More than 1 spkr. Why?

[Sea Chief]

Might seem a pg1 Q, but what is the basic idea of splitting say a Dlx Rev instead into one 8Ohm speaker.. into two 16Ohm speakers? In my case this is exactly what Im doing (bored of my dull sounding 12" so going 10"x2 for a change/ a jensen P10R and a C10Q recommended by my amp tech).

But apart from a change, I dont know what the basic principal differences is between having one or two speakers. Or even 3 say in a bandmaster.. or 4 in a Bassman.

IE does multiplying the speaker number inherrantly add 'depth', or some sort of 'complexity' to the sound? is that the principal idea? Cant say I noticed when I had a MMan 2 x10 that it sounded any more 'complex' with its same two 10" than my single 12" peavey bandit amp.

And going on further, what is the idea instead of two same, to have 1 ceramic/ 1 alnico? (so I could ask- wtf am I doing?!? I dont know but seems terribly exotic!).. surely you can distinguish between different spkr esp if ceramic/ alnico, say if sitting close and practicing, instead of the sound gelling together as 'one speaker source' as 2 same would simply do?

And to further again, I notice sometimes seeing bass rigs with multiple smaller spkrs say a GK set up with 6x 8" or more. The Bassman itself orig a bass amp of course having 4x 10" perhaps for the same reason.. whatever that may be in principle.

tha nks SC.

[Mick Bailey]

Speaker dynamics is a really involved subject. A simple answer is the cone area is greater and the air movement is over a greater area. There is also a level of interaction between two speakers and this varies according whether they're series or parallel connected. Naturally a 2x12" requires a larger cabinet than a 1X12" and this also has a bearing on frequency response. There is also a difference in phase cancellation (in an open or semi-open cabinet) between the different speaker configurations.

Smaller speakers have a lower inertial mass to overcome - the coil and cone are lighter and this can result in quicker attack.

The enclosure design plays a large part in how a speaker sounds. The same speaker an a larger or smaller enclosure, or in an open or closed back, can sound remarkably different. The same goes if the enclosure is filled with acoustic wadding.

Having two speakers with different characteristics is pretty commonplace. Usually it would be two ceramic speakers (as per the Bogner Alchemist). In theory it would combine the individual characteristics of either speaker and add in more complexity due to the interaction between the two units. It can also extend the frequency response - you have to compare the curves of both speakers and see that there are peaks and troughs in each speaker's response.

[Sea Chief]

Hi Mick -Im not talking speaker dynamics. Im not asking whats the difference between a 10" and a 12" speaker. I know this.

And comparison of cabinets isnt what Im talking about either: the cabinet as I mentioned in the eg, is the same: a DR for eg with a single 12" or a pair of 10"'s for the purposes of a simple example to go on for the thread.

As to your last paragraph: what do you mean by interaction between the two exactly, and is the interaction usually needing to be the same.. or is the idea to be different, to add 'something' IE with one ceramic and one alnico-? Id assume this 'something' wasnt there if 2 speakers are identical, or do 2 (exact same) speakers add something sonically different to one of the same? (say for eg two P12Rs in a fender tweed twin).

And what about the sonic mix: can you tell for eg that that enclosure over there has one ceramic and one alnico just by listening.. or does the sound gel together seamlesly so the idea is you are meant NOT to be able to tell any difference between the two, the sound as a -whole- only discernable.

[R.G.]

Might seem a pg1 Q, but what is the basic idea of splitting say a Dlx Rev instead into one 8Ohm speaker.. into two 16Ohm speakers? In my case this is exactly what Im doing (bored of my dull sounding 12" so going 10"x2 for a change/ a jensen P10R and a C10Q recommended by my amp tech).
[...]
And to further again, I notice sometimes seeing bass rigs with multiple smaller spkrs say a GK set up with 6x 8" or more. The Bassman itself orig a bass amp of course having 4x 10" perhaps for the same reason.. whatever that may be in principle.

It's a complex issue, even to list the principles. Speaker and enclosure design is a continuous tradeoff forced on us by the physics of the situation and the incredibly wide range of signals processed by the human audio system. As of yet, the only speaker technologies that can produce the entire audio range are enormous ribbon speakers and huge flame speakers. Possibly it could be done with large electrostatic speakers, but the driving system for them introduces its own difficulty. So (1) getting wide speaker response is HARD.

The physics of the situation is that the cone, voice coil and surround mass, stiffness, and compliance (springiness) introduce limits to the low and high frequency response of any given cone, and resonances in the midrange response of any cone. Humans are very, very good at identifying changes in midrange resonances, as witness the ability to positively recognize another human by voice alone.

As a generality, the smaller the speaker cone, the lower its moving mass and the better it can produce treble. 10" speakers are better at treble than 12" speakers. 4" speakers are better than 10s, or 8s or 6s, and for really good treble, you need a tiny moving mass like a horn diaphragm, metallized ribbon or ionized atoms in a flame tweeter. By the same underlying physics, smaller speakers are worse at reproducing bass because they can't move as much air.

And finally, speakers are as individual as people. No two speakers have exactly the same frequency response. Close, but not exact. And "cousins" like the same cone with alnico versus ceramic magnets are similar but different too.

What I'm getting at here is that there is no one- or two-sentence generality that answers your question. Some people spend their lives studying the underlying technology to make a living by juggling the compromises there.

But apart from a change, I dont know what the basic principal differences is between having one or two speakers. Or even 3 say in a bandmaster.. or 4 in a Bassman.

IE does multiplying the speaker number inherrantly add 'depth', or some sort of 'complexity' to the sound? is that the principal idea? Cant say I noticed when I had a MMan 2 x10 that it sounded any more 'complex' with its same two 10" than my single 12" peavey bandit amp.

Then you get into the acoustics of speaker number and placement. Having one source gives a simpler radiation pattern than having two. With two radiation points, the waves reinforce and cancel depending on the travel times from the exact point of the two sources and the frequency of the sound. Sound travels about 1100 ft/sec in air, so each foot is a little less than 1mS delay. 1mS is a full cycle of 1kHz sound, so each half foot is a half cycle, and a *difference* in path length to the ear is the same as causing a +/- 180 degree change in phase - cancellation. Each foot plus or minus three inches causes a peak from reinforcement. And that's just at one frequency. There are peaks and nulls at all frequencies above the one where the speaker center separation is greater than 1/4 of the audio wavelength in air for that frequency. It gets complicated. Three is more complicated, four is more complicated... until you get to "many", where the ear simply gives up on this and notes the sound source as "complicated".

Speaker positioning matters. For best horizontal dispersal, you want the speakers in a vertical line. The interferences are all in the vertical axis, and the speakers reinforce smoothly in the horizontal axis so dispersal is best horizontally - sound spreads better from side to side, and less energy is wasted on the ceiling and floor. Good for audiences, and that's why line radiator speakers are/were popular. Horizontal, side by side speakers disperse better up and down - oops, this is what most guitar amps do because tall, thin speaker columns are awkward to carry around and set up, and so they don't sell well, and so they aren't sold at all.

And going on further, what is the idea instead of two same, to have 1 ceramic/ 1 alnico? (so I could ask- wtf am I doing?!? I dont know but seems terribly exotic!).. surely you can distinguish between different spkr esp if ceramic/ alnico, say if sitting close and practicing, instead of the sound gelling together as 'one speaker source' as 2 same would simply do?

As a matter of practicality, yes, they sound different, and your ears (if not damaged by loud noises) can hear the differences, but it's a difference of "tone" rather than being defined, and the tone varies with how the speakers are arranged (i.e. vertical, horizontal, diagonal, how far apart, etc.) and how far YOU are from the speakers. After some distance, the sound all diffuses together and you only hear a general overall tone. This is the reason that stereo guitar amps are usually not useful; YOU can hear the difference on stage, but the audience can't hear the magic sounds because they're all mixmaster-ed by the time the sound gets to the audience.

So - yes, there are general principles, but that doesn't help much, because the principles are *complicated*, requiring long study and practice to make sense of; and because the differences change with physical positioning; and because the differences between two 12" speakers may be as big as from one 12" to a 10", and because the differences between two 12s from different lots and manufacturers may be as big as the differences between alnico and ceramic. We haven't even touched on the difference that an aluminum center dome can make in treble, or the differences in resonances and peakiness from speaker to speaker, or how speaker efficiency (as in sound pressure level per input watt of signal) is usually a trade off with peakiness and coloration. Nor on what open back versus closed back versus ported makes in bass response and peakiness.

So this is another of those questions that seems like it ought to have a simple answer, but doesn't. The fastest way for you to solve this is to try out some different speakers and cabinets.

[gnappi]

"Speaker dynamics is a really involved subject."

Is right on the money.

The rest is about:

From an amp manufacturing perspective it's about cabinet design (compact versus large), portability, wattage capability, extension cab compatibility and buyer perception.

I know players that won't touch 10" or 15" speakers (too bright or bassy) and fuss over number (and type if mixing) of 12's in a cabinet, and whether or not the cab back (another subject to thrash about) is open or closed.

I think ultimately the number of speakers in a cab is determined by need for sound projection and power capability in a given space. Every maker of cabs that are used in large venues have more speakers in a cab. The larger venue = more speakers. Plain and simple.

[Sea Chief]

Ok thanks for the replies, and the info is very much appreciated.

I still think my point is unfortunately being missed. Im not asking about differences between speaker sizes, or size or properties of speaker enclosures, or why gtr amps have them side-by-side (portablility quite obviously), or cone materials, or indeed different manufacturers of speakers. These are areas Im not needing to know, here, because A) its far top complicated B) it doesnt address my simple Q in the OP.

---------------------------------

Let me simplify. I have a DR cabinet with one P10R in. Then I change & put two P10R's in. Same speakers.

Theoretical Qs:

1) Why would one do this?
2) What sonic differences are there. There has been hinted at here that more speakers add more -volume-. So
3) is this the reason why people multiply speakers? or indeed is this the -principle/ primary- reason for having multiple speakers?
4) are there any other reasons for muliplying the same speaker to two?

[pdf64]

I'll lump all 4 together, as there's a degree of repetition.
Reasons to use 2 speakers in a cab instead of 1
- to obtain the changes made due to mutual coupling of speakers in close proximity, eg 3dB increase in SPL / watt over much of the relevant audio range.
- to achieve greater power handling / improved reliability / system resilience.
- to reduce the effect of power compression.

Reasons not to use 2 speakers are that the mutual coupling creates a more directive response, eg increased forward beam, poorer spread of SPL to the sides, and a comb filtering effect on the higher frequencies, due to the phase cancellation RG described. And increased cost / weight / minimum cab size

[Sea Chief]

I'll lump all 4 together, as there's a degree of repetition.
Reasons to use 2 speakers in a cab instead of 1
- to obtain the changes made due to mutual coupling of speakers in close proximity, eg 3dB increase in SPL / watt over much of the relevant audio range.
- to achieve greater power handling / improved reliability / system resilience.
- to reduce the effect of power compression.

I understand only more power handling here (but in my simple eg, it is meaningless as the single speaker fender would have made powerful enough for the amp in Q.. so I cannot/ would not perceive any difference whatsoever with multiplying it to 2) but

"to obtain the changes made due to mutual coupling of speakers in close proximity, eg 3dB increase in SPL / watt over much of the relevant audio range" means nothing to me, or most. Nor does "to reduce the effect of power compression".

Im trying to ask as simple an eg to get a condensed, simple reply. Im not able to understand complexities (or tbh ever wanting to).
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Ok let me simplify again. A spotty teenager goes into a shop eyes a DR amp. the shopkeeper says its available in a single 10" or for a bit more money, two 10" spks. The speakers are the same type. The spotty teen asks this simple Q:

What are the differences mister shopkeeper?

What would he reply? he's unlikey to parp on about spl and cone parameters and alu dustcaps, graphs, cabinet resonances, open-back or closed debate, vertically aligned speakers or 15" speakers.. the spotty herbert would have by this stage either walked out or have rolled a joint, smoked it and unable to understand anything whatsoever. the guy wants to sell an amp. The spotty twat wants a realtively quick answer. "Why two mister, whats the advantage?"

[pdf64]

Two speakers are louder than one, to a similar degree that a 100 watt amp is louder than a 50 watt amp, ie 3dB.

[rjb]

Two speakers are louder than one, to a similar degree that a 100 watt amp is louder than a 50 watt amp, ie 3dB.

But 3dB doesn't mean anything to Spotty Hubert.
Tell him two speakers "push more air".
That ought to impress him.

Edit: My apologies to Spotty Herbert. I don't know how I got him confused with his cousin Hubert.

[R.G.]

Im trying to ask as simple an eg to get a condensed, simple reply. Im not able to understand complexities (or tbh ever wanting to).
... The spotty teen asks this simple Q:
What are the differences mister shopkeeper?

What would he reply? ... The spotty twat wants a realtively quick answer. "Why two mister, whats the advantage?"

The shopkeeper will reply any oversimplified answer that will sell the amp, whether or not the answer has any grounding in reality. That is, he will make up any oversimplified or just flatly incorrect statement that will make the teen smile and fork over the money.

You're insisting on the answer being simpler than the question requires. You have a few choices here. You can:
(1) Pick any one issue we've mentioned (i.e. more power, different sound distribution, different tone, whatever) out of the many we presented, and focus on that.
(2) Go learn what the answers we've given you mean, then figure out what to do from that learning experience.
(3) Keep asking for a simpler answer here and in other places until someone makes up an oversimplified answer you like.

There are some questions that don't have a simple, straightforward, one-sentence answer without the answer being so simple as to be fundamentally wrong.

[Sea Chief]

Two speakers are louder than one, to a similar degree that a 100 watt amp is louder than a 50 watt amp, ie 3dB.

Ok. I understand that, I didnt know that two speakers had such a profound difference compared to one as that eg though if the same amp is simply delivering the same output split into two same-type speakers rather than one.

So that's the only reason for having two P10R's as opposed to one then? well that certianly simplifies things. Ok so there's no benefit to me then having two as opposed to one then. No bad thing, the C10Q Im pairing with the P10R is only £30. I'll just see if I can tell any diffrence one side of the speaker to the other close up. Fine, I was just curious to know if there were any other benefits, sonically (rather than power increace which wont matter a mite to me if i'll never ramp the vol up past 1/2 anyway) of multiplying a speaker.

Ok thanks/ done here.

[Sea Chief]

But 3dB doesn't mean anything to Spotty Hubert.
Tell him two speakers "push more air".
That ought to impress him.

That doesn't impress me- Ive no interest whatosever in increacing the volume. It might be a bonus, or not as the case may be (IE if there is a higher dB then the speaker pair would break up later then).

Im very surprised no-one has mentioned such an obvious characteristic difference between one speaker to two: seems like exactly what the shopkeeper would likely say to the spotty herbert in a concise sentence without needing to go into a physics lesson.

So afaict the benefits are twofold then. 1) the dB rating of the pair increaces over the single, so volume will increace. And 2) there will therefore be more headroom.

"So spotty herbert its mainly a Q of whether you want more volume and more headroom with 2, or less volume and less headroom with one spkr". (Im sorry am I missing anything- how is that complicated? Ive answered half my own OP!).

[Dave H]

Have you been tokin on spotty Herbert's joint SC?

If I were the shopkeeper I'd just say that a 1 x 10" sounds different from a 2 x 10" so you pays yer money and takes yer choice.

I don't hear much difference in volume between my 1 x 12" and 2 x 12" speaker cabs. I was using the 2 x 12" but I switched to the 1 x 12" to save my back. Now the 1 x 12" is a smaller but deeper cab and I think it sounds better. It's clearer and has a more solid bass. Just use the cab which sounds best to you, Nothing else matters.

[Sea Chief]

Have you been tokin on spotty Herbert's joint SC?

If I were the shopkeeper I'd just say that a 1 x 10" sounds different from a 2 x 10" so you pays yer money and takes yer choice.

I don't hear much difference in volume between my 1 x 12" and 2 x 12" speaker cabs. I was using the 2 x 12" but I switched to the 1 x 12" to save my back. Now the 1 x 12" is a smaller but deeper cab and I think it sounds better. It's clearer and has a more solid bass. Just use the cab which sounds best to you, Nothing else matters.

Not arf- cor blimey Dave H.

Ok so there is a sonic difference then perhaps. I dont have the opportunity of comparing one to twin similar speakers (Id need one 8 ohm as well as the two 16 ohm on their way) so its not a Q of which config sounds better per se in my situation. I was just wondering what the dickens Ive actually done, buying two speakers! as apart from going on trusted advice that this pair of C10Q and P10R should be a great match according to the graph spiel and dB mumbo, thinking on it I'd no actual idea why Im buying two whatsoever! so it was just a crazy techno thinking experiment, very much like Einstein I'd imagine probably.