Rethinking Frequency Dividing

[Ducatista47]

I will start with these thoughts I posted yesterday:

The past few years my personal experience kept demonstrating that for critical listening and enjoyment

1) Class A sounds much better than the alternatives
2) High efficiency speakers are a must to get the highest level of reproduction sound quality, and not only because of the amplifier situation. The only exception I can think of is electrostatics
3) Passive crossovers are something else in the circuit to degrade the signal; better off without them
4) Since only the very best active crossovers are good enough, no crossover is the ideal

My full range Hammer Dynamics Super 12's are my go to speakers for private listening. The 4345's, wonderful as they sound, are being relegated to party duties and the odd music or situation where it has to be quite loud. Five or ten watts through the top of a biamped 4345 could break glass.

There is a reputedly excellent active designed by Ian and Nelson Pass; you build it yourself. I do not know if anyone besides Ian has built one. http://www.passdiy.com/gallery-misc-framed-total.htm Click on the top entry,"Hi-LO Xover." As you can see, it is no simple matter.

There is nearly endless discussion here (and elsewhere) about biamping, crossovers and crossover points, etc. It does seem to me that we have never gone outside the box here. By that I mean doing it the way it has always been done.

How it has been so far was dictated by the available hardware as well as tradition. Perhaps especially so at a site like this, where the point of departure - if there is any departure at all - is existing systems. Doing what JBL and Altec has always done is understandable given that this is a heritage site.

I think everything thus far has been based on what could be done at the dawn of the audio age. You had cones that would go so high and so low, and compression drivers above that. All horn loaded at that point, not so much in the modern era.

One of the reasons I am currently enamored with Full Range augmented is the huge improvement in how high the High Fidelity is when the midrange is not sliced up with a crossover and more than one transducer. Definitions vary, bit midrange is usually defined as 160hz to 1300hz. Some say 300hz to 2000hz, and I am sure there are other opinions as well. Let's just agree that the midrange is the heart of the instrumental and vocal band, where most fundamental and low harmonic frequencies produced by voice and most instruments is found. It is a no brainer that if we don't have to complicate the reproduction of this most critical range, we should not.

So what kind of transducers are required to do this? A subwoofer from say 80 or 100 or 160 hz on down. A compression driver or tweeter for 1600 to 2000 hz on up. And a driver, either a cone or a compression driver and horn (a la Cogent style) for the midrange.

What is desirable is avoiding the usual 500, 800 or 1000 hz crossover. Not that hard, as we now have really good tweeters and great subwoofers. The trick, if you really don't like 12 inch full range cones like the Hammer Super 12, is to make the midrange cone smaller than is the normal practice. It is not difficult to cover the 100 to 6000 hz range with an eight inch cone. Squeeze down the range and it becomes a pretty much off the shelf solution, and a ten or twelve inch woofer will give good dynamics. The reason why the 500, 800 and 1000 hz crossover is sacred is because the two way has been made into a holy grail and a fifteen inch woofer is necessity for that.

Look at the extremes JBL had to go to for quality coverage of a huge band with a compression driver in the Everest II, a $3500 Be driver they probably break even on (remember the raw diaphram costs them $500) and can't be serviced. All in the name of two way, and the result was in name only and the midrange is still divided. I have no doubt that the speaker sounds magnificent, but it uses engineering and technology way out of reach of hobbyists building speakers. It is also possible that those resources applied to the concepts I am discussing here would have resulted in an even better sounding system, and at less cost to the buyer.

I see no reason, other than the challenge of it, to pursue two way systems without top and/or bottom augmentation in this day and age. The price in sonic degradation and compromise is too great, and the solutions are ready at hand, unlike in the early era of audio where good tweeters and subs were not even dreamed of yet. The fact is that a crossover and two different drivers in the midrange is a huge compromise, and outside of that range it is not.

I still think the twelve inch 40-9700hz cone combined with a supertweeter and a good sealed box sub is better than a 160-1300hz or a 300-2000hz solution, but you can see where I am going with this. The point is that HiFi is compromised much more by dividing the midrange to get a two way than it is by going three way and leaving the midrange alone.

Zilch and Ian are going to hate me.

All this comes with the usual caveat that this does not matter if you don't listen critically or use so-so equipment that is not HiFi anyway.

Clark

[speakerdave]

Yep--the Tannoy 10" dual concentric played with a subwoofer does that thing nicely.

The original idea of a full range--Hartley--was to get the 60-9000 range and write off the above and below, which wasn't much in the recorded medium of the day anyway.

Now we have the means to add both of those inexpensively and competently.

Equal bandwidth duties for specialized drivers, achieving low IM distortion, though, is not a trivial notion, especially for higher levels.

[Mr. Widget]

I still think the twelve inch 40-9700hz cone combined with a supertweeter and a good sealed box sub is better than a 160-1300hz or a 300-2000hz solution, but you can see where I am going with this. The point is that HiFi is compromised much more by dividing the midrange to get a two way than it is by going three way and leaving the midrange alone.

I agree that there is magic in getting the midrange covered without all those nasty crossovers with the inherent two or more drivers reproducing the same frequencies. The down side is that every "full range" or extended range system that I have heard is either far from linear or is dynamically challenged or both.

I'd love to lose the 900Hz crossover in my system... but every imaginable way I look at that I give up too much of the other stuff I love about my system.


Widget

[Ducatista47]

I'd love to lose the 900Hz crossover in my system... but every imaginable way I look at that I give up too much of the other stuff I love about my system.
Widget

Are there possibilities for 160 or 200 hz to 1300 or 1500 hz? And yes, I pulled those numbers out of the air. The ten inch 2122H sounds plenty dynamic from 290hz to 1300hz in the 4345. Just a little more range might not be a challenge for a factory designer. Maybe a different cone? Do you think that if there could be a solution for higher spl it would most likely be a ten inch?

Another advantage of a ten inch main with a sub would be a very small enclosure for the ten. It would solve so many issues with something besides brute force for once. A sub is by nature a large or at least a robust solution, so why duplicate that in the mains? I notice that in both the 4345 and the Super 12 the bulk of the enclosure is only for the the last low octave or less. No need to port a midrange!

Going at it from the Full Range perspective instead of the multi way mindset could produce a better solution. There would be few to no compromises if a good full range type driver only had to cover this range instead. It is the 40-9000 requirement that has produced the results that you find wanting. For any company that could produce the LE8T so long ago and make it work so well, a ten that could do this would be a piece of cake.

I have noticed that at 100hz or below there is no problem with directionality or system integration. How much higher that window extends is knowledge I would like to have.

Clark

[scott fitlin]

I agree that there is magic in getting the midrange covered without all those nasty crossovers with the inherent two or more drivers reproducing the same frequencies. The down side is that every "full range" or extended range system that I have heard is either far from linear or is dynamically challenged or both.

I'd love to lose the 900Hz crossover in my system... but every imaginable way I look at that I give up too much of the other stuff I love about my system.


Widget

I use 750hz 12db butterworth. I FEEL that although YES 1 driver does it BEST IF you have a dirver that can, I give up too much in power handling, volume, and distortion to go the SINGLE driver + augmentation route!

The funny thing is, I DO augment, and my system is a TWO WAY + TWEETER, with sub and super tweeter augmentation. I find, through the years, that INDIVIDUAL DEDICATED bass woofers and comp drivers on horns, 2395,s to be exact, produce a very SEAMLESS, AND COHERENT, AND BELIEVABLE MIDRANGE, USING 12db slopes. Low order filters, in spite of what THEY ( INDUSTRY ) say!

BUT, IMHO, IT HAS GOT TO BE HORN LOADED!

[Ducatista47]

I agree that there is magic in getting the midrange covered without all those nasty crossovers with the inherent two or more drivers reproducing the same frequencies. The down side is that every "full range" or extended range system that I have heard is either far from linear or is dynamically challenged or both.

I would like to think that my 12 inch system is less problematic. It is not perfect and it won't fill a barn with high spl, but the notch filter seems to work quite well and in my room it is to me both dynamic and loud. Of course loud is a relative term. I would say that it seems to lack distortion as compared to multi way systems I have heard, actually.

From 4313B

The system is insanely good. The Everest II doesn't care what all the theorists, double e's, physicists, and armchair speaker designers think, say or blog on about, it just works.

I can't argue with anything in your post. I'm following my ears on this too!

Clark

[Ducatista47]

Yes, sometimes I muse about what an Olympus S7 would sound like with modern electronics, but life is short and "Why Bother?" keeps flashing in front of me. I like to move forward.

In 1969 LE-15A's in S8R kits impressed me greatly. My Hammers Dynamics were designed in the 1995-2001 time window, and they are an improvement methinks. That I could build a pair for $1000 is also an improvement. In those days we would have gladly paid that for one of today's $100 tweeters if they had been available then.

[Allanvh5150]

There is a company here in NZ that makes some very nice speakers. The company is called Arvus. All of their individual speakers are made to exacting specifications for frequency response, sensitivity etc, which means that they do not need to run crossovers. They solve the problem very nicely.

[scott fitlin]

No doubt! It all impressed me back then.

They sound "dated" today. But, if you're listening to "dated" media with "dated" electonics I'm sure it all works out just fine.

and IN 2008, JBL 2242 AND TAD 1603 IMPRESSED ME GREATLY! Dated sounding? hardly!

[Hoerninger]

The idea of an augmented one-way system is appealing. A good midrange is a key for great listening delight. The early telephone engineers knew about the importance of the 300Hz to 3kHz range. With a modern speaker this range can easily be extended.

I am not a friend of a minimalistic design, bass and highs should be added. But when I think of the advantage of several subs in a home environment than a dividing frequency of 80-100Hz would be desirable (dictated by room and hearing psychology). Now, what is to do in the range between the sub and the midrange? A speaker for about 100 - 300Hz, less than two octaves!? So I see two speakers for the midrange devided with 800 - 1000Hz - as ever. (Augmenting with a tweeter will finally give a 4way system.)

I follow your desire for a high efficency system. I had a good experience with a 3way full horn system with 500Hz and 3kHz deviding frequencies (15 inch, 6 inch cone drivers and a compression driver for the highs - more than 100 dB /W /m system efficiency). The realism of sound reproduction was amazing! I used it up to 400 W per channel, the only restriction seemed to be the clipping of the amp.
Although this system was very big, some would demand a sub for modern sound tracks. (I did not miss it.)

It is about the compromises or the good choices of the engineers. As I have heard the following speakers I want to agree that the Everest II and the Array 1500 are very fine speakers which fulfill many demands.
___________
Peter

[Ian Mackenzie]

Clark,

There are compromises everywhere.

JBL chose this route for power handling and deliberately limted the range of each driver to obtain the most accuracy of the particular drivers.

Sure you can have the crossover point at 3.5 kertz so the woofer is running 30-3.5 kertz and a tweeter above that.

(I find these system all but limited for afternoon tea while listening to low level classical music.)

Find a system with comparable efficiency and low power compression. Typically they above would be a 5-6 inch woofer and a 3/4 -1 inch tweeter like the smaller BBC monitors. They have lovely midrange but are not suitable for large as life reproduction.

Okay you want to raise the sensitivity. Pick a large woofer, say 8 inch.

The tweeter crossover point has to come down to aroud 2 khertz to avoid beaning of the woofer. Problem : tweeter distortion rockets because the tweeter has to work harder and move more.

Go to a 10 inch woofer and you need a horn loaded device.

Some makers like Kef and Monitor Audio use multiple smaller cones to raise sensitivity and control baffle step but then to run into problems of muitple sources at need time alignment and the tend to be low impediance systems..

The best option is to find a nice little 8 inch dual concentric coaxial like BMS rated at like 97 db sensitivity and use a larger help woofer below 150 hertz. This would be a poor mans Tad.

Other makers are resorting to guide loaded tweeters to enable improved performance of the tweeter. The 4208 by JBL is a case in point.

Despite being an 8 inch two way this system is as close to an affordable ideal loudspeaker from JBL at least that you are talking about.

Sensitivity is a still a bit on the low side at 89 db but the crossover point is 2.6 khertz and is out of harms way. This is a nice loudspeaker that does a lot more things right than it does wrong as far as I am concerned and its light years ahead of the 4 vintage ways in terms of midrange accuracy.

http://www.jblpro.com/pages/recording/4200.htm

If you have a read of the LS series brochures they are in many ways an extension of what I have discussed above. The LS80 has dual 8 inch woofers, crossover point is 2.5 kertz and there is a nice horn/compression driver and then a super tweeter. So in that respect JBL is going are competing in that same market as Kef and Monitor Audio.

When I was over in Japan they said there was an emerging market for this type of system and they have good WAF as well.

I agree with Giskard that a properly optomised crossover and driver set is going to work much better. As nice as the 4343-4345 they have some issues in the mid cone horn transition and Greg has made mention of that previously. I propose to trial a 1500 hertz wave guide with a 2123H when I get around to it.

[scott fitlin]

Well said,iAN a+++

[demon]

how about electrostatic speakers, like martin logan? they are (mostly augmented) one ways (and i love them).
also, if you think of the problem with dynamics and higher volumes, why not try a line array using a bunch of 8" or maybe 1o", augmented of course by a sub and tweeters. could even look like an old infinity IRS.

imho this subject is very interesting.

cheers,
mikey

[Robh3606]

Hello Clark

The best "fullrange drivers" I have heard were 8's. That seems like a good compromise between bass extension and high frequency response and dispersion. They were really very nice in the sweet spot which was narrow compared to CD type horn/Wavequide.

I basically agree with Widget I have not heard a fullranger that didn't have what I felt were more issues than it solved. That said, it is one thing I have not tried. One of these days I have to give a pair a try just to see how much I like them at home.


Not to go too off topic

Hello Ian

Nice post you really like those 4208's! Me too I think they are a sleeper system. I have a pair at work I use in my music system there. Get lots of hours on them and they certainly do please.

I propose to trial a 1500 hertz wave guide with a 2123H when I get around to it.

Definitely give it a whirl. Some are quite shallow so the V Coils line up within an inch or two much better than the 2307 offset. You could actually line them up with an angled offset baffle.

Rob

[Doc Mark]

Greetings, Friends,

I have a corner cabinet that I bought quite a few years ago, which looks to have been made at the end of the "mono" period. It has a marble top, and is vented through a vertical slot in the tapered back of the cabinet. Inside, is a JBL D130 and a University horn and driver, with crossover and L-pad. I've never really tested this system, and wonder if it's original purpose was to fulfill exactly what Clark is discussing here? Is anyone familar with such systems from "the old days"? I would imagine that the D130 would sound pretty good, running full range, and that the horn/driver was intended to add just a little more top end, with better dispersion of same, to the overall system. I seem to remember that several of you have similar old systems in use in your homes. What do you like about them, and what do you not like? I've thought about dragging that old system up from the Hobbit Hole, and giving it some testing, just for fun. But, getting to it is much easier said, than done, unfortunately! Thanks for any thoughts, or comments, you can share with me on this! Take care, and God Bless!

Every Good Wish,
Doc

P.S. Back when I bought this Old Timer, I paid just $30 for the works! I still think I got a very good deal, especially since everything worked when I got it home, and ran some music through it. Fun!