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Adding a second subwoofer

Buckeye Amps

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Long story short: My Funk Audio 21.0L sub is phenomenal for my MLP in most regards...it digs down to 14Hz (audible) and has more output then needed from 20-50Hz (Trinnov has to bring the response down here). BUT it suffers from a serious null from 60-90Hz. This is due to placement but I absolutely have no other space to move it to another spot.

I do, however, have room to fit up to an 18" sealed sub in an optimal spot behind my seating. This spot shows great flat response from 30-90Hz.

So I want to add a second subwoofer purely to boost the 60-90Hz range where the null is. I would probably give it an HPF around 30Hz so it would not need to have any meaningful output under 30Hz.

The main goal is to make sure it can audibly match/keep up with the Funk in the mid bass range of 50Hz+

The Funk 18 inch offering would be a tad too big. However a Rythmik or PSA 18 would fit, just barely (it would impede how far back one of my seats could recline though).

Ideally, a 15" PSA or Rythmik would be the best for size, or even a 14" SVS.

For what I am looking to achieve, would a 15" offering be perfectly suited? Any other sealed subs I should add to the list?
 

DWPress

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If you're going to keep the Funk and it already digs deep have you considered adding one or two small subs to fill that 60-90hz null with placement? I've done it in the past and it worked well enough. Also, do your mains go down to 60Hz? If so, have you tried shifting your XO down to 60? My mains will go down to 40 but I place my XO at 50Hz for similar reasons.
 

Dj7675

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Long story short: My Funk Audio 21.0L sub is phenomenal for my MLP in most regards...it digs down to 14Hz (audible) and has more output then needed from 20-50Hz (Trinnov has to bring the response down here). BUT it suffers from a serious null from 60-90Hz. This is due to placement but I absolutely have no other space to move it to another spot.

I do, however, have room to fit up to an 18" sealed sub in an optimal spot behind my seating. This spot shows great flat response from 30-90Hz.

So I want to add a second subwoofer purely to boost the 60-90Hz range where the null is. I would probably give it an HPF around 30Hz so it would not need to have any meaningful output under 30Hz.

The main goal is to make sure it can audibly match/keep up with the Funk in the mid bass range of 50Hz+

The Funk 18 inch offering would be a tad too big. However a Rythmik or PSA 18 would fit, just barely (it would impede how far back one of my seats could recline though).

Ideally, a 15" PSA or Rythmik would be the best for size, or even a 14" SVS.

For what I am looking to achieve, would a 15" offering be perfectly suited? Any other sealed subs I should add to the list?
While not a 15, if you want compact sub with even more driver area that a 15, a dual 12inch sealed might do the trick... I have 2 larger subs in my front corners but did not have room for 2 more in the back 2, so I picked up 2 of these
With dual 12 inch drivers and 960w amp (2100 peak), It seems to be quite the performer to me and increases a lot of options on where it can go.
 
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Buckeye Amps

Buckeye Amps

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If you're going to keep the Funk and it already digs deep have you considered adding one or two small subs to fill that 60-90hz null with placement? I've done it in the past and it worked well enough. Also, do your mains go down to 60Hz? If so, have you tried shifting your XO down to 60? My mains will go down to 40 but I place my XO at 50Hz for similar reasons.
Absolutely, that was what my post was about (sorry if it wasn't clear). I have a spot where a smaller sub would fill in the null well. Just not sure if there is a "right" sub that would match well with the Funk or if any good performing sub will do.

I currently have my mains crossed lower to help but I would rather add a second sub to really help fill the range
 

DonH56

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Rythmik's subs also reach 14 Hz @ -3 dB so a 15" Rythmik might be a perfect fit. :) Close to you I doubt you need the extra output of an 18" model.

Disclaimer: I am a fan of Dr. Brian Ding, the man behind Rythmik. We have similar day jobs and I have a number of his subs. Be sure to say "hi" from me to he and Enrico.

Mixing subs it is wise to have similar output capability, but in your case the closer one can have less. The other challenges are matching low-end frequency extension, usually not too hard, and staying with either sealed or ported. Mixing sealed and ported can be done, but they roll off very differently in both magnitude and phase, so aligning them can get tricky.
 
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Buckeye Amps

Buckeye Amps

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While not a 15, if you want compact sub with even more driver area that a 15, a dual 12inch sealed might do the trick... I have 2 larger subs in my front corners but did not have room for 2 more in the back 2, so I picked up 2 of these
With dual 12 inch drivers and 960w amp (2100 peak), It seems to be quite the performer to me and increases a lot of options on where it can go.
I didn't even see that option.
12" is also on the table....again, basically anything that would be appropriate to help in this situation. Wasn't sure if 12" would be "too small" but this dual design seems very enticing.
 
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Buckeye Amps

Buckeye Amps

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Rythmik's subs also reach 14 Hz @ -3 dB so a 15" Rythmik might be a perfect fit. :) Close to you I doubt you need the extra output of an 18" model.

Disclaimer: I am a fan of Dr. Brian Ding, the man behind Rythmik. We have similar day jobs and I have a number of his subs. Be sure to say "hi" from me to he and Enrico.
Thanks. I had a 12" Rythmik YEARS ago and loved it, albeit it was in a very small room.

Essentially it seems like any well performing 15" (or the dual 12" PSA) would work well?
I had some people on AVS either tell me I had to match the Funk or get a robust 18" to "keep up with the Funk", which didn't seem right to me since I am only asking it to handle frequencies well above 20Hz.
 

DonH56

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Thanks. I had a 12" Rythmik YEARS ago and loved it, albeit it was in a very small room.

Essentially it seems like any well performing 15" (or the dual 12" PSA) would work well?
I had some people on AVS either tell me I had to match the Funk or get a robust 18" to "keep up with the Funk", which didn't seem right to me since I am only asking it to handle frequencies well above 20Hz.
Opinions vary. My experience has been asking about subs leads to an endless stream of boys pushing bigger and bigger subs, and more of them. I have a quartet of 12" Rythmik F12's in my media room, chosen to alleviate some nasty nulls, not output. They play way louder than I can stand, and the in-room response reaches about 7 Hz (lower than I need).

Funk is highly-regarded with very good performance, as is Rythmik, thus my fan-boy recommendation for a nice Rythmik to killl the null and give you some extra low-end punch.

Matching models is always safest, but my guidance for many years (from my first DIY servo sub around 1980 until now) has been the same as I stated above. I prefer similar outputs but weighted by distance, similar -3 dB points, and will not willingly ever again mix sealed and ported (vented) models in a system (yes, I did it, and it was a royal PITA).

I have not yet tried MSO or SFM using my JBL/Trinnov, with or without a miniDSP, as it sounds good enough to me that I don't want to spend more time futzing with it.
 

alex-z

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Only needing to cover 30-90Hz drastically reduces how big of a subwoofer you need. Even a sealed 12" can provide a lot of output in that range.

I would suggest building something like a sealed Dayton Ultimax 15", they sell a kit with a 3ft cabinet for $355, just add your choice of amp and binding posts.

I do highly recommend external DSP, it makes the integration much easier. Even the upper mid-range of AV receivers tend to EQ the dual subwoofer pre-outs together, only the delay and level is actually independent.
 

DonH56

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Only needing to cover 30-90Hz drastically reduces how big of a subwoofer you need. Even a sealed 12" can provide a lot of output in that range.

I would suggest building something like a sealed Dayton Ultimax 15", they sell a kit with a 3ft cabinet for $355, just add your choice of amp and binding posts.
I still say Rythmik and done, but gee, wonder what sort of amp he might use? :)
I do highly recommend external DSP, it makes the integration much easier. Even the upper mid-range of AV receivers tend to EQ the dual subwoofer pre-outs together, only the delay and level is actually independent.

He's got a Trinnov, it does them separately, or however you care to do it.
 

nerdoldnerdith

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There's no 15" sub that can keep up with the Funk in midbass other than a custom job with an efficient driver with a high Fsc and an amp that can dump a lot of voltage into it.

Your best best as a turnkey solution is the Power Sound Audio S1512, but even that has nowhere near the output of the Funk.
 
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Buckeye Amps

Buckeye Amps

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I still say Rythmik and done, but gee, wonder what sort of amp he might use? :)


He's got a Trinnov, it does them separately, or however you care to do it.
Ahh so you have a Trinnov (or JBL "Trinnov") as well? And you just let Trinnov handle your multiple subs without any external device (like MiniDSP) or program like MSO?
Glad to hear it, as easy integration is what I was hoping for (another opinion I kept getting was I would need MSO or a MiniDSP to make it work properly)
 

phoenixdogfan

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SVS should have something, and they're in the same state you are (in Youngstown).
 

Sancus

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Ahh so you have a Trinnov (or JBL "Trinnov") as well? And you just let Trinnov handle your multiple subs without any external device (like MiniDSP) or program like MSO?
Glad to hear it, as easy integration is what I was hoping for (another opinion I kept getting was I would need MSO or a MiniDSP to make it work properly)
There is no reason to buy a miniDSP with a Trinnov, I don't think. As far as I know they let you set basically unlimited PEQs for each channel in addition to level and delay. That's all you need. MSO is just a program for generating those values with an exhaustive algorithm, so you can use it with a Trinnov, or do them manually, or use REW, or whatever you prefer.

It doesn't sound like you have a very complicated set of room modes so REW or manual tweaking should be OK.
 

Slayer

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So I want to add a second subwoofer purely to boost the 60-90Hz range
The main goal is to make sure it can audibly match/keep up with the Funk in the mid bass range of 50Hz+
Have you thought about an 18'' pro audio sub? Electro Voice or QSC would work great with what you are trying to accomplish.
Neither one will have any problem keeping up with your current Funk subwoofer.
 

dualazmak

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Just for your reference, precision time alignment between subwoofers (SWs) and your main SP's woofers (WOs) measured at your listening position would be important for nice total sound quality as I shared on my thread;

- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-1_ Precision pulse wave matching method: #493
- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-2_ Energy peak matching method: #494
- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-3_ Precision single sine wave matching method in 0.1 msec accuracy: #504, #507

Also let me suggest you that you would objectively observe the tightness and cleanliness (transient characteristics) of the bass sound around the crossover Fq, just I shared in my post here and here. These objective observation would be useful for your decision of crossover FQ, I assume.
 

sarumbear

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So I want to add a second subwoofer purely to boost the 60-90Hz range where the null is. I would probably give it an HPF around 30Hz so it would not need to have any meaningful output under 30Hz.
Have you considered the passive solution: using a Helmholtz resonator similar to this?
 

sarumbear

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Never even knew of such a thing or how it works
You tune it to alter the room response within a narrow frequency range. As simple as anything.

For some reason not very common but Helmholtz resonators like the one I showed is a simple but effective solution in the 50-100Hz range. The purest low bass is generated by an organ, which use similar resonators.
 
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