ski

I always thought that if you had, say, a 400W RMS amp, your subs should NOT have power handling less than 400W. People were telling me today though that your sub can be like 300W RMS for a 400W x 1 amp.

True? Or should your sub have higher power handling than amp, for fear of blowing it out otherwise?

Gosh, wish I knew these things!


EDIT: Also, what do you think of this box? $30ish is about my budget... it's either that, or the $30 ported one from Wal-Mart, and I don't want to go ported

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Airencracken

Actually you always want an amp with a higher RMS rating than your speaker. First of all most speakers are rated for peak power handling not RMS. Second, you want lots of headroom so when you push your amp it doesn't clip and give you crappy distorted sound. Most of the time pure power doesn't blow speakers, distortion does. More powerful amp is a must. Also make sure you know how much power said amp is delivering at a certian rate of ohms, then match up your speaker's resistance to that particular rating.

Edit: Nothing wrong with ports as long as they're tuned correctly. I doubt the Wal-Mart box will have ports that have been tuned.

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ski

Thanks man

Will a cheap sealed box, for $32 shipped like in the link above, suffice? They used to sell 1/2" thick ones at Wal-Mart, so CLEARLY I stay away from that, but this one seems quailty... what you think?

Airencracken

MDF is pretty good for speaker enclosures, and for 30 doesn't look bad, but of course an in person inspection would be better.

The pic doesn't show the terminals so I can't comment on them.

ski

Can I go too wrong with this from Sears clearance?



Jensen 12 in. Subwoofer, 525 watts Peak, 175 watts RMS

I'm KICKING myself because there's an Audiovox CD head unit with RCA preouts for $30 NEW... and I bought a used Jensen for $44 The eBay seller still hasn't applied the charge to my MasterCard, and they're a pretty big company www.buyessex.com ...

mechmike0034

Here's a site for ya: http://www.the12volt.com/

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StonedWheat

That doesn't really make sense to me. Won't that potentially allow you to blow your speakers if you turn it up?

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ski

What are "spring terminals" on subwoofer boxes?

link

CynJon

Spring terminals are the spring-loaded connection to the speaker wire...link

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AlpineJay

Be careful with buying cheap boxes, though. I bought one of those cheap MDF boxes from WalMart for the basic system for my old car(pretty much configured same way as yours) and for the life of me could not get it to sound good. I knew that I shouldn't expect audiophile grade sound, but something in the low end was really missing even after the addition of a sub.

It turned out that the box had a sound leak - not cool because that can really screw your sound. Once I changed the box to a QLogic (and paying double what I paid for the WalMart box) my system sounded much better. Of course, I have graduated from that system, and sport something much better now.

Good luck with your system, man. The first one's always the fun one. Try and do most of the work by yourself (it seems like you are) - you'll get a lot out of it.

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DarkFury

Honestly, I wouldn't buy any of that stuff... if "price" is your motivator over "sound quality" then I do understand where you are coming from even though I don't agree with it.

Also... your original post stated about a 400W amplifier... Well a TRUE 400W amp (i.e. clean RMS power versus max power with a ton of distortion) is gonna cost a bit more than the budget that it looks like you are trying to maintain here.

But all things being equal... if I had a true 400W amplifier, I generally like to match it up with a combination of speakers that are equal to or exceed that power rating. (i.e. a pair of 200 - 300W subs for instance).

Power doesn't kill speakers... distortion does. The problem is, most folks treat the "gain" knob on their amp as if it were the "volume control" and this is totally wrong. Trust me... distorted bass DOES NOT SOUND GOOD!!!!

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ski

If I had an income, I wouldn't either I make $10 an hour, a few hours each week for spending/food cash. I'll start makin the big bucks in another semester when I graduate, but till then I'd like to make all my driving time a little more enjoyable.

Thanks for the help though... I'll be on the lookout for an affordable sub now.

Airencracken

No. You want headroom.

StonedWheat

So what you're saying is, if you have a 700W RMS amp, and 500W RMS 1000W peak power speakers, it's better because you won't have distortion? I always thought distortion was caused by overpowering your speakers. I guess I should read up on this stuff.

Airencracken

Pretty much. Distortion can come from overloading your speakers, but it is more common because of having a lack of headroom in your amp so it clips. I'd put a 1500W RMS amp on 1000W Peak speakers and just keep the volume down. Much cleaner.

DarkFury

Distortion comes from overdriving your signal source... like turning your radio ALL the way up, beyond the level that it can produce a "clean signal" at... (in the hood... this is known as "boomin'" ... which gets so bad that all you hear is bass and NO recognizable vocals whatsoever...)

This "distortion" is amplified and passed onto the speakers where they attempt to play a sound that they were never intended to play.... too much distortion and you rupture the speaker and/or melt the voice coil... (i.e. "dead speaker")

More or less... to avoid damage by distortion, never turn your stereo up beyond the point where it can play a clean signal and try not to put the gains on your amp up to 100%... 3/4 gain on an amp is usually more than enough... but then again, you really would need to match the gain on the amp to the signal level of your stereo to acheive an "optimal" sound situation. (that... and buy good stereo components to begin with with low total harmonic distortion and good signal to noise ratios)

zero2dash

(Sorry for digging up an old thread but I wanted to search and do this rather than start a completely new thread.)

Did anyone ever come up with a concrete answer to this problem?

I'm getting ready to buy some new car audio equipment to replace all the factory (ie literally "$#!t") in my car (03 Focus). I'm a big Alpine fan, so I'm going with their products almost entirely (where I can at least).

***

head unit:
Alpine CDA-9856 CD/MP3/WMA Receiver 16w RMSx4 - $199

speakers:
Alpine SPS-570A 5x7 2way speakers - $59/pair
(x2 pairs - one speaker for each door)

(incidentals)
XTC 5x7 speaker baffles - $8/pair (help protect the new speakers, maybe produce a little better sound)

amp:
Alpine MRP-M350 350w RMS x1 at 2 ohms mono amp (class D)- $179

(incidentals)
Street Wires PS08RI 8 gauge amp wiring kit - $39
Q-Logic QLC-1.0010DE dual 10" hatch/trunk box vol=1.0 cubic $89

subs:
Alpine Type-E SWE-1042 10" 4ohm component sub 50-250w RMS - 2 for $129

***

Ok, I know to pay attention to the RMS and discard the bogus #s that some amps/subs say (ie 2000 watt!!!) 'cause it's BS. And (from doing a little research on Crutchfield), I see that if I wire those 2 subs in parallel, the amp will see them as 2ohms so it will put out 350w to the subs.

My question is -
if the subs are 50-250w RMS apiece and the amp only puts out 350w, that would be 175w per speaker RMS put out by the sub, correct?
Basically, I'm scared that I'll damage the speakers by not putting out enough power, but at the same time - I see reviews all over Crutchfield by people who have that amp and 2 of those subs (or 2 of the 12" model, SWE-1242) saying that it hits really nice and there's no problem.

Sounded like (from the previous posts) - DF you said that it's better to have subs that RMS above what the amp RMS's, and Airen said the opposite. Who to trust...?

edit they (Crutchfield) will be getting an Alpine MRP-M450 amp that is 400w RMS x 1 @ 2ohms for only $20 more ($199)...should I pick up that one instead? (Or do I still need more power?)

Any one have any advice?
TIA for any help...

DarkFury

Basically, it's always better to have too much power than "not enough" power. You can turn the gains on the amp down and not worry about blowing any speakers, hence it is better to have an amp that can put out more clean power than a speaker can handle. Clean Power generally doesn't kill speakers... distortion caused by nasty underpowered amps does. (now don't get me wrong... I wouldn't put a 1000W amp RMS amp on a 250W speaker saying... "clean power doesn't kill"... but certainly a 500W amp to a pair of 250W speakers does quite nicely.

You should be fine putting a 350W amp (from a reputable company) on a pair of 250W speakers. You may have to turn the gain up about halfway... but that is fine. Just don't try to overdrive them and you'll be ok.

Alpine makes some good amps... if you are willing to pay the price. Personally, I'm currently using a Kenwood "D" class amp in my 'Bird and an older HiFonics Hercules sub amp in the Hemi.

AlpineJay

Basically what he said from my experience. I have a single dual-coil Alpine type-R sub tied in parallel to an MTX Thunder 801D (outputting 900Wx1 at 2ohms I believe) and my sub was rated at 500W RMS at 4 ohms, I believe. I have the gain set just at halfway and gets me awesome volume. I know if I went with a mono class D amp with RMS power on the lower end of the recommended spectrum by the sub (200-500) I would have some clipping at high volumes and distortion due to the overgain.

Generally it's smart to go with an amp that can overpower rather than underpower - exceeding the sub's power handling is good in that it gives you a lot of headroom and the system performs better at loud volumes, but you gotta think cost/benefit here at some point. While I wouldn't turn down 400Wx1 at 2 ohms if this was a DVC sub, I think you would be right around the middle with this setup. Remember that if you wire your speakers in parallel (which I would have to assume you will do since you're getting a mono amp), you are doubling the RMS rating on the subs due to the impedance reduction.

Of course, if you're not planning on keeping it loud but you're looking for just some low note backup to your everyday music, this setup is fine. In that case I'd even go out on a limb and suggest that a two-sub setup is overkill.

zero2dash

The subs are 250w RMS max @ 4ohms, and the amp is 350w x1 RMS @ 2ohms. From my (limited) education, I know that if I buy 2 subs and wire them in parallel, the amp sees 2ohms and pushes the 350w output. I'm (obviously) putting out 350w vs the subs wanting 500w max with 2 of them.

These subs are single voice coils. Originally I thought about purchasing the S series subs which are DVCs but they cost more, that's the primary reason I chose not to get those. Those run like $120 per sub (no discounts if ordering 2).

Basically, I'm looking for good bass..not overkill, but not weak at the same time. I thought about maybe just getting 1 sub but can't help but think that it'll be way too weak (and not be loud enough for me). I chose 10's 'cause my car isn't as roomy as say, an SUV, and I'd rather have nice, clean tight bass vs overkill on loud bass that a pair of 12's would probably give me. The next step up on an amp would be the MRP-MP650, which is 600w RMS x1 @ 2ohms (perfect for these two) but it's also $100 more ($299). I'm basically not wanting to spend too much, but, in the end, I might go ahead and get the larger amp and just spend the extra $100 to get better sound (which is what it sounds like would happen).

Frickin' tax return money...we've already spent half of it and we don't even have it yet.

edit
Well I've decided to just go with 1 Type-S 12" 4ohm DVC sub for now...with this amp. If I wire both coils in parallel, I'll get the 2ohms and the RMS on the sub is 300w RMS (150w RMS per coil), so with this setup I'll end up 50w over with the power, which will be a nice, solid number and a great sound (hopefully).

Thanks for all your help everyone
I just hope 1 12" sub is good enough
I hope I don't get the 1 and then want it to be 2...and then 3...and so on...(carful etc heh )

zero2dash

..

AlpineJay

looks good. I have the same audio needs as you do and mine is served quite well with the single 12" DVC type-R. In fact, sometimes it's so loud that I have to turn the sub down for casual listening. I love the fact that I only have a single box in my trunk as opposed to a dual box, too.

your next logical step is probably a 4-ch amp for your speakers and possibly a speaker upgrade. I drive a Ford (groan) as well right now and I've found the Infinity Kappa Perfect 572.5cfs to work quite well - 5x7/6x8s are not the type of speakers that gets you a whole lot of bass response so I wound up choosing the ones with the best sound without going overkill.

zero2dash

Hey Jay - what types of music do you listen to? I'm just wondering to see what you use the sub with...me, I'm primarily a rock/hard rock guy (Linkin Park, Breaking Benjamin, Seether) with occasional techno and rap thrown in. I spoke with someone from Crutchfield (really nice girl named Jenny) and she said that with me primarily listening to rock, one sub would suffice.

I might eventually get an amp for the 5x7s but for right now, I'm going to wait and see how everything else sounds...I may not need it, who knows. Guess I'll just have to tune that gain setting on the sub amp and try not to drown out the 2-way 5x7s from the bass of the sub. (subs?)

AlpineJay

I really listen to a bit of everything. Lately I've been on a hip-hop binge but you can find me listening to anything between country, techno, hard/soft rock, pop, to Jay-Z. Hard rock is obviously pretty bass heavy and the one sub has served me extremely well. One advice is that you should avoid a bandpass/ported box under all circumstances because it won't flow as nicely with your choice of music - nice, tight bass is what you would be looking for.

I own a DVC 12" Type-R as I mentioned before, and have no experience with the Type-S. I can assume, though, that it's basically a lesser-power version of the type-R, which has quite honestly been an overkill for me and my taste.

I'm not the guy on the streets with the stereo turned up all the way and muffled bass coming out of the car - although I occasionally enjoy that to poke fun at the cars next to me trying to show off. My bass needs are more than satisfactorily supplemented with this single setup and I'm in a large car - Ford Explorer. I suppose with the open air setup of SUV trunks, more bass travels into the cabin than an enclosed space on your Focus, but I still believe that based on your needs, you should be fine with the single sub setup, and the amount of space you gain from the single box will come in handy down the line.

I never was too thrilled about the 2-for-the-price-of-one sub deals because in most cases, the subs in question are cheap and not worth the money you'd throw down in a box and a larger amp. A single DVC sub may not match the sound of two separate subs, but it is a good compromise between going one versus two.

zero2dash

Well I've got the final decisions made; other than getting the different h/u (Alpine CDA-9851), I decided after talking to a buddy of mine (the one person other than you guys that knows a lot about subs...I should call him "JL" Rob since that's what he uses)...he said I should get the 2 Type-E's instead of the 1 Type-S, and he helped me decide to get the 10" Type-E's 'cause I'd rather have tight bass than low bass. Found a really good box...a QLogic that is 1.25cu per sub and can be used either ported or sealed for $69. Going with this setup, I save a little money, and I'm sure I'll get more sound out of the two vs. the one (even though it won't be pushing the subs all the way). I'm just gonna keep the gain down as low as possible; I don't think I'll need to fiddle with it all that much anyway.

Now I've got to figure out how to secure the box so it doesn't move around in the trunk. I've seen people say that they use bungie cord and hook it to the slots where the 60/40 fold down seats connect - I guess that's probably what I'll do. I don't really want to bolt the thing to the car...

DarkFury

Honestly... how big is the box in relation to the wheel wells? Personally, if it is big enough to sit between the wheels and not flop around, I wouldn't screw it down.... so that you could be able to take it out if you needed to (to get to the spare... or for more trunk room.)

Personally, when the boxes in my trunk were made... I just had them made large enough to wedge them in there really good... and that secured them. My subs were "rear firing" with grills so they were pretty protected from stuff in the trunk.

You could also try using one of those "telescoping wedge bars" like they use across the back of pickup trucks to secure them in and force them against the back seat if you REALLY feel uncomfortable with them just sitting there.

zero2dash

Do you mean that your subs face the front of the car and the 'butts' of the speakers is towards the road, or vice versa? I've always thought that you get more sound out of the rear of the sub; at least my friend Rob has always had the face of his subs facing the street towards the rear of the car, with the intent that the sound would bounce off the end of the trunk and reverberate back through the rest of the car.

I wonder though...why 99% of premade boxes (like I'm getting) are wedged to fit behind the seat, but the faces of the speakers face the front of the car...when (I'm under the impression that) you get better sound the other way around.

How is your setup aimed, DF?

AlpineJay

Loading your speaker pointed backwards basically creates a resonance effect with the back of your car so sound waves readily have a surface to bounce off to. So rearward is usually the right choice. If you mean the wedge design needing to face forward, like the box I have, the speaker can go either way because both sides are tapered?

zero2dash

(That's the box I'm getting)

See, I was wondering if both sides were tapered on this (like a trapezoid) but from the picture, it looks like the rear wall (? for lack of better terms) is connected with a right (90 degree) triangle to the bottom of the box, like the front where the speakers are installed is the only tapered end. I guess I'll figure out when I get the bloody thing??

edit
I called Q-Logic after doing a chat with a Crutchfield rep (he didn't know), and the guy from Q-Logic said only their truck boxes aren't trapezoid-shaped, so I should be good to go then.