A 5-Way active horn system..

Non-Smoking Man

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There was a healthy interest in this unusual type of system on the 'Old Wam' - ( the archives support this with the epic Monster Looney system 5 of us put together for a previous Scalford Show from disparate sources that had never before been combined in one system - bit of a gamble!) - but, of late, we have had Mondie's Lenard Audio HE speakers, MF1000's excellent efforts, but not much else.

I have reassembled the active 5 way system that showed at Scalford in Coleman a few years back. (The two stacks of horns were supported by a pair of podium steps (mini scaffolding.)  (Thanks due to Lurch for loan of storage facilities - much appreciated.)

There have been a number of detailed changes but this is basically the system featuring the famous Speedysteve Horns that were previously demo'd at that Venue in conjunction with the also departed i_should_coco some years earlier and which were the end result of a build that was detailed on the Wam under the title 'Big Boy 5 Way horn System' (or words to that effect).

In the course of this thread I hope to bring out how a big active horn system works and can be assembled and the scientific reasons why it can work effectively (and more).

The system will be described in more detail in ensuing posts and pictures will follow.

This system will be available for demonstration purposes to 'one at a time' selected attendees at Lurch's twin bake offs in June and July.

Preference will be given to those traveling from distance as local Wammers will have other opportunities.

I will be interested in what reactions I get from Wammers who are new to horn sound.

Jack NSM

 
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rabski

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Need to figure a way to get there. I remember it well (or sort of well) from it's Scalford iterations. Not to mention the hacksaw job to get some of it through a door. On occasions, it sounded utterly stunning.

 
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Non-Smoking Man

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Need to figure a way to get there. I remember it well (or sort of well) from it's Scalford iterations. Not to mention the hacksaw job to get some of it through a door. On occasions, it sounded utterly stunning.
I remember you sitting in at Scalford, Richard, and chatting to Martin (my helper and RH man) about Pink Floyd and playing an ex Floyd band member's record (Waters? Gilmour?). I got a lovely compliment from Guy Sergeant as we were loading up - 'best bass in the Show'. It was the horn system put together by himself, Jonjin and i_should_coco in a previous year that had persuaded me to put a horn system together myself.

Speedysteve went on to make tractrix versions of these horns, hence the conicals' availability.

Jack NSM

 
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Lurch

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@rabski @greybeard

You'll not miss out on the horns, as I plan to have atleast 2 more BOs this year. 1, Aug/Sept and another in November (5th anniversary BO). 

 
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Psilonaught

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An a planarphile I have no interest in hearing anyone's cone speakers, but I would like a listen to a full range horn system.

Sounds like a very nice project indeed.

 

Psilonaught

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You could be missing out if you rule out all cone speakers, I would not swap mine for maggies...
Depends which ones. The smaller Maggies aren't full range and are deeply flawed. The 20x series are not and are deeply impressive.

Let's not side track Jack's horn thread however :)

 

Non-Smoking Man

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Ahem...what's been going on behind my back whilst Ive been listening to the Europa Cup Final :D

In answer to James's question, David (Lurch) Bailey is partly right - the bass 15" conicals are centre in John's tip, sorry, garden, with the cut out 'quadrant' not in place (but in shot, right). Referring to Rabski's shot of them when they were plain ply, they are the bottom speakers. (If you look closely you can see tape covering the cut which had to be made to get them through the entrance at Scalford (where this shot was taken) - Steve and I decided on the same cut when I got them.)

That's half the story only - the sub bass folded horns are supporting a bicycle to the left of shot. Each contains an 18" JBL driver whose cut off is 35 Hz. Ive two more of these. The four are half the Happy Mondays touring sub rig. All four were used in the Monster Loony Horn system in Scalford's dim and distant past.

The 5 ways are as follows: the Mondays subs run from 80 Htz down to their cut off; next up are the aforementioned 15" conicals (3 foot diameter mouth); they go up to 500Hz where a BMS 2" compression driver takes over to 1.2 KHz. There's a very nice tractix Autotech waveguide attached to the next driver, a JBL 2435Be and the 5th 'way' is a Visaton ring radiator supertweeter with a small horn. That takes over at 8KHz.

The division is done by two analogue active crossovers: the full signal enters the first crossover, a 2 Way Marchand XM9, which passes 80 Hz and below to the subs and sends the rest to a 4 Way Ashly XR4001. That handles 80 Hz and above and divides it into 4 levels, each level has a horn and driver designed for that frequency according to calculations derived from 'Hornresponse'.

Each of the 5 'ways' has an amp, again chosen to suit: solid state on the bottom and valve amps, or at least class A amps higher up.

(At present, to get us off the ground, we have a couple of interlopers doing a stop gap job till two more suitable amps are fixed. One of them is a humble Rotel 840Bx on the 115 Db/w BMS comps which sounds much better than it has a right. But then in a big frontloaded horn system like this each amp has an easy time of it and exerts maximum damping on the drivers without a pesky passive crossover in the way.

In Rabski's picture the smallest 1" comp conical has gone, to be replaced in my set up by the 1.5" tractrix (not shown in Kew Gardens, but safely stored indoors). But I DO have the frames that Steve used at Scalford. They replaced the scaffolding steps I had used at Scalford in Coleman.

The heart of this fully balanced horn system had been in a smaller room in the flat driving a pair of Jantzen 2 way floorstanders. So when it was carried next door and connected up I had the benefit of a pretty direct comparison between the Jantzens and the 5 way horns. That was a TD124/Wilson Benesch Act0.5 (modded)/Miyajima Shilabe > Iota Signature Reference phono stage (ss) > Ayre K-5xeMP (pre) section that was common to both systems. (The valve amp I had been using on the Jantzens also came across but, of course, was only on one speaker.

The difference was more information, more 'life' and much greater soundstage. Also much greater differentiation in recorded soundstage.

There's more to come too, when I get the right amps.

Martin Ware, my RH man, and I spent 3 full days getting this outfit from the garden (see above) shed to the living room, assembled and connected and I owe many thanks to him.

Ive had 2 visitors and they seemed to enjoy what they heard.

Pics to follow ( a real 'before and after' thanks to Lurch's candid back garden shot..!)

Jack

 
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Non-Smoking Man

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When embarking on a project such as this it takes a deal of time and effort (ask Mondie, the author of a similar very readable thread on here). Not least there is the planning stage which requires a comprehensive review of the literature.

I cant provide a bibliography here (it would take too much time and we all have the internet) but I can direct the reader to some names to look out for when browsing. Bruce Edgar springs to mind. Bruce Edgar has passed away but there is an excellent biographical and technical piece in an interview he gave to 'Positive Feedback' dated Dec/Jan 2003 (interviewer Dave Glackin).

You will come across a paper entitled 'An Introduction To Horn Theory', by Kolbreck. I would avoid that as it is highly technical and the maths, at this level, is way beyond MY pay grade at any rate. If you skim it you will see he discusses the different types of horn 'profile' i.e., what the different horns look like side on, sliced in half. There are 3 main types: exponential (where the horn expands over its length increasingly as it reaches the 'mouth'); conical (where the horn expands with length but has straight sides (like mine) and 'tractrix' (where the horn expands like the exponential, but unlike the exponential, the lip of the mouth is curved back right at the death to 180%, ie., flat. A horn that provides a further 'roundover' so that the lips curl back on themselves, a tractrix plus, so to speak, is a Lecleach, after its originator.

Basically there are two areas of possible distortion in a horn - at the throat (self-explanatory) and at the mouth. The faster the 'expansion rate' at the throat the less the distortion (where the conical scores), the greater the roundover (where tractrix and Lecleach score) the less distortion at the mouth. This is where the conical loses out as the airwave meets a disconuity and is reflected back down the horn. And refraction, a turbulence, also occurs. If you look carefully at the Speedysteve set up 'in the buff' you will see that Steve took great trouble to add a roundover comprising several layers of additional ply smoothed over to provide a pseudo Lecleach of sorts. (If any of you get to see the midrange horn close up (the middle sized one) you will see what a great job Steve did there. (In conversation with Steve he said it makes greater difference the higher the frequency, hence he left the bass horn at it was. (Bruce Edgar delves into this in the PF interview.)) The success of the tractrix 'profile' led Steve to get a pair of Autotech waveguides (small horns) to replace the smallest conical and  JBL 2435 Be (beryllium) drivers which he imported from the USA. I acquired those too. We tried them both in my system back then and the sound quality changed from good PA to High End domestic in a stroke!

Other names that will crop up are Voight (an early theorist), Geddes, Dinsdale et. al. and places to find overviews and information are Wikipedia, the High Efficiency Speaker Asylum, the Goodsoundclub (weird and wacky) and the Altec Lansing Forum (for everything JBL). Also we musnt forget Kevin Scott's heroic, upmarket Living Voice speakers, most notably the Vox Olympian (and Tone Scout), which was based on a Vitavox (important brand for horn people) design - reputedly the Thunderbolt. (I owned a prototype Vitavox Thunderbolt and Vitavox AK157 drivers - it was my first horn. I bought it from the original Klipsch importer who had a pair of Klipsch cornerhorns in a backroom driven by a Decware amp. Had a listen to them. Very nice. I bought a pair of AK157s and had them reconed at Wembley Loudspeakers - they are the drivers in my 15" bass conical.

One story from Bruce Edgar's interview made me laugh as it typifies views on horns - he showed the 'Edgarhorns' at a posh Hifi show in the States and got 'best in show' from a number of scribes, and 'worst in show' from another group. haha..

Jack NSM

 
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Non-Smoking Man

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Similar ground relating to horn shapes and dimensions can be found in J. Dinsdale's articles in Wireless World 1974. Dinsdale M.A., M. Sc., was head of the Cranfield Institute at the time of writing. (He may be the same Dinsdale who wrote his Masters dissertation on a no compromise turntable design that later emerged as the Original Cranfield Gramaphone (or Rock).)

But he also covers the topic of the increased efficiency of horns, and its benefits.

One of which is the ability to use high quality, simple and low powered valve amps to create the same SPLs of other loudspeaker systems; SETs come to mind here, though this type is not without its critics (Lenard).

Secondly, having pointed out that bass horns are up to 50% efficient, and mid and treble up to 10% efficient, compared with < 2.5% for reflex loading and < 1% for IB loading, he argues that this reduces the amplitude of the movement of the loudspeaker motor thereby reducing the effects of the non linearities in its magnetic field and suspension. The less the speaker diaphram is required to move the less distortion is created.

This advantage accrues in spades with compression drivers (used from 500 Hz upwards in front loaded horns) whose diaphram movement is fast and short. The lighter the material used the greater the effect, hence the use of beryllium by various high end manufacturers such as  Yamaha, TAD, JBL (as in my 2435Bes) and Usher (who may buy in).

In my case, transferring the heart of a balanced hifi system from a 2 way floorstanding hifi system (albeit rear horn loaded) to one operating with comps from 500Hz upwards I have noticed an increase in perceived speed. There is no 'lag' in the way a compression driver works! (Though they are not perfect transducers in that they squeeze the wave through a tight gap - more of that later..)

I had previously thought of my Thorens TD124 based front end to be slightly laid back in a relaxed, classy way, but now it seemingly moves along with alacrity.

We need to look at the way horns focus the sound, as another advantage lies under the heading 'directivity'. When pictures of my set up are eventually available you will see that the horns almost completely remove the side walls and ceiling from the equation. These horns in this room certainly 'image', where they didnt do so in a previous room. Khorns are reported to image not very well.

Directivity, then,(perhaps of more relevance in PA systems) will be dealt with soon.

Jack NSM

 
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Speedracer

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