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Best type of Sub to consider?

I'm not looking for a brand or model recommendation at this time, but rather the best type of sub to fit my room and system. If you access my System pics, you will see that I have open corners behind my speakers and that my Horning speakers are rear ported. This has caused some energy loss, especially in the bass when compared to my previous setup in my other home.

I am a newbie to subs and see different design types that fire up, down, up and down, and forward. There may be other variations. So, does any of this matter when applying the best design type to a room, my room? My knee-jerk reaction is to go with forward firing in my situation, but that's complete speculation on my part, so why I'm asking.
Kenny
kennythekey
almarg's avatar
almarg
9,670 posts
 
One of the brands I am considering is sealed, and the cable it comes with connects directly to my Horning speaker posts. Then, I read on another brand’s website that this is an inferior design flaw. So, another can-of-worms that can be opened up.
In most cases connecting a sub that provides speaker-level inputs to the terminals on your speakers will work fine. The circumstances I can envision in which it would not be a good idea, and might result in hum, noise, or other issues, would be:

1)If the amp(s) driving the speakers have outputs that are balanced, meaning that both the negative and positive output terminals have signals on them.

2) If the amp(s) driving the speakers have outputs that are bridged, meaning that both the negative and positive output terminals have signals on them.

3)In a few cases, such as certain ARC balanced amplifier designs, where the amp’s circuit ground is connected to its 4 ohm output terminal, rather than to the "common" output terminal.

4)In the case of certain older class D amplifier designs, where both the + and - output terminals of the amp are offset from ground by a large DC voltage.

In all other cases, which comprise the majority of amp designs, I don’t think there would be any problem at all doing that.

Regards,
-- Al

whart's avatar
whart
3,217 posts
 
Kenny: I'll share my thoughts, though I don't know your main speaker (which, I gather is a modified Lowther-type driver augmented with woofers and depends on corner reinforcement):
1. If I had to choose between a coherent speaker that was optimized for its full range vs adding on subwoofers to augment the bass, I'd probably do everything I could first to optimize rather than add. I know you said you have no options, but looking at that room, the side facing the system looks like it has "corners" (I assume there are windows behind the blinds, so you might have to deal w/ inserting some kind of rigid panel behind the "corner" blinds when listening). Perhaps with cabling, power outlets and the like, it's too much of a pain.
2. The notion of feeding the woofer amp from your main amp isn't crazy- my Avantgardes are set up that way and though their woofers are driven by their own internal solid state amp, the thinking is that they take on the behavior of the main amp feeding them (in my case, a SET amp).  The cables to do this made a difference- I went through various "jumpers" before I arrived at one that sounded better than the others.
3. The woofer design may be less important than placement and dialing in- read some of the other threads here- about swarm woofers, about dipole kits to match the behavior of panels. 
4. I've been messing with subwoofers for a long time for music and was never happy, having had various Quad loudspeakers (electrostats) and then horns. (I didn't even bother trying to sub-woofer my Avantgardes until quite recently). Right now, I am achieving some improvement using an unmatched pair of subs, crossed low, no roll off of the main woofers, and have been fiddling with DSP. I didn't want the discontinuity typically associated with subs and planars or horns, and didn't want to muddy the midrange. I've managed to get it 'just so'- more foundation without screwing up the mids---
5. Your system looks like it came from Jeff at High Water, who has very good ears, and is a cool guy. Even if he doesn't sell subs, does he have any advice for you?
bondmanp
1,836 posts
 

I know you're not looking for brand recommendations, but few subwoofers are designed intentionally to be placed in corners, as you want to.  I, too, place my two subwoofers in the front two corners of my room.  They are down-firing through a slot.  But you will see that many subwoofer users go through heroic efforts - bass traps, EQ, etc., to get good, somewhat flat bass response from corner-placed subwoofers.


That said, my Vandersteen 2Wq subs are specifically designed to perform best when placed in corners.  And I have found that they need little if any in the way of EQ or room treatments to compensate for corner placement.  I urge you to research this subwoofer and its unique hook-up scheme.  I think it might be a good fit for you.

kennythekey OP
593 posts
 

Al - Again, great information, so thank you.

1) No, not balanced.

2) No, not bridged.

3) No, single-ended.

4) No, 300B SET.

Wow, four out of four!

Whart - Thank you, it sounds like you're having success with careful tweaking. Yes, the driver is a modified Lowther DX65.

1) This back wall that you see only has the one useable corner, so you're only seeing one half of the room. The other corner is 31' from the corner you see.

2) It would be great to know what jumpers you liked best.

3) Interesting, I'll look into those. And, an indication that design may not play such an important role.

4) That's very reassuring.

You got me there, because Jeff is my dealer. And, the best one I've ever had the fortune of meeting. He doesn't sell a subwoofer line, but he has spent a lot of time, setting up his Cessaro subs.

bondmanp - I think you may have misunderstood, because I don't have corners. If I did, I probably would not want subs.

Kenny

bdp24's avatar
bdp24
10,285 posts
 

Your system suggests you would appreciate the sophistication of an OB/Dipole sub. A very unique one is available as a joint venture between GR Research and Rythmik Audio. The sub is not a normal Open Baffle sub, which are already unique enough, but an OB in an H-Frame, superior to a flat baffle because of it’s greater structural stiffness and non-resonance. And of course it’s open baffle design prevents the often boomy sound of even the best sealed subs.

A dipole sub excites the room modes of it’s front and back output, but not those of the room dimension to it’s sides, where there is a dipole null. There are a few OB/Dipole subs available, but the GR Research/Rythmik is unique in that the two (or three) 12" woofers (facing in opposite directions in the H-Frame) are Servo-controlled by the Rythmik plate amp. The amp also contains a 6dB/octave shelving circuit to offset the dipole front-to-back cancellation at very low frequencies.

The sub is offered as a kit only (one kit includes the amp and two---normally, though you can use three---12" woofers). The H-frame into which the kit is installed is available as an easily-assembled flat pack from a couple of wood workers who frequent the AudioCircle GR Research Forum. A pair of kits (for two subs) runs about $1500 shipped, and the flat pack (CNC cut from 1.5" MDF!) about $600. The highest sound quality, though not quantity, sub available.

Details of the design available on the GR Research and Rythmik Audio websites, and discussion of the sub on the Forum.
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