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Topic: Backed or backless speaker? |
Gerry Brown
From:
Asheville, North Carolina, USA
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Posted 10 Jul 2019 10:32 am |
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I’m building a speaker cabinet for a quilter rackmount and wondered if there is a detectable difference between a backed cabinet and a backless cabinet. If there is, what is the difference? Thanks.
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Williams 700 S-10 Fessenden SD-10 Quilter Tone Block 202 Taylor 414 CE |
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Jack Stoner
From:
Kansas City, MO
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Posted 10 Jul 2019 10:58 am
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I used it with an open (mostly) back speaker cabinet. The cabinet was the size of a Nashville 112 except 1" taller to accommodate the 15" speaker.
If you enclose (closed back) you will have to port the speaker cabinet (I don't have the formula for calculating porting requirements for a given cabinet).
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GFI Ultra Keyless S-10 with pad (Black of course) TB202 amp, Hilton VP, Steelers Choice sidekick seat, SIT Strings
Cakewalk by Bandlab and Studio One V4.6 pro DAWs, MOTU Ultralite MK5 recording interface unit |
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Jerry Overstreet
From:
Louisville Ky
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Posted 10 Jul 2019 12:03 pm
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Generally, open back speakers have better dispersion on the stage or out in the room. A closed back speaker generally has more bottom end and is more focused to a general area.
For musical instrument use, it is not critical but you can find Thiele-Small parameters online for enclosed cabinets, but you have to know the characteristics of the speaker used in order to follow them.
In my own experience, I have built a half dozen or so closed 12 and 15 cabinets for use with Black Widows. My parameters are just to build a cabinet that allows the speaker to fit comfortably, use a 2 in. door hole saw for a couple holes in the baffle somewhere and don't worry too much about Thiele-Small. Those parameters are more widely critical in use for cabinets for use in sound reproduction as in home stereo speakers for listening to recorded music.
In fact, Tubeworks and others built open back cabinets with a panel that fits the opening for both open back and closed back sound.
As musicians, we need cabinets that work reasonably well and have a fairly friendly tote factor as well.
FWIW and I'm quite sure someone will offer more technical info. Good Luck. |
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Bill A. Moore
From:
Silver City, New Mexico, USA
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Posted 10 Jul 2019 12:04 pm
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I usually put an oval port in an extension cab for better bass response. (I don't know the correct formula, but the same width, and 1/4 the height seems to work so far!)
Here are a few:
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Gerry Brown
From:
Asheville, North Carolina, USA
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Posted 10 Jul 2019 7:29 pm
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Thanks for the informative replies. That demystified it for me.
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Williams 700 S-10 Fessenden SD-10 Quilter Tone Block 202 Taylor 414 CE |
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Godfrey Arthur
From:
3rd Rock
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Posted 10 Jul 2019 8:19 pm
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An open back cab, the front wave and the rear wave bump into each other cancelling out some frequencies, lower frequencies, mostly which is why there is less bass.
Putting a back on the cab keeps those waves from meeting and cancelling out those frequencies.
The backs on the cabs in the photos above are a combination of closed/open back and there are so many ways for those openings to be.
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ShoBud The Pro 1
YES it's my REAL NAME!
Ezekiel 33:7 |
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George Kimery
From:
Limestone, TN, USA
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Posted 12 Jul 2019 5:29 am open or closed back speakers
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For 50 years, I never had anything but open backed cabinets. Then I got a Stereo Steel system that has closed back cabinets. They are loaded with JBL D-130 speakers. I like the sound of these cabinets better than anything I have ever had. I have an open backed cabinet with also the D-130 speaker. it is good too, but there is a smoothness in the enclosed cabinets that I can't get in the open back.
The cabinets are about as small as you can get for a
15" speaker. They are built at a slight sngle, have 4 port holes, and are lined with insulation inside. I will be happy to send you photos and dimensions with GD Walker's permission. He is semi-retired and I don't know if he is building cabinets any more, so he probably won't care if you make a cabinet for yourself. He made hundreds of these over the years, so they should be right by now. |
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Gerry Brown
From:
Asheville, North Carolina, USA
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Posted 12 Jul 2019 5:44 am
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Thanks George. The nice thing about doing this myself is that I can build two backs, one ported and one more open. I'm pretty far along with the design, which is based on the Quilter Steelaire, minus the height needed to include the power amp. I decided to go with a Telonics TSNEO 12 speaker. I'm already thinking about making a twin 12 cab.
Are you playing over this way any these days?
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Williams 700 S-10 Fessenden SD-10 Quilter Tone Block 202 Taylor 414 CE |
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George Kimery
From:
Limestone, TN, USA
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Posted 12 Jul 2019 7:29 pm backed or backless speakers
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You will still need to put ports in the front of the cabinet for the times you have a solid back in place.
I am not playing much in NC any more. Three of our band members have taken a job playing at the Stomping Ground in Maggie Valley every Saturday night from May through October. The only thing we have booked is Pickin' in the Park on August 30th in Canton. |
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Ian Rae
From:
Redditch, England
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Posted 13 Jul 2019 12:34 am
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I like Godfrey's diagrams. An enclosed cab with no port will generally have a strong resonance in the form of a low-frequency "honk". A port typically splits this into two lesser ones which may actually beef up the tone in a helpful way. It all depends on the characteristics of the speaker and the dimensions of the box. Luckily this is an area in which experimentation is cheap and easy. The idea of a cab with interchangeable backs is on a par with swapping out pickups.
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Make sleeping dogs tell the truth!
Homebuilt keyless U12 7x5, Excel keyless U12 8x8, Williams keyless U12 7x8, Telonics rack and 15" cabs |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 13 Jul 2019 7:03 am
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| One advantage of closed-back cabinets that hasn't been mentioned is their high acoustic efficiency when compared to open back cabinets. Open cabinets are terribly inefficient, and they convert only a tiny fraction of the electrical watts fed into them into actual audio watts. A good sealed and ported cabinet can be several times more efficient, and therefore far louder, than an open cabinet. |
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Ian Rae
From:
Redditch, England
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Posted 13 Jul 2019 8:40 am
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And they get cleverer. My recent model Roland 60 bass amp is fearsomely loud and sounds way bigger than the 10" speaker it actually is.
_________________
Make sleeping dogs tell the truth!
Homebuilt keyless U12 7x5, Excel keyless U12 8x8, Williams keyless U12 7x8, Telonics rack and 15" cabs |
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Godfrey Arthur
From:
3rd Rock
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Posted 13 Jul 2019 9:01 am
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| Ian Rae wrote: |
| And they get cleverer. My recent model Roland 60 bass amp is fearsomely loud and sounds way bigger than the 10" speaker it actually is. |
This is why research and development is a plus when trying to match an amp with a speaker inside a cab.
Unless one has something tried and true, studied to an Nth degree, it's all just guessing and YMMV.
The open back cab like a Fender amp was designed to be that way and it has its place. A closed back cab is designed to throw sound far distances like a Marshall 4x12 but there are trade offs in the frequency response.
A Fender Twin can be heard above the din by more than one person on stage with the cancellation of lower frequencies that would normally compete with the bass player.
Makes it easier to get things in perspective to where guitars occupy the mids and the bass takes care of the lows.
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ShoBud The Pro 1
YES it's my REAL NAME!
Ezekiel 33:7 |
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Gerry Brown
From:
Asheville, North Carolina, USA
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Posted 14 Jul 2019 9:44 am
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Thanks so much for all the helpful comments. I've done all I can do until the speaker gets here on Wednesday. Since I used the Steelaire combo as the model for my cabinet I've decided for now to use a similar back. Here are some photos from the bench.
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Williams 700 S-10 Fessenden SD-10 Quilter Tone Block 202 Taylor 414 CE |
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