[jackman]

It's clear when even someone like me can understand it!  Okay, last question, why would anyone use multiple tweeters in this configuration?  Power handling?  It's an added expense and more complexity but I don't understand the payoff.  In line arrays I can understan the benefit but in designs with just a few tweeters (or two) stacked vertically or horizontally, I don't see the benefit.   

[Danny Richie]

It's clear when even someone like me can understand it!  Okay, last question, why would anyone use multiple tweeters in this configuration?  Power handling?  It's an added expense and more complexity but I don't understand the payoff.  In line arrays I can understan the benefit but in designs with just a few tweeters (or two) stacked vertically or horizontally, I don't see the benefit.   

If there is more of something it has to be better right? More is better than less...

https://www.youtube.com/watch?v=XLHglL7FCNY

Just marketing...

[sts9fan]

I guess the question is: What do they believe that does better?  What is their goal when placing 5 tweeters like that?

[jackman]

I guess the question is: What do they believe that does better?  What is their goal when placing 5 tweeters like that?

That's what I should have said!  I heard the Mac speakers at Axpona and they sounded pretty good.  Didn't check the dispersion or how they sounded outside the sweet spot.  Looking forward to doing this at this year's Axpo with speakers that have lots of tweeters.  Danny's explanation was perfect and I have a much better understanding. 

[Norman Tracy]

Danny, you are such a nice guy and so free sharing your knowledge. THANKS!

Your experiments with the stacked A/V-1s certainly illuminate how Dynaudio's "Dynaudio Directivity Control " works.

http://www.dynaudio.com/int/home_loudspeaker_systems/evidence/ddc.php



I will point out multiple tweeters as in the McIntosh and Dynaudio Evidence and Confidence really help with the power handling of these big statement series models. At a CEDIA demo I was shocked to see those big blue meters nearly pegged while the very loud sound from the McIntosh many-many-many tweeter speakers remained effortless. On the way out of the demo I asked the McIntosh rep "how many watts does that demo peak at?" He replied "about a kilo-watt". And that demo was running all day long at a trade show. I doubt a single pair of 1" done tweeters would have been up for that abuse!

[Danny Richie]

Danny, you are such a nice guy and so free sharing your knowledge. THANKS!

Your experiments with the stacked A/V-1s certainly illuminate how Dynaudio's "Dynaudio Directivity Control " works.

http://www.dynaudio.com/int/home_loudspeaker_systems/evidence/ddc.php



I will point out multiple tweeters as in the McIntosh and Dynaudio Evidence and Confidence really help with the power handling of these big statement series models. At a CEDIA demo I was shocked to see those big blue meters nearly pegged while the very loud sound from the McIntosh many-many-many tweeter speakers remained effortless. On the way out of the demo I asked the McIntosh rep "how many watts does that demo peak at?" He replied "about a kilo-watt". And that demo was running all day long at a trade show. I doubt a single pair of 1" done tweeters would have been up for that abuse!

I don't know that I'd call comb filtering cancellation patters "controlled directivity".

And I have seen the McIntosh display at CES where the guy running the control room quickly cranked the level up to a point that had everyone in the room covering their ears. He then claimed the speakers just handled a thousand watts from each amp. And I think they had four of those amps on them.

Then Gary Dodd reminded me as we walked out of the room that the system was on a 20 amp circuit. Total max output from the 20 amp circuit was 2400 watts. If the amps were 60% efficient (being generous) then 1440 was the total max output of all four amps. Divide that by 4 and each amp could only draw enough current to max 360 watts. And it would be likely that a circuit breaker would trip before then.

So it wasn't near as much power hitting those speakers that they claim. However, using that many drivers power handling will be high.

[Danny Richie]

I did measure a pair of these things. They also used two tweeters.



Here is the on axis response of the tweeters and mids individually (green line), then the lower woofers (blue line), and then the red line shows them all playing together. There was actually comb filtering effects going on between the woofers and the mids from 600Hz to 2.5kHz as the combined output was less than the individual output of the mids alone.



Okay here is the on axis at 1 meter and then each additional measurement is made by going up 4" at a time.



There were a lot of cancellation effects going on over the whole range, but the tweeter peaks and cancellation effects spanned more than a 25db range.

[srb]

Then Gary Dodd reminded me as we walked out of the room that the system was on a 20 amp circuit. Total max output from the 20 amp circuit was 2400 watts. If the amps were 60% efficient (being generous) then 1440 was the total max output of all four amps. Divide that by 4 and each amp could only draw enough current to max 360 watts. And it would be likely that a circuit breaker would trip before then.

That would be true for a continuous sine wave load which music is not.  However amplifiers with very large power supplies and storage capacitance can supply instantaneous and peak current and power on demand that can surpass what is available from the external AC supply circuit.

Steve

[Danny Richie]

That would be true for a continuous sine wave load which music is not.  However amplifiers with very large power supplies and storage capacitance can supply instantaneous and peak current and power on demand that can surpass what is available from the external AC supply circuit.

Steve

That is true. It is hard to say just how hard the speakers were hit for that brief second where the dial was whipped to ten and back, but for sure it was not appreciated by the small crowd of people and it certainly didn't help sell the speakers. Everyone looked at the guy with the look on their faces that clearly said, why did you do that?

[jackman]

Danny, thanks for the measurements. I would never consider those speakers because I would hate to listen withy head in a vice. Why would anyone buy them? Also, it's interesting the manufacturer ident seem to have measurements on the website. I wonder why?

[harley52]

Danny thanks a bunch for the clear explanation.

Jackman upper tweeter has a waveguide on the Argos making the sweetspot larger. And that's always a good thing imho.

I did find a review of that Mac speaker and moving from left to right the #2 and #4 tweeters are wired out of phase which as you guys know cancels the output of tweeters #1 and #5. Leaving the output of #3 tweeter being the one we hear. I don't get that as being a logical and efficient way of producing a speaker. Btw I ran across a Mac dealer who is selling those speakers for $499 each. That's for a $2000 retail  of each speaker. That speaks loudly of a speaker that isn't selling. And for the dealer to sell them at a discount would require the ok from Mac themselves. In other words the speakers just, suck.

[jackman]

Danny thanks a bunch for the clear explanation.

Jackman upper tweeter has a waveguide on the Argos making the sweetspot larger. And that's always a good thing imho.

I did find a review of that Mac speaker and moving from left to right the #2 and #4 tweeters are wired out of phase which as you guys know cancels the output of tweeters #1 and #5. Leaving the output of #3 tweeter being the one we hear. I don't get that as being a logical and efficient way of producing a speaker. Btw I ran across a Mac dealer who is selling those speakers for $499 each. That's for a $2000 retail  of each speaker. That speaks loudly of a speaker that isn't selling. And for the dealer to sell them at a discount would require the ok from Mac themselves. In other words the speakers just, suck.

Hi Harley,

Thanks for the info but I'm now confused.  How can a waveguide make the sweet spot bigger?  I thought waveguides controlled directivity and that waveguide looks too small to do that.  Also, in my understanding, two tweeters used in this manner results in comb filtering which reduces the sweet spot, right?  I was under the impression this cannot be corrected with a crossover or other means. Hopefully the experts will chime in. Also, I'd love to see some off axis plots. Cool looking speakers by the way, I'm just trying to learn.

Thanks

Jack

[srb]

The McIntosh are the only speakers I've seen with horizontal tweeter arrays except for some center speakers where they are placed between woofers.

Although somewhat of a rarity, here are some other speakers with multiple vertical tweeters (that aren't line arrays) that also seem to buck the acoustic theory:

Two vertical tweeters:
Axiom M80 v3, M100
Bryston A1, A2, A3, T

Two vertical tweeters separated by 5" midrange (TMT):
Opera Grand Callas (also has 3 vertical tweeters in rear)

Three vertical tweeters:
RBH (multiple tower models)

Steve

[Folsom]

If you had an active crossover network you could possibly do something... "special" with that many tweeters. Would it be worth your time? Hm...

The one huge line array I distinctly remember wasn't too cheap at $25k a pair or so, but it wasn't that impressive either. Did it sound low effort? Yes. But that doesn't explain why it was so boring. The imaging was good in the spot, very good. But I don't prescribe to being overly interested in an overly prescribed sweet spot. Frank Sinatra also sounded like he was shrunk. Are giant line arrays meant to make you and the people in the music feel small? 

It seems to me on the electronics side you can tame (or let free rather) a lot of the "constricted" feel a stereo can give.

The speakers with only a couple tweeters beg the question, what's the crossover like? They may not be playing all of the same frequencies.

[Danny Richie]

Although somewhat of a rarity, here are some other speakers with multiple vertical tweeters (that aren't line arrays) that also seem to buck the acoustic theory:

Two vertical tweeters:
Axiom M80 v3, M100
Bryston A1, A2, A3, T

Two vertical tweeters separated by 5" midrange (TMT):
Opera Grand Callas (also has 3 vertical tweeters in rear)

Three vertical tweeters:
RBH (multiple tower models)

Steve

They don't really buck the acoustic theory or the laws of physics. They confirm what is known and are actually examples of why such designs are avoided by most companies.

[steve f]

A follow up question. What happens when a planar or ribbon type tweeter is used in multiples?

Steve

[bdp24]

Just what I was going to ask, Steve. Amongst Eminent Technology LFT-8 owners, there is a set-up called "stacking" two pair of the speakers. It's not literal stacking, it's placing two of the speakers (which are mirror-imaged, tweeters on opposite sides of the left and right speakers) side-by-side, with the edges that the quasi-ribbon tweeters are mounted right up against placed together. This creates a sort of large co-ax driver, with the two quasi-ribbons surrounded by magnetic planar mid/woofers. The problem I saw with the arrangement is that, though the ribbons are next to each other, there is still a couple of inches separating them. Comb-filtering?

[JLM]

The basic purpose of a waveguide is to control dispersion (popularly now also termed constant directivity), so that in the crossover frequency range, the dispersion of next lower frequency driver (woofer or midrange) matches that of the tweeter.  By limiting dispersion the waveguide also helps concentrate the sound into a smaller space thereby increasing ultimate output and efficiency. Amphion is just one company that successfully relies on waveguide design (they also use it to lower the crossover frequency).  Although looking similar waveguides are not considered horns which pressurize the sound wave.

By the way this whole effect we're discussing can happen with every speaker designed with a crossover if the size of the sound wave at the involved frequency is high enough compared to the distance between drivers being crossed over (which is one reason why midrange drivers are placed close to the tweeter in most designs).

So, as Tannoy knew decades ago and a few other vendors also apply nowadays, the best application of midrange/tweeter (or woofer/tweeter) is a coaxial driver design which takes care of the comb effect and provides the advantages of a waveguide.

[FullRangeMan]

It's clear when even someone like me can understand it!  Okay, last question, why would anyone use multiple tweeters in this configuration?  Power handling?  It's an added expense and more complexity but I don't understand the payoff.  In line arrays I can understan the benefit but in designs with just a few tweeters (or two) stacked vertically or horizontally, I don't see the benefit.   

The same thing happen in the tubes amps of this expensive brand, its circuits are know to use alot of parts, much more than the average joe amp.
They are not minimalist amps.

Why use huge blue VUs and output transformers in solidstate amps?=Marketing.

[sts9fan]

Deadalus also uses two tweeters.  I still am not sure what they (think/believe) they gain if what Danny says is 100% accurate.