Tapped Horn Build TH-SPUD Discuss Tapped Horn Build TH-SPUD in the DIY Subwoofers and Build Projects forum; Tapped Horn Build TH-SPUD For an exercise I have decided to build a Tapped Horn. Tapped Horns for those unfamiliar are the latest brainchild ...

**aceinc** · **02-14-09, 11:19 PM**

For an exercise I have decided to build a Tapped Horn. Tapped Horns for those unfamiliar are the latest brainchild of Tom Danley, who has brought sound to the world in ways others have never thought of. Some of his designs include Servo Drive, Unity Horn, Synergy Horn, and Tapped Horn.

At any rate I have been on the side lines watching various forums, waiting for an opportunity to build something that had a reasonable chance at being close to one of his designs so that I could determine what all the hubbub was about. I wanted to build something physically similar to one of his designs rather than design one from scratch because I don't trust my design prowess.

Danley Sound Labs has recently started building a HT sub with reasonable specs, and somehow a copy of a design document with physical measurements has gotten on to the web. Other folks identified the drivers used as Tang band W8's The name of the sub is TH-SPUD. Well, I took the design, plugged in the horn geometry to a program called HornResp, and tried two different types or drivers, the Tang Band W8's and the CSS Trio8's. The Trio8's make prettier graphs.

The Trio8's are a bit pricier at $80 each vs $65 each for the WB-740P, but in addition to having a better HornResp plot, they are 8 ohms each, using two should yield a nice 4 ohm enclosure.

I started the thread by saying "For an exercise" and what I mean is that once I am done with testing it, I do not have a place in my home for it. I have an associate that says he has a place that it will fit in his house so I will be giving it to him. I will be testing it against my current set up which includes two 10" Titanics, and 1 Rythmik Audio DS15. If I get some help, I might have a sub shoot out in my front yard (rather large) with the TH-SPUD clone, the speakers just mentioned and a 12" ported sub I built a number of years ago.

The amp that currently drives the Titanics, and will be used for testing the new sub is the an older NAD stereo power amp rated at 100 Watts RMS per channel @ 8 ohms. I am currently running it into the Titanics, 1 per channel. It can be set up bridged I believe, but I've never tried it.

Hornresp says I can get about 113 DB at 20hz using 200 watts with this enclosure/driver configuration. I will be testing with REW.

I am at the stage where I have most of the construction complete, and should finish it tomorrow.

I will post pictures in future posts.

Paul

**aceinc** · **02-15-09, 12:10 AM**

I actually do have a question for the masses.

Does anyone have an educated guess as to whether any acoustical treatment of the horn's path would have a benefical affect on the quality of quantity of the sound?

For no particular reason I was thinking of treating the bends with felt or foam padding.

I haven't made up my mind, and I will be sealing the cabinet later today, if anyone has any input I'd love to hear it.

Paul

**Mike P.** · **02-15-09, 12:10 AM**

The Danley Sound Labs TH-SPUD has some rather impressive specs. 19 Hz – 125 Hz - 3 dB, 94 dBSPL, and 123 dBSPL Peak is quite good considering the use of two Tang Band W8's. I'm looking forward to your testing of the clone against the 10" Titanics, and the Rythmik Audio DS15. I assume your cabinet size will be the same as the TH-SPUD, 11" x 48" x 45"?

**aceinc** · **02-15-09, 12:33 AM**

Due to my wood working skills (or lack therof), the actual size is 11" x 47-5/8" x 45-1/2". I am using POS (Piece Of Shizzle) Home Depot 7 ply birch, which is full of voids. I have followed the dimensions as closely as possible with the exception of the 60 degree angle piece for the second driver.

Since the Trio8's are fairly shallow, I offset the portion of the throat by the thickness of the wood (18 mm) and the Trio fits nicely.

All joints are butt joints which are glued & nailed with 2" brads. I didn't think it was needed but I did round over the wood in the labyrinth with a 3/8" round over bit.

Since I can get to both sides of both drivers, I will be mounting them with 10-32 x 1" phillips pan head screws and nuts.

If anyone has a good idea on how to mount the driver access panel so that it will seal well and can be removed and replaced I am all ears.

Paul

**Mike P.** · **02-15-09, 07:33 AM**

Some pics of the cabinet and the access panel would be good, it would make it easier to see what you're up to.

**aceinc** · **02-15-09, 11:20 AM**

Here is a picture of the access opening. I have not installed the top panel yet.

I also added a view of the innards.

Paul

**Ricci** · **02-15-09, 01:06 PM**

Subscribed...

Are you documenting this guy at DIYAudio too? Post up your HR modeling if you don't mind. I want to see what you've got going. I'm thinking of trying a small 30hz TH later this year. Has anyone seen the internals on a THSpud yet? I'm wondering if it has any resonance control ports like the DTS-20 does? Do you run REW or something similar that you can get some FR response graphs later on?

**Mike P.** · **02-15-09, 01:31 PM**

The access panel mounts to the left and right sides as shown in the pic. Add a 3/4" x 1" x the width required to the top and bottom to complete the frame. Add 1/2" weatherstripping to the frame and screw the panel on.

**aceinc** · **02-15-09, 01:53 PM**

I'm asking questions at DIYAudio collaborative tapped horn, but unless I start a new thread my build would get lost in the sauce, so I decided to post my build thread here. I may start a build thread there as well.

I was going to attach the panel to the top & bottom of the enclosure, as the top & bottom sit inside the sides. Do I need the extra wood? Things might get tight in mounting the drivers.

So you are suggesting standard wood screws? About 3" centers?

I have PE 260-540 speaker gasketing tape. My concern is how to get the tape joints to seal.

Paul

**aceinc** · **02-15-09, 02:18 PM**

Below are screen prints from HornResp. If you notice the EG box, it has 28.28 which translates into 200 watts at 4 ohms. Each of the Trio 8's are rated at 200 watts at 8 ohms.

In my research (Mainly reading & partiicipating in other forums) I am led to believe that the wild fluctuations at the higher frequencies are not really there when the sub is built. Some folks postulate that it is due to the Hemholtz effect caused by the multitude of folds. This is of course one of the things I want to empirically test.

**collo** · **02-15-09, 02:26 PM**

Quote:

aceinc wrote:

Do I need the extra wood? Things might get tight in mounting the drivers.Paul

Adding the extra wood will give you a complete surface for the tape to sit against, ensuring a good seal. The corners can be sealed with silicone (from the inside of the box) before the door goes on.

It looks tight, but you can tilt the drivers as they go in. With careful checking before you glue, you should be able to get a wide enough piece top and bottom to get your screws into.

**aceinc** · **02-15-09, 09:19 PM**

Well my first test results;

The purpose is to loosen up the drivers.

Playing various "ultimate bass" videos off of YouTube through my Carver Reciever.

My 16 year old son's comment, while standing right in front of the sub, "that isn't a sub, it's an air conditioner."

My lovely bride working on her computer about 5 feet a way said she was getting nauceous, and asked me if the sub could do that?

I will do proper testing soon. My rat shack meter says I was getting up to 105 db at about 1 meter in my computer area. I have no idea what the power rating of my Carver receiver is.

Paul

**aceinc** · **02-16-09, 12:31 AM**

I thought I'd post one more picture of the unit with the top off. It looks a bit better in the fresh air.

The bad news is I don't have a garage or a basement, the good news is that this is S florida and this is the best time of year to be outdoors.

**myn** · **02-16-09, 02:44 PM**

Looking good!

Looking at this URL here:
http://forums.audioholics.com/forums...ad.php?t=49678

I see a jpg that outlines 2D specifications. Are these the plans you were referring to? Is there other pages/scans that document the other dimensions like width of enclosure or anything else? I see you have a mouth opening where as the design below doesn't show any output besides where the drivers are mounted. How did you determine the size of this opening? And is there confirmation these are truly the TH-SPUD designs from Danley and not someones own idea?

Has there been anyone else besides you that has tried out this design yet? I'm anxious to see some discussion about this design and it's results!

I peaked over at DiyAudio forums and saw a couple of posts by you in the big collaborative TH post but didn't see much other activity of others trying to recreate the TH-SPUD like you are.

Are you planning on getting another amp to power your TH-SPUD?

**aceinc** · **02-16-09, 02:54 PM**

Over at audioholics, there is a thread that has the drawing that you posted above. In the same thread pretty early on there is a copy of the spec sheet which defines external dimensions, panel placement, etc.

I don't know if anyone is trying the same thing. I suspect that once I post the results of my testing other folks may make up their mind. I believe I will have time to test it this weekend, I will post the results afterward.

Paul

**aceinc** · **02-16-09, 02:55 PM**

Since I am giving the sub away after I am finished testing, I'll let the new owner worry about an amp.

Paul

**myn** · **02-16-09, 03:43 PM**

Can't wait to hear your results.

**myn** · **02-16-09, 03:46 PM**

Quote:

aceinc wrote:

Over at audioholics, there is a thread that has the drawing that you posted above. In the same thread pretty early on there is a copy of the spec sheet which defines external dimensions, panel placement, etc.
Paul

This thread: http://forums.audioholics.com/forums...ad.php?t=49678

or is there another?

More specifically:

**aceinc** · **02-16-09, 11:47 PM**

Myn, between the two pictures you posted, you should be able to build the box. The material used is 18 mm thick. I adjusted the throat end as you can see in the photos posted earlier, instead of a 60 degree angle for the second driver I followed the same geometry, and stepped it down by 1 thickness of the material, 18 mm.

My approach was to have Home Depot cut two ~43.5" x ~46.5" pieces out of 1 piece of plywood, and rip 4 - 11" x 48" and 5 - ~9.5" x 48" pieces out of another. I took the like pieces clamped them together and using a hand planer made them as even and square as possible. Which I could have done better.

I think the most important part of the project was this step;

I then took the measurements from the first drawing you posted and using a 48" ruler I laid out the position of all of the internal pieces on three surfaces, the top (for nailing), one inside (for placement), and the bottom (for nailing). This took the most time, and I redrew some of the lines three times to make sure I got it right and that they would all line up.

I attached the sides first, though if I were to build another one, I might only do the two sides that internal pieces attach to (I think). I then used lots of glue and two inch brads and a nailer to put in the internal pieces. Don't forget to use a square to get the internal pieces perpindicular to the base. I drew lines on the outside everywhere I needed to nail.

One trick I used for doing the real shallow angles since I didn't trust my cheap protractor, was I used a framing square and a ruler and measured the distance off of square the pieces were at 11.5" which is the width if the bed of my mitre saw. I then cut a piece of scrap that thick and placed it under the piece I was about to cut (11.5" away from the cut). This seemed to work out well. On the piece with the largest angle, the internal piece nearest the mouth, I used the protractor which gave me 94 degrees, and that worked well too.

I am still trying to exercise the drivers so that I can test this weekend. I have disconnected my DS15 and have the sub out of the receiver going to my NAD Amp. On one of the two channels I have the TH-SPUD, nothing on the other channel. I allowed the MCACC auto setup function run, and it had a problem, saying that the sub was too loud. I bypassed the error and let the auto eq finish, when I looked at the settings it had the sub at -10 DB. I watched the Fantastic 4, Rise of the Silver Surfer BD, since I really don't have any movies with good sub wooferage.

I'm not sure about the sound. There are a couple of scenes where I thought there should be more bass, but I haven't watched the movie in a while. I didn't want to do A/B testing with the DS15 just yet. In addition my wife was watching 24 in the family room, and I couldn't turn it up too loud.

Perhaps tomorrow I will take the time and hookup the NAD in Bridged mode.

One other thing I did recently and I would recommend is I had an electrician wire a dedicated 20 amp circuit behind the Entertainment system. Now my lights don't dim when I fire everything up.

Well that's all for now.

Paul

**mcallister** · **02-17-09, 06:47 AM**

Very cool. I've been reading the thread about this sub (well not this diy sub but the danley one) over at avs and it is a very cool design. Would love to see a tapped horn utilizing a Maelstrom or something similar. Would probably be giant though.

**Ricci** · **02-17-09, 11:55 AM**

Aceinc,

Keep the data coming. Can you do FR measurements? I'm really interested in the upper end response where all of the nasties are in the models.

McCallister,

Yes a low tuned TH for an 18" or 2 12" is going to be huge. Probably way bigger than a huge low tuned ported alignment.

**myn** · **02-17-09, 12:07 PM**

Thanks for the info on your cutting process. If this project deams sucessful it sounds like it may be a pretty easy build for people who follow your lead. We all appreciate all of the hard work and testing you've done so far.

On another note. Do you happen to have any pics of the SPUD with the top on now? Would love to see how she looks!

**aceinc** · **02-17-09, 08:10 PM**

I should be able to do FR graphs ala REW, but that will have to wait until Saturday.

I am at the office right now, I will try to get a few more pics with the top on. It is standing in my living room and looking rather large. My wife is rather understanding as long as I promise it is not permanent. Don't expect beauty, as I am not a cabinet maker.

Paul

**DrWho** · **02-17-09, 10:32 PM**

How are you bracing the internal panels?

**Allanf714** · **02-17-09, 10:56 PM**

Great idea Paul. I'm anxiously awaiting measurement data on this project. If you're successful at cloning the spud, I suspect a lot of people will follow suite.

Let's see: Potential world class performance and you can build a pair + amplify them both for maybe $700-800.

I had a couple of questions though. Why did you change the original 60 degree angle on the second driver?

I see in another thread... that there does appear to be some degree of dampening material utilized in the real unit..... are you planning on using any?

Allan

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