Why horn-loaded loudspeakers are subject to design tradeoffs

[DrWho]

To be honest, I try to look at every measurement to get a holistic understanding of the behavior. It still doesn't tell the whole story but it's a really good start.

[Max2]

It would have been nice to see a basic 10 watt or so burst across the range. I think they are doing 100watts, but maybe im wrong. The measurement constraints are unclear to me and the explanation written isn't really to the point for non audio engineers. I tell you, the Danley DTS 10 looks really good across the board, but it sure has oddball dimensions. 20-100 cycles @ -10db. Maybe I overlooked something better, but that looks really good to me.

[Deang]

I don't have a wide enough range of experience to know if the things mentioned in this thread are comparable from the perspective of fairness, for example:

"Want something better than a La Scala? Take a Danley SH46 and park it on top of a Bill Fitzmaurice DR280. Drive the pair of them with a DEQX."

I paid $1200 for my LaScalas and I have about $600 into the networks. Does the above example really qualify - is it in the same area cost-wise?

@Don, thanks for clearing up the issue with the BMS plot.

@Gil, really nice post on the other page. Analogies are powerful teaching tools, especially when you use one like that. Not all of us "speak" mathematics.

@Mike, you made a blanket, generalized statement which you limited to performance factors. You said Klipsch didn't have anything that competed favorably with the Othorn, apparently it does. 6 x 4 x 2 isn't "gigantic". In fact, in my basement, that unit could easily sit between my LaScalas, and I could hang my display on the wall just above it.

@Bobdog, I just thinking out loud about some things I've been curious about. Dana Moore first tried the BMS what seems like forever ago. Since it was only one of two drivers in the 2" exit format capable of going down to 400Hz using low order filters - I began promoting its use. You have nothing to be concerned about regarding the direction you're going - it's going to sound great.

Edited July 18, 2014 by DeanG

[DrWho]

So a more realistic 128dB keeps up with 134dB? And the crazy part is the DIY will be much cheaper. Don't forget 6dB is a doubling of displacement....

I'm just trying to understand what you're getting at here.

Does a Chorus II keep up with a Jubilee, khorn, or lascala? That's less than 6dB according to their specs....

[jason str]

Where would you need that much output besides a large nightclub or pro sound applications ?

Would it not be more about the quality of sound and the way your system blends together more than anything ?

[Chief bonehead]

From the product page.

An industry-first horn-loaded vented cabinet design

Ported horn loaded. I still haven't quite wrapped my head around that but it's a biggun for sure.

Bill Fitzmaurice has been using ported horn design for some time.

Not the same

[Chief bonehead]

I was directing it towards all the Math geniuses to put all these flaws on a note pad and build something similar with none of them. It AINT happening.

Well I've been working on several approaches for a good 3 years or so.....you're right, it's crazy near impossible to do.

However, I do think an improvement can be made if you only target an LF corner of ~80Hz or so....and can get away without folding the horn. If I had big dollars and better tools, I'd have it done already, but I've been limiting myself to simple construction methods (and that phase plug requirement gets annoying).

Btw, the Othorn blows away anything that has come out of the Klipsch gates - and that was entirely DIY. I'd be willing to stack that design up against anything that takes up the same volume and covers the same bandwidth - it's just that good. The only piece missing in an ideal 3-way system is that MF unit to go between the Othorn and the HF unit...

I've been stubborn about hitting a 1kHz corner with constant polars so I can use a 1" throat tweeter. Relax that to a 500Hz xover to the K402 and that's already finished. I've also been stubborn about the 80Hz xover frequency - even though the Othorn sounds just fine up to 150Hz or so...

But the short summary is that there will always be compromises...even with that "ideal" system floating around in my head.

Blows away anything from klipsch huh?? Another "expert " opinion......

Allow me to clarify what I feel are facts and not opinion:

Klipsch claims 130dB at 1m ground plane: and it is a calculated maximum - not measured. Usually that's a convenient way to ignore power compression and claim a big number. But let's take that number at face value...

At 1m ground plane, the Othorn measures 132dB with a CEA - 2010 measurement:

http://www.data-bass.com/data?page=systems&col=7&type=1&sort=desc&mfr=-1

http://www.data-bass.com/know-how (NOTE: Ricci uses a 2m measurement for a variety of reasons, so I added the 6dB to correlate to a 1m spec).

One might even claim 134dB with a more insane driver.

The Othorn dimensions are 2x3x3 feet, which is over 3x smaller than 6x4x2.5. Coupling three Othorns together will net 141dB versus a (calculated) 130dB in the same footprint.

By my measure, that's a 10dB improvement and justifies using language like "blow away".

I'd be all ears if someone from Klipsch comes back with numbers showing greater performance with the same solution size. CEA-2010 numbers would be a great start. I don't want to diminish the genius of the 1802-HLS design, which clearly is doing a lot more with a lot less. However, there's only so much room in the back of the truck, or your living room so I think it is very fair to compare designs that take up the some amount of space. Amplifier power requirements and cost are inaudible traits so I don't worry about them too much if there are existing solutions that meet the needs....

Anyways, that's where I'm coming from. I'm all ears for another way to make the comparison. Is there something about the 1802 that will sound better for other reasons? Obviously maxSPL is a completely arbitrary spec for normal listening, but it does give insight into the potential linearity of a system (generally we see distortion decrease as level is reduced until we hit the noise floor). The Othorn is under 1% THD even all the way up to 110dB....

Coupling three othorns.... Gee. Isn't that a calculation???

[jason str]

From the product page.

An industry-first horn-loaded vented cabinet design

Ported horn loaded. I still haven't quite wrapped my head around that but it's a biggun for sure.

Bill Fitzmaurice has been using ported horn design for some time.

Not the same

Not exactly but is a port tuned horn loaded bass bin that's been around for some time.

[DrWho]

Coupling three othorns.... Gee. Isn't that a calculation???

What's wrong with calculations? Side point: do calculations or measurements carry more merit?

Is there a physical reason to doubt the addition of acoustic pressures in this scenario? If so, what magnitude of error might be expected in that regard?

Concerning voice coils, thermal compression is very real. I've measured it myself and there are several papers discussing the topic. Klipsch isn't even being consistent with their own calculations.....93V into 8 ohms is 1100W, but they claim the system is 6ohms, which would actually be 1400W. That's a 2dB difference - maybe that's a sneaky way of ignoring the power compression issue? Or is someone just being lazy about always using 8 ohms for the power numbers?

[ClaudeJ1]

Concerning voice coils, thermal compression is very real. I've measured it myself and there are several papers discussing the topic.

According to Danley, who makes the most powerful speakers on the planet, power compression sets in at 10% of maximum rated power, which, makes horn loading make the most sense, since there is a 16 db gain in efficiency. This lowers the power input requirements and the IM distortion too. Unless you are filling stadiums with sound, the benefit in the home is effortless bass at very low distortion.

You already know all this, but I'm adding to the benefit of others.

Edited July 21, 2014 by ClaudeJ1

[Chief bonehead]

Coupling three othorns.... Gee. Isn't that a calculation???

What's wrong with calculations? Side point: do calculations or measurements carry more merit?

Is there a physical reason to doubt the addition of acoustic pressures in this scenario? If so, what magnitude of error might be expected in that regard?

Concerning voice coils, thermal compression is very real. I've measured it myself and there are several papers discussing the topic. Klipsch isn't even being consistent with their own calculations.....93V into 8 ohms is 1100W, but they claim the system is 6ohms, which would actually be 1400W. That's a 2dB difference - maybe that's a sneaky way of ignoring the power compression issue? Or is someone just being lazy about always using 8 ohms for the power numbers?

You are the one that dissed calcutions. You can't have it both ways. Edited July 22, 2014 by Chief bonehead

[DrWho]

You are the one that dissed calcutions. You can't have it both ways.

I beg to differ, so clearly there is a misunderstanding here. I have never had any issue with calculations in general - especially when it's just addition.....

If you read closely, I said I was willing to take Klipsch's claims at face value for the sake of making my point:

Klipsch claims 130dB at 1m ground plane: and it is a calculated maximum - not measured. Usually that's a convenient way to ignore power compression and claim a big number. But let's take that number at face value...

My second point was that I will always defend a measurement over a calculation - and in the case of calculated maximum SPL's there can be a lot of errant assumptions. Here is a paper from Mackie on the issue:

http://www.mackie.com/products/hdseries/pdf/hd_real_spl.pdf

And a quick summary of the section I'm talking about:

The Calculated Maximum SPL is a purely theoretical specification. The manufacturer uses the known power of their amplifier and the known sensitivity of the transducer to mathematically calculate the maximum SPL they can produce in a particular loudspeaker.

For example, a compression driver’s peak sensitivity may be 110 dB at 1W at 1 meter. When powered by a 100W amplifier, which is equivalent to 20 dB of gain, the calculated Maximum SPL is then 110 + 20 = 130 dB SPL. This number is often increased by 3 dB since sine waves have a 3 dB crest factor; in our example, this gives a Calculated Maximum SPL number of 130 + 3 = 133 dB SPL!

They go on to show that the maximum SPL is closer to 10dB less when actually measured. I think they're being a bit misleading by not also including an extra 6dB crest factor from the pink noise source (to make it more apples to apples), so it really ends up being about 3-4 dB less than the calculated. That 3-4dB also shows up frequently in all the measurements I've seen too. I spent a whole summer doing nothing but max output measurements for an audio company in Michigan...nothing ever hit the maximum calculated SPL without going up in flames. Actually, that was the best part....finding the true failure point of the system. Ironically it was usually the crossovers that burnt up first...

So is Klipsch deviating from a standard "Max Calculated SPL", or is the output actually less? I'd be willing to wager lunch that it measures lower

What really needs to happen is we need to get an 1802 in the hands of Ricci to make the measurements as apples to apples as possible. Maybe you can loan him one of yours?

Edited July 22, 2014 by DrWho

[DrWho]

Hey Mark, I would contend that off-axis response is improved with a horn versus a direct radiator. I would also contend that the efficiency is slightly less important for the horn than the reduction in Doppler distortion. Doppler is a fixed entity for a given driver intended to cover a certain bandwidth.

Also, the holy grail of the horn is that the amplitude response be perfectly flat....I think some of the newer designs are starting to get close to the direct radiators in that regard.

Sidepoint, but have you heard the K402 Mark?

[Chris A]

Earl Geddes even says that "waveguides" (as he calls them) are only useful because of controlled directivity, NOT efficiency.

YMMV.

Edited July 22, 2014 by Chris A

[Khornukopia]

Is it true that horn loaded drivers have better transient response than direct radiator cones when compared at equivalent acoustic outputs?

[DrWho]

What is transient response?

Turns out that's actually a loaded question...

[Khornukopia]

I meant to ask, is it true that horn loaded drivers respond to oscillating electrical signal impulses more quickly than direct radiator cones when compared at equivalent acoustic outputs?

[Chris A]

I meant to ask, is it true that horn loaded drivers respond to oscillating electrical signal impulses more quickly than direct radiator cones when compared at equivalent acoustic outputs?

The best high-SPL impulse responses that I've seen have all been from horns--if you also include the relative absence of modulation distortion at the same time.

Chris

[DrWho]

If a point source is considered the ideal...

Is a point source really considered the ideal? I'm not sure I subscribe to that premise...

[ClaudeJ1]

If a point source is considered the ideal...

Is a point source really considered the ideal? I'm not sure I subscribe to that premise...

An infinitely large point source with 100% efficiency would be the ideal loudspeaker. It could pass perfect square wave from 1 Hz. to 40 Khz. with zero distortion of any kind. But the laws of physics dictate compromises.

Edited July 22, 2014 by ClaudeJ1