Audio Chews: the hi-fi and music community

Alan

I have been quietly coveting a pair of Zu Druid speakers that are for sale at the moment, and their unusual design has prompted a rare thought: Brace yourself...

Only in our loudspeakers does 'signal' finally become sound, which interacts with the room and then with us. We buy a): the very best speakers we can integrate into our room, and b): afford. This is after we take such care of our precious 'signal', amplifying it and attenuating it in turn with the finest quality HiFi known to man, or at last our wallets, and providing it with absurdly expensive -for what they are- cables to be relayed upon. We like to hope we get results because we take care over the whole chain.

But when it all finally becomes sound to taste and experience, our speakers have to square the circle of electrical signal into mechanical movement. A different set of challenges are now being overcome in the quest to bring music to our ears, which while not instruments of measurement, are immensely sensitive to a variety of triggers of 'rightness' that either make or ruin the musical experience for us. Our ears are most sensitive - in ideal circumstances - between 1kHz and 5kHz.

So why are we still stuck with speakers with crossovers smack bang in the middle of that range where our ears are so sensitive? This question mostly applies to 2-way speakers of course, my own speakers crossover at 4kHz.

I am inexperienced in the broader world of HiFi, but what I have experienced and learned is that simple is almost always best. Therefore, I imagine the world of full-range speakers would be very fulfilling - except that upon reading the forums it becomes apparent they struggle with the laws of physics the same as any other drivers do. They can't get high enough for some tastes, nor can they completely satisfy in the bass region. I generalise massively of course, but these same mechanical limitations are why in conventional speakers we split the signal so each driver can operate in it's own comfort zone. So one problem is successfully overcome - but now we have this issue of crossovers sitting on the music. Good speaker designers and quality parts help mitigate the issue, but does the issue need to be there?

Why is it not usual to utilize a real full range driver at the heart of most loudspeakers? A nice tweeter could take care of things up high, stepping in somewhere above that 5kHz threshold leaving us to revel in an uninterrupted frequency range. Also, a more conventional bass driver - say 8" or more - with whatever implementation is appropriate (part transmission line, bass reflex, compound loaded, acoustic suspension, whatever) in a sealed part part of the cabinet could come in really low. Wouldn't this result in a real full-range loudspeaker with minimal crossover sitting on our music?

Just a thought...I am really quite curious about this. If this type of speaker does exist, lets see some pictures please. It must be harder to make than I imagine, or more manufacturers would do it.

sq225917

Any speaker is a compromise. Ideally you would have one drive unit for the entire range, but physically, that really isn't 'possible'- people make those drive units, but they are far from ideal in many parameters.

It'd be interesting to see a good driver run wide open from 500hz -5khz, but I'm not such a thing exists.

Of course there is always electrostatics, which can do just this....

now there's a thought. WB-Torus sub, EL57's and Murata S-tweeter on top... Oooh sir...

Alan

Ah - so I take it even a 'full-range' driver cannot "run wide open from 500hz -5khz", which is what I thought they did. Still, perhaps one could be incorporated into the type of setup I mentioned within its parameters?

Docfoster

Si,
I like the sub/electrostatic/supertweeter idea. :-)
Is it Martin Logan that have some sort of electrostatic with a sub, or something like that...? If so, I've never heard them myself.
Actually thinking about it, didn't they have a pair in the Friends apartment...?

uglymusic

It's a long time since I've heard Martin Logans, but they always sounded like two different technologies that would never play nicely together.

Mervyn

Easy Alan - room size permitting get a set of Quad 57's !!! Work superbly with NVA. QED as they say.

bhobba

Sure you can use a full range speaker - and they surely exist - with or without crossing over to a tweeter higher than usual. And they can sound fantastic. However I have spoken to Mike Lenehan of ML1 fame (many people think it is the finest bookshelf money can buy - but without doubt it is up there) on this very point and the issue is those drivers are not as good as the ones that operate over a more conventional range. For further info about this sort of stuff check out an interview that was done with Mike:

http://www.stereo.net.au/articles/mike_lenehan_interview/

Thanks

Bill

bhobba

uglymusic said:
It's a long time since I've heard Martin Logans, but they always sounded like two different technologies that would never play nicely together.

Bingo - same with Ribbon speakers as well.

Thanks

Bill

Alan

bhobba said:
"....the issue is those drivers are not as good as the ones that operate over a more conventional range"

Thanks
Bill

That would be an explanation that fits, I hadn't thought of that.

Mervyn - '57s with QED cable? I would love to hear the '57s for sure. Still, the proposition was for conventional box speakers rather than musical electric fences!

bhobba

Alan said:
Mervyn - '57s with QED cable? I would love to hear the '57s for sure. Still, the proposition was for conventional box speakers rather than musical electric fences!

Now we are starting to talk guys. Interestingly my speakers during their design were voiced using Quads as the reference - and you can hear it - they are very close except the treble, bass and dynamics leave the quads far behind. There is a guy in Alice springs who was a stacked quad fanatic but got rid of them once he heard the ML1's. But there is one area Quad Electrostics will best my speakers - midrange transparency - it's close but the Quads do have the edge. And in my experience that is the strength of single drivers - their midrange is often killer. Another speaker that bests mine in the midrange is the Goodman's single driver. In fact a bloke out here in Aus, Steve Garland, is considered to have one of, if not the best, reference system in the country and he uses the Goodman. People who have heard it say there is nothing like it for midrange clarity - if you listen to vocals a lot like I do then it is supposed to be sublime. So why not go that route? The answer is in other areas my speaker leaves speakers like that far behind - eg bass, slam and treble extension. By going the conventional route you end up with a speaker that is much more 'cosmopolitan' and can handle a wider variety of music with greater ease - and yet is still close to those speakers in the critical midrange.

Thanks

Bill

Alan

That's just it - why not use the driver such as you mention - in this case a Goodman - and simply have a bass driver implemented in each speaker (I don't like subs). Then a supertweeter (or bordering on such) to finish off the tops. The best of all worlds? - Of courese everything is compromise, and I'm sure it would still be fraught with difficulties.

bhobba

Alan said:
That's just it - why not use the driver such as you mention - in this case a Goodman - and simply have a bass driver implemented in each speaker (I don't like subs). Then a supertweeter (or bordering on such) to finish off the tops. The best of all worlds? - Of courese everything is compromise, and I'm sure it would still be fraught with difficulties.

Yea you can do that. But then you have a three way with a much more complicated and expensive crossover - and the fact it has to pass through that crossover compromises the midrange transparency to some extent. And what the speaker designers I know tell me is the crossover is the most critical thing in a speaker - you generally achieve better results by using a two way and making its crossover better. Generally if you want to use that approach it is better to use a single driver and a crossover-less subwoffer - that way you retain the midrange.

Thanks

Bill

Alan

But it would not pass through the crossover in that critical range where our hearing is so sensitive, would it? The uninterrupted full-range driver could be free to do it's magic.

The woofer comes in low (and I agree with the need for well specced minimalist crossovers - my current speaks have modified 1st order), and the tweeter just where the full-ranger starts to roll off. Why would the crossover need to be more complicated than the 1st order crossovers my current speakers use? I do see there would be in effect two crossovers, one high & one low, but being both simple the advantages they and the additional drivers would bring must be a good thing. We are in effect discussing a full-range driver speaker, augmented with a woofer and a (super?)tweeter.

bhobba

Hi Alan

It passes through the crossover at all frequencies ie it goes through coils and capacitors that affect the sound. Best to have none for optimum transparency. I have heard speakers where the only difference was in the coils used in a 1.8khz crossover (they used much thicker wire) and Duelund capacitors instead Mundorf SIO. Mundorf SIO is a very expensive premium capacitor that would represent the ultimate capacitor in just about any manufacturer would use - but the Duelund's are better again - and even more expensive - so expensive virtually no one uses them. That speaker used over $3.5K at wholesale prices in capacitors alone. It made improvements all over the place - bass for example was noticeably better. If you have a crossover it will degrade performance.

Check the interview with Mike Lenehan for what he found out about first order crossovers:

http://www.stereo.net.au/articles/mike_lenehan_interview/

'So I dropped the 1st order time coherent crossover and designed a quasi 3rd order filter which crossed at 2khz. The drivers natural roll out combined with the electrical filter topology to effect a fourth order acoustic result. Now the speaker measured with very low distortion both harmonic and intermodulation because the tweeter wasn’t jumping back and forward like a randy silky terrier on a visitors leg. Likewise the bass driver wasn’t exposing it’s cone breakup mode at 5khz.. The sound was now fluid, dimensional, fast, and the bass, no comparison. That was the day time coherent loudspeakers were out of time for me.'

I know other designers that found similar things.

We are getting into some really deep technical stuff of speaker design here. I have to say at my level of knowledge I am quickly getting way out of my comfort zone. I think the best approach, unless you actually want to a speaker designer, is simply evaluate the finished product by ear rather than get deep into these details.

Thanks

Bill

Alan

Perhaps that answers the "why don't they...?" in the thread title then.

I suppose the crossover frequencies needed for such an application would be unusually low/high, so the possibility of finding or modifying drivers to mechanically roll-off successfully is slight.

Hugo

This same "why don't they" question appears to have prompted Martin Colloms to design a DIY speaker for HiFi Critic, using a Balanced Mode Radiator driver that allows a crossover point very much lower down the frequency range than is usually the case. There is a thread on HiFI Critic's Forum at http://www.hificritic.com/forum/default.aspx?g=posts&t=469 . As if the low crossover point is not enough, the speaker is also intended to be used against a back wall, which is where many of us would love to place our speakers in our small UK listening rooms. If I wasn't so happy with my Avalon NP2.0 speakers, I would have a go at building a pair of these.

sq225917

Alan, the point of my middle paragraph was the 'good driver' bit, there are lot of drivers that will run 500hz to 5k, but none of them do it as well as multiple drivers covering the same frequency.

All things being equal I'd take a speaker where the midbass unit is run wide open with just a little cap to save the tweeter from frying, my ES14's are like this. i'd love to hear a new version of them with a better tweeter. Reference 3a use a similar set-up on their speakers. Their Grand Veena is still the best sounding 'sensible' money speaker I've heard, £7k for a 3 way.

The BMR drivers do offer some interesting possibilities but then again they don't do treble anywhere near as well as something like the Raal ribbons which are to my ears about the best tweeter going at the minute, (my Focal Be's aren't even in the same league- as good as they are).

I've heard some great panel speakers, planar magnetics and electrostatics, but they all need some help in the bass and that needs to be incredibly well powered to match the speed of the panels.

Sometimes I just like th slip the old headphones on and forget about all that multi driver nonsense. ;-)

Alan

It's a very wriggly can of worms all this - I'll not think so much next time....all very interesting though.

Was Martin Colloms the chap who was associated with Musical Fidelity some time ago and had a hand in some speaker design for them?

Hugo

I thought that he used to be connected with Monitor Audio.

Uzinusa

Yes, I was also coveting those Zu :-) Would be an interesting, but un-auditioned punt for me.

sq225917

Zu's- reach out and touch dynamics and presence, with a sprinkling of quaky mids.

PAC

A very interesting observation Alan and one I concur with. The other problem with crossovers at these critical frequencies isn't just in their synergy with the drivers used but the fact that they (and some tweeter designs) suffer from thermal drift so they don't all operate consistently and the net effect is a changing reactive impedance with frequency and wattage applied.

I searched for a decent full range crossover-less design and couldn't find one which excelled at full frequency range. I was almost tempted to a pair of ESL's which have always been a tempting proposition, untl I got into conversation with someone who'd met and chatted to Tommy Horning, a Dutch designer of some repute. He's also in the camp which eschews crossovers which is why some of his designs engineer them above some critical frequencies and keep them as simple as possible. The Agathon Ultimate is one such design:

http://www.6moons.com/audioreviews/horning/agathon.html

I had the chance of auditioning a rare pair of these last year and haven't looked back. They operate in a compound horn design with two 12 inch bass units firing into the horn enclosure at the rear and (in this case) a Lowther DX4 unit taking up the mid duties. The whizzer cone (often a source of hardening or screeching at higher frequencies) has been removed and replaced with a damping cap and the unit is used down to several hundred Hz where as it starts to roll off, the Beyma bass units kick in. No crossovers used or needed. At the higher end of things, a simple 6Khz crossover is used to roll in the lotus horn loaded tweeter of Tommy's own design and its almost of undetectable seamlessness they way it rolls in, and extremely natural sounding.

I'd never go back to conventional loudspeakers after auditioning these (indeed I bought the pair I auditioned) and would only consider a full range electrostatic if I were ever to replace them. With youngsters in the house though, live panels are a no-no, so I'm happy to stick with the Hornings for now. I cannot recommend these speakers highly enough for anyone wanting genuine full range performance without the unnatural detachment and occasional phase shift problems that multiple crossover units sometimes give.

Alan

I have only heard of horning agathons, Paul - I feel a google coming on.

PAC

That's the one's I have Alan. There were different evolutions of the Agathons, ending with the Agathon Ultimates. Earlier models didn't have the Beyma bass units or the DX4 units. The Ultimates are a far cry from earlier models which didn't really cut the mustard. The 6 Moons review I posted above is a good review and echoes my own findings with the Ultimates.

uglymusic

So are these, like the Royds, a product of hi-fi days gone by?

PAC

Hi Dave. No, not at all. They are currently available via a few select UK importers. I think that Walrus systems used to sell them and Jim at Audiolincs still does. They don't come cheap though. A pair of Agathon Ultimates will set you back a cool £10,500 these days, but in comparison with just about any high-end speaker, they're a complete revelation. Tommy Horning has a few other speakers in the line up including the Eufrodite and Aristotolese models, the former dwarfing even the mighty Agathons and the latter a more space friendly design, but all high sensitivity. TheAgathons remain my personal favourites though being a true horn loaded high efficiency full range loudspeaker with breathtaking bass and dynamics. There's a review of a pair of Eufrodites speakers on this link:

http://www.stereophile.com/content/high-water-sound-all-important-tear-factor

Tear factor is an aptly named expression for the sheer musicality and involvement when listening through a pair of these Horning loudspeakers!

uglymusic

Maybe not today, then :(

I have a soft spot for good horns, but generally not for valves. And, as I don't have horn space, I prefer not to address that particular can of worms ;-)

mattlynch

hi guys,
i read this the other day, pre production samples but utterly intriguing all the same , http://www.hi-fiworld.co.uk/index.php/loudspeakers/65-reviews/267-eminent-lft-16.html ,
it would seem that some folks out there are trying to get the x-over point outside that critical point and still keep things affordable, worth a quick read at least.
all the best,
matt

uglymusic

Only to be listened to in a fully blacked-out room, I'd say. Only their mother could love them :-D

mattlynch

uglymusic said:
Only to be listened to in a fully blacked-out room, I'd say. Only their mother could love them :-D

i must confess i like the look of them ( ok so i have issues), a cross between a martin logan and 70s council house under floor heating vents,, could be just what i have been waiting for, i will wait a bit longer for NK's final thoughts before i arrange a listen

Alan

You'll have to let know Matt. They remind me of the old SD Acoustic range, complete in gleaming black Ash!

uglymusic

mattlynch said:

uglymusic said:
Only to be listened to in a fully blacked-out room, I'd say. Only their mother could love them :-D

i must confess i like the look of them ( ok so i have issues), a cross between a martin logan and 70s council house under floor heating vents,, could be just what i have been waiting for, i will wait a bit longer for NK's final thoughts before i arrange a listen

You trust NK's ears to stand in for yours? Why not just arrange for a listen?

mattlynch

because they are from the U.S it will cost me just to have a listen ,also NK found issues with the samples he was sent, aparently they will be sorting them for the final 'magazine review' if he still finds the same bass issues they may not be for me , my room has a lot of lift at 50hz so a speaker that is exagerated at that frequency would be bad . of all the reviewers out there in magazine world i have found every product i have owned that NK has also reviewed ,his findings match what i have heard, a rare thing, we must have similar ears i guess, i wouldnt buy something just because he says its good though!!

;) all the best,
matt

uglymusic

Fairynuff! I'll shut up :-)

RobHolt

I'll nominate the Quad ESL63 as perhaps the most successful full range design.

Genuinely clean 40Hz-20Khz in room, good dispersion pattern and no intrusive crossover. Damn near phase perfect too.

Recently finished restoring a pair to add to my speaker collection.

I accept that opinions will vary as to what constitutes 'full range' - extending below 40Hz would be nice but hat takes one huge dipole unless lots of EQ is used.

Drain_Dead

Just a tip,

I was around at Basel home today, listing to his old Naim system with Isobarbaric Speakers, he thought the bass was cracking up a few weeks ago so it put a vegetable oil on the rubber surround, which had removed the cracking. I must admit they did look better and on the horrid piano piece he played it sounds nice.

Has anybody else tried this?

Best Col

uglymusic

Putting a little sea salt and olive oil on scored skin on a pork joint gives great crackling :D

(I'll get me coat)

Drain_Dead

Beer and food. is that all you got? sounds good I be right round. No piano music please I hate it, unless it the backing to the " Ink Spots"

uglymusic

What else do you want? B-)

Drain_Dead

Jazz and blues (no not black and blue) and good music, with deep rich bass a sweet mid range and top end that makes piano sound like a musical instrument.

uglymusic

Ahem! The piano was a musical instrument last time I listened.

What have you got against dear old Joanna?

Drain_Dead

No it a poor excuse for a block of wood, great at keeping the house warm, he he, yer it great with blues and jazz.

As to Joanna my grandma played hers for silent movies before you and I were born.

And there was always Mrs. Mills and Russ Conway, and Monty Python.

Go to www.archive.org some real old music as well as some crap on that site, some good books to.

It all copyclone four stuff.

mattlynch

Drain_Dead said:
Just a tip,
I was around at Basel home today, listing to his old Naim system with Isobarbaric Speakers, he thought the bass was cracking up a few weeks ago so it put a vegetable oil on the rubber surround, which had removed the cracking. I must admit they did look better and on the horrid piano piece he played it sounds nice.
Has anybody else tried this?
Best Col

i did use e45 moisturiser on some old b139 drivers i had a few years ago, also used it on the b200's in my old Celef's, veg oil goes sticky after a while, the moisturiser is an old trick cyclists use on the rubber hoods of brake levers as they can dry up and crack from the salt in the sweat from your hands,
best regs , matt

Alan

What pampered, well moisturised speakers!
;;)

uglymusic

And with Oil of Olay they never even look their age :-)

Has anyone tried botox on their bouncy surrounds?

:>

mattlynch

:-))

Drain_Dead

uglymusic said:
And with Oil of Olay they never even look their age :-)

Has anyone tried botox on their bouncy surrounds?
:>

But it might work on your old Edison phonograph, it could then play good music without piano,s. Sorry. ;;)

Drain_Dead

Alan said:
What pampered, well moisturised speakers!
;;)

Not another wet sounding system, it got to be crisp and fresh, Like lettuce.

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