home audio questions

[t-maxxracer32]

o and

why is some saying a 500 amp plate ok for a 350rms sub

but others say its bad for the sub?

[rschoi_75]

I think you're mixing up what brian was saying about peak watts vs rms watts.

If both those values are rms, the amp could blow out the sub. If the amp is rated at 500w peak, then you should be ok to power a 350w RMS sub.

[BrianG]

Actually, I always speak in rms terms. And it is better to run a higher power amp than the sub can technically handle because of the duty cycle of the signal; where you only run max rms power for about 10% of the time, and MUCH lower power on average. For movies or any other dynamic media, you want some headroom. If you are running 200w to the sub during normal listening, then a car explosion hits, the sub will want more power for that time then the amp can deliver and will clip. It's much healthier for the sub to see clean power than dirty clipped power.

[t-maxxracer32]

Originally Posted by BrianG

Actually, I always speak in rms terms. And it is better to run a higher power amp than the sub can technically handle because of the duty cycle of the signal; where you only run max rms power for about 10% of the time, and MUCH lower power on average. For movies or any other dynamic media, you want some headroom. If you are running 200w to the sub during normal listening, then a car explosion hits, the sub will want more power for that time then the amp can deliver and will clip. It's much healthier for the sub to see clean power than dirty clipped power.

ya thats what i thought.

it just makes more sence to me.

[_paralyzed_]

well.... then..... If you are going to run two 12" car subs off a plate amp there is something you need to consider, speaker impedance. Most car subs are 4 ohm impedance, but some are 2, 8, 6, or even dual voice coil models which have two impedance values. It should say, "4 ohm" or something similar on the magnet of the woofer. Lets assume they are both 4 ohm subs- you can either wire them in series for an 8 ohm load, or in parallelfor a 2 ohm load. Those are your options for wiring 2 subs to a single channel plate amp. Most home audio amps are rated at 8 ohms, so the 8 ohm in series example would work, but a 500 watt rms amp would only give 250 watts to each sub, power is split equally. A 2 channel amp rated for 4 ohm operation would also work, I just thought you should keep this in mind when selecting an amplifier.

[t-maxxracer32]

hmmmmm... well.

idk what im going to do yet. i guess ill see how it goes when i get my 12 hitting harder.

also i was thinking right now...

how do i connect the sub to run at the same speed/time or w/e as all the other speakers? since it is being ran by a separate unit how would i do that?

[JThiessen]

Originally Posted by t-maxxracer32

hmmmmm... well.
how do i connect the sub to run at the same speed/time or w/e as all the other speakers? since it is being ran by a separate unit how would i do that?

When I first read your post on setting up three subs, that was my number one concern. Yes, you'll have bass up the wazzzooo, but its all going to be out of phase and sound like crap unless you have crossovers (do plate amps have these built in?). If they dont, then you need to purchase them, and add them to the circuit. For your front subs - you can purchase a RCA "sub splitter jack" - basically allows for one in and two out. Run your sub out to it, then individual RCA's to each sub. (my M&K has "networking" built in for running subs in series or parrallel?) For the rear surround sub - I'd look for a plate amp that allows you to run both your R and L surround speaker wires into it, and has sub out, and R/L audio out. I dont have a clue if they even make such a thing, but in that scenario, your sub would be carrying the low bass for both the surrounds.

[BrianG]

First, what is the power rating and impedance of the sub? Is it dual voice coil? If so, what is the impedance of each coil?

I really don't get the second question. Plate amps usually have hi-level inputs that you can route your main speaker wires through and it picks up the signal from that. Also, they usually have a low-level signal jack (RCAs) if your receiver has those types of outputs. There shouldn't be any kind of delay worth considering since the signal is not being carried by squirrels or something like that.

[t-maxxracer32]

well what im saying is thatttt
usually when u have an amp you hook it up to the player and you run all the speakers ad everything through the one amp

with this one I need to run the plate amp to the other amp without using any power from that amp.
I didn't know if there were just rca cords to connect
ill see when I get it though

[_paralyzed_]

usually just an rca cord, you don't have to worry about delay, it will all be up to speed

[_paralyzed_]

I'm curious about current plate amps now, I've been out of the audio loop for awhile, BrianG- got any good links for amps??

[BrianG]

PartsExpress is where I shop at for fairly inexpensive DIY parts. You might find cheaper stuff elsewhere so shop around. For plate amps, this is what they have.

Looks like the 240w version is about the max you'll get for a relatively low price of $100. It gets expensive for more power than that, and they don't have speaker in/out terminals. And usually, if the amp has speaker in/out terminals, it includes a crossover to limit the low frequencies to your main speakers. The 240w version is the output rating at 4 ohms. If using an 8 ohm sub, it's 170w. So impedance does play a role here, which is why it's important to know what you plan to run on the amp.

In case your sub is dual voice coil:
- If each coil is 2 ohms, hook them in series for 4 ohms total
- If each coil is 4 ohms, hook them in series for 8 ohms total. Hooking them in parallel gets you 2 ohms and that's too low for most amps and the amp would be unstable.
- If each coil is 8 ohms, hook them in parallel for 4 ohms total.

Hookup of a plate amp is as simple as cutting out an opening in your sub box, hooking up the sub's wires, screwing the plate into the hole, and hooking to 120v and to your system. If your receiver has sub RCA outputs, use those. If not, route your main speaker wire to the sub speaker inputs and then to your speakers.

And about the phasing issue: Yes, it can make a difference, but he's not running high end stuff to make a difference. Usually, simply using the phase reverse switch on the sub amp to adjust to 0* or 180* is adequate. Ideally, you'd want all your speakers to be mounted on the same vertical plane for proper phasing, but then your sub response might not be the best in that location. Higher-end sub amps have adjustable phase control for this, but those are more expensive and I'm sure cost is an issue here.

[Serum]

Check out partsexpress.com, they have got nice low-budget subs (diy)

I've got a REL upstairs in my hobbyroom, and i am using a 15" 800watts rms powered sub in the living room..



If you want to build your own subwoofer, i can help you with designing the enclosure.

Before i was into RC i was into building speakers. Stepped away from it since it took too much of my time.. Now here i am...

phase is very important in a sub, and so is the cross-over. Don't use two cross-overs on one sub; if the amp has one and the sub, dissable one of both; they interfere and can cause nasty phase problems.

Unlike what most companies make you want to believe, a sub needs to be in the center of the speakers, otherwise it's pulling away the entire stereo image. odd but true.

Speaking of nice subs.. I used to have 360 liter large subs, playing 20hz at a 104db/1m/1w efficiency. (at 10W they where playing as loud as most subs could do at maximum power) the FS of the speaker in that cabinet was 14 hz. at 2X800W rms they could help you breath.. it was the most impressive bass i ever had.

[_paralyzed_]

skellyo- thanks for the schooling, phase coherence eludes me
BrianG- thanks for the link
Serum- that is a beuatiful speaker cabinet, you do fine work man
tmaxxracer- good luck
everybody- damn yous, damn yous all, i'm getting the audio bug AGAIN, I never visited parts express before, my money will be gone, my neighbors will hate me, i will get tinitus(ear damage) and all my lipos will probably blow up. But the s.p.l. will be amazing.......................................

[Metallover]

my rich friend has some canton karat speakers. I cant think of anything better. He also has a sub and center, but I dont want to do any more searching.

http://www.canton.de/en-produktdetai...karat795dc.htm