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Can I use two very different Subs in a 5.2 system?

post #1 of 18
Thread Starter 
There is a very nice sub for sale on craigslist. The price is right too. HSU VTF-3 HO w/ Turbocharger.

I was orginally going to get one FV15HP... I am thinking of getting the HSU and seeing if it can do what I need solo. If so...saved big bucks...

If not, I would like to use this AND the FV15HP but am not sure I can incorporate two so different subs into one system seamlessly.

I am looking to purchase a Onkyo 818 as well..but can be pushed to the Denon 4311 (Sub EQ) if that would make a differance.

I have read only good things about the VTF-3 HO but dont think it will give me quite the output I want below 20hz.
post #2 of 18
I think you could get the two subs to sound good together. The 4311 would be better for this since it has dual sub calibration
post #3 of 18
If you go down the route of having two different performing subs in a room you will want to be able to measure how the subs are interacting in the room at specific frequencies. This requires something like the Dayton Omnimic V2, or REW (REW is free and with a $80 mic, is pretty effective, but REW takes a little more work).

And then I would recommend something like a minidsp so you can use EQ and filters to get the subs to interact better and put in filters to cutoff the lesser sub before it starts distorting.

As long as you are willing to do a little extra work, I think it can be done and you will learn a lot along the way.

Otherwise I say just get two similar performing subs that will be easier to integrate with something like Audyssey.
post #4 of 18
Thread Starter 
I am contemplating this because I hope the used HSU will satisfy me...but I really want good bass so I have allot of doubts.

The cost is very low...but I am reading and reading now and it seems the FV15HP is in about 4 legues away from the HSU. I am really looking for great bass below 20hz.

My room is 22x12 (8 foot ceilings but fairly open to kitchen and hall to the right.

I am using this for movies 75 and music 25. So I *think* for the price I am willing to gamble and try the HSU but if I dont like it...then I dont want a huge paper weight either.
tongue.gif
post #5 of 18
If the price is good, you could always resell the VTF3HO if it doesn't quite do the job for you, so I don't see much of a risk here.
post #6 of 18
Quote:
Originally Posted by Newbie01 View Post

I am contemplating this because I hope the used HSU will satisfy me...but I really want good bass so I have allot of doubts.

The cost is very low...but I am reading and reading now and it seems the FV15HP is in about 4 legues away from the HSU. I am really looking for great bass below 20hz.

My room is 22x12 (8 foot ceilings but fairly open to kitchen and hall to the right.

I am using this for movies 75 and music 25. So I *think* for the price I am willing to gamble and try the HSU but if I dont like it...then I dont want a huge paper weight either.
tongue.gif

If you are looking for good extension below 20hz, you may want to consider sealed subs as well. A couple of PSA XS30's would be very solid. Start with one and add another.

I can't blame you for wanting to try the Hsu,it is good sub. Do you think it would be easy to sell where you live? Once you start dealing with shipping it becomes a PITA...
post #7 of 18
Thread Starter 
Wow...I think I need to go read about subs again.

I thought ported subs = more out put below 20 hz? That is why they are used in HT.

Geesh..I have so much to learn its not funny. Sealed sub give more output from 20-50hz? No, yes...grr!eek.gif
post #8 of 18
Quote:
Originally Posted by Newbie01 View Post

Wow...I think I need to go read about subs again.

I thought ported subs = more out put below 20 hz? That is why they are used in HT.

Geesh..I have so much to learn its not funny. Sealed sub give more output from 20-50hz? No, yes...grr!eek.gif

ported subs will typically have more output at whatever the port tuning frequency is, whether that's 20 Hz, or 30 Hz or something else. The port lets the sub get more output out of the same power. But below the port tuning point, ported subs roll off rapidly. Also, the air pressure in the box is important as part of the control over speaker excursion, and below tuning the driver becomes "unloaded," basically meaning the port keeps the cabinet from providing any back pressure on the driver. It makes destruction of drivers possible if loud sounds below tuning are played. For that reason, many if not most ported subs will have an electronic rolloff that cuts output below tuning even faster, to protect the woofer itself.

Sealed subs, appropriately designed and left to their own devices, haea a much slower rolloff below their peak output frequency, and for manypeople the room provides "cabin gain" that can match that roll off, keeping things flat in the room well below the point where the sub itself begins to roll off. BUT lots of tiny sealed subs are not optimally designed for the driver and box to work together very deep. To compensate, they use a lot of electronic equalization to keep the level up down into deeper frequencies. In these subs, once you get deep enough in frequency to be below the EQ boost, the rolloff will be very fast, too. So it kinda all depends.

If you search in the subwoofers forum you can find some tests (the one I particularly remember was done by member Archaea in Kansas City) in which essentially nobody could identify by hearing which sub(s) were ported and which were sealed, once they had been equalized using Audyssey for the room. My guess is that experienced folks (like Mark Seaton, who was there) know what to listen for and can identify a lot more about the sub just by listening than an ordianry attentive and interested listener. FWIW.
post #9 of 18
Quote:
Originally Posted by Newbie01 View Post

Wow...I think I need to go read about subs again.

I thought ported subs = more out put below 20 hz? That is why they are used in HT.

Geesh..I have so much to learn its not funny. Sealed sub give more output from 20-50hz? No, yes...grr!eek.gif

It depends on how the ported sub is tuned. The advantage for ported subs is around the tuning frequency. You get more output typically than a sealed sub, but then the ported sub drops like a rock after the tuning frequency, whereas a sealed sub will typically have more useable extension.

Tradeoffs smile.gif

In your example above the ported sub will typically have the advantage between 20-50hz and the sealed sub would be more useful below 20hz (depending on the port tune) and between 50-80hz it is usually either a wash, or the sealed sub might have a slight advantage.

WAF factor is something to consider. Ported subs are typically larger. Sealed subs are typically smaller. If you have a situation of having a fairly big open room and multiple subs are not an option, I say go with the biggest, baddest ported sub you can get.

Here is an example of multiple ported ported subs (grey with a 20hz tune) vs multiple sealed sub (yellow) that I modeled from my build thread:



You can see the advantages of each. In my room I was able to incorporate four smaller sealed subs vs two larger ported subs, which gave me about the same output from 20-50hz but I was able to get much more extension and also having 4 subs to smooth out bass response vs 2.

Hope this helps.
post #10 of 18
In a large room, you are going to need multiple sealed subs to be able to get a sense of any sub 20 hz bass at all. You may or may not get room gain, especially if you're room is open to other areas. Ported subs usually do a better job of getting you that deep bass, as they do not rely on room acoustics for deep bass. If you want to be sure you are getting the deep stuff, go ported, otherwise it is rolling the dice.
post #11 of 18
Oh, and your room plays a big role in all of this. Some people are lucky and have smaller sealed spaces and get good room gain (typically when placing a sub near corners, you can get an extra 3-6db depending on the room). Some people have big open rooms (like me) or have limited placement. So you have to take the room into account. If you have a crappy room, you will need more output and extension vs a good room.
post #12 of 18
Quote:
Originally Posted by shadyJ View Post

In a large room, you are going to need multiple sealed subs to be able to get a sense of any sub 20 hz bass at all. You may or may not get room gain, especially if you're room is open to other areas. Ported subs usually do a better job of getting you that deep bass, as they do not rely on room acoustics for deep bass. If you want to be sure you are getting the deep stuff, go ported, otherwise it is rolling the dice.

Beat me to it smile.gif

I have confirmed in my 6K cu sq ft room that I am getting very useable bass below 12hz (my mic won't accurately measure below that but I suspect I am good to about 8-10hz). So it can be done with a large room and multiple subs. I use 4 15" subs powered by a 3K watt amp. Cost me $1K out the door for everything. The power of DIY smile.gif
post #13 of 18
Thread Starter 
Do makers normally release where a sub is tuned to? I see on the Rythmik Sub you can choose the tuning of the sub? 14 Hz, 20 Hz, and 28 Hz

I can't see anything on the HSU site.

So if I set the sub to 14 hz...it will have much more output at 14 Hz than a sealed sub...but whereas a sealed sub may get to 10 hz...the fall off a ported sub may max at 12 hz?

What am I giving up to "tune" a sub that low? Do I loose power from say 15-20hz or 15-28hz to get allot of output at 14hz?

HSU info...means in Bass Extension mode this is tuned to 16 Hz?


I looked on HSU site:

VTF-3 HO At a Glance
Amp Power (RMS) 500 Watts
Bass Extension (max extension mode) 16 Hz
Bass Extension (max output mode) 22 Hz
Woofer Size 12 Inches
Crossover Bypassable 24 dB/Oct, continuously variable 30 - 90 Hz low pass filter
Ports Dual flared 4 Inch
Phase 0/180°
Inputs speaker level (2), line level (2)
Power Outlet Requirement 600 Watts
Ship Weight 93 Lbs
Dimensions 21.5”(h) X 17”(w) X 25”(d)


Rythmic site:
post #14 of 18
Quote:
Originally Posted by Newbie01 View Post

Do makers normally release where a sub is tuned to? I see on the Rythmik Sub you can choose the tuning of the sub? 14 Hz, 20 Hz, and 28 Hz

I can't see anything on the HSU site.

Most do. Personally I trust third party measurements from someone like Ricci much more than manufacturers specs.
Quote:
So if I set the sub to 14 hz...it will have much more output at 14 Hz than a sealed sub...but whereas a sealed sub may get to 10 hz...the fall off a ported sub may max at 12 hz?
]]

Pretty much. Typically the lower a ported sub will go, the larger the box, driver, etc. So to get useable sub 15hz extension from a ported sub, you are usually talking about a big box. There are some massive ported subs out there that can get to 10hz, but we are talking huge boxes that are usually DIY or kits.
Quote:
What am I giving up to "tune" a sub that low? Do I loose power from say 15-20hz or 15-28hz to get allot of output at 14hz?

You are giving up output. Consider the Hsu VTF 15H. One port plugged gives you maximum extension. Two ports open results in less extension, but more output. No free lunch. Most movies have far more content above 20hz than below 20hz so you have to decide which you prefer, one port open, or both ports open. It is nice to have choices smile.gif

HSU info...means in Bass Extension mode this is tuned to 16 Hz?

Quote:
I looked on HSU site:

VTF-3 HO At a Glance
Amp Power (RMS) 500 Watts
Bass Extension (max extension mode) 16 Hz
Bass Extension (max output mode) 22 Hz
Woofer Size 12 Inches
Crossover Bypassable 24 dB/Oct, continuously variable 30 - 90 Hz low pass filter
Ports Dual flared 4 Inch
Phase 0/180°
Inputs speaker level (2), line level (2)
Power Outlet Requirement 600 Watts
Ship Weight 93 Lbs
Dimensions 21.5”(h) X 17”(w) X 25”(d)


Rythmic site:

Max extension would be with the one of the two ports plugged and max output would be with both ports open. Same with Rythmik or Outlaw. So you really have to take it all in when researching. This is what I love about data-bass.com where you can compare one port vs two ports open and the effect on output and extension. You also want a well engineered ported sub, because if not properly designed, you can get port chuffing if you are pushing the sub too hard. The nice thing about the Hsu and Rythmik subs is they really let you tune the sub to your preference (max output vs max extension). Of course this means taking the time to make the changes and then measure them to see what you like best. If WAF is not a concern for you, the Rythmik 15HP seems like a great sub. Potentially add a second down the road.
post #15 of 18
Thread Starter 
Well...the Rythmic FV15HP is bought! I did get the 550 watt vs. the 600 though. Now to see if I still get the HSU. It is going for $325 dollars and looks pristine condition. I may still get that too.

So I take it tunning the Rythmic to 20 hz makes the most sense in general for movies and 28 hz for music?
post #16 of 18
Quote:
Originally Posted by Newbie01 View Post

Well...the Rythmic FV15HP is bought! I did get the 550 watt vs. the 600 though. Now to see if I still get the HSU. It is going for $325 dollars and looks pristine condition. I may still get that too.

So I take it tunning the Rythmic to 20 hz makes the most sense in general for movies and 28 hz for music?

Congrats man, that is a great purchase. I would probably just leave it at 20hz and see what you think for music and movies. The nice thing is you can make adjustments and see what you prefer best (max extension or output). With my Hsu I found myself enjoying max output (both ports open) more.

Kudos. Now for the hardest part, the waiting...
post #17 of 18
You can tune it to 28 Hz but it will not be needed for music is my feeling
post #18 of 18
$325 is a very good price for a VTF3HO if it is in good shape. Its basically a more powerful version of the VTF3 mk3. I would jump on that. If it was at that price on a buy-it-now sale at ebay or audiogon, it would be gone in a heartbeat.
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