Subwoofer Amp Selection

Joined
Dec 18, 2007
Messages
579
Location
Madison, Wisconsin
I'm looking for a bit of a second opinion on a good pro amp to power subs with. I also lurk on the AVS site, and the Behringer iNukes are pretty much the default recommendation over there. But any time I see just one option being recommended as THE option, it either makes me think its really, really good - or else there's a current flavor of the day and that's it. I'm not 100% sure what this situation is.

I'll be powering two 18" drivers in 4cuft sealed enclosures. The drivers are rated for 600 watts RMS, but can be pushed to 1,000 watts in these enclosures before they approach xMax. Link To Drivers

I'm considering two options:

1) inuke3000 dsp. The specs are horribly inflated on it's promotional material, but it's been tested to output 1,000 watts @ 2 ohms in stereo. It's a Class D amp, so it's more efficient - and it comes with DSP so I could equalize my sub. Downside is that it has a fan in it that sounds like an airplane taking off, and Behringer quality is suspect. Many overlook this because life as a sub amp is much easier than the life it was intended for - but it's still a concern in my book. One can do a fan mod and change it out for a quieter fan, but then you are messing with the cooling and I'm not sure I want to do that.

2) Go with an older style iron amp. I've been eyeballing this Crown Amp which is priced very aggressively. It can output the 1,000 watts into 8 ohms stereo, and it does have changeable input sensitivity which might eliminate the need for a Clean Box to increase my sub signal from my AVR. Downsides are no DSP, and the fact it's less efficient than a Class D amp. Not sure if efficiency is a big worry in my world or not. If I wanted to equalize the sub, I'd need to buy a miniDSP or something like that since my reciever doesn't do that. (And yes, I ignored the advice from wise people on this forum last fall when I failed to buy an AVR with subwoofer equilization ability such as Audessy. Just putting that out there before someone else does
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I'm curious on opinions. Would you go with a Class D amp with DSP, knowing it's running hard at 2 ohms? Or would you pay a bit more for the old school amp that is quiet and can provide the same watts @ 8 ohms, but not offer DSP? I'm torn, because I feel like the Crown amp has a better name/quality, and it wouldn't be working as hard ( i think) which might give me more headroom. The opinion on AVS is that the DSP swings the argument in favor of the iNuke.

I looked at plate amps, and love their simplicity and fact I don't need to find a spot to put them in my equipment rack. But they are more expensive solution, and it seems like the pro amps will do everything they can and more.

Thoughts? After watching the crossover discussion on the DIY speaker thread, I know there's a few electronics gearheads out there. I'd appreciate some new perspectives.
 
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That's a big "no". I have a very large open basement. We are looking at 6,500 cubic feet or so to fill. Believe it or not, this system is likely underkill for the space if you follow typical theatre room type recommendations.
 
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Long ago for home use, I had found the 200w Carver Cubes in bridged mode controlled large woofers like an iron fist. The Carver cube was really not good enough for Hi-Fi wide band use IMO, so relegating it to sub duty made some sense.
 
I have QSC RMX 850 that I use in bridge mono with my DIY TC Sounds 15" LMSR in a sealed 5 cu ft enclosure.

I bought it on craigslist for $150 and it has been rock solid for 4 years now.

Amp is not in cosmetic prefect condition but typically pro amps arent the most beautiful things anyway.

I did do a fan mod on it which brought the db levels to a more tolerable since it is in my living room.
 
I have 650sq ft basement rec area, with another 200 through french doors within 10 feet of my sub. I understand your space since I *think* I have something similar.

I only have a single 12" sub with 200w RMS. It's not what you are looking for and not what I would recommend, but I mention it because my Audyssey keeps it pretty tame. I actually turn it up from what Audyssey tunes it for. So you didn't miss out on too much buying a receiver without sub equalization since it seems your preference will probably be significantly higher than reference.

I'm not sure on the amp since it's so far out of my league (for now). But my barely-educated opinion would be that the space isn't that huge, I wouldn't be willing to have an amp with a loud fan in it, if for the same price I could get something without even if it provided less power. Also, class D for a sub seems like the best solution for price and power efficiency.

I would say that a 120" projector setup in my size room is awesome. Despite my wishes for a larger sub I never wish for a larger screen.
 
Not really an answer to your question, but I just wanted to comment that I had a Crown XLS1500 amp for a while, driving 4 speakers in my large basement. Even if I cranked it up to the point where it was painful to listen to for extended periods, the amp would barely get warm. You could not hear the fans on this thing at all. Granted, this was an easier load to drive than something rated at 2 Ohm. Still, I would have no problem with a Class D amp for a sub.

The only issue was that being a pro amp, it required a higher level input than what typical home audio sources provide. Make sure you can work around it.

Other than that, I'd say give it a try. Just make sure you can return it if you don't like it.
 
Originally Posted By: bepperb
I have 650sq ft basement rec area, with another 200 through french doors within 10 feet of my sub. I understand your space since I *think* I have something similar.

So you didn't miss out on too much buying a receiver without sub equalization since it seems your preference will probably be significantly higher than reference.



We do have very similar spaces. But I'm not a reference volume listner. I'm usually around -35 to -25. I'm just trying to figure out what I "need" for subs based on what I've read on forums. On audio forums, 2 18" subs isn't a whole lot. But in real life is what I care about. I don't need to shake pictures on my second floor or anything like that...

If you were to move up from your 12" sub - what direction would you go? I'm curious because it does sound like we have very similar rooms.
 
Those are some nice drivers and would probably benefit from something that can feed them properly. My setup isn't anywhere near as nice, it is a bit of a hodge-podge of stuff (discussed elsewhere) but I am driving both my mains and my sub now with some older Yorkville gear (2x AP 3000's) and they do an admirable job.

A few links:

Their less-expensive series:
http://yorkville.com/downloads/ownersman/om_px1700.pdf

One from their AP series, made in Canada (about an hour from me):
http://yorkville.com/downloads/ownersman/om_ap40x0.pdf

They have variable speed fans on them that are extremely quiet and only operate when needed, which sounds like something you are concerned about.
 
When I made the 12" diy sub it was for a room that was 11x15 and the box needed to be small to fit into the decor. In my new basement the size of the sub doesn't matter, so going up to 15 or 18 would be a no brainer. The benefit of the upgrade in driver size would be in a lower roll off and going to a sealed enclosure for more accurate bass, I really don't need more volume or power handling, which was surprising to me.

I love AVSForum but it's never enough over there. It's a better resource to get specifics and to solve problems. When you ask a "what do I need" sort of question it's always 10 times what you want to spend.
 
i've never looked in this forum before---

I have years of professional music and PA experience. Behringer has its place. IDK the particular model you are looking at, but the past models are copied QSC RMX series and generally handle sub duty in multi KW environments just fine. the original QSC has deeper lungs, however, so if you really push it you'll want something more stout.

Classic "iron" amps handle sub duty better in my experience, but the class D stuff is ok too. I have an entry level class D crown that drives 2 15's for small venue work that does fine. for the money, I'd rather by a cheap crown or smaller QSC than go behringer. behringer gear is can get quirky with age, though in a home environment where it's not constantly moved, exposed to varying temps, humidity, beverage spills, it will probably last a while.

You want an amp that has twice the power as the speakers are rated.

You want an amp with highest damping factor you can to control cone movements.

you want quiet fans for indoor use.

note the entry level crowns are said to be chinese made, while the upper lines get better assembly. Mine sees limited use, but it'll run bridged 8 hours at a time outdoors in the sun and doesn't stress, and pushes the 2 15's just fine.

good luck!
 
Originally Posted By: meep
You want an amp that has twice the power as the speakers are rated.

You want an amp with highest damping factor you can to control cone movements.

you want quiet fans for indoor use.

good luck!


I like this decision framework. I'd not paid serious attention to damping factor before, but did some quick google reading. The Crown puts a tick in the box for all of these, the inuke is a bit short in both wattage and damping factor (160 vs 200 for the crown - although both are relatively high), and needs a fan mod to make it quiet.
 
The Yorkville AP amps (2nd one) I linked have a damping factor of 600 BTW.

Code:


Amplifier class AP4020: H

Continuous Average Power @ 8 ohms BCD (Watts) AP4020: 475 (x2)

Continuous Average Power @ 4 ohms BCD (Watts) AP4020: 750 (x2)

Continuous Average Power @ 2 ohms BCD (Watts) AP4020: 1200 (x2)

Continuous Average Power Bridged BCD (Watts) AP4020: 2400 @ 4 ohms

Burst Average Power @ 8 ohms BCD (Watts) AP4020: 625 (x2)

Burst Average Power @ 4 ohms BCD (Watts) AP4020: 1200 (x2)

Burst Average Power @ 2 ohms BCD (Watts) AP4020: 2175 (x2)

Burst Average Power Bridged BCD (Watts) AP4020: 4350 @ 4 ohms

Frequency Response (Hz, +/- 1dB) AP4020: 20-20,000

Hum and Noise (un / Aweighted -dB) AP4020: -103 / -106

THD -1kHz- 4 ohms AP4020: 0.0001

THD - 20Hz-20kHz, 4 ohms AP4020: less than 0.1%

Slew Rate (V/uS) AP4020: 25

Slew Rate Bridged (V/uS) AP4020: 50

Damping Factor (30 Hz - 400 Hz @ 8 ohms) AP4020: 600


http://www.amazon.com/Yorkville-AP4020-A...keywords=AP4020

Not overly inexpensive, but it is made in Canada, not China
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Originally Posted By: OVERKILL
Not overly inexpensive, but it is made in Canada, not China
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They must pay you Canadians well up there!
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But seriously, I'm all about buying North American sourced equipment where possible - unfortunately that amp would obliterate any semblance of a budget I have. I just can't go that high - as nice as it is.
 
Originally Posted By: sleddriver
Which sub-drivers did you buy? VC resistance?


I've not ordered them yet. As luck would have it, they completely updated the format of their website after I posted the origional link. I'm looking at the HT18 drivers - the VC configuration will be dependent on the amp. They are dual VC with 2ohm and 4ohm configurations - so depending on the configuration I pick I can go with either 2,4,or 8 ohm loads to the amp. And 1 Ohm, but that's probably not going to be of much use.

Updated Link to Drivers
 
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Before going with a pair of 18's and the large boxes necessary, I'd look up Earl Geddess' site and read about his method of multiple subs. Not only do multiple subs acoustically load the room better than one, but they also result in much more even response. Further, he employs a simple measurement technique to use in your own room to equalize the overall response. I think he's in Michigan.

If I remember correctly, your room is in the basement. So that means a concrete floor and concrete walls, correct? (Even if they have been framed out with studs). So you're going to have multiple images when anywhere near a corner. This means you'll have plenty of room gain to assist you.

Re: Damping. Remember that both source and load are frequency dependant, so we're not dealing with a resistance, but a complex-impedance instead. We're also dealing with heat. As the voice coil heats up, it's impedance will change, also affecting damping. Damping is important...up to a point. But it's not the end-all it's often made out to be.

Also remember a well designed and performing sub is a system comprised of the driver, alignment, box, amplifier and crossover...plus the room and the location within the room, it's placed in. Quality matters...not just quantity.
 
You are correct - I'm in a basement. I have a concrete floor and some concrete in the walls, but it's a walkout so I also have some "normal" walls. Due to the floor plan, any corner I'm going to be in will have standard drywall/studded walls. Two sides of the room have additional rooms next to them, the other two sides have 1/2 concrete walls. But I do have a concrete floor.

I appreciate the reference. I read a couple of his articles from 2011 which got into a bit more detail than I pretend to understand - but I think the key concepts are:

1) A minimum of at least three subs to smooth room variations. One sub in a corner near the mains (I can do), another near a side wall (can do) and the third somewhere random.

2) He has an equilization technique that I'm going to have to read up on further. I get the main concept, but need to do more studying on the details.

3) 200 watts per sub is sufficient. I saw a 12" driver in a cubic foot box referenced somewhere as a good model to follow.

I like the minimalistic approach (although some would argue three subs isn't minimalistic!) but it is from a floor space and amp power requirement perspective. I'd like to model it in WinISD tonight and see how it compares - realizing that max SPL is not the holy grail for me that it is for some. I'd rather have a system that accurately reproduces bass at the appropriate level, vs. one that can rattles the walls for effect alone.

What have you seen for DIY builds utilizing the Geddess method?
 
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