Will Removing One Speaker From a 2x12 Make It a Detuned 1x12?

Discussion in 'Amps and Cabs' started by Josh O, Sep 15, 2006.

  1. Josh O

    Josh O Member

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    I had this thought on the car ride home from a work trip yesterday. Granted my brain was fried after two days of meetings but I was wondering if I removed the upper speaker from my vertical sealed 2x12, if I would essentially have a detuned 1x12 cabinet. Before I go through the trouble of opening up the cabinet, unsolder wires, remove the speaker and reconfigure/resolder wires, would this just sound complete crap or would I be getting the detuned cab benefits. This idea would solve my impedance mismatch problems I'm having as now the cabinet would be 8 ohms and also my power efficiency problem as now this would a 100W cab instead of a 200W cab. But I'm not sure of the tonal outcome.
     
  2. mmorse

    mmorse Member

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    It will essentially be a detuned cabinet. How well it sounds is subjective. You just have to try it and see. If it's a closed back cab it will probably sound better than if it's open back. I've tried the detuned thing with both my 212 and 412. It worked well both times. It's surprising how little volume drop there is despite halving the number of speakers. In fact, in my 412, it was the only way I could get my RI Celestion Greenbacks to sound good.
     
  3. Josh O

    Josh O Member

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    I guess it's worth a shot. My cab is closed back, time to get out the screwdriver and heat up the soldering iron!
     
  4. Josh O

    Josh O Member

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    Well I gave it a try and so far, I'm pretty happy. I pulled the upper speaker out, rewired it and slapped the back back on. I didn't notice any appreciable volume loss, it sounds a little less sound dense so to speak since I don't have the two speakers any more but it still seems to have good bass response when compared to my GT 1x12 cab with it in a sealed cab config and it sounds a little clearer. This could be what the doctor ordered for me and it didn't cost me anything. Need to play some more when I can crank the amp up and also try with my pedalboard but so far with just my amp dialed in for some lower level clean, the Matamp cab seems to be responding more efficiently on its own and is matching up better with my GT 1x12 since they are now both 8 ohm loads and are now pretty evenly matched in the power handling capacity. Running this combo right into my 4 ohm speaker jack on my Fuchs, don't need the Z-matcher. If this works out for me in all regards, I think I'll be putting my money towards my other desire, a Z (or Komet) Airbrake.
     
  5. rwe333

    rwe333 Supporting Member

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    It will get you in the ballpark, but will not be to the exact dimensions Kevin O'Connor suggests...
     
  6. Josh O

    Josh O Member

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    Is he the guy from London Power?
     
  7. rwe333

    rwe333 Supporting Member

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    Yes...
     
  8. mmorse

    mmorse Member

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    People forget that speakers radiate as much out the back as they do out the front. With closed back cabs, that back wave has no place to go. Provide a big hole out the front and that back wave can escape. There's a time alignment issue but that acts as a millisecond delay making the overall tone a little fuller. Plus you get the added bass response usually lost in the cabinet when all closed. Think of it as a large ported 1x12. :D
     
  9. Darth Tater

    Darth Tater Supporting Member

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    I would think you would lose lots of low end though, because of the back waves from the speaker cancelling out the front waves...the whole entire reason a speaker needs an enclosure in the first place.

    This is not an issue with an open back because of the time and space between the waves, but with a big 12" hole right next to the speaker there is no time delay for the waves and they will cancel out. At least that's how it SHOULD work from physics standpoint :)
     
  10. mmorse

    mmorse Member

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    Of course there is a delay. The back wave travels straight back, hits the closed back and then is redirected to the front and out the hole. The front wave travels straight out. And if you think you would lose lots of low end, try it sometime for yourself. Why do you think many 1x12s are ported?
     
  11. Scumback Speakers

    Scumback Speakers Gold Supporting Member

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    I've got a demo cab with one of my 10" and 12" speakers in it, with a 3" port cut in the lower left front corner (10" is on top left, 12" lower right). There's a lot to be said for that back wave pressure mmorse talks about, and the low end it provides. I had a guy with a Marshall Plexi JTM 50 come try out an old basketweave cab I was selling, and we plugged it into that demo cab for ***** and giggles.

    To my surprise, the grill cloth was puffing out a good 1/2" by that port when he hit lower register bass notes (say below the 10th fret on the A string and down to the low E), and the cab sounded much more 3D than the 1970 Marshall Slant basketweave cab I had four original G12M bass cones in (T1511, 102 014 Pulsonic cones) that he came to try. He passed on the old BW cab, and came back to me later to order some Scumbacks.

    Moral of the story, & you may not have experienced it yet, but... sometimes all of the "theory" and "scientific calculations" actually get their butts kicked by "what if?" experiments like I did with that 12/10 mix with the 3" port. I would have never predicted those great results as that demo cab was a mistake made by my previous cab guy, and it was supposed to be a 2x12 cab with diagonal mounted speakers. Only after it was made 1/2" too small did I decide to "figure out how I could use it" for something useful... :jo

    Needless to say, the change to the front ported 12 & 10 setup was a huge success. Surprised the crap out of me. I had no clue, and wouldn't have had a clue if I hadn't tried/experimented with the "mistake" cab.
     
  12. Darth Tater

    Darth Tater Supporting Member

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    A port is a totally different thing. Porting an enclosure means that you are tuning the enclosure. What you're doing is DEtuning. There is a formula that you use that involves the enclosure volume and the tuning frequency that you want. You don't just cut a hole and stick a tube in the box, it has to be tuned to a certain frequency. On a guitar cabinet you probably want to tune it to around 70hz.

    Taking one speaker out of the box just give you a big hole allowing you to hear the waves coming of the back of the cone, it does not tune the enclosure. By taking one speaker out of the circuit you are also doubling the useable enclosure size the other speaker sees which will also give you more bottom end. No longer do both speakers have to share the same small space. This, along with the fact that it now acts like an open back cabinet (back waves can now be heard) is why you can get more bottom end from 'detuning'.

    And as far as trying it for myself...after 15 years of cabinet building, I've tried it a few times. It has never outperformed a good open back enclosure.
     
  13. mmorse

    mmorse Member

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    I'm familiar with tuned porting. Back in my audiophile days I had a couple of cabinets made for subs based on the frequency response curve of the Weber drivers I had. Had to make the cabs a certain size to get the proper "Q". Since I was using 3 12" drivers in each cab, I opted not to use a tuned port. I got quite a bit of thump out of those two subs but they had to be fast enough to keep up with a pair of ribbon Apogee speakers I had at the time. By experimenting with crossover frequencies, I was able to get them to blend rather well.

    I had 4 RI Greenbacks in a 412 stereo cab. In an open cab they would flub out badly when pushed. In the 412 (closed back) they held up better but were light on the bass even though the enclosure is much bigger. Running just 2 speakers didn't yield any more bass. However, pulling 2 speakers resulted in alot more bass with no appreciable loss of volume over running all 4.

    I tried the detuned thing to see if I would get a quieter cab but found that not to be the case at all. The increased bass response was a pleasant surprise.
     
  14. Darth Tater

    Darth Tater Supporting Member

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    I wonder what effect you would have with say a 6" hole instead of a 12" hole? Something smaller than the diameter of the cone so the waves wouldn't just go straight out....make a smaller hole so it's a little more 'work' to for the sound waves to sqeeze out :)

    Sounds like an experiment to me!
     
  15. Josh O

    Josh O Member

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    Well, had a chance to crank up the Fuchs, forget it, I guess the Matamp cab isn't ready to be deemed a detuned 1x12!!! The speaker is distorting like you wouldn't believe, it just sounds ugly! Guess I'm back to a 2x12 arrangement, it was worth a shot. Still would like to get this cabinet setup as an 8 ohm load without using the Z-matcher. The only way to do so is get a couple of 16 ohm speakers and run them in parallel.
     
  16. declan

    declan Member

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    Ive just read o'connors book and built one of the cabs, his argument from memory is that the waves dont cancel out, as after the wave bounces of the back of the cab it reverses phase, implying that there is no contradiction to the physics.

    From building his 112 i can confirm that regardless of the science there is a hell of a lot more bottom end and the sound seems to fill the room as opposed to coming from the cab, which is what i think you guys mean by more 3D

    The diffuser in his design is supposed to help this too as normally highs are washed out to some degree when listening from an angle. The diffuser which according to O'connor should be on both the speaker hole and the empty hole is an integral part of the design.

    According to O'Connor, the 16" depth of the enclosure can be reduced to 12" and the effect will be a little more emphasis on the highs, i have no reason to doubt that one.

    Im now going to frankenstein my Valve combo, cutting the speaker out, making it into a head and making a smaller detuned version of a 1X12 leaving me with a more portable 1X12 for home practice. It will be interesting to see how a smaller version compares and will hopefully answer to some degree the original question of this thread.
     

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