5 way horn speaker system project - tapped, bass, mids and tweeter passive active

Was up in the attic sorting a few things.
Came across the 400Hz tractrix horns🙂
Instant thought was, Wonder what they sound like with horn length / mouth distance adjusted alignment?

Got them down.
Treated them to better damping
2mm self adhesive bitumen damping sheet. Was left over from another job.


More than tripled their mass!

Fitted to the Vitavox S2 drivers


Get that throat nicely aligned - critical


Both installed


Then I had to re-timealign to the diaphragm alignment, as these 400Hz Tractrix are 45mm longer than the Le Cléac'h 550Hz!
Also realign the Tweeters.
Some 45mm farther back..

Then compute the new mouth alignment delay samples value.

Listening now...
There some different detail.
They are more efficient - had to throttle back the gain to the S2s a bit.
Under evaluation...
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Took some plots.
Vitavox S2 Driver , 3uF Clarity cap 1st order.
No EQ - as always.

Tractrix 400Hz in red vs Le Cléac'h in green 1m directly in front.

LH Tractrix 400 Red vs Le Cleach 550 green 1m bitmap.png

Can see the extra gain of the Tractrix!

Without the phase plot

LH Tractrix 400 Red vs Le Cleach 550 Green 1m no phase bitmap.png

Both sound great TBH.

I'd like to try a 3d printed ATH wave guidey thingy with the rippley throat some day!
Don't think I could make them..
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Where is dB scale? If it is +140 and -140 it is not very impressive. I limit to 55-110dB usually.
Silly me, too quick / focused with the snip-it screenshots. Used bitmap save instead.
See above.

I've been listening more.
This mouth alignment method brings out the strengths of the Tractrix, or perhaps that is, it reduces the strengths of the Le Cleach, when compared?
Perhaps that is more to do with the cutoff freq than profile - I do not know!

With diaphragm alignment, I prefer the Le Cleach. That's what I found before and I stick by that still.

With Mouth alignment the Tractrix are more direct and involving, the drivers detail and appealing tones more to the fore. I thought I might find it tiresome but I haven't yet.

Less mouth rounding of the Tractrix means less is going out into the room in that harmonious Le Cleach way, than direct at me of the longer narrower Tractrix. Direct vs reflexed?

I also do like a change every so often. This certainly affords me that - for free too:)
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After years of time aligning - 1st peak positive (what I call Diaphragm alignment), and as per above recently been using the horn mouth alignment method (subtracting the time sound takes to exit each horn), I finally got around to

Phase alignment😀

I've been reading up and measuring and experimenting (keeps my brain active😀).
Focus is on getting the phase plots correlated at the X/O points.

Holmimpulse (free tool) is great for this.

Here's a plot of my RH upper mid Vitavox S2 driver in green, and Raal Lazy Ribbon tweeter.
Both are on 1st order crossovers.
So the phase correlation is pretty good.


It's interesting looking at the time alignment plot differing from perfect time alignment.

Doing this for the other 5 drivers (4 X/O points per side) that are a mix of 1st order (upper mid horns), 2nd order (mid horns), 2nd order (mid bass horns) and 4th order (tapped horn subs), was more of a challenge for me.

The phase plots are more complicated and don't always follow such nice cascade flows of the above.

Doing all takes about 1 hr, inc. check / double check.
This is once I'd figured out how to do it - some great guidance in old threads on DIYAUDIO.

I did a first pass and had a listen.

What I can say is the upper frequency channels alignment have a much more profound effect on the sound than the bass channels.

Getting the phase right also affects the amplitude at X/O a bit.
This can be evened out by choice of X/O type, amplitude and slopes chosen and then revisiting phase measurement to see the effect.

Thus far it's been an interesting experience.

Again a pretty big change in what things sound like.
The presentation is noticeably different, the dynamic, perception of detail and depth / placement is different.
Width, balance and timing are different too.

Like a different pair of speakers but with the same family sound.
Same drivers and system after all, but I cannot stress enough, how different each alignment method sounds.

I'm still evaluating and tweaking (that will never stop 😀).

I think phase alignment at the X/O points has real legs.

I could never go back to basic Time Alignment again!

The day after the above, I revisited all my settings, measuring again and checking.
One or two small changes as I'd changed the SPL a fraction on the tweeters.

Listening now, I'm not sure I will use horn mouth alignment again either, and that was a big jump up from time alignment!

They are useful reference points to have.
It will be interesting to demo the differences.
I will always keep Diaphragm aligned as base reference, Mouth alignment for interest and now the best yet / end game phase alignment at X/O in the setup presets.
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Less mouth rounding of the Tractrix means less is going out into the room in that harmonious Le Cleach way, than direct at me of the longer narrower Tractrix. Direct vs reflexed?
Tractrix and LeCleach are quite similar, although their development may have been independent. Tractrix is not unlike a LeCleach T=low with no roundover.

Bjorn Kolbrek did some intersting sims comparing LeCleach with different completeness in the roll back (some of these are down lower in the page) - https://kolbrek.hornspeakersystems.info/index.php/horns/bem
Tractrix and LeCleach are quite similar, although their development may have been independent. Tractrix is not unlike a LeCleach T=low with no roundover.

Bjorn Kolbrek did some intersting sims comparing LeCleach with different completeness in the roll back (some of these are down lower in the page) - https://kolbrek.hornspeakersystems.info/index.php/horns/bem

Interesting. I'll read that.

I'm back on Le Cléac'h upper mids at the moment.

More on phase alignment..

I was wrong about the effect of phase alignment being most noticeable at higher frequencies.

More extensive A / B comparisons demonstrate it also cleans up and unlocks bass response and clarity.

I've thrown all sorts at this setup.
Simple, large complex, fast, slow, all sorts of replay gain etc, it just takes it all in its stride.

I'm next going to have a play around with different crossover slopes and types for fun.
Maybe there are advantages of steeper slopes or 3rd order with different phase shifts to 4th, 2nd etc, that are unlocked by phase alignment that I've not previously come across?
Worth playing around and I enjoy it.
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I tried various X/O slopes and X/O points (within my usual ballpark).
Minor'ish changes to phase alignment values required.

Much evaluating.
Nothing I did sounds better than my usual X/O setup first time aligned, and then redone for phase alignment.

Crossing the mids to upper mids lower than 800Hz is my goto.

The phase alignment instruction list, post #869 by jtalden in the

HOLMImpulse: Measuring Frequency & Impulse Response​

thread is an excellent help.

It took me a few goes to get nice clean measurements on all of the drivers.
Being a horn system I've perhaps less room reflections than some might.
Nice work Steve the Swede! How do your wood horns sound compared to other materials? I am curious as you have commented on my folded horns inside my guitar that are Hard Maple 1/4" thick.
Thx, the journey goes on 🙂

I've made the bass horns out of high grade birch plywood.
The tapped horn subs are braced. They play 20Hz to 100Hz, no vibrations or dramas. They still shock and awe me to this day, on the right music.
The mid bass horns are thick round rings of birch plywood laminated up. Again no nasties.

The mid horns (200Hz cutoff), (pictured out wide in current room), are a thick composite.
They didn't ring when struck, but sounded a bit hollow so
I added 3.6mm thick bitumen damping sheet to them.
The sort they sell for car and van panel damping.

The upper mids Le Cléac'h profile 550Hz cutoff (smallest horns), I made of very soft redwood pine, pretty thick.
Using the softest available for this frequency use was written up on another horn forum. Who I am I to argue, they sound great.
I didn't try balsawood though😀

I've also got 550Hz tractrix I turned, and 400Hz tractrix I made in GRP (again heavily damped with bitumen).

It's a toss up between the Le Cléac'h and the 400Hz tractrix sound wise.
I switch between the two sometimes.
But the Le Cléac'h do integrate with the room better and measure slightly smoother.

I think it's a bit different between hifi horns (that should faithfully reproduce the frequencies and amplitudes thrown at them), and an instrument like yours.
There the material you use can accentuate the sound and dramatic affect, give it it's signature sound, so it rocks out🎸🙂

I guess the need for sympathetic, great sounding resonating in an instrument is different to the need to dampen resonations of a hifi horn, so only the accurate tones come out.

I guess you do have consider the need to have a nice resonation / timbre across the whole instrument frequency though.

Or are your horns faithfully reproducing / amplifying the string and soundboard?
In which case you could try damping the 1/4" hard maple.
But you might lose a bit of SPL😱

I am enjoying following your journey on your thread.
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Yes that is correct Steve, my guitar is a producer and reproducer in one instrument, so different requirements, great to hear your horns are working so well. I am using Baltic Birch also for my soundboard. Harps use Baltic Birch for soundboards, I hear they sound the very best just before they crack. Major pressure with all those strings!
I've been messing about refining the phase alignment.
Got the procedure off pat now, I think

Do these look sensible?
It's the overlap of phase plots I'm concerned about.
Where and how much they should overlap? What best practise?
I've current gone with intersection at the X/O point, rather than then being parallel lines
Is that right?

All taken at the ear listening spot.

Upper mid horn in red, Mid horn in green

RH Upper Mid and Mid Holmimpulse.PNG

Mid horn in red and Mid bass in green

RH Mid and Mid Bass Holmimpulse.PNG

Finally the Mid bass and Tapped horn

RH Mid Bass and Tapped Horn Holmimpulse.PNG

Note the room mode bass hump at 30Hz.
Left as it is for comic effect when folk visit. Various tracks vibrate the sofa under them nicely🙂
I've also got a version of the setup with a healthy EQ cut that tames it nicely.
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I believe part of your question is how far up and down in frequency do they need to remain in cooperation. The answer lies in how loud they are relative to each other. Once each has dropped out sufficiently, you can let it go. Depending on the situation and on the builder, some choose this level to be 20dB or more.
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Thanks Allen that was the logic I needed!
What you can't hear much won't hurt you🙂

I also visited each of my crossovers points again for overall smooth SPL when both drivers are playing.
Apart from trying a steeper slope on the upper mid Vitavox S2s high pass, they are good.
The 3uF cap I irrationally prefer😀 on them actually measures like a L-R 2nd order if I re-create it in DSP!
I'm going to listen to it with a DSP X/O at slightly higher frequency.

It's interesting seeing how small X/O changes of course affect the phase alignment in turn.

The nuances are a matter of tonal taste at this point.
I've got a couple different setups to try to see what I find preferable.
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