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Topic: One speaker or two? |
Tommy Boswell
From:
Virginia, USA
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Posted 10 Feb 2018 6:12 am |
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I like the sound of two speakers, either a 2x12 cab or a combo amp plus an external cab or a head driving two cabinets. There's something about a single speaker that sounds a little harsh to my ears, at least from where I sit with amp behind me.
Does it make any difference to listeners in the back of the room? |
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Jack Hanson
From:
San Luis Valley, USA
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Posted 10 Feb 2018 7:11 am Re: One speaker or two?
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| Tommy Boswell wrote: |
| Does it make any difference to listeners in the back of the room? |
My guess is unless they're also steel players, it would make no difference whatsoever. |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 10 Feb 2018 11:37 am
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| I agree with Jack, most wouldn't notice or care. Unless you're a "star", never underestimate the apathy of your audience. |
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Jim Sliff
From:
Lawndale California, USA
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Posted 10 Feb 2018 11:57 am
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| Quote: |
| Does it make any difference to listeners in the back of the room? |
Usually, whether they "notice" or not.
But first - there is absolutely no technical reason one speaker can sound more "harsh", unless 1) it's a different type or impedance, or 2) not broken in properly, or 3) you are running one or the pair at a higher volume level.
If the speaker types are identical, both are broken in fully and the volume level is the same (and not distorted) all you're doing in moving more air. The overall voicing of the speaker(s) is identical.
The difference to those in the back of a room is - everything else being equal - is that the huge increase in speaker cone square inches moves a LOT more air.
This normally causes the "more distant" listener to perceive the sound to have a more balanced frequency response. There's no actual change oin sound - just in perception due to "hearing efficiency" because there's more air in the room being moved.
If you asked most back-of-the-room listeners if they could hear a difference (and you switched back and forth) they'd notice.
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional |
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Steven Paris
From:
Los Angeles
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Posted 10 Feb 2018 10:04 pm
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Two speakers from the same wattage will be +3db louder.
_________________
Emmons & Peavey |
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b0b
From:
Cloverdale, CA, USA
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Posted 10 Feb 2018 10:46 pm
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I know a guy who uses two matched speakers in separate cabs, wired out of phase! He gets the best tones I've ever heard out of a steel guitar, everywhere in the room.
_________________
-πππ- (admin) - Robert P. Lee - Recordings - Breathe - D6th - Video |
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Steven Paris
From:
Los Angeles
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Posted 10 Feb 2018 11:00 pm
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| b0b wrote: |
| I know a guy who uses two matched speakers in separate cabs, wired out of phase! He gets the best tones I've ever heard out of a steel guitar, everywhere in the room. |
I wonder how much of that sound is attributable to the 'out-of-phase' component. Were you ever able to hear him with the speakers IN phase?
_________________
Emmons & Peavey |
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Tony Glassman
From:
The Great Northwest
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Posted 11 Feb 2018 12:35 am
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| Donny Hinson wrote: |
| I agree with Jack, most wouldn't notice or care. Unless you're a "star", never underestimate the apathy of your audience. |
............so true ! |
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ajm
From:
Los Angeles
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Posted 11 Feb 2018 7:59 am
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To add to Steven Paris' question to Bob:
The first thing I wondered was how far apart are the cabinets?
If they were next to each other or stacked I'd think that at some point you'd get some phase cancellation.
And: Are they the same type/model of speaker?
If they are not, and one is more efficient than the other, that could affect things.
Last edited by ajm on 11 Feb 2018 8:20 am; edited 1 time in total |
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ajm
From:
Los Angeles
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Posted 11 Feb 2018 8:17 am
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Steven Paris wrote: "Two speakers from the same wattage will be +3db louder."
Correct me if I'm wrong here.
I'll use a simple example of a Deluxe Reverb (it has 1x12").
Note that this does not take into account any obvious impedance mismatch issues that we would be faced with in the real world. Let's assume that our amp has a "magic" impedance matching switch.
Or.........That we use different combinations of speakers in the various set ups to keep the load on the amp constant.
All of that is just a way of saying that we are concerned with volume increases related to the amount of speaker "area", keeping all other factors constant.
And it goes without saying that all of the speakers being connected are of the same model/type, and that they are all wired up in phase.
Whew........so, all that said............
Adding another 1x12 would get +3db.
(Total is 1x12 plus 1x12.)
Adding another 2x12 to that would get another +3db.
(Total is 1x12 plus 1x12 plus 2x12.)
Adding another 4x12 would get another +3db.
(Total is 1x12 plus 1x12 plus 2x12 plus 4x12.)
So going on the base assumption as stated above that all impedance loading on the amp remained constant for these different configurations:
Our Deluxe Reverb pushing 8x12 would be 3+3+3 = +9db louder than the stock 1x12 combo.
Do I have it correct?
What did I miss? |
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b0b
From:
Cloverdale, CA, USA
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Posted 11 Feb 2018 9:12 am
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| b0b wrote: |
| I know a guy who uses two matched speakers in separate cabs, wired out of phase! He gets the best tones I've ever heard out of a steel guitar, everywhere in the room. |
| Steven Paris wrote: |
| I wonder how much of that sound is attributable to the 'out-of-phase' component. Were you ever able to hear him with the speakers IN phase? |
Only on records, where they only mic one speaker (or reverse the phase of two mics). Every part of his rig, from guitar to speaker, is tweaked for tone. The out-of-phase speakers are just one element of his live sound, which is spectacular.
| ajm wrote: |
To add to Steven Paris' question to Bob:
The first thing I wondered was how far apart are the cabinets?
If they were next to each other or stacked I'd think that at some point you'd get some phase cancellation.
And: Are they the same type/model of speaker?
If they are not, and one is more efficient than the other, that could affect things. |
Matched 15" speakers and cabinets. I think he usually puts the cabs right next to each other.
_________________
-πππ- (admin) - Robert P. Lee - Recordings - Breathe - D6th - Video
Last edited by b0b on 11 Feb 2018 11:54 am; edited 1 time in total |
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b0b
From:
Cloverdale, CA, USA
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Posted 11 Feb 2018 9:41 am
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| Steven Paris wrote: |
| Two speakers from the same wattage will be +3db louder. |
I've never heard that before. I know that when you add a speaker in parallel, the impedance drops and the wattage increases, making it louder. But how does keeping the wattage constant add 3db of volume?
Watts are power. I always assumed that the power would be evenly distributed over the 2 speakers. If wattage is constant, where does the extra power come from?
_________________
-πππ- (admin) - Robert P. Lee - Recordings - Breathe - D6th - Video |
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Steven Paris
From:
Los Angeles
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Posted 11 Feb 2018 11:47 am
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The two speakers add as phase-coherent sources. Taking the Deluxe Reverb as an example---nominally 22 watts, but for simplicity, let's just say 20 watts. Assuming one 12" speaker with a sensitivity of 100 db SPL at 1 watt/1 meter. 20 watts into this will produce an SPL of 113 db. (10 x power = +10db; 2 x more is an additional +3db). If you put ANOTHER 12", 100db speaker in parallel with it (switching the output transformer now to a 4ΓΒ© load), you have 10 watts into each speaker---110 db SPL from each. They are phase-coherent sources, so they add +6db, giving you 116 db total SPL---a 3db increase in volume.
Of course, this is assuming the same wattage with either one or two speakers, which is achievable with a transformer capable of switching load impedance. But it also works similarly with solid-state amps, as long as you figure the wattage difference. Take for example the beloved Peavy Nashville 400--it nominally puts out 210 watts into 4ΓΒ©, or 130 watts into 8ΓΒ©. If you put our same 8ΓΒ©, 100 db speaker onto this, you'll get 121 db SPL--- this is following the formula: Power in db = 10 x Log (P1/P2). If you add another speaker in parallel, you'll lower the impedance to 4ΓΒ©--now we have 210 watts output from the amp. 105 watts into each speaker. Each speaker then puts out 120 db SPL---add them as phase-coherent sources and you'll get 126 db SPL. This time it's a 5db increase due to the additional +2 db delivered from the amp (210 watts/130 watts). Again, this is assuming speakers right next to each other as in a 2 x 12" cabinet.
_________________
Emmons & Peavey |
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Steven Paris
From:
Los Angeles
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Posted 11 Feb 2018 12:00 pm
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ajm: you are correct. But you have to be careful to wire the speakers to provide the correct load for the transformer. Two 4 x 12 cabinets wired in series-parallel will produce a 4ΓΒ© load.
_________________
Emmons & Peavey |
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Steven Paris
From:
Los Angeles
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Posted 11 Feb 2018 12:04 pm
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| b0b wrote: |
| b0b wrote: |
| I know a guy who uses two matched speakers in separate cabs, wired out of phase! He gets the best tones I've ever heard out of a steel guitar, everywhere in the room. |
Matched 15" speakers and cabinets. I think he usually puts the cabs right next to each other. |
THAT guy could great tone out of a diddle-bow into a Pignose!!
_________________
Emmons & Peavey |
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Jim Sliff
From:
Lawndale California, USA
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Posted 11 Feb 2018 2:48 pm
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| Quote: |
| Two speakers from the same wattage will be +3db louder. |
there seem to be a lot of questions about this - because it's wrong.
At least as written!
It's only true if (first - everything else being unchanged) 1) the speakers are identical; 2) they are wired in parallel, not series; and 3) the amp's output impedance can be adjusted to *match* the combined impedance of the two speakers.
In that case the 3db increase in loudness (I really don't like the word "volume" in this context) is due to the increased air movement from the total square inches of cone area.
Several audiophile websites have graphs or calculators that demonstrate loudness increase based on different factors. It's a subject rarely covered on musician sites.
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional |
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Steven Paris
From:
Los Angeles
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Posted 11 Feb 2018 4:52 pm
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| Jim Sliff wrote: |
| Quote: |
| Two speakers from the same wattage will be +3db louder. |
there seem to be a lot of questions about this - because it's wrong.At least as written!
It's only true if (first - everything else being unchanged) 1) the speakers are identical; 2) they are wired in parallel, not series; and 3) the amp's output impedance can be adjusted to *match* the combined impedance of the two speakers.
In that case the 3db increase in loudness (I really don't like the word "volume" in this context) is due to the increased air movement from the total square inches of cone area.
Several audiophile websites have graphs or calculators that demonstrate loudness increase based on different factors. It's a subject rarely covered on musician sites. |
It's NOT wrong---as you said yourself, the loudness increases by 3 db---if you care to describe it as "due to increased air movement" or someone else describes it as increased speaker efficiency, or I call it phase-coherent addition---it's all the same---It's freakin' 3db louder!!
_________________
Emmons & Peavey |
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Len Amaral
From:
Rehoboth,MA 02769
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Posted 11 Feb 2018 5:59 pm
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| If you are using a stereo rig with 2 separate speakers. Could you have a switch on 1 speaker that would reverse polarity on that speaker to get the out of phase sound when you wanted it? |
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Jim Sliff
From:
Lawndale California, USA
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Posted 11 Feb 2018 6:06 pm
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Dude, chill! Did you see the "laugh"? Sheesh!
And it's not true *as written* - again - as written.
The qualifiers are absolutely necessary to make it true. As written, arbitrary variables can be entered in place of the qualifiers that would make it "wrong".
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional |
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Jim Sliff
From:
Lawndale California, USA
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Posted 11 Feb 2018 6:12 pm
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| Quote: |
| If you are using a stereo rig with 2 separate speakers. Could you have a switch on 1 speaker that would reverse polarity on that speaker to get the out of phase sound when you wanted it? |
Errr - seriously?
Answer - no. The "out of phase" sound I *think* you mean is created by out of phase pickups - not speakers.
If you wire speakers out of phase you can run into sound cancellation issues when one cone moves forward and the other backwards. Certain frequencies will be completely inaudible at times.
That's why you *don't* wire speakers out of phase.
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional |
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Steven Paris
From:
Los Angeles
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Posted 11 Feb 2018 6:31 pm
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It's still not wrong, "dude"---the simple fact is that two identical speakers driven by the SAME wattage are 3 db louder than one.
_________________
Emmons & Peavey |
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b0b
From:
Cloverdale, CA, USA
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Georg SΓΈrtun
From:
Mandal, Agder, Norway
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Posted 11 Feb 2018 10:52 pm
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Steel guitar strings are not tone-generators with constant phase neither for main note nor harmonics, so audible frequency cancelling for reversed speakers doesn't follow the "normal" and "stable" rules neither in theory nor in practice. No mathematical, technical, or other rules are broken, it all just changes too fast and unorderly for our ears and brains.
Because of how each string vibrate and rotate, having two speakers pretty close to each other with one wired in reverse, will create a pretty rich sound that floats in space in front of and around the speakers as the polarity gets "flanged" back and forth between the speakers in perfect sync with the string rotation. As the rotation and vibration isn't one-way or constant, the sound becomes "spacy" (in lack of a better word). Some may prefer to call it "wide and roomy".
The only time one speaker is really "pushing out" and the other is "pulling in" (in reverse) and cancels some sound, is the moment when the pick(s) hit and let go of the string - one way to "moderate" the attack sound a little. The rest of the time as the sustained tone(s) ring out, it will be pretty hard to determine which speaker is wired positive and which is wired negative just by listening.
The only condition necessary for a good result, is that the two speakers must not occupy the same space - which is impossible anyway, and not be too far apart - the "phasing/flanging" between the speakers becomes noticeable and annoying if they are. |
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Georg SΓΈrtun
From:
Mandal, Agder, Norway
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Posted 11 Feb 2018 11:05 pm
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| b0b wrote: |
| Watts are power. I always assumed that the power would be evenly distributed over the 2 speakers. If wattage is constant, where does the extra power come from? |
Watt is power, but only if there is a load to draw that power. Therefore Watt is not a constant, and, if the amp can deliver, two, three or more identical speakers will each draw as much power as their individual load determines for a given signal (presented in Volt). |
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Steve Sycamore
From:
Sweden
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Posted 12 Feb 2018 1:11 am
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There is also an issue with regard to geometry. A single cone type driver will project a spherical wave. A lot of 12 or 10 inch speakers will further project a somewhat cardioid or shotgun pattern imposed over that. That sounds very harsh to my ears. With that, the very tip of the cardioid pattern gets very intense sound volumes while the angled trajectories get a much varying sound intensity. That does not fill a room with sound in a nice way.
Adding another speaker gets you a little bit into the realm of projecting a planar wave. With four speakers it starts to become a reality. But to create a full planar wave generally a line of speakers at least 6 feet or 2 meters long is required. With a planar wave sound intensities drop off with distance half as much as a spherical wave (3db per meter rather than 6 db per meter). So with a planar wave you get a very even distribution of sound at any angle and reflections off walls, floors and ceilings are very much reduced in comparison. That makes it sound very, very nice.
I'll take a full stack please. |
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