Yeh, perfect match... but what if...

[herbu]

First, hey. Enjoy reading you guys. First post.

Recently upgraded HT. HD-3D TV, Bluray, Yamaha RX-V671 and KEF KHT3005SE 5.1 speaker set. (Old speakers were JBL satellites & sub.) Kids say we've finally moved into the new millennium.

Room is big and T-shaped.
The horizontal bar of the "T" is 35'x15' w/ a 2-story cathedral ceiling.
The vertical leg of the "T" is an additional 15'x15' w/ 9' ceiling.

Setup sounds a lot better than old one, but I'm reading 2 subs are better than one, it is a big tall room, (plus a leg), and I'm thinking why not. We listen to some music, but mostly use for TV/Movies, (love the action stuff).

Here's what I've learned here:
> When adding 2nd sub, best idea is to match 1st sub.
> SVS PB12-plus seems to be the daddy-o choice in my price range.
> About the only post I found here on KEF called their sub "junk"... (2007).

To my ear, the KEF H2B2SE sounds miles better than my old JBL.
But its freq response is only 30-150Hz.
Since action movies are main use, sounds like I'm missing out w/ 30Hz min.
(I learned that here. Seems ~10-30Hz is important for explosions.)
If I add a KEF match to it, it's another ~$900.
The SVS is in roughly the same ballpark.

So I see these choices:
> Do nothing and enjoy the improvement from old system.
> Add another KEF for $900... perfect match... miss the movie lows
> Add the PV12 and match w/ KEF best I can
> Add the PV12 and ditch the KEF.

Hope I've provided enough info. Would really appreciate opinions or considerations I've missed.

Thanks,

 

[its phillip]

If you're set on the PB-12, get the PB-12 and sell the KEF. Then buy another PB-12 if you want

 

[Adam]

I'd tend to tell you to enjoy your nice, new system because you've said that you like a lot better than the old one. However, your post makes me think that you're already thinking that two KEF subs aren't going to give you what you want (maybe not now...but it'll eventually get to you unless you just decide it isn't that important to you).

Four years ago, I got the itch for a new sub, knew that I wouldn't be satisfied until I got a sub-20Hz system...so I got an SVS PC13-Ultra. I'm totally happy that I did because I don't wonder if I made the right choice.

So, if you think that you'll always second guess the KEFs, I definitely agree with Phillip - get the SVS (or any other sub that hits the lows that you want).

 

[GranteedEV]

First, hey. Enjoy reading you guys. First post.

Recently upgraded HT. HD-3D TV, Bluray, Yamaha RX-V671 and KEF KHT3005SE 5.1 speaker set. (Old speakers were JBL satellites & sub.) Kids say we've finally moved into the new millennium.

I have read before that, while they`re still puny output limited satellites, those KEF eggs do sound amazing in many ways because of their diffraction characteristics and coincident drivers. I would love to hear them.

> When adding 2nd sub, best idea is to match 1st sub.

The main reasoning for this is output. You don`t want one sub running out of steam while the other hasn`t broken a sweat yet.. you`re only as good as your weakest link if that weakest link is going to create audible distortion or mechanical noise.

However as with many things, there is more than one approach to solve a problem. The Geddes approach for setting up multiple subs does actually suggest different subwoofers, where the third sub doesn`t need to be great, just light enough to place high above the ground, and close to you so it doesn`t have to work as hard to match SPL with other subs. It will fill in some room dips as long as it isn't being taxed heavily at high output levels. So if you get three dissimilar subs, with one that can reach deep (this is called your ULF sub as per the Geddes approach) and two others, it might work really well. It's probably not going to be as "plug and play" as the Welti/Devantier approach of four identical subs at midwall points but it has been measurably proven to be effective in getting people really flat response.

As a person with a 200+lb beast of a sub, I think I like Geddes approach more from a practicality perspective

> SVS PB12-plus seems to be the daddy-o choice in my price range.

Eh, the Rythmik FV15 seemed to outperform it on last year`s sub tests. It appeared the only reason to get the svs instead is if you`re big on DSP limiting.

Since action movies are main use, sounds like I'm missing out w/ 30Hz min.
(I learned that here. Seems ~10-30Hz is important for explosions.)

You`re missing some, but don`t know how much. Below 30hz is essentially rumble, and below 20hz is `pressure` that you can`t even hear.

Getting flat in-room response and increased output above 30hz is probably going to be the most audible improvement or "punch". The rest is more tactile.

If I add a KEF match to it, it's another ~$900.
The SVS is in roughly the same ballpark.

I presume that the SVS will wipe the floor with the KEF.

But don`t forget the Rythmik. It costs less and has more output at every frequency except 20hz:

http://www.audioholics.com/reviews/speakers/subwoofers/pb12-plus/pb12-measurements

http://www.audioholics.com/reviews/speakers/subwoofers/rythmik-fv15hp/fv15hp-measurements

 

[FirstReflection]

The whole notion of using two or more subwoofers is, unfortunately, over-simplified. You can't just put two subwoofers anywhere in any room and expect to automatically get better sound just by virtue of there being two subwoofers instead of one!

The "standard" placement of two or four subwoofers at the mid-way point of each wall is based on the assumption that you have a perfectly rectangular room with your seating area more or less in the middle of that room. That's not what you have and it's not what a lot of people have.

Basically, what you really need to do is measure your room's acoustics. Don't get me wrong, I'm all for using more than one subwoofer! But I just want the full information to be given, which is that two subwoofer isn't automatically better: you have to position those dual or quad (or whatever number) subwoofers in the correct locations in YOUR room in order to benefit from smoother, flatter frequency response at a greater number of seating locations.

If all you truly want is to hit lower and louder at ONE primary "sweet spot", you can often get that with just one subwoofer that is properly placed in the room and EQ'd to take out the worst "humps" in the frequency response. Multiple subs is typically all about trying to get better frequency response at multiple seating locations.

I'd just like for the OP to be aware of what he's getting into and to have a better idea of what he's after

 

[herbu]

The main reasoning for this is output. You don`t want one sub running out of steam while the other hasn`t broken a sweat yet.. you`re only as good as your weakest link if that weakest link is going to create audible distortion or mechanical noise.

Thanks, GranteedEV. So maybe not too stupid to match KEF w/ something else.

Looking at Rythmik, and considering your comment above, it would be better to match the 370w FV15 w/ my 250W KEF, rather than the 600w FV15HP... right?

 

[herbu]

If all you truly want is to hit lower and louder at ONE primary "sweet spot", you can often get that with just one subwoofer that is properly placed in the room and EQ'd to take out the worst "humps" in the frequency response.

That's exactly what I want. 99.9% of the time, it's just my wife and me. Our chairs are together.

The volume of the KEF is adequate, and I can set it louder if I want.
But its freq response only goes down to 30Hz, and although I can't find a graph, I suspect it is tailing off considerably before it hits that.

I asked tech support about pairing/matching another sub to my 250w KEF.
I thought maybe the 370w FV15 would be a better match than the 600w FV15HP. They told me I needed the HP due to the size of my room, and pairing/matching would be no problem.

So now I'm a little confused again.
Tech support of what I believe to be a reputable company is suggesting I pair their 600w sub w/ my 250w sub. I asked about a down side, and they said "don't worry about it".

So is the down side really so subtle or inconsequential that only a true audiophile/enthusiast would notice, (or care)?

I'm just an average guy looking for advice from the experts.

Thanks,

 

[GranteedEV]

Looking at Rythmik, and considering your comment above, it would be better to match the 370w FV15 w/ my 250W KEF, rather than the 600w FV15HP... right?

Not really. A properly set up multisub system will have balance no matter which subs you use. watts alone mean nothing - a low sensitivity driver might need 1000 watts to match the output of another driver fed 50 watts.

I would go for the 600w FV15HP, and consider a second eventually. Try to mount the KEF above the vertical center line of the room, and close to you.

 

[Adam]

The volume of the KEF is adequate, and I can set it louder if I want.
But its freq response only goes down to 30Hz, and although I can't find a graph, I suspect it is tailing off considerably before it hits that.

Hi. Do you have, can you borrow, or are you willing to buy a sound pressure level (SPL) meter? They cost about $40-$50 new and can be quite handy. You can buy (or download for free) a set of test tones at different frequencies, which combined with the use of an SPL meter, can help you characterize the performance of your sub.

I have an example plot shown in one of my threads here (please forgive the crudeness, it was my first thread ever ). I have plots for my current sub, but I'd have to get those off my other computer.

 

[herbu]

Thanks, guys.

Think I'll go w/ the Rythmik FV15HP.
Start w/ it in what I guess is a good corner spot in front.
Add the KEF in behind corner, elevated and closer to listening area.
If I just can't get it so it sounds good to us, I'll break for the SPL meter and keep trying, first by moving the KEF. (It's a lot smaller and lighter.)

Seems I should be able to find an acceptable arrangement for us w/ that combo of subs.

Can't guarantee any of you would agree if you heard it, but that's unlikely, and frankly is not a serious concern.

You helped me understand what to look for, what to consider, and what not to worry about. It is what I was hoping, and I REALLY appreciate it!!!

Thanks!!!!!!!!!!

 

[GranteedEV]

Thanks, guys.

Think I'll go w/ the Rythmik FV15HP.
Start w/ it in what I guess is a good corner spot in front.
Add the KEF in behind corner, elevated and closer to listening area.
If I just can't get it so it sounds good to us, I'll break for the SPL meter and keep trying, first by moving the KEF. (It's a lot smaller and lighter.)

Seems I should be able to find an acceptable arrangement for us w/ that combo of subs.

Can't guarantee any of you would agree if you heard it, but that's unlikely, and frankly is not a serious concern.

You helped me understand what to look for, what to consider, and what not to worry about. It is what I was hoping, and I REALLY appreciate it!!!

Thanks!!!!!!!!!!

Speaker and subwoofer placement, in my opinion, is 90% of getting bass to sound its best. Variable tuning modes can also really help optimize the bottom octave to sound its best. This is one place where the SVS beats the rythmik - by being physically smaller, it's a bit more placement flexible, although it's by no means a small sub.

I definitely think picking up a measurement mic and a cheap USB soundcard will be a great investment, and you might find that just messing with placement can REALLY improve the perceived sound quality and often percieved output of bass. Sometimes an inch left or right, forward or back, can completely change your sweet spot measurements, and sometimes you realize you'd be well served to give up on a certain placement altogether, and an alternate, seemingly unexpected placement works out a lot better for you.

I might even go as far as to say that while I think the Rythmik will be a great investment, the measurement microphone and sound card are probably an equally great one, dollar for dollar.

This is the measurement mic I use: http://www.parts-express.com/pe/showdetl.cfm?Partnumber=390-801

It does require a mic preamp, and this is what I use:

http://cgi.ebay.com/MOBILEPRE-Preamp-USB-Computer-interface-M-AUDIO-NEW-/200635985268?pt=LH_DefaultDomain_0&hash=item2eb6d62d74