Does a high power rated 15' speaker have more fidelity?

Is there a prefered ohm-age?

Thanks!

The comparisons indicate that 4 10's are the best choice as far as the physical strain on the cones is concerned. But this is all in theory and does not consider the way the various combinations handle the large frequency range of the steel guitar. As said above, you will sacrifice some highs in favor of fidelity for low notes with the 15" -- where the opposite is true for the 4 10's, with the two twelves falling somewhere in between.

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Steel what?

Also remember that within the different speaker sizes there are speakers with totally different sound characteristics. The JBL D130/140's are a good example of this. The 140's have ribs on the cone which make it stiffer, adding to the bass response and detracting from its ability to reproduce the higher frequencies. The 130's have a flat cone which is not as rigid, which has not quite as good bass response and better high frequency response than the 140's.

Another thing regarding "more than one speaker", they are never going to sound like one speaker because of the sound being generated from multiple locations. As soon as you have more than one location, you get phase cancellation depending on the location. So that means the frequency response is going to be different (from a single speaker) according to the angle from which you are listening.

Another reason why "a 15 will never sound like a 12 will never sound like a 10" is because when speakers reach a specific frequency they actually ripple, so that the outer part of the cone is moving in while the inner part is moving out. The frequency where the speaker does this is dependent on the size of the cone and how stiff it is. Because of that particular aspect of the speaker response, it is almost impossible to make a 10" match the frequency response of a 15". I found out that wonderful little tidbit about speakers while working at Fender R&D.

[This message was edited by Michael Brebes on 16 July 2003 at 08:00 AM.]

I remember a local player here who used two of my 8x5" systems and someone he knew came up to him saying how loud he was. We heard you two counties back; they were playing an outside job. And in clubs where I used them, people in the back would complain that the steel was loud compared to the rest of the band but the band said it was perfect on stage. I suppose the next phrase should be: GO FIGGER !!

Roy: Have you ever been exposed to a 8x5" system ?? It's the next logical move after 4x10"s. Also; do you recall a speaker system called "Sweet 16" from Popular Electronics magazine ?? If I'm not mistaken, my calculation for the area of 8x5" was just between a 14" and a 15" speaker area. I never did plot our what 4x10s" area was....

No, I have never seen a system with five 8” speakers, but I have heard of them. I have not heard of the "Sweet Sixteen."

The calculations are based simply on the area of a circular plane at the front of the speaker, and are just the formula for the area of a circle [(pi) times (the radius squared)]. One 8” diameter (4" radius) speaker would present an area of 3.1416 x 4 x 4 = 50.2656 sq. inches. Five speakers would then total 5 x 50.2656 or 251.328 sq. inches.

The single 15" diameter (7.5"radius) speaker would present an area of 3.1416 x 7.5 x 7.5 = 176.715.

Thus, if I have not miscalculated, the five 8” speakers would present an area that is approximately 42% greater than that for the 15” speaker. If bigger is better when it comes to speaker size, I suppose one could say that the five 8's are 42% better than the single 15.

Of course, these numbers are based solely on the cross-sectional area of the orifice from which the sound waves eminate. As stated above, there are other factors that affect the actual acoustical power generated and the quality of the sound.

The Popular Electronics Project took 16 small speakers wired into a configuration that would match the impedance desired. The power capacity was said to be equal to the sum of each of the speaker ratings. The best route was to use identical speakers sometimes going down to 3 inch units.

It was said that the low frequency responce was determined by taking the low freq rating of one speaker and for an example I'll state that as 200 hertz. Two of these speakers would provide a low freq rating of 100 hertz; 4 would provide 50 hertz; 8 would provide 25 and 16 would provide 12.5 hertz for a low frequency parameter.

Since the small speakers already had a decent high frequency ratings, that parameter was pretty high but a later mod provided for a tweeeter. They were used for home stereos and I built two sets; sold the first one before I had it set up for a day; someone just had to have it.

Another parameter the system touted was flatness, since if one speaker fell off at some point across the range, others would fill the gap. I tried to make the system work for steel guitar with an Eico Preamp and a JBL power amp but it was miserable to say the least.

30 years later I found replacement speakers for Bose types that might work so I built a few cabinets and used 5 inch 50 watt units with low in the 90 hz range and highs around 15kHz. I sent some to Reece who did live comparisons in music classes with JBLs. The students made the ratings and they compared the same as or better then the JBLs.

Scotty got a pair and told me I was sitting on a gold mine but I couldn't find a shovel.
They are labor intensive to build and for that reason may scare off some users and I stopped the research project at about 50 units and never made anymore. I've heard comments like: You would not believe the lows from these Texas Sound systems. And the highs are like glass, the notes seem to go out and break off.

But you heard the one about build a better mouse trap and the world will flock to your....... That was me. And this is now.
If I had some, I'd send you a pair to try out but you need power to push them. Each cabinet is rated at 400 watts continuous and 800 watts peak. They work really well with the new generation of power amps rated at 1kW or 1.4kW such as Peavey the DPC series.

I better get out of here before Jody catches me doing a long post. Bye-Bye !

On the matter an enclosure with multiple smaller speakers, My good friend Paul has made some interesting statements. It's true that the sound waves from the individual speakers will "combine" at an imaginary point somewhere in front of the enclosure. Suffice it to say (and without getting too technical), that the most significant parameters determing this point that the sound waves combine is the design of the enclosure, and the spacing between the speakers. From a short distance, say 3 feet, one would easily be able to detect different points of origin of the sound from the normal combo cabinet. At a increased distance, however, the sound waves would more or less combine to form a single wavefront. (Once you get a significant distance from the speakers, the the differing points of origin are totally lost.) Phase differences at differing angles from the center would be extremely small, unless the distance between the speakers was significant. In enclosures designed for portability, though, this would not be the case. Frequency response (and efficiency) would vary significantly at off-axis points, but this is true of single speaker enclosures, as well.

As to the the improved low frequency response of multiple small speakers, I agree with Paul's reference, but I'm not sure that this improvement would be linear. That is, I would not accept that the 16 combined speakers in PE's old "Sweet 16" would provide a 12.5 hertz low frequency cutoff without some sort of scientific data. In addition (and as most people familiar with speakers will attest), the importance of the actual performance curves (which give efficiency at various frequencies) cannot be understated, for not only are we interested the theoretical lowest-frequency resonance, but the speaker's efficiency at that frequency, as well. It does little good to be able produce a low-frequency of 12.5 hertz if the output at that frequency is down by 40 db.

As to Paul's remarks about someone commenting about the lead player's volume when using his multiple-speaker enclosure, this is easily explained. Small speakers can be quite efficient at producing high frequencies, and is is probable that the lead player in question was playing with a tone closer to Don Rich than he was Chet Atkins. High frequencies propogate extremely well. (This is the reason we can hear crickets chirping a quarter-mile away, even though their "radiating elements" are only a fraction of an inch in area.) Small speakers are usually quite efficient at higher frequencies, but lose efficiency rapidly at low and low-middle frequencies that we steelers are interested in. I never cease to be amazed at the fidelity of my Altec-Lansing computer sound system, but the simple fact is that though it reproduces lows and highs at home with equal aplomb, it would literally "fall on it's face" if asked to do what even a modest musical instrument amp does. Here, as in most enclosures with small speakers, the fidelity might be great, but might rapidly diminish at a distance. (You won't find many 5" to 8" speakers at large venues like theaters, concert halls, and outdoor concerts, because they simply don't perform well covering large areas.)

This brings me to the next point in my discourse.

The power handling capacity of a speaker, in itself, means very little. A 150-watt light bulb will handle 150 watts of audio, but it won't sound very good! All you need to increase the power-handling capacity of a speaker to ridiculous extremes is to make it's voice coil out of heavy-guage wire. Sure, it would handle lots of power, but the efficiency and frequency response would be gone, due to the mass of the "magnum" voice coil. The efficiency, frequency response (curves), and power-handling capacity must all be considered together. Only then can you make a judgement about a speaker's possible performance. Then...you have to take into account the efficiency and frequency characteristics of the enclosure.

A speaker resonating in free-air might have an efficiency of less than 3%. That is, for every 100 watts of (electrical) power you fed in, you'd get 3 watts of audio. Putting that same speaker in an open-back enclosure might double that 3-watt figure to 6 watts. Using a bass-reflex design cabinet might increase the efficiency by another 50%. So you see, there's an awful lot involved in speaker and cabinet design, a lot of which (magnet shape and material, cone design and material, enclosure materials, etc.) I haven't even got into yet!

(Sorry for this lengthy post.)

And based on your comments in earlier threads along these lines, I for one, would put you at the top of the mountain along with that guy who told those fascinating stories about early work at JBL. That was good reading to my way of thinking.

There is nothing magical about this. Simply look at the "horn" on a Trumpet versus the horn on a Tuba.

Great posts. I'm learning a lot about speakers from you two guys.

Polar response of speakers (the way the spread sound waves) changes dramatically with frequency, and while it can be pretty even at low frequencies, it's more focused as frequencies increase, such that at frequencies over 1khz, they can become extremely directional. Small tweeters (made to propogate highs effectively) usually have flat, or even convex, radiators to combat this "focusing" tendency of cone radiators.

For Donny: since speakers in combinations, act as a single entity; would using two amplifiers like he did, change anything ??
And I'm wondering why this question never occured to me before.

Come to think of it; when I went to see Gary Hogue with Marty Stuart, Marty was using four Twin Reverbs. That would make 8 twelve inch speakers. I don't think it was for power. The PA they had with them could have given him that. So maybe it was the low end he was after as well. And I can see now that my earlier question for Donny; would be as valid for four amps as it was for two.

Anyone got an e-mail for MS ??

And yet if I were a betting person, I'd bet each of them used a 15 inch speaker.

Bob Hoffnar makes a valid point about dispersion of lows in a room but the other side of that coin is when they are being recorded. Then a microphone is placed almost directly in front of the speaker and perhaps, a bit off center of the cone either up or down or left or right. So we might suppose there would be plenty of lows in a recording effort. However, when these players went to the lower strings on this album, the sound was still very bright and crisp; very Emmons-like in delivery.

There was a cameo appearance by Ray Price on one of the cuts and it would have been a landmark effort if BE had been included as well. Looks what's happening when we heard he was coming the ISGC.