Subwoofer size and connectivity

I have Maggies.

I’m moving into a space with a listening area approx 18’x18’x13’, but the space is semi open and extends well behind the 18’ area. What size sub would you recommend? I’m considering a Rhythmik sub, and they recommended a 15” sealed sub. (Their subs are servo controlled.)

They have seveal amp options as far as connectivity. High level, line level, XLR… there is a warning against connecting a class D amp with differential outputs to speaker level inputs.


I really prefer my twin JL 10 inch subs. Super quick, detailed, extremely musical, and with two of them, have no issues at all filling that size room.

I would recommend REL S series subwoofers for consideration. I learned about REL from Paul McGowan’s video. REL website has excellent subwoofer finder for various brands of speakers, models and size of room. For size of my listen room / speakers one REL S3 SHO should suffice. I had one for less a year and added second one later, which brings out noticeably better / fuller imaging and deeper, clearer low ends than having one REL. Adding RELs and P20 power regenerator are the biggest sound improvements to my system. Hope this helps;


I have dual S3/SHO and they are great. You don’t really notice how good they are until you turn them off and see the hole… great subs… they should paint the legs black… :slight_smile:

Using them with Sonus Faber Guareni Evolution book shelf speakers.


When I was doing my search for subs it came down to Rel 212/SE, Martin Logan BF212. I’ve listened to them and either are superb. Price is almost identical. The Logan’s can be installed similar to Rel’s, but their real advantage is DSP in my opinion.

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One other well know manufacturer and Class “A” Stereophile rating are SVS. I have a pair and I swear by them. Dollar for dollar against other manufacturers you’ll acquire a larger Sub with full features for the same money. As for a bargain, SVS Feet are very inexpensive at around $50 for a quad.


skip the Bulk tab and it shows you the available spray colors, they have matte or gloss black!

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Yes, my next step thanks; however, looking at other isolation feet options before that step. REL indicates using Blu Tack for keeping the sub from walking. The feet are 2in tall and I want to get isolation that is similar in height and does not cover the passive radiator protruding from the bottom. So far the closest is 1.6in high.

I have a similar issue - medium room with openings to several other rooms makes for a loss of low-end volume.
I’ve got a pair of Velodyne DDP-10 subs coming in a couple of days.
These feature servo control to minimize distortion, and have a built-in equalization/phase-shifting computer that works with their calibrated mic and the main speakers to create custom DSP for each sub.

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One sub is OK, two can be better, but 3 or 4 (staggered around the room) is best for reducing in-room standing waves that are location/frequency dependent. So I recommend 4 smaller subs. Look into Audio Kinesis Swarm.

I run (3) 10 inch subs to disperse bass generation in an 8ft x 13ft x 21ft room and they’re dialed in at roughly 50% to provide plenty of bass. Note that I’m an old fart and NOT a basshead.

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Rythmik is an excellent choice. I am a huge fan of servo controlled subs. My first was a Velodyne ULD15 over 30 years ago. I have twin Rythmik 12SE’s (boxes built by Jim Salk) and they blend perfectly with my sats. Jim builds a much heavier cabinet with stouter internal bracing. Here’s what he says: “Non-resonant cabinet coupled with exclusive Rythmik Direct Servo technology insures that accurate, impactful and genuinely musical bass. What more could you ask for?”

Highly recommended!


Any suggestions regarding my connectivity questions?

I use high line w/ REL Baseline Blue cable from BHK250 to REL subs (sub black wire floating w/ insulated sleeve). I also add an RCA line (GND) from the BHK250 L & R input (I use XLR from PRE to AMP) to the REL sub L & R 0.1/LFE input (potentiometer CCW) to stop REL sub hum with BHK250 ON. In the evening I shut down Roon (source material) waiting for the REL signal sense to place the sub in standby (30min), then I turn off the BHK250 amp and no hum from REL subs with BHK250 ON or in standby modes.

From your setup image, bass from each woofer/subwoofer will propagate in phase, magnifying the in-room bass node phenomenon: visualize a bathtub filled with 4 inches of water where you move your hand back and forth through the water from end to end; the waves move to the end of the tub and bounce back until they meet the next wave where they will cancel, double the wave height, or something in between; this is exactly how bass waves behave in-room. Note that where the dips and peaks occur varies with location and frequency. DSP can only correct for a single location.

Putting all the bass generators side-by-side multiples the effect. Best to randomly stagger them around the room. I have (3) subs: one about 12" from front left corner; one about 48" from front right corner along the side wall; and one roughly 2/3rd’s the way back along the left side wall. My monitors are 56" from the front wall and 36" from the side walls in my 8ft x 13ft x 21ft room (Fibonacci ratios). Read Floyd Toole’s “Sound Reproduction” 3rd edition.

(and @cardri):

I just replaced the stock feet on my office REL today with the SVS “SoundPath Subwoofer Isolation System” (a/k/a some kind of rubber feet). Too early to discern any sound improvement, but I kind of like the look. Can’t post pictures at the office – will try to follow up with a couple of snapshots later this evening…


[Edit: Here are the pictures I promised.]

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@scotte1 - thanks, I am putting together a diagram of the approach I will use with the SVS isolation feet. Adding a 5/8in cylindrical piece (same diameter) to extend the feet to 2.10in and keep the same launch height for the passive radiator firing downward.

[edit] - I just finished painting one black spacer a gloss black; looks OK. I think flat black would have been to much of a contrast with the piano black REL sub paint. I also just ordered (2) sets of SVS isolation feet. Shipping should arrive this SAT (02/23/19). That should give me enough time to paint all (8) spacers and prep for the sub feet modifications. I should have the mods up and running by end of weekend. Then critical listening set for next week.


Thanks for your comments. I am somewhat space and placement limited so currently my system functions like a 2.1 with full range floor standers, with a third sub halfway down the left wall. To the right the space opens up to a stairwell, then a pony wall, then even further back another alcove. I do use DSP for my listening location. I’m planning to relocate in two years to a new home with a dedicated room. My intent is to add two more subs at that time.

I’ve not heard a bad recommendation in this thread yet.

Two things I would mention.

First, I do not believe the lower end SVS subs have crossover controls. It seems they just have it fixed at 80 Hz. This is not something I’m a fan of since the crossover point is important when integrating your sub with your speakers. Everything from their 3000 line up is awesome, though.

Second, I prefer high level connections to subs. It tends to allow the sub to blend more naturally with your system and almost always sounds better than RCA or XLR in my experience. You mentioned something about Class D amps, though - what amps are you running? Generally it’s not an issue though it’s worth making sure.

As I said, there hasn’t been a bad recommendation yet, so it will come down to your budget and what features are important. SVS seems to have DSP down pat, Rhythmik has servos helping out, and REL just makes some of the most darn musical subs I’ve heard.

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“and REL just makes some of the most darn musical subs I’ve heard.”

This ^.

I have an older behemoth of an SVS ported sub (1000 watt amp, three ports and dual 12 inch drivers) and an REL T/5i (8 inch driver and less than 200 watts). I love my SVS in my big rig with decent-sized room and high ceilings; but I agree with @schroedster regarding the musicality of REL’s products.

I have the M700s. That’s why I’m worried.

And i have a SGCD.