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Third subwoofer for below 25hz only?

JPK123

Novice Member
Apologies if this has been covered before.

I guess some sort of in line EQ would need to be added, but in my case it seems like a good way of picking up the slack after my other two start to taper off.

This allows me to keep the 2x sealed 12's I have which sound great above 25hz, but also have the low end a big ported sub can give - without the sealed and
ported working in the same frequency range.

Thoughts?
 

Conrad.

Active Member
You could do this with a minidsp. A single out from the receiver in to the minidsp then using three of the outputs to the various subs. You can set low and high pass filters on each output channel to route the signal as you describe.

While this would technically work, someone more knowledgable than me will tell you whether you'll it'll give you the results you want.
 

paulst10

Distinguished Member
Do you already have the third sub? As there a probably better solutions available if you can accommodate such a design..
 

Conrad.

Active Member
A ton of questions then!

What subs do you have now?
What size is your room?
Is that room dedicated or is it a shared space?
What sort of volumes are you listening at?
What's your floor (concrete, laminate, carpet, suspended)?
Do you have the ability/interest to measure and tweak your response?
What AVR are you using?

My intial thoughts are to sell the 2x12s and get the biggest sub (or two) you can that is allowable (assuming a living room set-up). You'll get much more depth and headroom and an easier time integrating it into your system.

My guess is that Paul's going to suggest a boss platform, which is an excellent idea if you're still struggling for sub 10Hz feel.
 

paulst10

Distinguished Member
My intial thoughts are to sell the 2x12s and get the biggest sub (or two) you can that is allowable (assuming a living room set-up). You'll get much more depth and headroom and an easier time integrating it into your system.

My guess is that Paul's going to suggest a boss platform, which is an excellent idea if you're still struggling for sub 10Hz feel.
Like you, I was going to suggest buying bigger subs, or the cheaper option of adding tactile transducers/BOSS etc! Which'll give excellent TR around 30hz down to single digits..

The way I see it, adding a ported sub for an extra 10hz of frequency range with only around 5hz of that being audible as most ported designs have little output below about 15hz (unless you spend a lot of money) So you're essentially spending four figures for an extra 10hz extension, this could be done a lot cheaper with TT's.. And possibly be done better with larger sealed subs or ported subs to begin with..
 

JPK123

Novice Member
All the info you asked about Conrad is in the link in original post.

In the middle of build but have tested the 2x KEF Kube 12 subs in another room and overall happy with output. I am simply interested in options for a bit more low frequency extension without selling what I have and starting again.

I have prewired for another subwoofer behind the seating area.

I did look at tactile tranducers and that might work well. Main concern there was it seeming a bit gimmicky, especially as most seem to crossover at 50hz (far too high?).
 

Conrad.

Active Member
Ok, thanks.
Given that you've bought the other two subs and don't want to change them, a third sub isn't a bad idea.

I would stick to sealed and follow the same advice, get the biggest sub you can afford/fit. That way you will have less urge to upgrade at a later date. A large sub can always be turned down, a small sub can only do what it does.

The problem I think you'll find though is that if you buy a good sized larger sub (say a 15") it'll probably outperform your Kefs to the point that they're not really adding anything.

How about putting one of the Kefs as a very near field sub (something a 12" would be fine for) and swapping the other one for a pair of something larger, say a pair of SVS? There's much less importance in matching tone between LCR and subs as there is in matching tone across the front three speakers.

Or, use the Kef's line level input to augment the front LR speakers and run them full range, then the larger sub could handle the bass from the other channels as well as the LFE.
 

Ultrasonic

Active Member
Whilst multiple subs for different frequency ranges is technically possible, and I'm sure people have done it, my gut feeling here is that it would be unnecessarily complicated and expensive.

In the first instance I'd be looking to get a home demo of some subs capable of covering more of the 10 to 25 Hz range to firstly see if what they add is something you really want and secondly how you find they compare to your current subs if they just do everything.

Off the top of my head, a pair of PSA sealed 15" subs would be a good place to start, noting that counterintuitively these go lower than the corresponding 18" model. Or at least they did for S1500 Vs S1800 and I don't think it's changed for recent updates. I'm mentioning these as I remember seeing measured outputs with good 10-20 Hz coverage in the owners thread here.
 

paulst10

Distinguished Member
Off the top of my head, a pair of PSA sealed 15" subs would be a good place to start, noting that counterintuitively these go lower than the corresponding 18" model. Or at least they did for S1500 Vs S1800 and I don't think it's changed for recent updates. I'm mentioning these as I remember seeing measured outputs with good 10-20 Hz coverage in the owners thread here.
Yes the 15's do extend a bit deeper but how much of that is considered useable output would depend on your listening levels obviously, IIRC, you need around 110db at 10hz to actually feel it. After living with 18's for almost a year which are extremely capable to just under 15hz below their intentional roll off, I don't think anything is lacking below 15hz, they are also on average 4db more capable from 16-100hz so if you plan on pushing them hard, they could be worth it. But I'd probably go with the 15's and see how you get on as the 18's are quite big.. Although saying all this, are PSA available to buy in New Zealand? If not it's all irrelevant lol..

I'd still consider adding tactile transducers though as if the BOSS is anything to go by, they're far from gimmicky.. they should just act as an extension to your existing subs and give you that :eek: factor for a lot of movies that even my two 18's aren't capable of giving.. take my Overlord watching experience last night where I lost my snacks :D..

 

Ultrasonic

Active Member
Although saying all this, are PSA available to buy in New Zealand?
Ah, I hadn't realised that's where the OP was. A quick Google lists a dealer for New Zealand.
 

Conrad.

Active Member
The 15s vs 18s thing is interesting. I have an S3000 (dual 15") and an S3600 (dual 18"). The S3000 goes ~3Hz deeper, down to about 7Hz (at 90dB+) in my (small) room compared to the 3600's 10Hz. The 3000 can do the same volume as well. But when running sweeps individually you can just tell that the 3600 is the larger sub. It has more weight to it, it's very strange. The combination works very, very well though.
 

Ultrasonic

Active Member
FWIW I think I read that the reason for the 15s going slightly lower is a result of a decision on the DSP applied to each.
 

Topmetom 2

Well-known Member
Yes the 15's do extend a bit deeper but how much of that is considered useable output would depend on your listening levels obviously, IIRC, you need around 110db at 10hz to actually feel it. After living with 18's for almost a year which are extremely capable to just under 15hz below their intentional roll off, I don't think anything is lacking below 15hz, they are also on average 4db more capable from 16-100hz so if you plan on pushing them hard, they could be worth it. But I'd probably go with the 15's and see how you get on as the 18's are quite big.. Although saying all this, are PSA available to buy in New Zealand? If not it's all irrelevant lol..

I'd still consider adding tactile transducers though as if the BOSS is anything to go by, they're far from gimmicky.. they should just act as an extension to your existing subs and give you that :eek: factor for a lot of movies that even my two 18's aren't capable of giving.. take my Overlord watching experience last night where I lost my snacks :D..

You need a projector, hahaha madness that boss thingy
 

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