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Discussion Starter #1

I am interested in discussing amplifiers that are used to power subwoofers. I have four DIY subs powered by a Crown XTi-2002, wired for 2-ohm operation. I had recently read the Crown I have is less than ideal for sub duty, due to an overly aggressive high-pass filter. After two calls to Crown tech support, I came away convinced Crown does not have much interest in the subwoofer amp segment.

 

Prior to the Crown, I was running a Behringer iNuke 6000 at 8 ohms. The iNuke's marketing specifically pitches it as an amplifier that is good at reproducing bass frequencies. Both amps do their job reliably, and without stumbling. The question is this: can I do better strictly through amplifier upgrades? If the answer is yes, then what parameters matter most? I have read that one "ideal" amplifier for sub duty is the Lab Gruppen FP10000Q professional amplifier—is there better out there?

 

I am curious what qualities allow an amplifier to approach the "ideal" for subwoofer duty. Should it play flat to 1Hz? Should each amp be able to handle a 1-ohm load—or a 2-ohm load when bridged? Should the amp's cooling be entirely passive, or is it OK to use a very quiet computer fan? Does damping factor matter? Is it better to have four channels, how about four channels with the option to bridge into two?

 

Would modularity and expandability be appealing? How about a chassis with a transformer and slots for amplifier modules—three subs? Get three amp modules. Do you have six subs? Get six modules. If you have one great big subwoofer, get two modules and bridge them. Is your sub a dual-opposed 18"? Then try four modules total, bridged into pairs, with one pair powering each driver!

 

I am curious about output voltages and ultra-low frequencies. Do class D amps have issues with continuous output of infrasonic waves? Is there any advantage to class A amplification for low frequencies since it is the perennial favorite for full-range speakers? How about a dedicated 220 volt line—is that the ticket to real performance?

 

Finally, how about DSP? Would a stand-alone subwoofer amp capable of performing some kind of room EQ be appealing? What if delay, EQ, phase, high-pass and low-pass filters were all programmable through an app?

 

Now I know I could leave my amps alone and look at building new subs and/or shopping for upgraded drivers, but I really am more interested in discussing amplification. I've asked a lot of questions, am interested in serious answers. I appreciate any insights into the topic. Thanks in advance for keeping the discussion civil.

 

 



Big subs need big amps - photo ©2013 by Mark Henninger

 

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Hmm, well lets look at the ideal op-amp. Infinite gain, infinite bandwidth, zero noise and losses. Make that!


In all seriousness, if you can cleanly output from 3-120hz, you're good there!

If the amp is 2-ohm stable, you're good there!

If the amp can do large voltage swings, you're good there!

Class H or D (although D is more efficient), it won't matter, but give is a switch mode power supply with a very neutral power factor. Oh and we still want a lot of capacitance for those large voltage swings (explosions in the movie)


Beyond that, a person can add DSP. I don't know how you'd make it modular without having a huge chassis to add more power modules and some folks won't want a huge 7RU chassis if they only need two channels of amplification instead of six or eight.


Personally, I don't care too much about 2-ohm operation and would like an amp that can do large voltage swings for 4 or 8-ohm operation. I don't want to have 1 or 2-ohm loads run to the amp requiring 8AWG wire to prevent line losses.
 

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The ideal sub amp will provide the power you need into the load you have, for the entire bandwidth desired at low distortion and noise.
 

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A K20, PLM 14K and iT12k is about as close to perfection as there is. (Without weighing 1000lbs and being the size of a beer fridge and require 3-phase LOL).

But they are so expensive that they simply aren't practical for home use, by us peasants.

So The FP14k clone is the next best thing. Unless I'm missing something.


Based on this thread http://www.avsforum.com/t/855865/measuring-amplifiers I purchased an EP4000. It looked great on paper 1.6kW RMS bridged into [email protected] for $300 what could go wrong?

but in actual-use the clones smack the EP's around all the way to the horizon. Perhaps efficiency and peak-power was more important than I realised? (I'm still scratching my head over this.)


Someone really needs to measure the clones into various loads.


On a side-note: Do you like the XTI2k better than the nu6k?
 

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regulated power supply (power factor correction) in the clone?

into 4 ohms, behringer is 1600 watts. clone is 4400?

not sure about the capacitor reserves, probably more joules in the tank with the clone?


op, instead of reinventing amplification, just take a look at the cv5000 for a low cost pseudo copy of the crest ca18.
 

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I will be trying out a new amp soon that can sustain its rated power spec for a solid 5mins not 20ms New indian company. have to wait to middle of May to order. Will be A/B comparison of my Crest 7200 vs their amp that has 1000watts stereo in 4ohms. Cost is about 430 before shipping. They also have an amp that will do 4000watts x 2 4ohm. They are making all sorts of amps soon. Plate amps, four channel amps subwoofer amps that can be tested at DC with bandwidth only going up to 1000hz, does 5000watts mono 2ohm or 4ohm. Was designed for Roots style music. All sub amps are tested at 10hz for rated specs.


Anyways glad to see your still around Mark. I sent you a PM but never heard back. Busy people is all no prob. I am sure others can say more important information pertaining to this thread than I. I only know what I have used and figured out along the way.
 

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Quote:
Originally Posted by chrapladm  /t/1469111/what-qualities-would-an-ideal-subwoofer-amplifier-possess#post_23228590


I will be trying out a new amp soon that can sustain its rated power spec for a solid 5mins not 20ms New indian company. have to wait to middle of May to order. Will be A/B comparison of my Crest 7200 vs their amp that has 1000watts stereo in 4ohms. Cost is about 430 before shipping. They also have an amp that will do 4000watts x 2 4ohm. They are making all sorts of amps soon. Plate amps, four channel amps subwoofer amps that can be tested at DC with bandwidth only going up to 1000hz, does 5000watts mono 2ohm or 4ohm. Was designed for Roots style music. All sub amps are tested at 10hz for rated specs.


Anyways glad to see your still around Mark. I sent you a PM but never heard back. Busy people is all no prob. I am sure others can say more important information pertaining to this thread than I. I only know what I have used and figured out along the way.
Gotta site to learn more about these amps?
 

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Discussion Starter #11

Quote:
Originally Posted by chrapladm  /t/1469111/what-qualities-would-an-ideal-subwoofer-amplifier-possess#post_23228590


I will be trying out a new amp soon that can sustain its rated power spec for a solid 5mins not 20ms New indian company. have to wait to middle of May to order. Will be A/B comparison of my Crest 7200 vs their amp that has 1000watts stereo in 4ohms. Cost is about 430 before shipping. They also have an amp that will do 4000watts x 2 4ohm. They are making all sorts of amps soon. Plate amps, four channel amps subwoofer amps that can be tested at DC with bandwidth only going up to 1000hz, does 5000watts mono 2ohm or 4ohm. Was designed for Roots style music. All sub amps are tested at 10hz for rated specs.

Anyways glad to see your still around Mark. I sent you a PM but never heard back. Busy people is all no prob. I am sure others can say more important information pertaining to this thread than I. I only know what I have used and figured out along the way.
I can't find a PM from you, sorry about that. I've kept busy, no doubt about it 2013 is a real change of pace versus the last couple of years. Thank you for the input; subwoofer amps that can just run at maximum unabated, with no real restrictions on how low they can go, seems like a good idea. 
 

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I have high hopes for this new company after chatting with them for so long. They design their amps then have china build them. Same area as Sanway but not same company. that being said I will learn more when I get my first amp from them. Then I will know if it is true or smoke.


I sent you a pm on the other forum. Will send you one here.
 

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Quote:
Originally Posted by chrapladm  /t/1469111/what-qualities-would-an-ideal-subwoofer-amplifier-possess#post_23228813


I have high hopes for this new company after chatting with them for so long. They design their amps then have china build them. Same area as Sanway but not same company. that being said I will learn more when I get my first amp from them. Then I will know if it is true or smoke.


I sent you a pm on the other forum. Will send you one here.


Any idea of the expected cost of the 6402 or 8002? What about release dates?
 

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Quote:
Originally Posted by A9X-308  /t/1469111/what-qualities-would-an-ideal-subwoofer-amplifier-possess/0_100#post_23226717


The ideal sub amp will provide the power you need into the load you have, for the entire bandwidth desired at low distortion and noise.

In addition, IMO it would have a 12V trigger, NRTL safety certification, and be as small and quiet as possible, and a long warranty valid in the country of purchase. Ideally, it would be cheap as well, but that doesn't seem to go well with the other parts.


FWIW, for a home system the sweet spot for me is the ElectroVoice CPS-8.5. Adequate power and number of channels to run a multisub system with reasonably sized subs (maybe not 15's in 20L cabinets that need massive Linkwitz Transforms), NRTL safety certified, small (8 channels in 2RU), 12V trigger input. Would be better without a fan, but it's small. Also fairly expensive, but it's 8 channels with bridgeable pairs, small, and made in Germany.


For a nearfield system, IMO the sweet spot is the Paradigm X-850, despite the silly spring terminals, because ARC/PBK is sufficiently advanced that it does about as well as extensive measurement-listening-measurement loops, but takes a lot less time. Also has scads of power, NRTL safety certification, 12V trigger, no fan, etc. Again, not cheap, but IMO worth it.
Quote:
Originally Posted by BassThatHz  /t/1469111/what-qualities-would-an-ideal-subwoofer-amplifier-possess/0_100#post_23226869


***

So The FP14k clone is the next best thing. Unless I'm missing something.

You are. There's no such thing as an "FP14k clone." There's a "counterfeit FP14k" or a "pirate FP14k," perhaps, but not a "clone."


Theft is theft and justifying theft just makes one, at best, an accessory to it.
 

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Quote:
Originally Posted by Rebel975  /t/1469111/what-qualities-would-an-ideal-subwoofer-amplifier-possess#post_23229017


Any idea of the expected cost of the 6402 or 8002? What about release dates?
I know the 8002 will be 1400. The 6402 I think was around 1200 but I dont recall. These are just ballpark figures. After Mays shipment they will have a more set price. Because they are a new company I dont want to dump a bunch of money into them so I am going to try their two smaller amplifiers. They are making a 4x150watt amp. That will be about 250-300. The 1000x2 will be about 440. So hopefully they all work just fine. They will be perfect for my outdoor setup.


PLUS I am willing to spend 500-600 dollars on a new company that I have chatted with for quite a while then 900 on the clone. Either way I am excited.
 

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Quote:
Originally Posted by chrapladm  /t/1469111/what-qualities-would-an-ideal-subwoofer-amplifier-possess#post_23228590


I will be trying out a new amp soon that can sustain its rated power spec for a solid 5mins not 20ms New indian company. have to wait to middle of May to order. Will be A/B comparison of my Crest 7200 vs their amp that has 1000watts stereo in 4ohms. Cost is about 430 before shipping. They also have an amp that will do 4000watts x 2 4ohm. They are making all sorts of amps soon. Plate amps, four channel amps subwoofer amps that can be tested at DC with bandwidth only going up to 1000hz, does 5000watts mono 2ohm or 4ohm. Was designed for Roots style music. All sub amps are tested at 10hz for rated specs.


Anyways glad to see your still around Mark. I sent you a PM but never heard back. Busy people is all no prob. I am sure others can say more important information pertaining to this thread than I. I only know what I have used and figured out along the way.

I'm also very interested in reading/hearing more about the 8002. Right up there with FP14K rated power and if this could prove to be a reliable option it would be a huge hit around these parts. Please do keep us posted.
 

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Oh - the ideal amp?



-Long term, sustained, full bandwidth power without built-in filters

-Low impedance stability at high levels

-Ability to run in stereo or bridged configurations

-Very high efficiency and ability to run on 120V a plus

-Integrated DSP would be a plus

-Lightweight a big plus

-Quiet or non existent fans

-12V trigger/relay a big plus for us home theater junkies

-Long term reliability and vendor support

-Low noise floor and adjustable gain

-Ideally American, Canadian, or European made

-Of course, it has to be relatively affordable



In the past year I've played quite a bit with the EP4000, inuke6000dsp, XLS5000, various plate amplifiers, and a few of the FP14000 Sanway clones. Each have their advantages but none of them are my ideal amplifier IMO. I'm starting to heavily consider some of the rack mounted amplifiers from speakerpower. No, they aren't cheap but they come highly recommended from some of the top ID speaker manufacturers. They seem to cover most of the bases I'm looking for as well.
 

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Quote:
Originally Posted by audiovideoholic  /t/1469111/what-qualities-would-an-ideal-subwoofer-amplifier-possess#post_23238027


Any info on tested speaker power rack amps? Like where do they drop off at? They look nice but are pricey for sure!

There is some info in this thread:
http://www.avsforum.com/t/1449918/new-speakerpower-rack-mounted-subwoofer-amps


I am wondering how the SP2-8000 can be run off 120V and maintain 2400W indefinitely as that would require 40A.

They are very interesting amplifiers, but would prefer more third party measurements, particularly power at 5Hz and distortion levels.


Also, I'm curious how they a pair of LMS 5400 would sound powered by a single SP2-8000.

Only downside is that one could get 3 Lab Clones for the price of a single SP2-8000.

Or one could see it the other way, you could get 2 SP2-8000 for the price of a single real Lab FP14000!
 
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