Speaker Efficiency Comparison

[Clipped and Shorn]

The other night we were listening to my large system, the one which is tri-amped to my custom built speaker cabinets containing mostly Altec components. I found that we were enjoying these at rather hefty volumes. Now if I look at the meters built into my amp, the one that handles the bass (to the Altec 416B), it looks to be utilizing something between 50-90 watts, I could crank things up even more, but this was fine for the music I was playing. Sometimes it looks like I am using as much as 120 watts if I really crank up that bass amp (a Carver TFM-55). The mid-range is handled by 35 watt tube amps, and something under 20 watts for the high-range.

I really enjoy this large sound sometimes, actually a lot of the time, and find it hard to imagine getting this with 2 watts. But then I have never had experience with the Khorn and was curious just how dramatic a difference the Khorn efficiency makes, if indeed that much more efficient than these Altecs.

I understand the Altec components to be fairly efficient. I am wondering how the efficiency of Cornwalls compares, and then also how the efficiency of Khorns compares. What kind of volume would you be getting with these using 45 SET, and would you pretty much need the Khorn to get good volume in a medium sized room of about 15' x 25'. Is a speaker's efficiency something mostly determined by the characteristics of the component, or is the cabinet design a significant factor. What is the most important factor determing efficiency? How much less (or more?) efficient are these vintage Altecs (416 or 515) than the Klipsch speakers/

Mostly I was curious, I currently have no room for anything else and am happy with this system, even though I need to upgrade some little things. I do know that some bi or tri-amps systems use SET for the mid-range and keep a more powerful amp for the low-range.

c&s

[garymd]

If the altec has a ported enclosure it's at least 98. My 411s are in a sealed enclosure and are only 92.5. I've found the altecs to sound significantly better at extremely high volumes versus the cornwalls but the opposite at lower volumes.

[Clipped and Shorn]

Maybe that is why I enjoy the Altecs at the higher volumes. I designed this system because I was frustrated with the Cornwalls to a certain extent. This is a ported system.

I still have the Cornwalls, and maybe bi-amping them might be the way to go. Either that or happening onto just the right pre/amp combo which works for them and for me.

I really like the control of bi or tri-amping. With the Cornwalls, if I turn up the volume in hopes of more bass, I get more of the harshness that can happen in the mids. At some point I will try biamping the Corns to see how that might compare.

c&s

[garymd]

It may also have something to do with the mc240 driving the altecs and the 299b with the corns. There seems to be more to it though. When I crank up those altecs they are just amazing. No strain whatsoever. The corns do begin to sound a little harsh in comparison.

I don't often listen to very loud music so I prefer the corns most of the time. There are time however, that I like to dust off the woofers. That's when I use the twin-amp setting on the 240 and set the 7c volume to about 2:00. Shakes the concrete floor in the basement.

[Clipped and Shorn]

It is not that it is "loud" as much as just being a Big Sound, it fills the house....I love it.

Hey, I had to pay some dues to make these things, and even more dues getting them into the house, and more dues knowing I will never want to move them out of here. It is like I am anchored here. I won't be doing much Speaker Rolling around here. These boxes were custom fit into the precise space available....let me put it this way, if I eat to many holiday goodies I will not be able to squeeze by these speakers into the bedroom......

cool....you want big soundz, stay thin....ok.....its like they are the diet police as well as some swell soundz.

What is nice is that I can be nearly 30 feet from the speakers in the house and do not feel like I am missing that much. Of course, when I get up close it is a real experience and makes me want to pick up an axe and join in. By axe I mean like to blow man, rather than the axe I was referring to in another thread which had to do with a fantasy about cutting up fire wood.

"a blow is like an instrument"

-Shorty Pederstein from Interviews Of Our Time.

you remember: "Art is a small town cat........on the band with Stan etc."

c&s

furthermore when I go outside to get more firewood I can still hear the house jumping.....

[jnorv]

For what it is worth, I have 828/515Bs tuned to about 35 Hz, 1005/288s, crossed at 500 Hz.. Driving them at about 95 db in a 16x27 room takes about 3 watts input to a pair of Tripath stereo amps . I see peaks of 6 watts. At this level the amps are about 70% eff.

Jim N

[Deang]

Well Clipped, I don't know how to say this, but just to say it -- but I think SET will probably get just as loud, and do it with sublime sublimity.

[Deang]

blah blah blah

[djk]

A K33E is about 3% efficent, as is an Altec 416-8B. An Altec 515-C is about 6% efficent.

As a direct radiator above 100hz the 2.83V/1M SPL will be 3dB louder than the Altecs. This is because the DC resistance is lowest on the K33E (3R4, 6R8, and 12R respectively). If you hooked them up to the 4R, 8, and 16R taps on a tube amp the 515 would be 3dB louder, the K33E and the 416 the same.

Below 50hz as a direct radiator the K33E will have more output due to its higher Qts, the 515 will have problems going much below 100hz.

Adjusted for their impedance, the midrange horns will be about 10~13dB more efficent than their direct radiator woofer brothers. This is only up to 3Khz or so, the power entering the throat of the horn rolls off at 6dB/oct above this point.

Many horns are designed to gradually narrow their dispersion above this point so that up close they may measure reasonably flat on axis.

In the back of a large room they still sound dead, you hear the power entering the throat rather than the up front response.

A CD type horn sounds rolled off up close (it sounds like what is going into the throat). It also sounds the same in the back of the room. Adding HF equalization makes it flat in both the front and back of the room.

Contrast this with an old style horn: if you EQ it to be flat in the front, it sounds dull in the back. If you EQ it to sound flat in the back: it will shave your eyebrows up front.

The real question everyone wants the answer to is: what about the Klipschorn.

The Klipschorn is the benchmark.

Everybody wants Klipschorn performance in a box the size of a package of pop-tarts (Bose).

The Klipschorn sounds better than the Altec drivers in the 50hz~400hz region. Not because the driver is better, but because its horn loaded.

OTOH an Altec 515 in a horn does a number on the Klipsch.

Everything involves choices (compromise).

What do I think is the least compromised (the best choices)?

Horn loading over the widest possible range, with the HF horn being a CD type. Push-pull pairs of direct radiator woofers can actually have less distortion than a horn, go much lower for a given size, and still have that 'fast, tight' quality in the bass.

There is no such thing as a free lunch, this will have to be a bi-amped (possibly tri-amped) system with a larger amp for the bass section.

People generally object to a horn larger than 100hz. Build whatever you are comfortable with size wise, look at horns with an 80hz~150hz cut-off.

Avoid CD horns with narrow slots and/or long tails. The Peavey Quadratic Waveguide style horn is easy for DIY.