What is a 'servo' subwoofer

[Steve81]

But assuming it is, I've been looking at my sub options and for all the rage about SVS subs, their frequency response graphs don't look that great to me. For example, with the SVS SB-2000 If it's showing 93dB in the response curve at 30Hz, it's like 87 dB at 20Hz (apparently -5dB is "fit in" with the +/-3dB by averaging in the middle instead of where it sits even at 30Hz and above, which is misleading in the numbers, but obvious in the graph) and 83dB at 15-16Hz or so (graph isn't easy to read precision). OK, so in other words, that sub is WORTHLESS at 16Hz. It can't put out the pressure wave to "feel" 16Hz and you can't hear it, so I'm not going to get anything out of that.

A few things to keep in mind...
1. That's an anechoic response curve, not in room.
2. SVS is specifically shaping that response with DSP to mesh with the low frequency boost typically seen in smaller rooms.
3. Hoffman's Iron Law has yet to be beaten, so you can't really expect miracles out of such a small subwoofer.

Where's the improvement of this "modern" sub compared to my "ancient junk" from the mid to late '90s? It's down 4dB at 20Hz and only 1dB at 21Hz compared to 30Hz in my room. How is that "junk" by "modern standards"?

If your sub is able to maintain that response at the output levels that you desire with low distortion, than it's not "junk". What sub are you running now?

Overall, I just don't know if it's worth the expense to pursue 16Hz or if I should just be happy with 20Hz and work on evening out the room modes with a second sub like I originally planned.

Might be worth taking up SVS on a free trial to find out. How big is your room, and what kind of budget are you working with?

 

[William Lemmerhirt]

So, even though you completely discounted my opinion before I could explain , I can’t help but offer a couple things to help.

First off, the drivers and amps used in modern subs are designed and built better. They are much more controlled with better damping, and lower Q. So yes, to answer your question they will sound tighter. My gut says a pb2000 will outperform the pf1500 in every metric. Also, see Steve’s comment about measurements.

I owned an sb2000 and it’s an amazing little sub, but it’s not made for huge output, so I don’t think that’s a great example although the former owner of home theater shack had two in his room that were flat down to 10hz. I don’t remember output level. Also consider that your 15” is 56% larger than the little 12. Yes that’s an advantage.

Maybe @Ed Mullen can add some things for you. Or @@TLSguy

Apologies for yesterday.

Btw, got any screen caps of your sweeps?

 

[VonMagnum]

A few things to keep in mind...
3. Hoffman's Iron Law has yet to be beaten, so you can't really expect miracles out of such a small subwoofer.

I'm not even sure what I'd need to get "proper" pipe organ playback or whether typical recordings properly capture it (and I don't listen to much pipe organ music anyway). Beyond that instrument, everything else is either a movie sound or artificial synth, etc. I think near 20Hz or less so I'm not sure what I'd even "need". I think it's a case of just wanting to have it to have it. I just bid $172.75 on a Hasbro Ark of the Covenant on eBay to display under my Raiders poster (didn't get it; one person had an automatic bid higher; I could tell since it advanced $3 exactly so who knows what their max was). It's a plastic flipping toy, but I thought it would look cool there (currently have the Fertility Idol and a Staff of Ra headpiece there which I was going to move to the bookcase instead if I got it). I'm clearly NUTS so...

If your sub is able to maintain that response at the output levels that you desire with low distortion, than it's not "junk". What sub are you running now?

It's a 1995 Def Tech Powerfield -1500 15" 250W. It was $1200 at the time that I got for 20% off at $800. That thing has been running strong for 24 years so I give it props for being well built, at least and it looks good (piano lacquer top),but even it's in a pretty big cabinet and weighs somewhere around 80 pounds. At my old house, it fell off in the much larger room around 25Hz, but it was strong enough to shake the walls above that. In this house, the room is smaller and reinforces the bass better. According to the AVIA disc and my sound meter, at least, it stays right flat as a grizzly's appendage from 40Hz right down to 21Hz and then suddenly nose dives (I've got a straight 20Hz tone and you can't hear the walls rattling, but not the tone normally). Now with Audyssey correction, you can actually hear the tone at 20Hz (it seemed to bump it up about 8dB and it's only down about 6dB now from the 21Hz tone). I'm not sure why it's such a sudden drop, but then the AVIA tone might not be visually syncing up precisely for all I know. It might be closer to 23Hz or even the 25Hz figure if so still. I should really download some closer in-between single tones instead of that slow sweep. Let's say it IS 25Hz when it drops down now 6dB to 20Hz. Do I actually 'need' more bass between 20Hz and 25Hz even? That's hard to answer with real material and clearly if it is, I didn't realize I was missing anything. Other than electronic music and a few pipe organ CDs, I have nothing that plays that low musically.

If a second sub improves the 20Hz response a bit flatter overall for the room and evens out the room nodes, I think I'd be pretty happy with that. I have no idea if I might be missing some magical "faster response" on a newer sub for music. It doesn't sound boomy crossed to the PSB speakers or anything so I doubt it's too distorted.

I think when William called it junk he was getting a bit defensive when I questioned throwing it out/replacing it as he suggested and buying two new subs instead of just one. I started out just looking for a cheaper sub to even the room nodes out above 40Hz (below that, the bass carries quite loudly to the back of the room and scares the crap out of me in the half bathroom as it's about 10-12dB louder in there at all <40Hz frequencies, even 20Hz) than in the room at the same volume. I figured I'd probably order one sub and if it were magically 'faster/tighter' sounding with music or whatever, I could always give my old Def Tech sub to my mother for her house and order a second one. But even then, there's the question of what would do well enough in this room that it's not actually 'worse' given the Def Tech is a ported sub and I've been thinking about a sealed one (it'd be nice to take up less space in the room not more to some extent, at least).

Might be worth taking up SVS on a free trial to find out. How big is your room, and what kind of budget are you working with?

The room is 12x24x8.5 feet. (See https://www.avsforum.com/forum/90-receivers-amps-processors/2321145-beyond-7-1-4-multi-avr-set-up-immersive-audio-54.html#post56799092 for photos). You can just see the sub in the forward view sitting behind the end table.

Well, the budget is a bit fluid. It's not so much what I 'can' afford as it is how much I'm spending in general on this room. I just spent about $8000 in the past year on furniture and speaker/components alone (and a few hundred more decorating it with movie props in the back and some key places) let alone all the movie I bought in the past year and a half (167 3D ones alone) and the 3D projector itself back then.

I don't have kids and I'm not married so I 'could' buy that $4000 sub if I really wanted to, but if I don't 'need' to I have other things to upgrade yet (thinking about a 115" 2.35:1 tensioned motorized screen and an Epson pseudo-4K/3D projector (I need lens shift where it's mounted) with zoom memory to do 2.35:1 movies; that would be around $2600 for both (installation is another matter as I'd probably need a stronger mount setup for the heavier 26 pound projector and I'd have to move my front height speakers outward to accommodate the screen that is about 16 inches wider each on either side.

Just keep in mind I only had evening out the back of the room for the occasional guest in mind originally, but looking at subs for days on end gets me in the "gimmme more" mood.

I'm really just considering my options at the moment. I'm not in a big hurry because it really does sound pretty good in the MLP at this point and I don't often have more than two other people in the room (front row alone covers them) so the two seats in the second row and the one in the back don't get a lot of use (OK the center middle row does because it's a heated massage chair by the fireplace; a nice place to watch sports and TV Shows...as in I'll sit there for those. I watched the Super Bowl from the back. It still looked like a 65" screen >20' away so I couldn't complain. With a 2.35:1 screen, it would look plenty big even in the back and maybe kind of ridiculous at 9 feet from the front row. But ridiculous is what's fun.

I just realized the sub is in my prop photo for my Hellraiser Lament box (along with the left front wide speaker and my Nvidia Shield controller charging). The sub makes a nice secondary end table as I discovered as I no longer had room for the tissue box with the cube there).

 

[VonMagnum]

So, even though you completely discounted my opinion before I could explain

I think it's more in the way you said it. If my bass sounded 'boomy' I'd probably agree. Maybe it could sound tighter, but without hearing a newer sub in the same room, I can't be sure of that. "Boomy" always seem to come from >100Hz in my experience. I actually like bass ramped up 6-8dB below 80Hz for sheer impact. I don't know of too many fast paced bass tracks that low (I've got some Primus albums, but they sound pretty sweet). I've read demeaning comments before about older subs, but much of it is in size/deep/ratio compared to newer subs. But if the sub is reaching deep/loud enough in a room and doesn't sound boomy/slow I see no point in tossing it while it still functions just fine. My mother absolutely loves that sub (I originally got it while in college along with the AL-III speakers when I still lived at her house); she said she'd take it if I don't want it.

First off, the drivers and amps used in modern subs are designed and built better.

Well, certainly Class D amps have come into their own in more recent years. They seem pretty well perfect for subwoofer amps. OTOH, I adore my old Carver TFM-35x and Yamaha M-45 amps I have on my AL-III speakers and the Carver is right from that period (The Yamaha is from the mid-80s; the THD figures on that thing os INCREDIBLY LOW and it has Class A operation up to 15 watts at the push of a button and auto-switches to AB above that (It's a damn space heater in that mode, though). So, quality amps were certainly made back then, but yeah high powered Class D can put a ton of power in to a small package. I dunno about that DefTech plate amp, but I've never had to turn the gain up more than 1/3 in this house (about 1/2 in the old one with a much larger room but it still shook the walls like jelly on some of my Japanese Anime soundtracks that my Bass Pig friend recommended to me back then; damn I paid $42 each for those CDs back then.... They still sound awesome.

They are much more controlled with better damping, and lower Q. So yes, to answer your question they will sound tighter. My gut says a pb2000 will outperform the pf1500 in every metric. Also, see Steve’s comment about measurements.

I kind of wanted a sealed sub this time. I was looking at the SB-3000. If anything would have tighter bass, I figured that would be it. I don't know if the SB-2000 would have enough output. Maybe two of them? Again, though, I don't question the PB2000 would outperform the current sub, especially for the smaller size, but that doesn't mean it would be audibly superior enough to just toss the Def Tech. Again, I'd probably want to buy one and compare and then go from there. If it blends well and sounds good, I'm set. If it sounds audibly superior in a way that I think would benefit me to get a second one, I'd order it (I think $100 discount is good for some time afterward?). Given SVS's return/upgrade policy, they would be a good choice to try out. I liked the looks of those Rhythmic servos, though but if the output isn't high enough, it wouldn't matter much and when it comes to subs, it's pointless if it can't play loud enough for my needs.

Really, getting smoother output in the back of the home theater is my main priority, but if pipe organ music would suddenly blow me away with a larger sub, it might be hard to resist. There is the move it around the room factor, though. I'd have to be able to get whatever sub in the house and move it on my own (at least into the garage until I could get a friend or family member to come over). Some of those larger subs are quite heavy and I'm no Arnold Schwarzenegger.

I owned an sb2000 and it’s an amazing little sub, but it’s not made for huge output, so I don’t think that’s a

That's the sort of information I've been having trouble locating is how loud a given sub can play in a given room size. My room isn't huge (12x24 with a half bath taking up some space too in a slightly irregular shaped room) and clearly was easier to drive the old sub than my old house, but even there in a 16x30 room it could shake the walls no problem.

Apologies for yesterday.

No problem. I also have a tendency to get angry easily when my judgment is questioned.

Btw, got any screen caps of your sweeps?

I actually used a slow sweep with the SPL meter to watch the sweep. I really need to order a mic for a MiniDSP anyway to try upstairs and I could run some measurement software with my Macbook Pro then too. I've got the Audyssey curves on my iPod Touch, I believe (don't know how useful those are). I was mostly trying to get a basic idea of the response behavior. In slow mode, the needle just sits there from 40Hz down to 21 on the sweep (drops a bit at 50 still with a room mode there that wasn't 100% corrected by Audyssey (at least wherei had the meter; I was too lazy to get up and put the meter where my ears are as it sounded better than the meter suggested and then is fairly even again to 100Hz).

 

[Steve81]

I think near 20Hz or less so I'm not sure what I'd even "need". I think it's a case of just wanting to have it to have it.

That's usually how it starts

Do I actually 'need' more bass between 20Hz and 25Hz even? That's hard to answer with real material and clearly if it is, I didn't realize I was missing anything.

That's not unheard of either. If your sub handles overloads halfway gracefully vs crapping the bed w/ mechanical noise or gross distortion, you may not notice anything amiss.

The room is 12x24x8.5 feet. (See https://www.avsforum.com/forum/90-r...r-set-up-immersive-audio-54.html#post56799092 for photos).

Well, the budget is a bit fluid. It's not so much what I 'can' afford as it is how much I'm spending in general on this room...I don't have kids and I'm not married so I 'could' buy that $4000 sub if I really wanted to

I kind of wanted a sealed sub this time. I was looking at the SB-3000. If anything would have tighter bass, I figured that would be it. I don't know if the SB-2000 would have enough output. Maybe two of them?

If you're looking at sealed subs and want to try out something that would significantly boost your low end capability (without killing your wallet or being the size of a refrigerator),I'd think about this guy:
http://www.rythmikaudio.com/F18.html
Measurements:
https://data-bass.com/data?page=system&id=145&mset=171

Or alternatively a pair of Hsu ULS-15s (AH review)

 

[shadyJ]

I kind of wanted a sealed sub this time. I was looking at the SB-3000. If anything would have tighter bass, I figured that would be it. I don't know if the SB-2000 would have enough output.

Sealed subs aren't 'tighter' than ported subs when tuned to frequencies this low. What people think of as 'tightness' is really just amplitude response. Sealed holds no advantage here. In fact, sealed subs will be at a real disadvantage at 16 Hz and most will be running into heavy distortion in this range when pushed hard enough. Ported subs tuned to this frequency will have much more clean headroom versus sealed subs. You are looking at the wrong design for this application.

 

[VonMagnum]

If you're looking at sealed subs and want to try out something that would significantly boost your low end capability (without killing your wallet or being the size of a refrigerator),I'd think about this guy:
http://www.rythmikaudio.com/F18.html
Measurements:
https://data-bass.com/data?page=system&id=145&mset=171

Oh yeah. I like that one.

 

[snakeeyes]

Oh yeah. I like that one.

Probably you should also consider HSU VTF15 and Rythmik FV15HP and Monoprice Monolith 15.

 

[Irvrobinson]

Oh yeah. I like that one.

I do wonder after reading your posts if you really need all of the sub capability you think you do. I know some action movie HT crazies with 6000+ cu-ft rooms who want their floors to shake, and have 2-4 big subs, but your room isn't that big, and you seem to be more music oriented. I'm all for having too much of whatever just for fun, but this site known for having a lot of bass-obsessed people who apparently like their bass bigger than life-sized. I use a single SVS SB1000 in my computer system, in a room with more cu-ft than yours, and when a couple of friends have heard it one asked where the other sub was.

Just my reaction...

 

[VonMagnum]

Probably you should also consider HSU VTF15 and Rythmik FV15HP and Monoprice Monolith 15.

Too...much...information...overload...Spock...Where...are...you?

 

[snakeeyes]

Too...much...information...overload...Spock...Where...are...you?

Oh and the SVS PB4000 is another one to consider.

Only the Rythmik is servo though.

 

[ryanosaur]

Too...much...information...overload...Spock...Where...are...you?

I think that’s a normal response to the options available while considering sub shopping.
There’s the Fischer-Price, My First Sub options.
Then there’s the step up, “ok, that’s cool” options.
Next is the standard fare of what we seem to like and recommend most: Outlaw x13, hsu Vtf 3 or 15, Rythmik, PSA, SVS, Monolith 15"....
And after that... JTR,Funk, Seaton, Deep Sea, BossoBass.

FWIW, Von, I chose Outlaw... and my goal was for the occasional Pipe Organ. They do fine: as would most in that class. I have no regrets. If this were a video game, I migh restart from an earlier save file, do a few extra missions, then buy 2ea 15" or 18" subs.

 

[VonMagnum]

I've been entertaining a new idea. Instead of going for ultra deep, I just get a reasonable fill sub like I originally planned (SVS PB or SB 2000 for example) and get a Crowson tactile actuator system for say 2-4 chairs (pretty crazy pricey to do all six when most of the time only 1-2 are in use). Since bass below 20Hz is mostly tactile anyway, it seems like that system would really cut to the chase and without worrying about generating massive levels to get any tactile or pressure sensations (especially give the concrete floor).

Has anyone tried the Crowson system or Buttshaker or similar for that matter? What do you think? Is this a good idea or gimmicky? Some on AVS were raving about the Crowson system to the point where they said they'd never do a home theater again without it. EVER. Now that is a ringing endorsement if I ever read one for a niche product.

 

[shadyJ]

I've been entertaining a new idea. Instead of going for ultra deep, I just get a reasonable fill sub like I originally planned (SVS PB or SB 2000 for example) and get a Crowson tactile actuator system for say 2-4 chairs (pretty crazy pricey to do all six when most of the time only 1-2 are in use). Since bass below 20Hz is mostly tactile anyway, it seems like that system would really cut to the chase and without worrying about generating massive levels to get any tactile or pressure sensations (especially give the concrete floor).

Has anyone tried the Crowson system or Buttshaker or similar for that matter? What do you think? Is this a good idea or gimmicky? Some on AVS were raving about the Crowson system to the point where they said they'd never do a home theater again without it. EVER. Now that is a ringing endorsement if I ever read one for a niche product.

I'm not sure where the idea that bass under 20 Hz is somehow especially tactile. It is, if you have huge SPLs in that range, just like any other range. It is not somehow more tactile than other frequencies, if anything it is less tactile. It's just not a range that humans are very sensitive too.

 

[VonMagnum]

Well if you're watching the movie Earthquake you need some 5Hz love....

 

[William Lemmerhirt]

I've been entertaining a new idea. Instead of going for ultra deep, I just get a reasonable fill sub like I originally planned (SVS PB or SB 2000 for example) and get a Crowson tactile actuator system for say 2-4 chairs (pretty crazy pricey to do all six when most of the time only 1-2 are in use). Since bass below 20Hz is mostly tactile anyway, it seems like that system would really cut to the chase and without worrying about generating massive levels to get any tactile or pressure sensations (especially give the concrete floor).

Has anyone tried the Crowson system or Buttshaker or similar for that matter? What do you think? Is this a good idea or gimmicky? Some on AVS were raving about the Crowson system to the point where they said they'd never do a home theater again without it. EVER. Now that is a ringing endorsement if I ever read one for a niche product.

For the first part above, I would still agree with getting a new, quality subwoofer. Definitely not an SB2K, but possibly a PB/PC2k. Hard to say how it will act in your exact room, but I believe for what your after something in the 3/4000 series might be better. The 2k will handle music fine, but IMO if you really want to shake the couch you’ll need to go a little bigger. As I said before, dB per dollar goes to HSU and probably Rythmik, but i recall you didn’t like the finishes. I would have SVS send a pc4000 and take advantage of the 45 round trip free trial. Worst case scenario, you can send it back with the full knowledge that you were right all along! :wink: yes that was a horrible attempt at a joke reflecting on our earlier...ummm...debate? Just having some fun.

Anyway, I have not experienced Crowsons, but have tried buttkickers. The crowson ma’s(motion actuators) are supposedly more natural, but are a lot more expensive. Ime they’re a lot like near field subs, in that I never felt like they integrated into the rest of the system.

I know they’re are a lot of guys on avs that love the MA’s but a lot of them also have six 18”s with four 15’s right behind the couch. I believe some are even in central mn so I’d be able to listen, but it seems like those systems might sound like...

In any case, I’m not against them, but ma’s just haven’t done much for me.(I do have an experiment in the works). So I would go with a really capable sub, see what you think.

 

[shadyJ]

Well if you're watching the movie Earthquake you need some 5Hz love....

If you are talking about the Charlton Heston Movie from 1974, actually that doesn't have any deep bass. It has a lot of bass in the 40 Hz to 50 Hz range. However, it is a relatively bass heavy movie from its day. Movies didn't start to use deep bass until Jurassic Park.

 

[VonMagnum]

If you are talking about the Charlton Heston Movie from 1974, actually that doesn't have any deep bass. It has a lot of bass in the 40 Hz to 50 Hz range. However, it is a relatively bass heavy movie from its day. Movies didn't start to use deep bass until Jurassic Park.

I was just being a smart ass.

 

[ryanosaur]

F'n Awesome!

High Five!

Winner Badge x5

And:

 

[William Lemmerhirt]

F'n Awesome!

High Five!

Winner Badge x5

And:
View attachment 29127

Thank you! Thank you! I’ll be here all week!

I always thought that gif was funny.