Multiple Drivers to Increase Efficiency

[cocolino]

Sometimes I irritate people on this forum because I tend to operate from a base of fact rather than opinion.
There are a lot of folks that want to jump into a forum and input their two cents worth.
That they don't know what they are talking about has never registered with them.
I think everybody reading this thread or actively is involved would rather enjoy it if You would follow through according Your above and first statement. As it appears now, the opposite is the case and You rather irritate folks by spreading opinions which furthermore have nothing to do at all about the actual discussion here.
In case You disagree with something that have been written here so far, it would be highly desirable that You CLEARLY name it and please tell us WHY You disagree, instead of making undefined claims in direction to those putting in efforts trying to contribute something useful here. After what You have posted lately everybody participating here must feel like a fool.

In addition, people go off on tangents and start injecting things into a thread that really have nothing to do with the question that started the thread.
Though the question of "pinkmouse" regarding co-entrant horns with multiple drivers does not refer directly to the initial question of "markkanof", it is not at all off the topic of this thread, which yes is entitled "Multiple Drivers to Increase Efficiency".

Things can often go downhill rather quickly and the thread becomes useless.
The point we agree about, though obviously due to different reasons.

Before you know it, someone is going to suggest that you pay attention to the directionality of your speaker cable.
Until now, nobody unless You has brought up something off the topic that`s only similar to this.

I want to offer help, in this area that I am very good at, but want to avoid getting dragged into the ******** that's bound to result because of my comments. If you want answers to your questions, I'm glad to give them to you.
Yes and again, please share Your knowledge with us and post something more useful for everybody.

But I'll be damned if I am going to get involved when some idiot is waiting in the wings ready to derail you.
I do not have a clue about what "idiots" You`re refering and also cannot notice somebody around here who meets Your "description" only to some extend (at least not in this thread)

Cocolino could you or someone else elaborate on the closeness of the drivers. I assume this is why the arrays..........

First I have to say that the term "acoustical coupling" I used in my first post may be somewhat misleading and is not the correct english term for this effect (sorry but English is not my native language). The correct term in German is "Strahlungskopplung" which better (??) may be translated with "Mutual Radiation Impedance (Coupling)". At least I found this explanation in the AES paper: "Some Aspects of the Self and Mutual Radiation Impedance Concept with Respect to Loudspeakers" while searching my library (Hey Bill, maybe You could shine some light on this and help us out with the correct term - no offend intended at all!!) . This was the unique useful information I have found about this and the article treats the topic to some extend, unfortunately by use of heavy math. As far I can follow this at all, the conclusion is that the increase in efficiency versus frequency of two equally (zero phase difference) radiating sound sources begins to decrease at the point where the center distance of the two sources equals (and >) the wavelength. This means if You want to benefit from the increase in efficiency at low frequencies in a multiple driver array up to a frequency of 500Hz without degradation, I would say that each two successive (in regards of mounting) drivers of a multiple array have to be mounted at least inbetween a center distance of the wavelength of 500Hz or closer, which is 66cm or about 26 inches. I do not think that the overall (center) distance of ALL drivers (if there were more than two) of an array have to be mounted inbetween this wavelength condition.
But in order to limit the "comb filtering effect" at higer frequencies mentioned first by "Audiofreak" it is also desirable to mount the drivers as close as possible as suggested by "pinkmouse".
Also the increase in efficiency can be true only if each of the drivers themselves (due to size) do not get into radiating directional, otherwise I guess no "radiating impedance coupling" can happen.
Here some examples at which frequency, drivers of different diameters are beginning to radiate directional:

10cm : 1082 Hz
13cm : 833 Hz
16cm : 676 Hz
20cm : 541 Hz
25cm : 433 Hz
30cm : 361 Hz
38cm : 285 Hz
(1 inch = 2,54cm)

Hopefully this was of some help.
BTW: everbody interested in the above mentioned AES paper may feel free to email me and I`ll try to scan it and email back.

[MBK]

A calculation showing the mathematical derivation of the increasing efficieny when using multiple drivers is shown here (along with megabytes worth of other useful information):

http://www.linkwitzlab.com/faq.htm

go to

Q21 - Why does SPL increase 6 dB for two drivers in parallel, when the electrical power consumed only increases by 3 dB?

MBK

[AudioFreak]

Originally posted by MBK
A calculation showing the mathematical derivation of the increasing efficieny when using multiple drivers is shown here (along with megabytes worth of other useful information):

http://www.linkwitzlab.com/faq.htm

go to

Q21 - Why does SPL increase 6 dB for two drivers in parallel, when the electrical power consumed only increases by 3 dB?

MBK

Because when you add 2 identical acoustical waves exactly in phase, you get an additional 3dB increase in SPL because you effectively create a virtual driver with twice the radiating area. Works well when they are very close at low frequency.

[MBK]

Yes, as derived in more detail under heading "Q21" (Question 21) in the link provided.

MBK

[Bose(o)]

I don't claim to be an audiophile mostly because I am still young and not had the oportunity to own or listen to many expensive systems.

This burns my ears every time I have heard it. Does hearing expensive systems mean you're an audiophile? My answer, no and hell no! Hearing systems from companies like BOSE (no comments please), JBL, audio and acoustics, B&W, Snell and maybe, just maybe Wilson Audio you aren't necessarily an audiophile. If you are interested by a company's beliefs, research and development then you are on the right track. Listen to music, all kinds--training your ears in the process to know what you are hearing and getting ready to compare those sounds with other speaks.

I believe an audiophile is somewhat close to being a musician. A musician appreciates music in many different ways. You DO NOT have to play an instrument to be a musician! Have you heard at least one musical note, rhythm, beat or been able to identify areas of certain dynamics? Welcome, you ARE a musician.

I have read online reviews about BOSE products and it is pure knocking, then, went to Klipsch on the same site, terrible reviews, Paradigm, awful! Pioneer, JBL, Infinity and KOSS! Great reviews Oh, I get it....those ppl don't know anything about speaks....oh well, too bad. Could save a lot of $$ building their own speaks.

Sorry, just steaming off....been waiting to do that for a long time.

[markkanof]

Bose(o),

I completely agree with you. And as a matter of fact I am a musician in the playing instruments sort of the word. What I really meant by that comment was something diffrent than came out. There are some fanatics out there that swear by super expensive speakers and act like resonably prices ones are not worth listening to. Some of these same people also swear by esoteric cables, construction materials, and setup methods, which have never been proven to effect sound in any way. I am not trying to say that anyone who calles himself an audiophile is one of these strange people, but they are out there. So by my comment I was trying to imply that I am not one of these people, and it sounds like you arn't either. Thanks for speaking your mind and doing so in a respectable manner, it's refreshing.

Mark

[Sparky]

I know what Series is, And I know what Parallel is,
But what in tarnation is Series Parallel???

What would be the prefered way to wire
2 1" Soft dome tweeters &
2 5" Midrange woofers
for best efficiency???

Series?
Parallel?
Series/Parallel?

I Have a Very low powered SET AMP
that craves Efficiency!

[AudioFreak]

series/parallel requires 4 drivers ... you place 2 in series and then parallel that with the other 2 that are also in series the net effect is that impedance remains the same as a single driver. Also, it will depend on which drivers you are using but please ... PLEASE do not use multiple tweeters in a single speaker it is asking for trouble.

[Sparky]

GADDAY FREAK!

Whats happening Down Under?

Thanks for the explanation of series/parallel.
I kind of figured it was a combination of the two(Duh)

I am going to take Your Advise on the Single Tweeter.

I have read elswhere that it is Not a good thing.

I am going to use (1) 1" Tweeter (probably a soft dome)

And (2) 5" Drivers (FULL RANGE-w/NO CROSSOVER)

The tweeter will have a CAP. in front of it.

The very bottom end will be handled by a pair of 12" SUBS.


Do You know of any really High Quality 5" Drivers with
a extended range Example: 65HZ on up to 10KHZ
that are under Not over priced (Like Lowthers) ??

I want to have a Midrange that is "To Die For"

Gadday Mate,


SPARKY

[Bose(o)]

G'day Sparky,

How are ya'? I have the following drivers--it wasn't any trouble to search for them.
Fostex FE103E 8ohm-4"
Fostex..mmmm....
From other sources, I believe that the FE103E is actually a Radioshack driver-40-1197 .
Radioshack Don't think you have a Radioshack down under, though.(?)
Vifa 5"-Partsexpress Vifa 5"
Vifa 5" mid/bass-
http://www.partsexpress.com/pe/showd...ID=15867&DID=7

Muahahah!! Perfect! http://www.partsexpress.com/pe/showd...ID=15841&DID=7
Have to make some mods on the whizzer, but after that she's just what the doctor ordered or, what you wanted, but c'mon. I wouldn't worry about the low-end much at all because you are using fairly large subs. The last driver I showed, looks to be the best value for extending up to the range that you wanted while have a fairly low bottom-end extension. I would only worry about extension to about 300Hz (upper bass area), but this one goes down to 90Hz!

-Have fun with your project! After all, that's what DIY is all about anyway.