Azura Bass Horns

[statman]

I put this article in my blog , but think it will be interesting to some here.  A great Australian design that perhaps doesn't have the recognition that it deserves. 

 

 

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Over the years I've had a few of Martin Seddon's Azura horns.  They are tremendously impressive - there's nothing else like a horn for dynamics  and "you are there" sound quality.

But I've never been able to live with them for long term. I need speakers that are accurate, and whilst its possible to use all sorts of implementation to get anything accurate these days, it isn't always agreeable.
Horns do have a "horn" sound - some call it a "honk" or "quack", but its just a slight tinge to the midrange that cuts a little naturalness from the response. Or at least that is the impression I've always had.
My Supravox 215 field coils in a large OB (see previous blogs) are the most natural and musical speakers I have , amongst my 4 systems set up in my (big) listening room.

All the previous horn systems I've had used bass reflex, Onkens or sealed enclosures for the bass frequencies. I've never had a full horn system where the bass is also produced by a horn.
The reason for this is that bass horns that can go down to the necessary 40 or 50Hz are BIG - they need a lot of floor space and dedication to own.

However I've always wondered if a horn system really needed to be a complete horn package , where bass, mid and treble are all covered by dedicated horns, and the resultant synergy produces a sound without compromise and weakness's.

Listening to Martins all horn system piqued my interest and for too many years now I've had a set of his 160Hz Azuras , with the intent to build his matching 50Hz bass horn.

Martin uses the Line Magnetic LM555 field coil compression driver in his 160Hz horn. Its not cheap at $US5000 a pair. Its a direct copy of the very famous and desirable Western Electric 555.

The Atlas PV5-HD costs about a tenth of the price and is reported to have been based on the WE 555, with some compromises, a phenolic diaphragm,  alnico magnet etc.

Martin suggested that it could be quite good in the 160 so I ordered a pair and we did some measurements that were very encouraging.

But this time I definitely wanted a full range horn system, and the picture you see here is the result of a very intense week of woodworking.

The bass horn is time consuming to cut out, and surprisingly quick to assemble.
Its a L shaped horn, which gives the horn length in a reasonably compact  shape (and appealing to a Ducati L-twin owner!)
Cut off is 50 hz, and simulation looked very good.

The driver is a Supravox 285 RTF , courtesy of my friend BobM , and ideal for this situation.
At this stage there is no enclosure behind bass driver, but building that soon. It can be used with or without enclosure.

 

 

 

With Enclosure
 

 

Without Enclosure

The 160Hz horn is mounted above the bass with wooden supports , and the treble tweeter is between the two.

The tweeter is a Yamaha horn with JA4281 compression driver- fairly common but it does the job.

The crossovers are something I just cobbled together out of my junk box to get it going - simple 6dB slopes with an inductor on bass, and caps on mid and treble for  crossover points at 300Hz and 2KHz.

Martin has a lot of experience with some sophisticated lower order crossovers (?) and I'll be investigating these soon.

Seperate amps for all horns, so 6 tube amps, all with level controls for very fine adjustment of tone.
Its consuming, but active/passive gets the results I require.

So how does it sound?

Well if you've only heard horns with non-horn bass , you haven't heard a horn system!!

The most obvious thing is the very low levels of distortion, bass is very clean and defined , quite different from conventional moving coil drivers and just so involving to listen to.

As is the midrange , that "honk" is virtually gone, and I think further work with crossovers/amps/adjustment will eliminate it completely.

I get tired of trying to describe sound , so I'm just going to say its as good as I've heard.

It takes a little re-conditioning of the mind , as there is so much that is so different , that you wonder if it is "too good" , but it soon becomes obvious that this is what it actually does sound like.

Then I just put record on after record, as if hearing them for the first time, and its only early days for this system!

I'ts a shame most won't get to hear something like this, let alone have the space (and dedication to fine music) to actually build it.

http://www.azurahorn.com/index.html

 

[davewantsmoore]

 

I have a similar bass horn to this, use with PSE-144.     I was going to construct using a similar method to Martin.... but I ended up turning it on it's side, and using a wider and shorter mouth (so it looks like an "L" when viewed from above - - instead of from the side like here)

 

... this allowed the horn to be built into the room corners better (I have limited space, like most people).    The high aspect mouth, means I don't run it up very high, but don't need to with the PSE cutting in around 300Hz.

 

1 hour ago, statman said:

Supravox 285 RTF

I couldn't find this driver?   Can you link? or confirm the actual model?

 

I use an AE TD15M driver in mine.... although this isn't the greatest choice due to the too low Fs/high VAS.    I have new drivers to try, but they will need a longer horn - and building another horn 'just to test' obviously isn't a small project.

 

Quote

Without Enclosure

How did you model that in hornresp?

 

Martin mentioned this too me also... and I was quite surprised that's how he runs it.

 

In theory it would work very poorly with no rear enclosure .... likely a lot worse than that sim shows.....   but in practise lots of 'badthings' don't sound like garbage, when theory says they oughta.    I would definitely shoot for the smallest rear enclosure possible.

 

Quote

lower order crossovers

This always seems like a real challenging endeavour to me....   If, an example, you have a mid-horn to cross over to, then it naturally has a 24dB(ish) / octave high pass response.

 

So the bass horn needs to have a 24dB/octave low pass response to match this.    This means the bass horn needs a ~18dB/octave low pass electrical filter (ie. not a very "low order" filter)  added to it's natural 6dB/octave low pass response.

 

Otherwise, it's into the territory of not having each driver totally in phase with the other....

[davewantsmoore]

Oh, so I just noticed how small the "285" Supravox drivers are.    Is that really the driver you're using?   What is the throat size in comparison?   (It seems like you would have "compression ratio" = 1)

 

In mine I went with a 15" driver (sd=850cm^2) firing into a throat of 650cm^2

[mwhouston]

Every horn (think Klipsch and Altec) I have heard I have disliked and a quad loving buddy has agreed, he has heard no good ones also. But at the beginning of this year I thought if ever some Aletcs came up cheap I'd get them. That happened some months back and to the Altec 511Bs I added a pair for Italian Faital Pro poly diaphragmed compression drivers. 

 

These sit on 12" woofers in s sealed box. I X to the horns at 1100hz, 2nd order woofers and 3rd order horns. Talk about a turn around, I absolutely love them. I had to drop the horns 20db to match the 92db effcient woofers but the whole exercise has been a a tremendous revelation. 

 

Your's are too big and the wife (who has her bags half packed all the time) would finishing packing and walk. Best stick with what I have and really are very happy and want no more. 

 

Good luck with your horny project.  

[nzlowie]

I'm pretty (very) happy with my 340 horn's atop the DTQWT by Troels Grevensen. Good size box and horn loading, what else do you need.

[mwhouston]

24 minutes ago, nzlowie said:

I'm pretty (very) happy with my 340 horn's atop the DTQWT by Troels Grevensen. Good size box and horn loading, what else do you need.

Have you tried your horns with SS amps. I got a big (but pleasant) fright when I powered my Altecs with a 150W class D monoblocks. Of course the baas from the 12 woofer lifted but the horns actually sounded fuller,richer and better. Detail increased but didn't become over bearing or tedious. Lets know if you have tried it. 

[nzlowie]

Have you tried your horns with SS amps. I got a big (but pleasant) fright when I powered my Altecs with a 150W class D monoblocks. Of course the baas from the 12 woofer lifted but the horns actually sounded fuller,richer and better. Detail increased but didn't become over bearing or tedious. Lets know if you have tried it. 

The Weston Topaz feeds the mid and tweeter, class d DSP amp looks after the bass section.

[mwhouston]

I have the opertunity to do similar. I have a couple of DIY 2W 6L6 SE UL amps I could use to drive the 109db efficient Failtal pro compression drivers on the Altecs and use the big Ds to drive the woofers. I would build a new or mod my current electronic Xover to feed just 1100hz  and under in to the Ds to drive the woofers and use the passive Xover for the horns.

 

have you tried the horns with an SS amp? 

 

 

[nzlowie]

 
have you tried the horns with an SS amp? 
 
 

I did have them running off the Pass ACA for a while, did sound good but not as smooth as the Topaz....

Good thing about the dsp amp is you can dial in some delay to help with alignment.

[THOMO]

Gainclone amps can sound excellent with horns .Over the years of trying all sorts of amps with my Edgar horns a simple 3876T gainclone sounds the best.Everything else sounds a bit hazy and lacking in dynamics by comparison.

[Stump]

Azura Bass Horns are world wide.I know of a Singapore dealer using them.

[davewantsmoore]

3 minutes ago, Stump said:

Azura Bass Horns are world wide.I know of a Singapore dealer using them.

?!?  There's no bass horn in those pictures

[Stump]

7 minutes ago, davewantsmoore said:

?!?  There's no bass horn in those pictures

My mistake.. ESD are all horns..

[almikel]

On 11/11/2018 at 9:51 AM, statman said:

All the previous horn systems I've had used bass reflex, Onkens or sealed enclosures for the bass frequencies. I've never had a full horn system where the bass is also produced by a horn.

I'm the same - I run PSE144 horns 350Hz up, sealed 18" bass below that down to 60Hz, and a tapped horn sub 20-60Hz.

My PSE + sealed 18 "stack" - the 18" is an Acoustic Elegance TD18

My T20 tapped horn sub - runs twin 12" Rythmik drivers and amps

Takes up more room than I'd like, and I've been too lazy to mount it outside the room, which was the original plan

 

On 11/11/2018 at 9:51 AM, statman said:

Well if you've only heard horns with non-horn bass , you haven't heard a horn system!!

I've never heard horn bass - I should seek some local systems out!

 

On 11/11/2018 at 9:51 AM, statman said:

The most obvious thing is the very low levels of distortion, bass is very clean and defined , quite different from conventional moving coil drivers and just so involving to listen to.

 

My bass is not horns, but my sealed TD18"s barely move even with the wick turned up - and the clean bass brings a smile to my face constantly.

I agree that a key is the low distortion, but in my case also the absorption in the room cleaning up 120 - 500Hz, and a leaky room helping reduce resonances below that.

 

The sub bass from the tapped horn is clean and effortless also.

 

Very nice build - well done!

My DIY skills don't extend to anything curved, and I envy all those who can drive Hornresp well...

...and where would we be without the people who develop these amazing free tools such as Hornresp, REW, QRDude, WinISD etc - huge kudos to them!

 

cheers

Mike

 

On 11/11/2018 at 9:51 AM, statman said:

All the previous horn systems I've had used... Onkens ....for the bass frequencies.

ps 1st time I've heard of an "Onkens" design? had to google it