Shiva or Servo Rythmik for Sonotube?

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Main question: What do you recommend for a 12" or larger driver for use with a sonotube along with a plate amp (also of your choosing)?

Loading a 12" woofer into a sonotube seems like an attractive option for someone on a student's budget/schedule. I suppose I could get a PB10 that would perform roughly as well for the cost of this project since I'm going to have to purchase all the tools I'll need, but at least I'll have them when it's all over.

Space really isn't an issue, so I'm going to fool around with some design parameters for the sub, but in trying to figure out how much this will cost I was just wondering if there are close competitors to Rythmic’s 12” servo. Initially I was attracted to the Rythmik servo as an attractively priced alternative to HSU or SVS, hoping I could pick up a cheap cabinet somewhere. Now, given that I will need to purchase most of the tools I'll need I'm looking for alternatives yet again. Can anyone say how closely a cheaper Adire or other driver could approximate servo performance in a tube?

Thanks.
 
I own both a Rava (Shiva Mk Iv and 25ow plate amp) and a sealed Rythmik servo kit. In the interest of fairness, both subs are closed boxes, though my box for the servosub is a lot stiffer and heavier. Both drivers have around the same excursion, and the rythmik amp has a good deal more power, along with the response/damping settings. My attempt at objective comparison follows:

IMHO the Servosub is a lot better for music, though the Rava is no slouch there either, particularly if EQed and and crossed fairly low. The Servosub on the other hand can be crossed above 100hz and sound very good indeed, I'd wager better than most midwoofers in that range, provided its centered. The lower distortion is really welcome on jazz, classical, electronic, or anything with a complex bassline, though some may find it lacking the warmth they are used to (read: distortion).

For home theater they are fairly even, the Servosub has lower distortion and sounds more accurate, but bass distortion often adds some 'rumble' to effects so its not always objectionable. On action movies with lots of explosions the differences are negligible, on soundtracks or movies where low bass is used for atmosphere it becomes more noticeable. Output capabilities are similar, with maybe a slight edge to the Rava, provided you set the Servosub's response shaping to a similar response curve as the Rava (Mid Q, 28hz on the toggle switches). If you use the response shaping to get the servosub flat to 20hz or 14hz, you will run out of excursion earlier, which is to be expected - if you EQed the rava flat to 20 or 14hz, it would bottom sooner as well.

One final diffference that I doubt many would care about, but I quite like about the aluminum TC sounds driver in the Servosub is the behaviour when you reach its limits. When you reach the limits of the Rava, you know because of the loud CLANK the driver makes as it bottoms. Its almost like there is no threshold, either no audible distress or CLANK. This can be quite alarming if like me you worry about damaging your gear, and many a time had me jumping for the volume control. The servosub driver reaches its limits with a soft tapping that gets louder the more its overdriven, which doesnt sound nearly as scary, though for all I know its just as bad.

I hope that helps.
 
Thank you both for your replies.

Especially appreciate the in depth comparison for both movies and music - very helpful.

The tube kit is pretty tempting for someone with no tools - I'll need to see how much I'd save doing it myself. Do you know which Shiva is included?
 
The newest shiva, just released this month I belive.

Waiting to here back on if it is the DVC 4ohm or DVC 8ohm.

I will be doing up a DIY article for www.hometheaterhifi.com which might not be published until March. I can however give you more info as I progress.

If you are interested let me know, and I can give you more info when the package arrives. It should be here before the week is out.
 
morbo said:
The servosub driver reaches its limits with a soft tapping that gets louder the more its overdriven, which doesnt sound nearly as scary, though for all I know its just as bad.

I'm glad you posted this. Is what you get a somewhat odd, almost metallic rubbing sound when over driven? Maybe even a Pac-Man-ish "walka walka walka"? When I put mine together, and decided to do some max output tests, I noticed that when I crossed the line. What was odd was, the odd sound continued for a second or two even after the volume was reduced, suggesting that it wasn't a physical bottoming out issue. Maybe some anomaly of the servo circuit when it's over driven? Maybe even some intentional audible warning? It really scared me at first, but both of mine do it, and it stops shortly after backing off. I don't consider it a BAD trait, certainly no worse than hearing a clack when bottoming out, but it was unnerving at first. What made it worse was, it's accompanied by an odd smell. Not a burning smell really, something that is unique that I can't describe. I don't know if it's from the amps or drivers. Have you ever noticed that too?
 
JRace said:
The newest shiva, just released this month I belive.

Waiting to here back on if it is the DVC 4ohm or DVC 8ohm.

I will be doing up a DIY article for www.hometheaterhifi.com which might not be published until March. I can however give you more info as I progress.

If you are interested let me know, and I can give you more info when the package arrives. It should be here before the week is out.
Welll it finnally arrived...last night I moved the dining room table and built the entire sub in less than 1.5hrs in my dinning room still in my fancy-pants from my day at work. Very minor mess created from drilling 4 holes in the mdf bottom plate. The glue used had no noticable fumes:clown: requiring ventalation and the only tools required were a flat-blade screw driver, power drill, 1 drill bit, a pair of scissors and one Philips driver.

The construction was very easy thanks to the instructions found at www.creativesound.ca.:smash:

I have only been able to hook it up to confirm that it works, so no SQ tests as of yet. Looks very nice though.

It is my first DIY home woofer and I was shocked just how quick and easy I could assemble it. If anyone is thinking of a fun easy DIY kit to try this one was great.
 
Jrace - glad you got it up and running! Let us know how it sounds when you get a chance.

I'm glad you posted this. Is what you get a somewhat odd, almost metallic rubbing sound when over driven? Maybe even a Pac-Man-ish "walka walka walka"? When I put mine together, and decided to do some max output tests, I noticed that when I crossed the line. What was odd was, the odd sound continued for a second or two even after the volume was reduced, suggesting that it wasn't a physical bottoming out issue. Maybe some anomaly of the servo circuit when it's over driven? Maybe even some intentional audible warning? It really scared me at first, but both of mine do it, and it stops shortly after backing off. I don't consider it a BAD trait, certainly no worse than hearing a clack when bottoming out, but it was unnerving at first. What made it worse was, it's accompanied by an odd smell. Not a burning smell really, something that is unique that I can't describe. I don't know if it's from the amps or drivers. Have you ever noticed that too?

That doesn't sound familiar to me, definately not the 'wakka wakka' sounds which I would notice easily. What I get is a soft tapping, sounds pretty much exactly like hitting the cone with my fingernail or a screw would sound like. The tapping stops immediately when the sharp transient does. And I have not noticed any smell, though I don't think it would be able to escape the box very easily anyway.
 
Hmmm, ok. As I said, I don't get it during normal use, only the few times I was testing to see where the limit was. One of my drivers is mounted inside out, and my amps are not in the box (and are open), so the smell could be from either one. The smell is similar to Ozone, and it's actually quite strong. May remain a mystery.
 
Last night I had the house to myself for an hour and poped in the Primus DVD from the HallucinoGenetics tour. The sound was fantastic. the highlight track on that DVD is the Drum and Whamolla jam, 11 or so minutes of Herb banging away on his huge drum kit. then out pops a srtange monkey-lookin dude playing what must be the Whamola. Basiclly a Stick with strings that is played with a bow. The bass response was quite impressive even at very high volumes. The kickdrumwas intense and the deeper notes were very smooth.

This is just my initial listning with the sub in my standard location. I have not yet done proper calibration or placement. I will post more notes as I get there. So far, I am very impresssed.

Associated eq:
Marantz sr5300 reciever
Panny DVD player
AV123 XLS bookshel speakers
Paradigm ADP rears and center
Powered by a hefty 1100watt (max) at 4ohms

The sub is the dual 8ohm version, wired to present a 4ohm load to the amp.
 
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