After the 4 way now a big boys 5 way

Tractrix are go

So, I took delivery of a pair of 600Hz horns made by Cube Audio. Thanks to Greg (G-Point) for the fast delivery.

Very well packed and nicely made. The thick walls means no risk of resonance at these frequencies...

They are dinky little things, just 110mm long and 200mm mouth diameter when made to take my 1.5" JBL 2435Be drivers... Designed to work from min 900Hz.
The 2435's bolted straight on and are a very easy to mount / deal with package, compared to my larger DIY birch plywood 12 sided conicals.




I've not had too much time for hifi lately - the pressures of a new job.
So this first review is confined to the a measure and first listening impressions.

First I compared the Tractrix-600 with my conicals in like for like swapped measurement position. This is with the mic where my ear normally is - that is real world for me.

First up is the comparison of the Tractrix-600 (green line) and my conicals with the rounded mouth (red line).
2nd Going to 1/15 oct shows the same thing. Both show a good adherence to the +/- 5dB rule across the freq I am using.



def more filling in of the sub 850Hz to 1.1 KHz region and the over 7KHz too. In general a little flatter here and there too.
These were done 1/6 octave.

This evening I got the time to plonk the pair down in the system and time align them in using hornresp to measure to the nearest ms
Listening now.

Can I hear any difference then? Well they certainly sound bigger than they look. Sort of weird seeing such small horns in my system after so long looking at the larger conicals...
First impressions - not a lot wrong with that sound. Def no regression in quality/realism or dynamics and speed.
They just sound sort of right too. I need more listening time before further utterances - which will come.

I can see a further benefit - the reduced size means I can pull the rig height down some. More compact focal point for the sound. Could equal better? Perhaps. Need to try it. That will be another time though as I have to work tomorrow too!

I am now tempted to try the Auto Tech Tractrix 200's with my JBL2482's as well.

 

Excellent work Steve.
Did you ever find that with such a tall rig the image height was unnaturally stretched?
I've heard the effect with large tall panels.
Pulling the height down might make for a more 'normal' image.

 

I've not found the height an issue. Might get to be even better though so worth trying.

 

Now having dropped the height by quite a bit



Only problem now is that the rack and the mid horns get together at the back and JBL2482 drivers on the mids are too far forward to allow time alignment. Yuck - not time aligned! I can't listen to it like that.

So, I have gone from the clamp on driver solution that required too much rear protrusion, to a flange arrangement in fibre glass with the drivers bolting on - more as usual. I should have done this from the very beginning I suppose. Ironic that I will prob have Tractrix horns to replace them in a few weeks but there we are. Can DIY, do DIY...

Will be cured tomorrow and in place and time-aligned

 

indeed. All cured and modded and in place.

Sounds much better. I have learned to become critical of time alignment and the smearing esp. of the mid & high treble a lack of it brings.

Now to watch F1 SPA and a bit of listening / cycling / walking when not doing those things.

 

A little update.

I got a pair of Tractrix 200Hz horns to try on the mid bass. These are 2" and the JBL2482's bolt straight on - well after a little throat fettling, they did.

Here's a pic or two.







I also took the drivers apart and checked them over



and found the foam to be manky. Apparently it can turn to goo but mine was just sort of mouldy.



The phenolic diaphragm is incredibly strong and is what helps the 2482 play down to 300Hz. New paper gasket needed...

 

I have now had a play with a borrowed BMS 4592 ND (2" mid driver with coax 1" upper driver all built int).
This measured well enough and sounded pretty good. Hard to tell on overall sound with just one though.

Then I borrowed a pair of the same driver but dedicated mids. There's how they look



So here is how they compare with the JBL2482 on the tractrix 200 horn



This is 330Hz and 1250Hz crossover points.

The steep lower cutoff is down to horn cutoff - works fine

Then I measured the coax one against a mid only one.



As you can see - practically no difference. Amazing when you consider that one driver is 8ohm and the other 16ohm - so I have two different crossovers - where component tolerance must play in a bit?!

Here is one on horn



I am getting a pair of the mid only ones - ordered already

They integrate so well with the JBL2435Be. Keeping up much better really.

I'll be testing borrowed Vitavox S2's on a 400Hz Le Cleach horns this afternoon... Fun hobby this.

 

Here's a pic of the horns in place



and I've sprayed them up a less sanitation colour, to match the little horns.


I liked the BMS4592 drivers so much I got a pair of the MID only versions for myself. This was after Paul F on the Wam kindly lent me his pair to test thoroughly - Thanks Paul.

I have for some time now been toying with DSP crossovers - Flexibility to cross at will and try different drivers and perhaps loose some of the losses and issues with passives - no doubt gaining a few new issues with DSP actives.

I decided to get a Behringer Ultra Pro 2946 - Why? Well they are readily available, cheap have lots of support and Tenson can do mods on them

I stated out getting one. It arrived this evening. But the XLR plugs and sockets I need will take a day or two longer.

I programmed it up for basic 3 way use in all of 10 mins, using my existing crossover points.
This is just to try on Tapped horn, lower/mid bass, and mid drivers.
No time delaying yet.

Once I have this working, I will try it on the upper 3 channels to better assess SQ with the ADC/DAC.

All being well I will get it and another one modded and compare before and after SQ.

In the meantime the passives sound pretty mighty.
Let the DSP / Analogue X/O battle commence.

 

Steve, I think you need more horns,





to hide those curtains

 

Sorry I didn't mention it earlier, but it only crosses my mind now. DSP crossovers will introduce time delay, even when not using the delay function. The A/D processing and D/A takes a little time in itself. You might want to bare this in mind when using part passive part DSP as a phase shift might be needed to match them.

 

Yes, I realise it will delay things.
I'll measure how much during the weekend.

The test box is here and I've had it running on the Tapped horn, Mid bass and mid horns.

Removing the passive components does bring out some subtleties I've not heard before - particularly on the mid bass and mid drivers where I had slopes for both low and high frequencies = more components = more mush.

The tonal quality of the Behringer through the mid horns is not bad.

I def need another box to do it the whole 5 way, and to play some more. Like to try the auto time align - I could do it just on the left channel and see how it goes / measures.

Basic set up and playing with slopes, X/O point etc is soooo easy.

I found 0dB input and 0 or perhaps -3dB to work well with my preamp and power amps. But there is too much gain on the output as you say Tenson.

Do you attenuate at line level after the DSP crossover? If so, what sort of controller? My prob is that I would need 10 inputs / 10 outputs.

Wife likes em They are more subtle without the million lumen back lighting them.

 

With the DCX I used to have a 6 channel transformer volume control. I don't have it anymore though, and if I were to use a DCX in my main system I'd put it after the pre-amp with modified analog inputs.

 

Interesting. 10 Way limits me a bit, perhaps a DIY jobbie...

Here as some measurements

Some measurements

All 5



This was after the following tweaking from 48 L-R on all as was set originally.

Here's how the individual drivers look

Notation.
OFF = no crossover / Cross Freq, BUT 48 = Butterworth 48dB/oct. L-R, BES etc

Tapped set too OFF / BUT48 90Hz



Mid bass 90Hz BES24 / 303Hz BES24



Mid
303Hz BUT24 / 1240Hz L-R48



Lowest 3 together

 

I borrowed a 2nd DCX 2496 and plumbed both in as mono 5 channel.
After some playing around wit slopes I got a sound I was pretty happy with.
Then I used the auto time and phase alignment tool.
This uses a sort of chuffing like a steam train pulling out of a station and is presumably a square wave form as that is easiest to pick up the first proper positive peak of the sound wave.
Unmute all 5 channels, set the volume to loudish but not deafening, and press ok.
it them cycles through each of the drivers, listening via the cal mic that is auto powered by the DCX.
!one side at a time it is all done in about 2 minutes.

I then had a listen and it sounded better - the upper registers are back to what I am used to and feel right / in time again.
Having had the bass and mid on DSP with associated delay, and the upper and tweet on passive it was not that happy a sound. Delay in the overlap of the critical 800 - 1500Hz region - not ideal.

Anyway I, wondered how the DCX's would handle to tapped horns.

The Antimode DSP i use on the tapped horns adds about 3.5ms delay. The pre-pulse (off teh back of the driver) and the main pulse (off the front and up the horn, as it were), are separated reportedly by about 7ms.
I assume the machine aligns to the prepulse as the measurement appears to be first positive peak.
Taken using the square noise setting.

Tapped horn is blue line, mid bass red. I used the Square wave function in Holmimplulse. I think I am doing it right...



6m between wave peaks on the tapped horn!
This is of course looking at the mid bass and tapped horns only.

So, it appears the mid bass has been suitably delayed as have all the others - a quick check confirmed this.

I can now bring all my drivers forward if I want, reducing reflections off the backs of the adjacent horns.
I could also now run the mid bass (biggest horns) nearer the back wall if I wished.
I did model it in Hornresp as Ang 1.0 x Pi, meaning it is next to floor and one other wall.
Up until now I have had it a fair way away to accomplish physical time alignment.
I tried this, and it did change the bass character a bit - not sure I like it more, perhaps just a bit different.

More messing about to follow.

 

Good read, thanks Steve Don't forget you can use parametric EQ to correct the worse driver response errors.

 

Yep, aware of that. I am a bit hesitant about it for some reason, of course I can go back at the click of the button
Irrational!
This evening I moved the mid drivers back and re-aligned them all again.

 

I didn't like the drivers pushed back, moved forward and aligned again.

Other happenings are trying 24dB / oct Linkwitz-Riley slopes on the upper 3 channels, keeping 48dB/oct on the bass.
Was not so convinced at first, on time aligning again it sorted it out. Not quite sure why re-aligning again after going to 24dB/oct slopes would make a difference. Perhaps the first peak positive or what ever the 2496 DCX uses or other cleverness is seeing a difference.
I am now a 24dB/och slope fan.

I've got 3 bars of input on the 2496 DCX, at normal listening levels and 1-3 on the output. it is sounding rather good actually.

Yesterday I swapped the JBL2482's back in (was using BMS 4296 mid drivers).
Hmm the JBL hit spots that the BMS can't. It's the tone! Also more lower freq punch!

 

Well I did a bit of OP stage modding on the 2496 DCX but it did not really take me anywhere. I put the passive X/O's back on and they just blow me away... So that is that for the time being on DSP.

In the meantime I have been busy making a different type of Bass horn.

This involved the madness of cutting 36 angled rings for each horn with a jig saw.



Gluing them together and then



and then spinning slowly on a Heath-Robinson horn lathe removing excess material and getting the correct hyperbolic profile.

Took a while and lots of dust.

The plans



I later found out that Horn resp can spit out the exact ring dims and correct internal angle of each ring - Clever chap David Bean.

The 2nd one was a bit easier - less material to remove and only a bit of filling / sanding.

The driver for this is the Hyperbolic profile allows for a smaller mouth and then I can lower the other drivers = better imaging possibly.



Trialling


More to come...

 

After listening to the first one I made it sounded pretty strangled in the upper registers compared to the big conical.
This was with the throat size that hornresp auto calc function gave for optimal freq resp for the drivers I am using.

That and SQ might be different.
I enlarged the throat a few times from 14cm dia ~ 230cmsq up to 20cm dia ~ 314cmsq. THe upper range improved sound improved a lot with this.

I was then confident to launch into making the 2nd one - It's hard to listen to just one side at a time and really tell what is going on.

With the 2nd one finished I was able to have a really good listen and measure.

Not bad sound, integrate really well with the mid horns - other have reported Hyperbolics being able to this.

Measuring, the lower had quite a stepped cutoff from 120Hz to 90Hz.

Time to load the back chamber - horn resp recommending just 14lt. Means I would need 12lts of stuff in the 31lt back box.

First I tied 1lt bags of sand



I only had enough kiln dried sand for 9lts. Getting that in there was not easy - I was leaving the felt in place.

I turned to expanding foam



This fills all areas. Once set I cut it around the driver for space and the cables. Then quartered it.
Each 1/4 piece I put in a poly bag and sucked the air out.

I then measured the volume using a large bucket on the till filled up to the spout. The displaced water was collected and measured.
I pared the foam down to give me 12lts.

With this in the back box I got the following measurements

In blue - no vol reduction. In red 12lts reduction. This is from the listening position - in room



Pretty damn good! As you can see the red is pretty flat from 330Hz all the way to 100Hz, +/-5dB in room is acceptable. From the listening chair it is amazing!

These are the sorts of measurements you find any commercial speaker manufacture ever releasing!

These are my X/O points. The chamber vol certainly is critical.
I have more fine tuning - when I can be bothered...

Sounded much better. Comparable to the conicals in the lower registered, a little but faster / tighter bass in the other freqs. Very clear, fast clean sound.

The next job was to lower the mid and upper / tweeters to suit. I did this as a quick fix. Extending the hanger rods on the 24kg mid horn / driver. Changing the clamping arrangement on the upper horn and simply sliding the tweeters down.



I will modify the stands at some point to suit. Plus paint them room wall colour I think. I might make some very thin face plates to match the others too for the ribbon tweeters too...

The sound is very good. The bass very involving and more'ish.

Lowering the other drivers has led to a very positive effect on the imaging. It was good before - now it is great.

Next up - I am expecting my Vitavox S2 upper driver to be refurbed and with me by mid Feb... Matches my already refurbed other one.

Then it's a Vitavox S2 / JBL2435Be shootout.

These are on the very critical 1.25 - 10K+ KHz range.

I have already had a BMS Mid VS JBL2482 shootout - the JBL's won that one.

So now I have 6 front loaded conical horns in storage! From large bass to small upper horns...