TH-18 Flat to 35hz! (Xoc1's design)

Lol, the Cyclops is a year older, a proven concept and build many times (probably more than Xoc1-TH18's). That it is less known on DIY is another matter. If you google more smart you can find out that the Cyclops is especially appreciated for large outdoor events. Actually, that was the original goal of the designer.

My bad...

But you are right about the downsides, it costs more to build, it is larger, needs two people to move around and has less low frequency extension compared to an optimised Xoc1-TH18 (and it is not optimised yet).

Considering that, especially that I would need two people to move it around, I might go with the TH-18. It seems like even though it will weigh about 150 lbs, with the driver near the bottom tilting and rolling it shouldn't be all that difficult for one person.

One more expense to consider for the cyclops is the larger grill area needed as opposed to the th-18 with the smaller mouth. From what I've seen the expanded metal needed can actually be quite expensive. I could be off base here but it also looks like the th-18 would be better protected from rain
 
Hi Tom,

Sorry Tom, I should have left out your name. My intentions were only to generalise the old fold-style and not how you use it.

Also considering the wavelengths involved, would be hard to find an acoustic reason for improved phase response and actually one can’t make that assertion based on measurement unless one has built an identical horn but laid out differently.

Many DIY designs of horns and tapped horns with a similar backwards rolled fold-style end up in a distance between the centre of the driver and the true beginning of the horn. Sometimes this is wanted but usually it is the result of errors in translating the model into an actual drawing. The distance between the driver and the true beginning of the horn has its influence on the phase response. You seem to have managed to find a solution which almost separates the horn and compliance volume above the centre of the driver. Correct me if I am wrong but it looks like there were times you had a different approach …

They reminded me of the failures when I was working out the Servodrive subwoofers. Those could fold the cone into a sort of a star shape and produce creases that ran from the center to the outer edge. To get a better feel for what was going on then, we made a Plexiglass window and found at a specific frequency, one could fold up the cones on command at that “just right” frequency (very disheartening at the time). The solution was to make a very strong cone, one a 300 LB could stand on and not collapse.
 
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Many DIY designs of horns and tapped horns with a similar backwards rolled fold-style end up in a distance between the centre of the driver and the true beginning of the horn. Sometimes this is wanted but usually it is the result of errors in translating the model into an actual drawing. The distance between the driver and the true beginning of the horn has its influence on the phase response. You seem to have managed to find a solution which almost separates the horn and compliance volume above the centre of the driver. Correct me if I am wrong but it looks like there were times you had a different approach …
Can you please show an example of this situation?
 
Many DIY designs of horns and tapped horns with a similar backwards rolled fold-style end up in a distance between the centre of the driver and the true beginning of the horn. Sometimes this is wanted but usually it is the result of errors in translating the model into an actual drawing. The distance between the driver and the true beginning of the horn has its influence on the phase response. You seem to have managed to find a solution which almost separates the horn and compliance volume above the centre of the driver. Correct me if I am wrong but it looks like there were times you had a different approach …
Can you please show an example of this situation?
 
Realized I haven't posted pictures of my TH-18s I've been using for a few months now. I went with the B&C 18SW100 (neo version of the 18TBW100). I used 3/4" baltic birch. My sound partner helped me up through the 3rd picture (1st cab) and I completed the remaining duties, including the 2nd cab. I also added cone make-up/correction (I'll post measurement comparisons later) and a decent sized broomstick brace with circular attachments. They are now finished with one coat of Duratex and are awaiting a few more coats. I also mounted some very nice (and affordable) casters with precision bearings and they ride very solidly and quietly. I cut handles and the back corner and bottom front. A pair of Speakon connectors are mounted on the back in the center. The driver is mounted with stainless bolts & washers and held snug in place with knife-thread inserts (thanks Don) mounted from the inside of the speaker baffle. Last, before mounting the last side, I filled the empty triangle with insulation (in the can) - this stuff is stickier than PL!

Special thanks go out to Xoc1, Djim, epa, jbell and plenty of others who have helped me throughout this journey. After building a couple folded horns and a couple SS15s, I can finally say I'm happy with the performance of my subs - the TH-18s. Since one TH-18 outperforms a pair of either of the other two and take up less space doing it, the SS15s will be for backup and folded horns will be up for sale.

On to the photos:
 

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Thanks gents! I really did put actual blood, a lot of sweat & some tears into these cabs. Many many hours and it was all worth it.

Here are some pictures of textured (one coat so far), loaded and broomstick-braced cabs. They now have Dayton square hole grills.
 

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Thanks again fellas!


Cresendo I noticed you were in Cali and checked out your fb page. Wish you were a little closer! I would totally go to one of your events if they were near San Diego. It's good to see djs making their own gear :)

What controller are you running? I'm considering getting into djing. Could be a great skill to have in college haha :D

Sweet! It'd be nice to have you at our show. I'd like to play in SD. I'll probably be in southern California in a few months, for fun, at Nocturnal.

I don't use a controller. I use turntables (with Serato Scratch Live). A controller would be nice to have in college tho. I'd go with either the Vestax VCI-300 or the newer VCI-380 (both are compact; both use Serato Itch) or one of the Pioneer units (bigger); one integrates Serato Itch - the other, Traktor.


Looking good man. :up:
When are you dragging these out to do some REW measurements?

I have the program downloaded on my Mac. I now just need to take a few moments to learn how to use it to do the simple measurement. Too bad there's not a quick start guide ;) Soon I hope.

I did measure the cab (before the driver was broken in) with and without cone volume correction at several frequencies at clip (amp limit light, rather) to see the benefit of cone volume make-up/correction.

The problem I ran into is with my multi-meter. When you test at clip, it should only be for a couple seconds. I set the meter to 'hold,' but voltage rises so quick, the meter gets pushed to 'over.' Anyone know of an affordable meter that will read and react nicely to quick jumps in voltage?

I would still like to test 100W/10M.
 
Disconnect the speaker when setting voltage prior to the test. Use the generator in REW to make a sine wave, note the output level & use that level in the measurement sweep setup.

WARNING
There is no benefit to running the amp into clipping for a FR sweep measurement and it can do evil things to your box that are not easily fixed.

For SPL testing get the "Goodies" and use REW's metering function. The siginal you want is in:~Keele - Tone Burst Testing Files/Composite Octave Bass Bursts

Can you fill us in on the equipment you have to test with?
 
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Disconnect the speaker when setting voltage prior to the test.

I can see doing this for max voltage tests - good solution to my multi-meter problem. But for sweep testing, I would set voltage (2.83, 28.3) at the speaker terminals to take the voltage drop over speaker wire out of the equation.


Use the generator in REW to make a sine wave, note the output level & use that level in the measurement sweep setup.

Ok, I'll check that out. Thanks.


WARNING
There is no benefit to running the amp into clipping for a FR sweep measurement and it can do evil things to your box that are not easily fixed.

Of course - I don't see FR sweeps completing within 2 seconds. I don't let the amp deliver that kind of voltage to my drivers for over that amount of time. I had a 3015LF start to smoke after several seconds. I learned my lesson.


For SPL testing get the "Goodies" and use REW's metering function. The siginal you want is in:~Keele - Tone Burst Testing Files/Composite Octave Bass Bursts

Can you fill us in on the equipment you have to test with?

I will be using a QSC PLX3402 to drive the TH-18, a dbx RTA-M to pick up the audio and an American Recorder Technologies SPL-8810 to help me calibrate REW's SPL display. Let me know if there's any other equipment or specifics you're interested in.