First DIY Subwoofer, Amp question

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Hi !
This is my first post here, please forgive me If my topic is under the wrong section.

I've got my hand on a subwoofer (MTX MSZ1204, 12'', rated 300W RMS)during the holiday sales, and started building a sealed enclosure for him. I know the woofer was made to be used in a car, bus since I already have two 10'', I would use the MTX as my audio/game subwoofer in my room. (May be used in HT later on, but that's not for now).

I did some research on the web about amp and plate amp to power the little beast. I was wondering If I should go with a 300W (rms) amp or a 500w (rms) one ? I guess i'd be better with the 300w, since anyway the woofer aint gonna take the 200 more watts, right ?. (On the other hand, I've heard that it was better to give too much clean power to a woofer than less but clipped)

I've saw 3 model that seems to fits my need on PartsExpress:
300w:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-750

500w:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-752
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-806

If I go the 500w way, ive noticed that a difference between the two 500w is the presence of an Eq on the Dayton. Is this gonna be usefull at all ?


Thanks for reading and helping.

Happy listening, Loka
 
it is generaly advised not to take the manufacture's word as gospel, 300w is the rms rating at a very specific set of circumstances, fryed a few speakers myself driving them at their "rms" rating. although 300w is alot of power and if everthing is designed properly and the sub is reasonably sensitive you can loosen ceiling plaster, among other things.... but then with a 500w amp used carefuly( stress carefuly) you will enjoy better sound quality for obvious reasons more headroom for transients for one. cool thing about diy, it's all about learning! have fun.:D
 
See thats where the dishonesty of specs starts to bite...
An amp being able to handle 300W RMS will handle longer peaks in excess of that than a speaker would...

What I'm trying to say is on a bass amp a true 200W amp may make a safer partner... especialy if your friends can get to the volume knobs...

Of course we have organic feedabck systems (our ears) which should tell us if speakers are being driven too hard... And I doubt you will ever turn the volume up far enough to become a danger...
 
Thanks for the reply guys, very apreciated.

300W woofer wil be killed by 300W amp after a few minutes without fail...
it is generaly advised not to take the manufacture's word as gospel, 300w is the rms rating at a very specific set of circumstances,

Yeah, i get it now. I've taken the habit to never turn up the volume pot higher than 80% when it come to audio, because of either distortion and these 'not-so-true-marketing claim'. Anyway. I guess I wont ever need to push this subwoofer to he's maximum output considering the room size.

I think I'll go with the Dayton 500W, because of the Eq (thx Jrace) and to be able to upgrade the woofer later-on, as wazzy said.

*I just saw that Nordic replied while I'm typing this replay*

I agree with you nordic, when you'r talking about friends reaching the volume know:rolleyes: . I'll buy the 500w (vs a 250/300 one) because I may eventually buy another,better, woofer and I dont want to spend another 200$ on an amp. I also think that it is better to drive a speaker a little too hard with a clean input that push it with a clipped signal (amp being driven too hard)

Furthermore, If the MSZ sound good, I always could buy a second one,but, well, I think 300W of bass is going to be enough for now:D

Thanks (again) for the replay.

Loka.
 
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for a 300W rms subwoofer driver i would probably use 200W or so amp

for a 300W rms 2-way or 3-way speaker i would probably use a 1000W amp

this is because in case of a subwoofer you would be more likely to destroy it with a big amp, but in case of a speaker you would be more likely to destroy the tweeter by clipping a small amp

on the other hand if the amp is not adequately protected (as i think could be the case with el-cheapo plate amps) it may fail itself if its just barely large enough to drive the speaker ... so maybe it if we're talking about a no-name el-cheapo plate amp you need to buy 500W to actually get 200W ...

guess this wasnt much help, but you cant always reduce these things to simple math :)

of course my standard advice regarding plate amps is not to use them :) get a crown I-Tech 8000 instead ... but nobody seems to listen :)
 
*Didnot found an 'Edit' Buttom, :( *
of course my standard advice regarding plate amps is not to use them
Is there any rack amp that would be worth buying ranging from 0-300$Can to power this subwoofer ? From what i've saw, plates seems to be cheaper, but I would be ready to burn a 'lil more money on a rack amp; any auggestion at this point will be greatly appreciated, I plan to order next week:D

I would purchase from creative sounds then.
If I end buying a plate amp (see above), I'll get it by CreativeSound, shipping will be way cheaper this way. Thanks for the link, Jrace
 
for a 300W rms subwoofer driver i would probably use 200W or so amp

for a 300W rms 2-way or 3-way speaker i would probably use a 1000W amp
.

While I would agree with you on clipping dangers in tweeters vs. woofers, I would still argue that the above is backwards, tweeters don't require a lot of power so "a couple hundred watts" is not necessary, there is less energy in the upper octaves.
For woofers you need the RMS rating at a minimum, some people suggest double this, but it depends on how loud you will be playing music or movies. If you don't have the main volume and the amp gains set to maximum, usually the case, then you have your reserve power right there and you don't need a bigger amp. However, if you are unsure of the overall quality of an amp it would probably be a good idea to oversize it.

A note on quality, I have two receivers one with a massive (~15lb) transformer and one with a much smaller one, they are both 5.1 receivers rated at 100W rms/ch (both Class H). The one with the large supply and whatever else is better, can reproduce drum beats at 110dB with a very clean and controlled thump, the other one produces a lot of uncontrolled cone movement and a significantly quieter and muddier sounding bass. Even eq'd flat it wont sound good.
So regardless of wattage, cheap garbage is cheap garbage.
 
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Joined 2008
nunayafb said:


While I would agree with you on clipping dangers in tweeters vs. woofers, I would still argue that the above is backwards, tweeters don't require a lot of power so "a couple hundred watts" is not necessary, there is less energy in the upper octaves.
For woofers you need the RMS rating at a minimum, some people suggest double this, but it depends on how loud you will be playing music or movies. If you don't have the main volume and the amp gains set to maximum, usually the case, then you have your reserve power right there and you don't need a bigger amp. However, if you are unsure of the overall quality of an amp it would probably be a good idea to oversize it.

A note on quality, I have two receivers one with a massive (~15lb) transformer and one with a much smaller one, they are both 5.1 receivers rated at 100W rms/ch (both Class H). The one with the large supply and whatever else is better, can reproduce drum beats at 110dB with a very clean and controlled thump, the other one produces a lot of uncontrolled cone movement and a significantly quieter and muddier sounding bass. Even eq'd flat it wont sound good.
So regardless of wattage, cheap garbage is cheap garbage.

i understand why you think its backwards but its not

i never said that you need smaller amp for your subwoofer than for your speakers.

i specifically compared a 300W subwoofer with a 300W speaker but nobody in their right mind would pair a 300W subwoofer with 300W speakers in the same system because a 300W speaker is a strong one but a 300W sub is weak.

within the same system i would probably use 2 times as much amplifier power for subwoofer as compared to main speakers but i would use a subwoofer driver with perhaps 10 times the power handling than that of the mains.

so relative to the driver (voice coil) power handling i would put less amplifier power on the sub than on speakers

in other words you need bigger amps for the bass in terms of absolute power but smaller amps for bass in terms of power relative to the voice coil thermal power handling

this is because when it comes to tweeters its about reproducing transient peaks without clipping but when it comes to subwoofers its about dissipating the continuous flow of energy into heat in the voice coil ...

an amplifier is mostly limited in peak power while a speaker is mostly limited in continuous power. if the amp is undersized the peaks will clip but if the speaker is undersized its gona burn the voice coil.

from the above 2 paragraphs hopefully you can see why what i said is not backwards ... in any case i dont know how to explain this any better ...

i do agree that a small transformer will make a weak subwoofer amplifier no matter what the paper specs ... this is why i use a transformerless amplifier on my sub. no transformer - no problems :)
 
Lokalazeros said:
Is there any rack amp that would be worth buying ranging from 0-300$Can to power this subwoofer ? From what i've saw, plates seems to be cheaper, but I would be ready to burn a 'lil more money on a rack amp; any auggestion at this point will be greatly appreciated, I plan to order next week

C$300 should get close to buying this hidden gem from Parts Express:
300-810 Dayton HPSA1000-R 1000W Rackmount Subwoofer Amplifier
US$400 and should be sufficient for most needs.

(I have no idea about your MTX woofer, but aren't car 'subs' generally hopeless in a house?)
 
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Joined 2001
Paid Member
Tosh said:
C$300 should get close to buying this hidden gem from Parts Express:

Keep in mind that buying from PE and bringing into Canada means dealing with the dreaded UPS customs factor, I'd check with Bob at CSS to see if this is something he can get. He uses his procimity to the US to avoid the UPS hassle and does a lot of PE stuff for Canadians.

dave
 
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Joined 2008
i actually have some 12" MTX woofers from back when i was in high school (MTX 8000 4 ohm)

i would describe them as crude

however they were pretty strong for the money ... i mean they're still alive ... they also pounded pretty good from a rockford fosgate amp

the quality however is not there ... not just the sound quality ... any kind of quality

for example when i just hooked them up first time one of the lead wires to the voice coil fell off and i had to solder it back ... at least thats how i remember the incident

those 12" MTXs did not disappoint me, i got exactly the performance i wanted out of them ... but that was long time ago ... today i would need something more refined
 
FWIW DSL uses MTX in at least some of its prosound tapped horns and I've yet to read a review that didn't praise their performance/SQ. They may still sell some cheap @#$% drivers, I don't know, but the ones I've seen/auditioned was anything but poorly constructed/'crude', so to dismiss their current offerings out-of-hand for sub duty seems unwarranted IMO.

GM
 
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