CES Review of HSU VTF3HO is UP: Way UP

[spyboy]

"The two big subwoofers sounded spectacular as they shook the entire suite with ultra low subsonic sound. We were able to hear the subwoofers shaking the room from the sidewalk! The large subwoofers appear to have excellent build quality."

Read the entire review here:

http:https://www.audioholics.com/ces/CESs.../HSUVTF3HO.php

[Lex]

Hmm, I'll leave this for a while, but the ownership of HTGuide is decidedly anti AH promotional here at HTG. Management has it's reasons for not being a supporter of that site.

Interestingly, these subs sound extremely close to my Velex subwoofers, that just happened to use dual 4" ports with large flared tips, and were tuned to 18 hz. go figure. Maybe they found my recipe and liked it...

Doug

[Lex]

Well, I found my original recipe for my Velex subs. You tell me is it my design or their's?

Below is a reprint of my DIY subwoofers write-up which I did for another forum long ago. I coloqually refer to my project as my "Velex" subwoofers. Of course, since I wrote the content, Mike agreed it was my content, though I am also allowing him to retain my subwoofer plans for his DIY sub section of HTT.

Anyway, here is a picture of the finished product, followed by a text description of the process of building them. Soon, I will append the construction pictures, limited though they are with my own website of my home theater.




Sometime around Thanksgiving 1999, I began building 2 subwoofers for my home theater featuring Shiva Drivers from Avatar Audio. Dan Wiggins was very helpful in this process of getting these speakers as well as good exchanging emails about my DIY sub project with VERY useful information. Tom V., Stan, EDP, and Mark were others who contributed with advice. But the design and final dimensions as well as construction techniques were all my own. The project was a lot of work, and very satisfying as well. I won't say this type project is good for someone that doesn't
feel comfortable with a power saw, drill, and using their hands. But if you do, the opportunity to build great subwoofers at a fraction of the cost anything that would compete with them would do, is certainly very real.

Below is a set of step by step instructions of what I did to build my DIY subs. I hope you find it interesting if your contemplating this type project. Pictures will be loaded to the site very soon and I will then reference them in this writeup.


Here are my Velex plans:

My exact exterior dimensions are 22" wide, 24" deep, and 27" tall for each enclosure. Exterior is 3/4" oak laminated plywood. The exterior box was built first, and then for simplicity, the box was lined with 1/2" MDF (Medium Density Fiberboard). The oak plywood was supplied by my cabinet maker. I paid him 180 bucks to build the exterior. This included cutting the speaker and port holes as well as putting a 1 X 2 bottom on it so that the bottom has something to be sealed to. I work from the bottom of the cabinets, so that when its upright, no seams show. This is accomplished by having the box mitred on 45 degree angles.

You could approach the project by building the MDF cabinet first and then overlaying the plywood. But it would be much more difficult to insure that the inside surface is glued firmly to the exterior. The outside in approach also enabled me to do the inside surface and save that much money at the cabinet maker. I would have built the exterior too, but I was concerned about getting a great fit. So I decided to let a professional do that.

If you do that, you should take 1 driver, port flange, and terminal connector to him to do the cutouts. Also, I recommend leaving enough space between the inner edge of the driver and the outter edge of the port for a 2 X 4 to lay flat on the interior, creating a band of 2 X 4 around the inner perimiter of the box, horizontally. Also, its best if the cabinet surface is countersunk for the driver due to the large flange of cork like
material on the speaker rim. I did this myself, but it does require a Dremel tool with the router attachment, and a flat bottomed router bit.
About a 100 buck investment in a tool. If you choose to do that part, I will tell you how I did that. Lastly, the flange for the bottom to be screwed into should be inset to allow a 1 1/4"
slab to be screwed into the bottom of the subs. That leaves only the raw edge of the plywood sides showing as the only rought edge.

Caulk each inner edge of the plywood box, sealing it from air. Before any bracing occurs in the cabinet, you need to secure your 1/2" layer of MDF to the 3/4" plywood surface. Of course, you need to make the same cuttouts in the speaker cabinet MDF as on the ply. This is accomplished easily by
laying the cut pieces of MDF inside the cabinet and drawing the cutouts onto the MDF prior to cutting.

You can either cut the pieces as you go, or cut them all at once. The top of the cabinet is the bottom for your work lining the cabinet. (looking down into it) Make a piece of MDF that completely covers the inner bottom. Then make the sides, and leave enough space for 1/2" MDF to be adhered to the bottom, (which is at the top of your work).

Drill a multiple pattern of holes into each piece of MDF for 1" wood screws. Probably at least 16 screws per piece spread out evenly.

Apply a liberal supply of Elmers wood glue (get a BIG bottle, probably 30 oz.) to each piece as installing. Apply glue, adhere to inner cabinet piece, then screw into place with 1" wood screws. You don't have to drill the plywood cabinet for
them just take a hammer and tap the screw through
each hole in the MDF into the plywood interior. Screw each piece down. A powered screwdriver would be nice! I did mine manually.

Once the 3 sides of the cabinet have MDF glued and
screwed. Caulk each interior edge liberally with the best silicone caulk you can buy. The top edge should be caulked to the 1" X 2" ledge in the bottom of the cabinet on the opposite side of the 1 X 2 as the bottom panel.

Once that is complete, you need to cut a 2 X 4" band which goes around horizontally , glued, screwed, and nailed to the inner surface. You want it as strong as possible and as tight to the sides as possible. When this is done, you need to cut a 1 X 2" strip to go from one top edge of the 2 X 4 on one side to the top edge of the 2 X 4 on the other side. Glue and nail or screw each piece into place. When this is done, you need to cut pieces which are screwed from each remaining side of the
cabinet to the center 1 X 2. What this amounts to is a contact point for the center of each panel with a center of gravity being created as each pice is attached to the other from all sides.To avoid having a pices come out to short or long, I did each extension as one pice, and when gluing and screwing in place, I simply extended it out until it was touching the cabinet surface (again, glued). Then nail or screw into the 1 X 2 that it
extends to. Hopefully a picture of the inside of the sub will help (see attached).

Now things are beginning to take shape on the inside structure. When its all dried, you should be able to pick up by the center of the structure and feel the solidness of the cabinet. Well, that is if you can pick it up, lol. Its heavy!

Now, I admit (added this on 8/26/00), that my methods of construction were a little convoluted. But the end result worked well. The absolute best way to do this would be to build the MDF 1 1/4" box, and then apply oak or other laminant to the box for the finish. This might be very expensive though. Production built oak plywood it probably the better value. I mean come on, 2 of these boxes for 180 bucks assembled!?! That is cheap. I think the ply was about 40 bucks a sheet, his cost. 2 sheets.

Now, once the bracing is done, your ready to worry about the exterior finish of the cabinet. My finish is oak, but just as easily, you could hunt down cherry or some other wood plywood. I wanted a honey oak stain that wasn't overly dark. To accomplish this, I applied 1 coat of Minwax Wood Conditioner. This keeps the wood from absorbing to
much stain. First, of course, you should finish sand the boxes, and use a low number (000) or higher steel wool to slick the wood finish up. Next apply the wood conditioner and allow to dry. Next, I recommend 2 coats of stain with a 12 hr dry time between coats.

After that, you can apply Formby's Tung Oil (satin low gloss finish). Use staining gloves for your hands and apply tung oil with a small clean cloth. Rub the first coat in using circular motions much like you are waxing it. Allow to dry overnight. Lightly steel wool, clean with a soft cloth, and apply another coat of tung oil. From here on, just use straight with the grain motions. Repeat this
procedure 5 to 7 times, until desired lustre is obtained.

Next its time for port installation. You could start assembly of the ports while putting on coats of tung oil. When done (26" for each 4" port), install the ports.

Ports were constructed of 4(each) port kits called 4FLARE from Madisound Speaker Components (www.madisound.com).

Also order 2 each TD-CUPS (twin cup with gold posts). 4 4FLARES @ 14.00 each= 56.00. 2 TD-CUPS @ 11.00 each. Total 83.42 shipped.

To get the ports to the prescribed 26" for an 18 Hz tune, I used 4" sewer pipe elbows, and attached the long tube of the 4FLARE to 1 each elbow. The other end of the elbow was attached directly to what is left (flared end) using 4 each pipe
connectors. The connectors came from Home Depot, and are rubber inside with metal around the outside with 2 metal clamps to tighten it. When
installing the ports, use pliable "putty" that comes on a role with like 6 "beads" ran together in strips. Use only 1 bead of the caulk under each port. Screw the ports to the front, and install a brace on the lower side if needed. Secure foam
rubber between the port and the lower bracket.

Keep in mind during bracing, that the ports will make a turn, and be sure to leave adequite clearance.

When this is done, your ready to wire the speakers. I will tell you the correct way to do this to your 4 post binding posts when your ready. This way you can run the speaker at 4 or 8 ohms as desired. You also have capability to run individual voice coils to seperate channels, or
4 or 8 ohms using both voice coils wired together or in sequence. I prefer to use wire clips so that they can be easily removed if necesary.

Assembly of the speaker terminal just needs to be screwed on, as it has a gasket under it. The speaker however, should have "ribbon caulk" applied under the seam to make it airtight.

I recommend brass screws for ports and speakers. Do not get screws long enough that they penetrate the inside of the sub cabinet ever! Calculate screw lengths very carefully.

Lastly, if you want, you can install brass audio points for the base. www.audionut.com. You want to get Fast Points with a 1/4" threaded screw on them. Use drill to install "wood inserts" threaded with 1/4" female threads. (exterior of this piece is 5/16", so use a 5/16 drill bit). Screw the female ends into holes drilled into the bottoms, but not through. If you use brass, expect them to
break off a little early and trim flush with the bottom using Dremel and the best cutting bit made. Screw the audio points in using a "jar rubber". You know, what you open cans with, if the audio points are slippery. So, that's about it.

[spyboy]

Doug

Sound very similar. You were way ahead of your time.

FWIW, I have no interest in promoting AH. I just think that the current pre-order price for the HSU VTF-3HO + Turbo of $950 delivered is a good value and wanted to bring it to the attention of your readers. From all accounts, this sub is a monster performer that also has ample finess with music.

[Lex]

I will say the Velex do kick a$$. Unfortunately, they are sitting in my garage, shelved, so to speak. Sad but true. I just could not effectively incorporate them into my front projection setup with my limited space. The two units stacked were designed to align close to the top edge of a 60" 4:3 Pioneer Elite. It was a massive display in it's day. But front projection necessitated a low profile sub (Aerial SW-12), and I shelved the Velex. I was going to sell them, but no takers locally and they are just to big and heavy to ship without professional pallet shipping involved pretty much, at least common carrier shipping anyway.

As you can see by my existing setup, I just ran out of room up front.

[Wayne E]

FWIW, I have no interest in promoting AH. I just think that the current pre-order price for the HSU VTF-3HO + Turbo of $950 delivered is a good value and wanted to bring it to the attention of your readers.

Sadly, the same information has been posted on all the audio forums I attend. Additionally, even using the word "review" for the two small paragraphs seems like a joke.

[Lex]

Well I didn't say anything about that, but it's true, I'd hardly call that a real review.

[Peter Marcks]

Dear Lex,

Interestingly, these subs sound extremely close to my Velex subwoofers, that just happened to use dual 4" ports with large flared tips, and were tuned to 18 hz. go figure. Maybe they found my recipe and liked it...

Doug

In the mid 1990's, Dr. Hsu had a cylindrical model named HRSW12Va that used dual 4" bent ports flared at both ends and tuned to about 18Hz. This was probably his inspiration, as the VTF-3 HO also uses dual 4" ports and is the same end-table friendly height (~22") as the HRSW12Va.

However, the VTF-3 HO will play a bit lower than the HRSW12Va, since it is actually tuned to 16Hz in extended bass mode. VTF-3 HO is also using a newer bent port technology that reduces turbulence associated with the port bend.

Kudos on your design, it certainly sounds like a good one! The Aerial unit is also really nice.

Sincerely,

[Lex]

VTF-3 HO is also using a newer bent port technology that reduces turbulence associated with the port bend.

What a coincidence, I used similar technology, called rubber sewer pipe elbows lol.

The Velex played loud, and they played clean, no doubt. I got more output than with the Aerial likely. But again, the Aerial suites my front end design now. We do what we have to do...

Welcome to the Guide Peter. Tell Dr. HSU I been saving him an ad spot here, but he better hurry before one of those other bass companies snaps it up, lol.

I'll give you a free signature this month, but next month, we may need to talk advertising if you hang with us as an HSU rep.

Doug
Owner
HTGuide.com

[curtis]

What a coincidence, I used similar technology, called rubber sewer pipe elbows lol.

....Peter forgot to mention that Hsu has a patent pending on the low turbulence design.

Your Velex subs are interesting. Do you ever plan on using them again?

[Lex]

Well, I was going to sell them. I've moved them around twice so far, they landed in my garage, so I just don't know. I had pics somewhere, lemme look for those.

I did run them locally in the paper once with an amp, but had no nibbles.

Doug

[Lex]

ok, really bad pic, but at least it shows them.

[Peter Marcks]

What a coincidence, I used similar technology, called rubber sewer pipe elbows lol.

Laughing out loud! :lol:

Thank you for the warm welcome, Doug. I will definitely talk to Dr. Hsu about this, and will get back to you. I like your DIY subs, by the way!

Thanks again, and take care!

Sincerely,