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Ported and sealed subs in the same room?
Ported and sealed subs in the same room?
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Old 17th January 2018, 02:19 PM   #1
homebuilder is offline homebuilder  United States
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Default Ported and sealed subs in the same room?

Greetings:

I've read that you should not mix sealed and ported subs in the same room due to phase issues. I don't grasp that concept fully, or even know if that is correct.

I currently have (3) powered subs. Each one has a 12" driver, and a 12" passive radiator. They are commercially manufactured subs. They are approximately 18" x 18" x 18". I do not play them head-banging loud. I'm looking for high quality sound.

Our new audio room, which is 4000 cubic feet net, is mainly for 2 channel, but will also serve as a home theater. I want to build (2) more subs, and am leaning heavily towards buying the new assembled cabinets from Erich at DIYSOUNDGROUP. Sealed, 5 cf, for an 18" woofer. The woofer I'd prefer to buy is the Acoustic Elegance TD-18. I've owned several sealed subs, and prefer the sound over other designs I've heard. My current main speakers are ported, but I also have Magnepans, and am restoring a pair of vintage ElectroVoice Marquis.

Is this going to create issues? Should I be focusing on ported designs, or use a passive radiator like my existing units? Space is not an issue. I've long considered doing infinite baffle woofers, but that forces me to place speakers and equipment on walls where it is less desirable functionally.

Thank you in advance for any helpful advice.
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Old 17th January 2018, 05:43 PM   #2
weltersys is offline weltersys  United States
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Quote:
Originally Posted by homebuilder View Post
Greetings:

I've read that you should not mix sealed and ported subs in the same room due to phase issues. I don't grasp that concept fully, or even know if that is correct.

1)I currently have (3) powered subs. Each one has a 12" driver, and a 12" passive radiator.
2) I want to build (2) more subs, and am leaning heavily towards buying the new assembled cabinets from Erich at DIYSOUNDGROUP. Sealed, 5 cf, for an 18" woofer.
3) My current main speakers are ported, but I also have Magnepans, and am restoring a pair of vintage ElectroVoice Marquis.
4)Is this going to create issues?
5)Should I be focusing on ported designs, or use a passive radiator like my existing units?
1) A passive radiator has the virtually the same phase response as a ported cabinet with the same Fb (Box tuning frequency). A "powered sub" usually has some sort of analog or digital processing which will alter the phase response in some fashion dependent on digital latency and filter topography.
2) A sealed box will not have the same phase response as a ported box unless the frequency response is identical.
3) Depending on the crossover frequency and Fb of the ported cabinets, they may not be "in phase" with the upper range of the subs.

In general, if the phase response is within 1/4 wavelength (90 degrees) two cabinets can be considered "in phase". At 100 Hz, 1/4 wavelength is 2.8 feet, but at 30 Hz 9.4 feet, so you must consider phase as a "moving target".

Art
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Old 17th January 2018, 07:53 PM   #3
homebuilder is offline homebuilder  United States
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Default Weltersys:

Art:

Thank you for your reply. Based on my very limited knowledge of what you describe, it sounds like I would need to acquire measurement gear in order to determine how my current subs perform, and then attempt to match that as closely as possible with any new subs?

I have no idea if any digital processing is going on with those subs. They have a modest amplifier, and an adjustable crossover, which I have set at 50 hz. The subs are units built by TAD, and unfortunately marketed under the Pioneer logo. Which is why they did not sell. They were designed by Andrew Jones as entry level TAD's.

The other thought I have had is to use a completely different set of subwoofers for home theater, than for 2 channel. I have plenty of amplification laying around to do that.

In the past, I've noted that John at Acoustic Elegance seems to be a fan of passive radiators, so that doesn't pose any problem in itself. My lack of knowledge is the issue here.
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Old 17th January 2018, 08:00 PM   #4
globalplayer is offline globalplayer  Germany
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I would not do it.
(Different enclosure types/speakers play the same freq range).

What could work though, use a dsp and let the different enclosure types/speakers play different freq bands according to their strengths.
Like one enclosure type plays 20 to 50hz and the other 50 to 100 hz.
For example.
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Old 17th January 2018, 08:14 PM   #5
bentoronto is offline bentoronto  Canada
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Ported and sealed subs in the same room?
You should always take any opportunity to get heterogeneity into your speaker system.

Talking about phase is often a naive textbook-diagram kind of simplistic thinking, rarely meaningful at your own music chair. Unless you are exactly equal distance from all drivers and all ports AND playing in an anechoic space, guessing the precise phase at your ear is just guessing. Stick with plain freq response and trim to taste.

So your best bet is to have averaging statistics on your side. Do the math.

B.
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Last edited by bentoronto; 17th January 2018 at 08:19 PM.
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Old 17th January 2018, 09:50 PM   #6
homebuilder is offline homebuilder  United States
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Default Beltoronto--?

Okay, that went right over my head. Not the language....I suck at math, which is the only subject that has ever stymied me.

I have no concept of how to apply your comment to my situation, other than that I should listen with my ears. I do that now. I simply don't understand the entire subject of "phase" and how that applies to my speakers or environment.

I believe that it is necessary to invest in some measurement gear, in order to treat my room, and get things placed properly.

Right now, my thought is to plan for a couple new subs this Spring or Summer, and what they should look like, and how they should be built. I'm busy with my other projects, so this is going to mean either hiring my cabinet maker to build from a set of plans, or buying something like the cabinets I mentioned in my first post...the DIYSOUNDGROUP units.

There are many people on this site who are really into the technology, the measurements, etc. I'm not one of them. My fall back position if I cannot get what I want from "DIY" is to go with "DIFO". Do It From Others.

In my first post, I alluded to an issue that to me is of concern....I have radically different speakers. Ported TAD, Magnepan, and vintage EV horn-loaded, Alnico drivers.

I'm not a bass freak. I want to experience the concept of distributed bass. I bought my TAD subs for $1000 each, new. That was a bargain in my mind. Where do I go from here?
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Old 17th January 2018, 10:02 PM   #7
scottjoplin is offline scottjoplin  Wales
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Have a look at this Multiple Subwoofer after Geddes Earl is a member here Gedlee. Different subs are an advantage. When it comes to placement of subs, measuring is of limited use
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Old 17th January 2018, 10:04 PM   #8
bentoronto is offline bentoronto  Canada
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Ported and sealed subs in the same room?
The concept of heterogeneity is simple. There are resonances and piling-on of loudnesses arising from various sources in speakers and rooms. No easy way to stifle them adequately. So best to even-out the peaks and valleys by avoiding clones* (except, of course, for matching your basic stereo pair, north of the non-directional bass band) and, instead, mix and match. That way things will average out better.

B.
*for example, not have multiple copies of the same subwoofer and arranging furniture so that you have least parallel surfaces the same distance apart. Just to give two examples.
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Last edited by bentoronto; 17th January 2018 at 10:07 PM.
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Old 17th January 2018, 10:22 PM   #9
homebuilder is offline homebuilder  United States
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Default ScottJoplin and BelToronto

Ah. Interesting. I have read some of Geddes work, and that is the main reason behind my interest in distributed subs. I will do more reading.

BelToronto: Okay, I see where you are going with this. Although it isn't strictly limited to sub-woofers, one concern I have with my new room is that it is nearly a square at 21.5' by 22.5' The ceiling is 9'. I'm trying to educate myself on how to treat different walls, and what types of furnishings to put in the room to break up undesirable modes. For example, I'm looking at those thin bricks to put on one wall to create an irregular surface. Also looking at bass traps, live-end/dead-end, carpeting, etc.

I do want to mention that all of the people who have responded so far are people whose comments I have read for many years. I really appreciate any help I can get.

Although this is off topic somewhat, last night I came across "Funk" woofers. Very interesting. My cabinet-maker was at my house today measuring up for some new kitchen cabinets, and we took about 30 minutes to look at sub cabinets, and 18"-21" drivers. Wow.
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Old 17th January 2018, 10:27 PM   #10
scottjoplin is offline scottjoplin  Wales
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Ok, have you read about double bass arrays? These work best in a symmetrical room, you don't need any traps, and theoretically there are no room modes.
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