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Discussion Starter #1
Just want to say I welcome and thank all advice given in regards to my first diy subwoofer. I've recently acquired an HSU sub-driver that was utilized in HSU's VTF-MK3 model and want to utilize the driver for a DIY project. I want to stick with what HSU uses to achieve optimal results, but have an open mind to listen to what the guru's here have to say. This subwoofer will strictly be used in my home theater setup, and I want to achieve low frequency output of anywhere around 18-21hz. I have no speaker-building experience, nor do I have any software at my disposal for such things but I'm very handy and can get ahold of said-tools when needed. The T/S parameters are
FO = 29.23 Hz
Sd = 53.24m M(squared)
Vas 102.51 Ltr
BL = 13.88 T M
Qts = 0.340
SPLo = 90.42 dB

In return, I will keep everyone updated on my progress and will be providing pictures up until finish. Thanks again, Freddy
 

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Discussion Starter #3
Thanks for the welcome!
Really the driver comes from the VTF-3 HO model (originally retailed $999)
Later, the driver I have was used in a VTF-MK3 model, the first one reaching output of 18hz (w/o turbocharger) and 16hz with TC while the latter model reaches down to 18hz with an even lower rated amp. These parameters were taken by someone that thoroughly reviewed the MK3 inside and out, since HSU Research doesn't give out such information.
 

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Discussion Starter #4 (Edited)
I'd post a link to my photobucket (but that would be against the new-member rules) so you can see the driver itself but I'll just edit it and post it here as an attachment.
 

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Discussion Starter #5
Bump, don't mean to come off impatient...the driver has been sitting for 2 months and I've got only 1 design that isn't even meant for this sub. I do have a Dayton 240W plateamp, and will be adding a switch and terminal plate to give me the ability to bypass the plateamp and power the sub via external amp. :D
 

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Without knowing the Xmax it can only be a wild guess with this sub. I suggest you build the cabinet the same size that the sub was used in. If you can find out the diameter of the ports I can figure out what length they need to be. As for its low frequency capabilities, be aware this sub was measured at 6 db down from 80 hz, further down at 18 hz.

http://www.hsuresearch.com/products/homeTheaterMagHb1ReviewMar2007.pdf
 

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Discussion Starter #7
I see....thanks for clearing that up. I usually see that sort of measurement +3/-3db, and I'm a post short of posting you the link but here it goes.
 

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Discussion Starter #8
This is the sub the driver was initially used/taken from - http://www.hsuresearch.com/products/vtf-3-ho.html

That was the higher-end model, then they incorporated the same technologies/size/everything except the use of a lower rated amp and newly designed woofer to create the VTF3-MK3 - http://www.hsuresearch.com/products/vtf-3-mk3.html

The ports are a 4" diameter, and heres the site I found that shows the insides of the VTF3-MK3 along with T/S parameters - http://www.audioholics.com/reviews/speakers/subwoofers/vtf-3-mk3-sub/vtf-3-mk3-build-quality

The link you've provided has the slightly smaller/weaker VTF2
 

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Thanks for the right links. If you build the original sized box which is 21.5"x 17" x 25" and power it with a 240 watt plate amp you can get away with one 4" flared port full length which is 17 inches which would tune the box to 21 hz. This is assuming the Dayton Plate amp you have is the one that does not have 6 db of boost at 30 hz. I have no idea if the sub will bottom out or not as I don't know the Xmax of the sub or the frequency of the Hi-Pass filter that the original amp had. The Dayton amp has a Hi-pass filter at about 18 hz, modeling shows a maximum cone excursion of 19 mm at 14.5 hz.

HSU.JPG
 

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Discussion Starter #10
That is awesome :D
I should've mentioned that when I read the instruction manual on the VTF3-HO, maximum extension without the use of the turbo charger was achieved when one of the ports was sealed. I kind of took a guess at the length of the port and estimated about 18" (for the port before the elbow) but from the elbow, it comes down several more inches as seen in the pic.

I'll take your advice with sticking to the factory dimensions, now I'm just worried whether I should stick with the side firing method? Go front firing, or even consider downfiring.

Wanted to add, WAF is not an issue...my other speakers are fairly decent sized already.
 

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Discussion Starter #12
It doesn't matter which side it fires from as long as there is enough clearance from walls or the floor.
Alright, that's the easy part. Speaker/sub placement and setup is something I know very well especially when dealing with my setup :D

I'll get started on plans tomorrow then. I've already had something drawn out utilizing the same size enclosure, but now will build it having only one port. Should be picking up a sheet of 3/4" MDF over at Lowes, finish is TBD. Just taking it one step at a time :daydream:
 

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Discussion Starter #14 (Edited)
Here's the plateamp, finally picked it up today from a friend. Not used, and came in the box for only 80 bucks. The sub was only 50 bucks from another seller, talk about a budget subwoofer all well under 200 bucks I would estimate :D

[email protected] Dayton plateamp

I've been working on the enclosure schematics over and over trying to determine which way I want the woofer to face. I'll post how much $ was spent on the MDF once I grab it and where it was purchased.

Also wanted to add, this isn't the one with the added bass boost and the transformer is bigger than the ones I've seen on other plateamps.
 

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Discussion Starter #15
So I purchased a DPDT (double pole double throw) switch that I believe should work for my application of utilizing it as a bypass switch so I can go from the built-in plateamp to terminal plate for external amplification. Question is, do I need to worry at all about voltage ratings/etc on the switch? Or will any switch do? I'll be running belden wire from the driver to the terminal input itself, and figured since the switch is such a short connection I wouldn't experience loss of SQ.

Another question is, when I purchase the MDF...whats the preferred glue around here?
Polyvinyl acetate (yellow glue), PVA glues (Titebond II), Epoxy, or would liquid nails suffice as the end all be all?

Sticking to the estimated 17" long 4" wide port, probably will come from parts-express.
 

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Discussion Starter #16
So I picked up some glue, a different bypass switch, terminal plate and some extra sand paper along with the MDF. $49 bucks total :D The board was $27 at Lowes 4'x8' and they cut down the panels I needed to size. Thing is I've still got about +2' x +4' left of board along with 3 smaller panels, think I'll use that for the internal bracing.



I do have a question, ok the port is a flared 4" diameter for this subwoofer. What is the actual diameter of the internal tube? Could I get away with what looks like 2"? I ask because I looked at 4" diameter pvc pipe and it was huge so I would assume the 4" flared port is the entire diameter of the flare itself. Any advice?
 

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Discussion Starter #18
The internal diameter of the tube is 4", for air speed issues this this is the minimum size for your build. It would take four 2" ports to equal the same surface area as one 4" port.
I just had to double check ever since I saw how huge that PVC pipe was over at Lowes :unbelievable: It wasn't really until I had my wife help me hold up the mdf pieces together with me that we realized just how big the box was...it's big :D

I think I'll be shopping around though some local audio shops and the sort for the tube-assembly. I'd hate to see if SVS, Epik or HSU has any around and order it from them because it'll put this sub off a little longer and more $.

Any thoughts on the switch I'm using? Supports [email protected] I wondered if I should worry about anything at all if I ever wanted to hook up lets say.....an adcom 555 or carver m-400.

Btw, I never posted my setup;
Pre/pro: Denon 2805
Amp: Modified NYAL Moscode 300
Sources: Denon DVD2800
Insignia Bluray player
Speakers:
Frnt. L/R Polk Audio SDA 1C's
Center Polk Audio CS350
Rear Cent Polk Audio CS150
Sur. L/R Polk Audio RT1000P's

Audioquest Sidewinder and Signal Cable interconnects between components and a few DIY power cords.
 

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Discussion Starter #20
If you mean the port tube Parts Express sells them.

And your switch will be fine.
Thanks so much Mike!

I've asked this question a few other times on my other forums/threads, and was just discussing it with a friend how it's yet to be answered.

Regarding the tubes, I kind of wanted to stay away from P.E. because like I said shipping time would set me back some more in terms of getting the sub done. I've got a good week or 2 free before I become really busy, and want to get the schematics/bracing/ports out of the way. I'll then take my time during the assembly/primer/paint and finishing touches.

You said the port length should be 17", will going a bit longer hurt in this case? I'm taking into account the elbow and such if I recreate the same port tube the original model has.

Again, thank you very much :D
 
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