135Hz Segmented Horn Midbass Build

[xrk971]

That's why we love horns. The efficiency requires less cone movement hence distortion is super low. Clarity of vocals must be stunning.

 

[JShadzi]

Hey everyone, I've got an update!

Hey Everyone!

Wanted to share these horns I've been working on, I initially built them last fall (like November), the midbass horn is tuned to 135hz and an Inlow design. He supplys plans, I took my own take on constructing them but was able to keep them acoustically accurate to the design, they measure quite accurately to the Hornresp modeling. They use a B&C 12PE32 12" midbass woofer, man this thing cracks, 100db efficiency, can't play bass to save it's life but it has a cone so thin it only has one side and boy does it do midrange and midbass well.

I built one first from Aruco ply and then the second from Maple ply, they are raw wood. Each one vary a little dimensionally but they measure basically the same.

The high frequency horns are obviously DIYSG Seos 24s with the Radian 745PB 1.4" compression driver

I originally, concerned about time alignment, mounted the Seos 24 to the back of the midbass horn so the voice coils of the 12" and CD were in alignment, I had them set up active and wasn't really happy with the sound possibly due to CD diffraction off the midbass horn, so I put them in the corner and worked on other projects. But last week I pulled them out and did some simple passive XO for them and built some new Seos mounts and wow, I'm thrilled with how they sound!

They measure quite flat from 100-18k and I brought the CD down to give things a downward FR, the CD is about 3db quieter than the midbass for a BSC effect and warmer sound. XO is around 550hz, 12db LR, I messed with a few configurations but ended up with a totally symmetrical XO with the same values in each, that sounded and measured the best.

Everything in the mounting stands are balanced (neither horn are screwed to anything), the midbass horn balances in the stand and the Seos sits securely in the base, the whole setup is quite stable and I really didn't feel like screwing holes in anything.

I sort of went "rat rod" with the XO and stands using some wood from some pallets at work that was nicely weathered. I figured it hearkened to the old fashioned heritage of horns =) The XO velcro to the midbass horn.

Here is a couple video of them playing with some closeup video detail, see my YouTube for more videos of them playing:

https://youtu.be/e_1PmbQ43Gw

https://youtu.be/NN1p-hyOtDA

These things sound incredible, BIG with wide and deep imaging. They are so fast, high hats CRACK, the horns are so smooth, its a different sound than the average dome tweeter but when that sax starts playing and you close your eyes, it is eerily realistic.

I'm not sure what I'll do about bass in the future, I have a few other big projects but will likely pair them with an upcoming 18" Aura build I'm doing.

Lemme know what you think, I had a blast making these and listening to them.

Thanks!
Javad

More pics

 

[POOH]

That's really sweet!

Now what are you going to do for the bass?

 

[carpenter]

I'm proud of you, Javad! That graph is interesting, as my room measured quite a bit flatter. That's a pretty healthy dip at 300 hz.

 

[frangus]

Looks cool Javad!

Is there any delay in the passove crossover? Maybe active will soubd better in the new position with digital delay?

I wonder if the dips are floor bounce cancellation since the horn is raised up from the floor slightly

 

[LewinskiH01]

Great build and great pictures, as usual, Javad! Thanks for sharing.

Glad to see you using a Seos 24 with a xo of 550Hz as this interests me too. How far from the mouth was the measurement taken?

I keep going back and forth between twin 10" midbasses per side in sealed enclosures, and a midbass horn like yours. Are you liking these better than your prior direct radiators? Assuming power is not an issue.

Are these keepers?

 

[JShadzi]

I'm proud of you, Javad! That graph is interesting, as my room measured quite a bit flatter. That's a pretty healthy dip at 300 hz.

Thanks John! Your help was incredible along the way to building these!

The dip really isn't that big, peaks at about 5db and it's quite narrow, looks worse than it is as I used a pretty fine DB scale. This was also a quick in-room measurement about 4' from the mouth so I'm sure that's part of it.

Thanks!
Javad

 

[JShadzi]

Looks cool Javad!

Is there any delay in the passove crossover? Maybe active will soubd better in the new position with digital delay?

I wonder if the dips are floor bounce cancellation since the horn is raised up from the floor slightly

No delay, I played with delay quite a bit with active and never really heard a difference even a/b testing it.

I can easily switch to active and I have all the hardware to do it (minidsp DA8 and 6 Adcom amps) and I may mess with it more but this passive setup sounds so smooth and sweet I'm tempted to just leave it.

I love active and I've built a number of active speakers this past year, but one thing I've noticed with active is what I'll call "over-tweet-the-****-out-of-it-itis" where you can never leave well enough alone and all of a sudden you find yourself obsessed at 3am trying to smooth out that .5db dip at 1.13kHz, that feeling like anything is ever done is hard to come by.

The main issue with this is what we're measuring isn't always what we're hearing and it can be tough to reconcile. Anyway, sorry for the tangent, I digress =)

Thanks!
Javad

 

[JShadzi]

Great build and great pictures, as usual, Javad! Thanks for sharing.



Glad to see you using a Seos 24 with a xo of 550Hz as this interests me too. How far from the mouth was the measurement taken?



I keep going back and forth between twin 10" midbasses per side in sealed enclosures, and a midbass horn like yours. Are you liking these better than your prior direct radiators? Assuming power is not an issue.



Are these keepers?

This setup is a keeper yes, and anyone could run this off a 1-watt amp, get to 100db and be thrilled with the sound.

I say you have to do it and see, it's just a different sound, in a good way, but to say it's better I can't do. Measurements were in room about 3' out of the mouth.

Of all the speakers I've ever built when I have guests over these get the most attention, and they hit 110db effortlessly with a 100watt amp, the same high hat you've heard 1000 times will startle you, really cool speakers.

Javad

 

[frangus]

No delay, I played with delay quite a bit with active and never really heard a difference even a/b testing it.

I can easily switch to active and I have all the hardware to do it (minidsp DA8 and 6 Adcom amps) and I may mess with it more but this passive setup sounds so smooth and sweet I'm tempted to just leave it.

I love active and I've built a number of active speakers this past year, but one thing I've noticed with active is what I'll call "over-tweet-the-****-out-of-it-itis" where you can never leave well enough alone and all of a sudden you find yourself obsessed at 3am trying to smooth out that .5db dip at 1.13kHz, that feeling like anything is ever done is hard to come by.

The main issue with this is what we're measuring isn't always what we're hearing and it can be tough to reconcile. Anyway, sorry for the tangent, I digress =)

Thanks!
Javad

I concur. If it sounds good, leave it alone. Sit back and enjoy the music ₩

 

[JShadzi]

Ok time to fire this project back up!

I've been enjoying these horns for the last year or so but haven't had a subwoofer solution to go with them.

I got a bug to build some subwoofers so here we are! Four 6.5 cubic foot enclosures will house 4 PA460 pro subs, tuning will be in the 25-35hz range. I'll be designing the enclosures for 2 configurations.

1- they will be able to be attached in pair to each other back to back in a dual opposed configuration, this will be how they'll be used with the 135hz horn and Seos24z which will both sit on top, and be crossed over around 115hz to the 135hz horn.

2 - stacked on top of each other with the Seos24 on top, crossed over at 500hz, the PA460 actually plays quite cleanly to 1000hz.

Got all the wood cut on Wed and have a great start by Friday morning.

Total wood is just over 3 sheets of plywood.

More to come!
Javad

 

[JShadzi]

Little update, coming along but 4 6ft cabinets simultaneously is quite the juggling act!

To continue the "rat rod" theme the front baffles will be made from reclaimed pallet wood

First I cleaned it all up with a brush and checked for any nails or metal

Then I trimmed and squared the ends

Then ripped them to create two parallel sides

Clamped up gluing

And out of the clamps after an hour

Driver and port layout

Center points for driver cutout and ports drilled, then transferred to the front pallet wood baffle which is doweled in 4 places to accurately locate it

4 subs with baffles doweled and located

All baffle through holes routed out, the 5" ports will attach to the pallet baffle, the sub will mount in the base baffle and be recessed by the pallet baffle

Little trick when routing large holes, leave a few perforations till the end

Sides doweled, glued and clamped

 

[manninen]

pa460 has quite low mms for 18" but inductance is so high.

for that price they cant put any copper inside.

i find 135hz horn bit rubbish, to get it play all the way 120hz you must put it to floor, to get it play all the way up you must lift it up (5-6meters listening distance helps bit upper register from floor)

but yeah crossing 120-170hz, is pa460 fast enough with its modulated motor?

i by the way have 52cm distance difference rear cover from horn back enclosure and front of 18" and zero dsp delay needed, 135hz bends phase curve a bit

 

[JShadzi]

pa460 has quite low mms for 18" but inductance is so high.

for that price they cant put any copper inside.

i find 135hz horn bit rubbish, to get it play all the way 120hz you must put it to floor, to get it play all the way up you must lift it up (5-6meters listening distance helps bit upper register from floor)

but yeah crossing 120-170hz, is pa460 fast enough with its modulated motor?

i by the way have 52cm distance difference rear cover from horn back enclosure and front of 18" and zero dsp delay needed, 135hz bends phase curve a bit

They are cheap and a good start, the enclosure will. E able to accommodate virtually any 18", but IME the PA460 will do very well in this range and even play well to 1000hz. The 135hz horn has no trouble playing in the 135-500hz range.

 

[JShadzi]

Started the morning with 4 enclosures with 4 sides

A little overhang on the sides needed to be flush cut, BTW if you're not using a 1/2" spiral up cut dual bearing bit, check it out you're missing out!

Next step to cut out the pallet baffle woofer flush hole plus port provisions, 2 5" ports per baffle. BTW these enclosures will be able to accept virtually any 18" on the market for future possibilities

I always clean up the router cut with a 2" sanding drum, works very well

All cut, baffle is located with 4 dowels

Sanding the backs so they'll take adhesive well

5" port tubes all cut to 9", this will give a 35/25hz port tuning option if one port is plugged

Back of baffle with receiver groove

Port tubes secured with wood glue and Loctite construction adhesive

Ready for glue up

Glued and clamped with Loctite heavy duty construction adhesive, I used this as the pallet baffles have an irregular surface that wood glue may not be viscous enough to grab.

Thanks,
Javad

 

[JShadzi]

Out of the clamps this morning, 2nd one in the clamps and 2 more to go. I'm letting the Loctite cure for 12 hours as the pallet baffles aren't perfectly flat and do load up a little when clamped.

 

[JShadzi]

Work continues! These showed up, and a damn nice driver for $90!

Tested out my port tuning, spot on!

One port blocked 24hz

Both ports open 32hz

Model for both, 12db XO at 110hz included, 250watts

Port velocities more than acceptable for both configs, both w/in xmax or so

1/2" Round over on ports and 1/4" roundover on baffle driver opening

And I had a special helper =)

Thanks!
Javad

 

[JShadzi]

Flushed up the baffle

And 45 degree bevel on all edges

And where all 4 stand

Next step is some sanding and filling, some more detail work and finally a few coats of Danish Oil.

Javad

 

[JShadzi]

Did some filling and finish sanding on front baffle interface to main cabinet

Some of gaps were as big as 1/8". Thanks, Javad

 

[JShadzi]

Since these subwoofers will be configurable in dual opposed or stacked, I made some brackets to connect them together in different configurations.

Here are the pieces cut and beveled

Holes drilled for fastening knobs

Fixture for transferring mounting holes and spacing brackets the same

Threaded inserts used on the inside of the enclosure, these are M8x1.5mm

Test fit, dual opposed

And stacked, dual bolt patters allow both configurations

Binding posts installed