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Open Back vs. Closed Back Speaker Cabinet?

Discussion in 'Amp Central Station' started by castpolymer, Mar 24, 2009.

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  1. castpolymer

    castpolymer Poster Extraordinaire

    May 27, 2008
    Edmond, Oklahoma
    I am getting ready to purchase a speaker cabinet. What is the audio / practical difference between open back and closed back?

  2. Red Paul

    Red Paul TDPRI Member

    Nov 4, 2007
    I use to dislike open-back combos, but now I've got one I find it really useful for storing mains lead, pedals, drinks bottle etc in the back! ;)
    As for sound/tone, you'll have to make up your own mind! :lol:

  3. Wayne Alexander

    Wayne Alexander Friend of Leo's

    Assuming two identical speakers in two identical cabinets, one open back and one closed back, the open back cabinet will have a chimier, more open and complex sound, will spread the sound around the room a lot more, will have looser bass response (but lots of speakers are designed for this, so that doesn't mean you won't have any bass if you have the right speakers). The closed back cabinet will be tighter, punchier, "simpler" and less complex sounding, less "airy" sounding, and much more directional (less sound at the back and sides). If you want to sound like Angus Young, or the Ramones, for instance, that's a closed back cabinet sound. If you want to sound like Tom Petty, that's an open back cabinet sound for the most part.

    To complicate this more, some speakers don't sound right in open back cabs, like the Celestion G12M Greenback, which has too small a magnet structure, the bass gets flubby and the breakup gets trashy (not in a good way) in open back cabs, but in a closed back 2x12 or 4x12 these speakers sound great. Conversely, some speakers don't sound great in closed back cabs. The Celestion Alnico Blue sounds much better in an open back cab - it has plenty of bass response either way, but it has more complexity and opennes and chime in the open back cab, it sounds "simpler" and "constricted" in a closed back cab.

    If you want some help with this from the forum, let us know what guitars and amp(s) you have, what kind of music you play and what kind of sound you want. References to specific recordings would be helpful - like "I want to sound like Angus Young on Back in Black" or " I want to sound like Tom Petty on Running Down a Dream" - that sort of thing lets people give you specific recommendations.

  4. Tonemonkey

    Tonemonkey Poster Extraordinaire

    What Amp(s) is the cab for and what drivers will you install?

  5. castpolymer

    castpolymer Poster Extraordinaire

    May 27, 2008
    Edmond, Oklahoma
    The cabinet will be for a Blackheart Handsome Devil 15W head. I want to buy only the cabinet so I can install my own speaker ( trying to save some $$ ). I plan on using a 12" speaker.

  6. Jakedog

    Jakedog Doctor of Teleocity

    Mar 26, 2003
    The North Coast
    Where do you gig? I prefer open back in most situations. Here's why-

    On small stages, closed back cabs can give me volume problems. They are quite a bit more directional in most cases, and if you can't get far enough away in front of it on the stage, it can be hard to hear, making you crank too loud. You'll think your fine on stage, when in reality, your killing the audience.

    I used to run into this with my Marshall 1936 cab all the time. Sounded amazing, and I loved the tight bottom end, but when I was comfortable with hearing myself in small places, I got lots of volume complaints from the audience, and lots of complaints from bandmates that they couldn't hear me.

    I went to an open back cab, and was much happier. It filled up the stage a lot more, and spread a lot better. I could hear myself better, the drummer could hear me fine on cramped tiny stages, and because of that, I was able to play quieter, and not get volume complaints.

    You might look into a convertible cab. Several companies make cabs with removeable backs. That way, if you're on a big stage, in a large venue, and want to keep your sound tight and get more projection, you can just close it up. And then open it when you're in a small room and need to fill more space with less volume, and lose the straight as an arrow directionality.

  7. castpolymer

    castpolymer Poster Extraordinaire

    May 27, 2008
    Edmond, Oklahoma
    I only play at my home or at a friend's homes. I am nowhere good enough to play for folks who have paid money.:p

  8. Tonemonkey

    Tonemonkey Poster Extraordinaire


    Mine are all partially open backed except my YGM-3, which I removed the back from to put in a C.Rex....I haven't put it back on yet (20 Screws!!).

    Remember, if you buy a closed back and check that you can easily remove the back...(some cab makers make front loaders!!) then you can make different back panels experimenting with the opening at the bottom or top and different sizes; these all affect the sound distribution (more/less bottom end etc). All subject to whether you can be a*sed to do it, of course. ;)

  9. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

    Mar 12, 2005
    Fullerton, CA
    Wayne pretty much said everything I was going to say :)

    I prefer open for some speakers (and or amps) and closed for others. Depends on the amp, speaker, and intended use.

  10. Steve G

    Steve G Friend of Leo's

    Nov 3, 2005
    LeeK (England)
    Post of the year!
    Great references and very helpful.

  11. 6942

    6942 Poster Extraordinaire

    Apr 15, 2006
    Santa Fe, NM

    Lopoline make a pretty nice convertible 1x12 cabinet for under $200.
    Good luck!


  12. castpolymer

    castpolymer Poster Extraordinaire

    May 27, 2008
    Edmond, Oklahoma
    That is exactly the manufacturer I am looking at! Great minds do think alike.;)

  13. celeste

    celeste Friend of Leo's

    Jun 24, 2006
    For what it is worth, I prefer closed back in small rooms, they seem to have poor interactions with the room modes less often.

    I am talking rooms in a house, because even a small bar is usually larger then any room in a home.

  14. bosstone

    bosstone Tele-Afflicted

    Oct 15, 2008
    Alameda, CA
    Detuned is great. I have built three of them but there are significant drawbacks as well. Almost nobody builds them. If they do, they are very expensive. They are also huge. My single 12" detuned cab has the internal volume of most 4 X 12" cabs, which makes them, expensive to build, heavy to move and they obviously take up a lot of space. (30" tall X 24" wide X 16" deep). The nice thing is that you only have to buy one speaker and it sounds more like a 4 X 12" cab that a even 2 X 12" cab.

    I have a single 10" detuned cab that measures 24" tall X 16" wide X 24" deep. I have a Celestion G10S-50 (10"s 50 watts) and it absolutely blows away a Celestion 12" 80 watt speaker in a Bogner Cube (closed Back single 12" cab) with the same amp.

  15. bosstone

    bosstone Tele-Afflicted

    Oct 15, 2008
    Alameda, CA
    I would just add that closed cabs can have significantly more bass almost regardless of speaker if the cab is big enough.

    Open back cabs are noticeably louder (more efficient), and the green backs can sound great in old Bluesbreaker 2 X 12" combos.

  16. WoodyTone

    WoodyTone TDPRI Member

    Jan 13, 2009
    Awesome advice, thanks

  17. jmaul

    jmaul Tele-Afflicted

    Oct 7, 2008
    one final point - the greater the interior volume of the cab per speaker, the less difference between open and closed back. I have two identical oversized 112's and was playing pretty much identical speakers with one open and one closed. There was very little difference beyond one: the closed back didnt have the audio coming out the back to hit against the wall and rattle things. The closed back was a bit more directional too, but had no problems filling a large room even off axis.

    These were Avatar Contemporary cabs and with the BH HD head.

  18. booncrusher2000

    booncrusher2000 Tele-Meister

    Feb 2, 2009
    ewing virginia
    one bh15hd user to another!!!

    we have had conversations in the past on this forum about the handsome devil 15 :twisted:-so i can tell you what i like for it speaker wise ! i like a closed back cab with vintage 30's while some folks don't like the ''midrange honk'' these produce .i do like that nasaly snarl that comes pumping out of them but that's a matter of taste!!! if you get a closed back cabinet then warehouse spkrs. makes a cheap vetran 30 or even a cheap version of a celestion blue called a black&blue (i think anyway) they sound really good, if you plan on loading your own cabinet, but blues sound better in an open back cabinet(my opinion) if you like classic rock go with a closed back cab for tight bass and good mids ( and vintage 30 type speakers) (think humble pie or ac/dc) that all depends on the tone you are after. you could always go with blending spkrs .......check out hd15 on you tube, the guy ''shniffem "" is playing a hd15 through avatar 2x12 1 eminence governor / eminence screaming eagle the blend sounds ""killer "" to me anyway...............good luck

  19. Simple technical reply!

    All speakers have what is known as 'free air resonance' (Rs). In an open back cabinet, there will be a lot of bass output at the the resonant frequency quoted by the maker... usually 75-85Hz for a typical 12" guitar speaker. Big open back Fender combos, and other makes, display silly amounts of bass at this frequency... open E (6th)... because the speaker naturally vibrates heavily at this frequency, even with only small amounts of power driving it.

    The same speaker(s) in a closed back cabinet will perform differently. The back on the cabinet seals the air inside the cabinet. So the speaker has to work harder to compress and stretch that trapped air. This places stress on the speaker cone and causes the resonant frequency of the speaker to change. The sound also only comes from the front of the cabinet, making it appear directional, as there's no 'spill' from the back of the cab.

    Regardless of the size or shape of the closed back cabinet, the resonance of the speaker will rise by about 2½ notes. This means that most closed back cabinets (even a Marshall 4x12) have a resonance of approximately 120Hz... or open A (5th). Great for rock!!

    If you're a blues, country or jazz player, then the closed back cab may exude too much chuggy open A bottom end. You can't turn it off.

    If you find that an open back cab is still too bassy for you, then you must replace the speaker with one where the resonance is down at 55Hz... lthat's much ower than open E. The Celestion G12H 30 Heritage does just this job. So does the JBL D120F or the Electrovoice EVM12L. They all have very supple cone suspensions which facilitate this low resonance effect.

    Larry Carlton's ES335 tone with the Crusaders is a good example of the EVM12L 55Hz sound. However, for some rock players it may sound a little flat and lifeless.

    !0" speaker have a higher Rs around 100-120Hz, but the same effects will apply... just raise the Rs by 2½ notes for a closed cabinet.

    Hope this helps.

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