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Unread 06-02-2013, 08:06 PM   #1
marzcap328
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Simple Amp Question

Alright. Either I'm far too tired to do effective research or it isn't a clear cut answer.

What I've got:
Two 8'' Pioneer Subs, 100W Nominal (250 Peak), single voice coil (One + and -)
These are both in the box set up to be wired on two separate channels.

Everyone seems to have their own opinion on whether you simple double the RMS or go 125%. What I'm looking for is someone to make this simple.

What wattage should I be looking for on a two channel amp to properly give me solid bass. Most of my music thrives off it. Thank you in advance.

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Unread 06-02-2013, 08:29 PM   #2
Indy
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You wont get solid bass out of 8 inch woofers, they dont have the surface area to get out of the midrange area. A 10 is about the minimum.

Beyond that, cant tell what you're asking really. So generically match the amps output to the rms value of the speakers.
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Unread 06-03-2013, 07:05 AM   #3
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Quote:
Originally Posted by Indy View Post
You wont get solid bass out of 8 inch woofers, they dont have the surface area to get out of the midrange area. A 10 is about the minimum.
Bull$...!
My computer has a 6" driver and it knocks.
Feed them at least 50 watts per channel. More if you can afford it.
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Unread 06-03-2013, 09:44 PM   #4
dB-SPL
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Quote:
Originally Posted by Indy View Post
You wont get solid bass out of 8 inch woofers, they dont have the surface area to get out of the midrange area. A 10 is about the minimum.

Beyond that, cant tell what you're asking really. So generically match the amps output to the rms value of the speakers.
You, sir, have sadly mistaken the potential of an 8" woofer.
Here's my 8's. I think they do alright outside the 'mid-range' area.
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Unread 06-03-2013, 09:57 PM   #5
dB-SPL
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Quote:
Originally Posted by marzcap328 View Post
Alright. Either I'm far too tired to do effective research or it isn't a clear cut answer.

What I've got:
Two 8'' Pioneer Subs, 100W Nominal (250 Peak), single voice coil (One + and -)
These are both in the box set up to be wired on two separate channels.

Everyone seems to have their own opinion on whether you simple double the RMS or go 125%. What I'm looking for is someone to make this simple.

What wattage should I be looking for on a two channel amp to properly give me solid bass. Most of my music thrives off it. Thank you in advance.
Okay. My quick explanation.
Throw 'peak' power ratings out the window. Whatever it says it can handle Nominally/RMS. Add up the total and there you have it. But you don't need to match it surgically. Before I can give you a definitive answer, what impedance are the coils? 4-ohm? If so, they get wired in parallel (pos to pos and neg to neg) and they'll drop to a 2-ohm final load. So.. If you were to go this route, you'd be looking for an amp that does 200+w RMS at 2-ohms. Subs are gonna sound best on a mono channel, but can be played stereo (2-channel) just fine. With this option, you'll be looking for an amp with specs such as 100+w RMS x 2 @ 4-ohm. Give yourself a little headroom if you'd like to open up options and go with a nice little 500w mono amp. When a speaker is placed in an enclosure, the impedance will rise causing the amp to put out much less power than it's rated for. And music is dynamic, not just a single sine wave. This is how we can run 3 times the rated power to a given speaker. So long as it's a clean, unclipped signal, it'll take it all day long.
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Unread 06-04-2013, 11:04 AM   #6
gily25
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This would be easier if you posted the model numbers for the sub or a link to the exact sub.

You can usually go up to 30% over the rated power so if the range is 100-150 you can do 195 without a problem. Multiply the watts times the speaker so 390 total drain on the amp. Then as dB-SPL noted, you need to know the ohms of the speaker and how you will wire them, then you can go shopping for an amp that is 2 channel (you'd need between 150-195 on each channel at the proper ohm load) or the multipled (390) watts on the proper ohm load.

Once you're all wired, put a test tone on the radio and properly set the gain on the amp with a DMM, this should prevent any clipping or distortion.
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Unread 06-04-2013, 11:30 AM   #7
dB-SPL
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DMM's have no way of checking for a clipped or distorted signal. All that does it put you in the ballpark of what your amp should be throwing out at "x" ohm load (given, the amp is honestly rated). The only way to check clipping is an oscilloscope or DD1.
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Unread 06-05-2013, 02:22 PM   #8
Indy
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Originally Posted by dB-SPL View Post
You, sir, have sadly mistaken the potential of an 8" woofer.
Here's my 8's. I think they do alright outside the 'mid-range' area.
http://www.youtube.com/watch?v=160jVITQ7WA
Its not very impressive sounding through my ipad.

I may be out of touch with newer 8's. the last time i compared several 8's didnt compare to 1 12. I always looked at 6'sas midrange, 8's as a little deeper 'woofers' and then 10 and bigger as subs. Volume wise you would get louder with 2 10s than 1 12 but the 12 would dig deeper in the hz hole.


Id guess theyre getting a lot longer throw to them now if theyre working well.
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Unread 06-05-2013, 03:02 PM   #9
dB-SPL
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Yea these newer woofers are starting to get a little crazy. They have a fair amount of suspension travel. They have a nice amount of motor force as well. So if you don't have crazy power, you can use cone area to your advantage and put them in an efficient enclosure and they'll play pretty low. All those woofers are about the cone area of two 15's. But being in a 6 cubic foot enclosure with tuning down in the low 30's, it gets down. It did 147.6 dB yesterday peaking at 37hz.


And that's with the amp gain at about 9 o'clock. She's got more in her.
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Unread 06-06-2013, 02:56 PM   #10
gily25
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Originally Posted by dB-SPL View Post
DMM's have no way of checking for a clipped or distorted signal. All that does it put you in the ballpark of what your amp should be throwing out at "x" ohm load (given, the amp is honestly rated). The only way to check clipping is an oscilloscope or DD1.
Not to bust ya man but the OP is asking such a simple question, he's not going to be going out buying any new tools for precise tuning.

Setting with the DMM and a test tune is the way to do it on the cheap and set the gain properly. How often people have come here to complain about blown subs/amps and it's because they used their gain setting as a volume knob.
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Unread 06-06-2013, 04:15 PM   #11
dB-SPL
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Oh I hear ya there. Just lettin dude know that a DMM is still not a great way. You're better off just taking your decks preout voltage and eyeballing it from there based the the sensitivity/gain.
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Unread 06-07-2013, 02:42 PM   #12
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Quote:
Originally Posted by dB-SPL

You, sir, have sadly mistaken the potential of an 8" woofer.
Here's my 8's. I think they do alright outside the 'mid-range' area.
Video Link: http://www.youtube.com/watch?v=160jVITQ7WA
Those have to be the v2s because my v1s are bad but not that bad.
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Unread 06-07-2013, 04:10 PM   #13
dB-SPL
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Originally Posted by alexrule123 View Post
Those have to be the v2s because my v1s are bad but not that bad.
Yessir.
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