigs I used a GK 700RB/112 combo. This amp tilts back to aim the mids and highs at my head, but IMHO, it sounds best if its elevated a bit.
    Chickenwheels likes this.
  15. five7

    five7 Supporting Member

    Dec 5, 2009
    picked up a powered monitor for $80 used. 12 inch 600 watts, works very well.
    Erik Asma, dkelley and Chickenwheels like this.
  16. Axstar

    Axstar SUSPENDED

    Jul 8, 2016
    East of Eden.
    The 115 is all you need.
  17. gil_mor


    Apr 24, 2006
    Talent, OR
    That ^ was an excellent sale pitch:
    So you *can* make it work. It will require a (somewhat) tricky crossover and it will sound Ok...
    Or... Use bigger better speakers with a simpler crossover and they will sounds better...
    Or... Use an even bigger speaker and put it on the floor and call it a monitor...
    But if you are building a monitor... Why not just buy a monitor?
    A very convincing argument to convince me NOT to build a mid box.
    HolmeBass and Wasnex like this.
  18. agedhorse

    agedhorse SUSPENDED Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    You might consider using your 210 for the gigs where you need one box (if you find the mid performance acceptable), and tilt it back some.
    meatwad, gil_mor and Wasnex like this.
  19. How much for half a foot of 2x4?
    wcriley likes this.
  20. gil_mor


    Apr 24, 2006
    Talent, OR
    The mids are acceptable. The weight/form factor isn't. I'm not 20 anymore and carrying it down two flights of stairs at 2am is unfortunately worse than keeping my ears happy. Getting old sucks.
    nbsipics likes this.

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