What's an ohm, and why you should care. - Page 2

7-12-02, 22:32

Alright I have a MTX Thunder6304 with 4 channels (660watts). But I don't have a sub(s). I am on a pretty tight budget. I heard that the MTX Thunder4000 subs are a pretty good buy for the money, is this true? Would dual 10s do my 91 mx6 justice?

Now here is the main question. Lets say the dual 10s are a fine choice. How do I know if I need the subs with 2 ohms or 4ohms?

**mxmissile** · 7-12-02, 23:02

If you intend to use the entire amp to run only bass, you would get 4 ohm subs, and bridge the two halves to make a two channel amp.

To get the most out of that amp and your system, I would recomend running 1/2 the amp stereo to your highs, and bridge the back channels mono to the subs. In this instance, you'd want 8-ohm woofers.

Both scenarios assume the use of two woofers.

The Thunder 4000's would be an excellent choice for the second option, you may want something with a little more power handling for the first.

As this question pertains primarily to product, not resistance, I have and won't get much attention in here. Please start a new thread in the audio forum with this question, you'll get a lot more responses!

**JohnathanJ** · 9-21-02, 14:09

I hate to do this but you guys know more about this stuff than I ever will. This is going to be a stupid question but I want to know for sure if I have this right, for my specific situation.

Does the final impedance have to be the same or lower than the Amp's rated impedance?

My situation:
I have an Autotek 300 Watt/2-channel/4-ohm Amp and just picked up a pair of Kicker Competition 10's which are 8-ohm.
So what I need to do is wire my subs in a parallel circuit? And that would give me a final impedance of 4 ohms?

I apologize for these questions but I am very confused.

Thanks,
-Jason

**mxmissile** · 9-22-02, 17:44

The final impedance should equal your amplifier's minimum rating or HIGHER. the Autotek is rated for a 2 ohm load stereo, 4 ohms bridged. The 2 8-ohm woofers in parallel would be perfect.

Sounds like a nice little setup! There are no stupid questions, that's why these threads are hear. I hope this helped, reply if you need more!

**JohnathanJ** · 9-22-02, 18:08

Quote:

Originally posted by mxmissile
The final impedance should equal your amplifier's minimum rating or HIGHER. the Autotek is rated for a 2 ohm load stereo, 4 ohms bridged. The 2 8-ohm woofers in parallel would be perfect.

Sounds like a nice little setup! There are no stupid questions, that's why these threads are hear. I hope this helped, reply if you need more!

Hey I really appreciate it MXMissle. I hope it will sound better than my setup now, the same amp pushing 2-Rockford 12's in a crappy built box. Thanks to your enclosure 101 thread I'm going to build my own box and do it right.

Off topic but do you happen to have a speaker enclosure program. I noticed when looking up specs on these 10's that Kicker has some kinda Thiele (spelling?) info you input into some type of computer program. Just curious to know what that was.

muchos gracias
-Jason

**mxmissile** · 9-22-02, 18:26

There are several good box programs out there, though none that are readily available or shareware that I know of. Not saying there aren't any, I just don't know about any....

In addition to the theil/small parameters, Kicker should give you actual box spec's. You shouldn't need The theil/small's if they give a recomended sealed and/or ported box recomendation, they did the work for you!!

**JohnathanJ** · 9-24-02, 21:39

Thanks again man. I did get the regular box specs from Kicker's site. I thought those small parameters was like a hardcore way to build an enclosure, basically I thought that by building the box with those parameters you'd get better results.

Thanks again,
-Jason

9-29-02, 21:54

Ok, you guys got me all paranoid now, i am also running 2 infinity perfects (4 ohm each). My amp is a new alpine MRD-500 mono channel amp.

Just let me know if i have it hooked up right....

Ok all i did was connect both the positive speaker wires to the 1 positive terminal and i connected both the negative wires to the negative terminal. Do my subs then make a 2 ohm load? Is this setup okay or are my subs gonna blow up? (well, not blow up...you know what i mean) And since i have 2 subs connected to a mono channel amp does the power from the amp get cut in half?

Burningcrap · 9-30-02, 20:50

I want to get the sony xm-1600gxd, which is at 1200 max at 2 ohms. It only does 300 rms at 4 ohms. I'd like to either get a 12 inch 4ohm sub or 2 10 inch 4ohm subs. Assuming that the wattage ratings are fine, i'm trying to figure which would let me better use the amps 400 watt rms the best. The amp has 2 speaker outs despite it being mono, a guy at bestbuy said that that autmatically bridges for you. I'm wondering if i can make the amp think that the 12inch 4ohm sub is 2 ohms, or if there is no way of doing that. I would like to get 2 10s, and i know i can do the 2 4 ohm subs in parallel to make the amp see 2 ohms, but i want to keep the box size small, because I have to put snowboards back there coming thanks giving. I now have a 99 mustang, and that has a little less room, if you needed to know. Thanks again, your faq helped a lot on my understanding of impedance, even after taking advanced physics.

**mxmissile** · 10-1-02, 17:19

OK....

BECKS - You are fine, it is connected correctly, and since the amp is a single channel amplifier, not a 2channel model running "bridged", it's seeing the normal 2 ohm load, not 1/2. All is well, and that combo should make some very nice bass!!

Burningcrap - If you're set on that Sony, do watcha' gotta' do, but I think there are better amps out there. As to the rest of your post.... That guy at Best Buy sounds like an idiot. The only reason a monoblock amplifier has two output terminals (many of them do) is to simplify the connection of multiple woofers. The 2 +'s and -'s you see there are actualy only one connection, with 2 screws on it. If you put a single 4 ohm speaker to it, you get the 4 ohm power, if you put 2 4 ohm woofers to it ion parallel, you get the 2 ohm power. Heck, it doesn't even matter which + and - you use on the amp, 'cause they're the same!! I hope that helped rather than making it more confusing!

**wowo76** · 1-6-03, 8:57

What would be the best way to wire 3 4-ohm SVC subs to get as close to a 4 ohm load as possible?

**mxmissile** · 1-6-03, 19:18

from one amp, you get either 12 ohms or 1.3, those are your only options. Get a 4th woofer, and you're in buiness.

**wowo76** · 1-13-03, 18:43

that's the problem - i have a 3 subwoofer enclosure and 3 MTX subs

**mxmissile** · 1-16-03, 21:17

Than either get a new box, or a new amp with high current capability!

Sorry!

kennyc28 · 3-11-03, 3:08

so you are saying jonathan that if you hook up two 4ohm speakers on a mono amp it automatically makes it 2ohms because in a sense it is already parallel? or do I sill have to make the wires parallel to make it 2 ohms?

7-12-02, 22:32	#16 (permalink)
mort0120 Location:	Alright I have a MTX Thunder6304 with 4 channels (660watts). But I don't have a sub(s). I am on a pretty tight budget. I heard that the MTX Thunder4000 subs are a pretty good buy for the money, is this true? Would dual 10s do my 91 mx6 justice? Now here is the main question. Lets say the dual 10s are a fine choice. How do I know if I need the subs with 2 ohms or 4ohms?
mort0120 Location:

7-12-02, 23:02	#17 (permalink)
mxmissile Join Date: Jan 2002 Location: Back in Vegas, baby!, NV, USA Age: 33 iTrader: (0)	If you intend to use the entire amp to run only bass, you would get 4 ohm subs, and bridge the two halves to make a two channel amp. To get the most out of that amp and your system, I would recomend running 1/2 the amp stereo to your highs, and bridge the back channels mono to the subs. In this instance, you'd want 8-ohm woofers. Both scenarios assume the use of two woofers. The Thunder 4000's would be an excellent choice for the second option, you may want something with a little more power handling for the first. As this question pertains primarily to product, not resistance, I have and won't get much attention in here. Please start a new thread in the audio forum with this question, you'll get a lot more responses!
	Car audio guy and resident domestic 4 banger advocate

9-21-02, 14:09	#18 (permalink)
JohnathanJ Join Date: Jul 2001 Location: Shelby, North Carolina, NC, USA Age: 30 iTrader: (0)	I hate to do this but you guys know more about this stuff than I ever will. This is going to be a stupid question but I want to know for sure if I have this right, for my specific situation. Does the final impedance have to be the same or lower than the Amp's rated impedance? My situation: I have an Autotek 300 Watt/2-channel/4-ohm Amp and just picked up a pair of Kicker Competition 10's which are 8-ohm. So what I need to do is wire my subs in a parallel circuit? And that would give me a final impedance of 4 ohms? I apologize for these questions but I am very confused. Thanks, -Jason
	*"Pain is just weakness leaving the body"* Evy: Mi corazon perdido en ti! John 3:3

9-22-02, 17:44	#19 (permalink)
mxmissile Join Date: Jan 2002 Location: Back in Vegas, baby!, NV, USA Age: 33 iTrader: (0)	The final impedance should equal your amplifier's minimum rating or HIGHER. the Autotek is rated for a 2 ohm load stereo, 4 ohms bridged. The 2 8-ohm woofers in parallel would be perfect. Sounds like a nice little setup! There are no stupid questions, that's why these threads are hear. I hope this helped, reply if you need more!
	Car audio guy and resident domestic 4 banger advocate

9-22-02, 18:26	#21 (permalink)
mxmissile Join Date: Jan 2002 Location: Back in Vegas, baby!, NV, USA Age: 33 iTrader: (0)	There are several good box programs out there, though none that are readily available or shareware that I know of. Not saying there aren't any, I just don't know about any.... In addition to the theil/small parameters, Kicker should give you actual box spec's. You shouldn't need The theil/small's if they give a recomended sealed and/or ported box recomendation, they did the work for you!!
	Car audio guy and resident domestic 4 banger advocate

9-24-02, 21:39	#22 (permalink)
JohnathanJ Join Date: Jul 2001 Location: Shelby, North Carolina, NC, USA Age: 30 iTrader: (0)	Thanks again man. I did get the regular box specs from Kicker's site. I thought those small parameters was like a hardcore way to build an enclosure, basically I thought that by building the box with those parameters you'd get better results. Thanks again, -Jason
	*"Pain is just weakness leaving the body"* Evy: Mi corazon perdido en ti! John 3:3

9-29-02, 21:54	#23 (permalink)
BECKS Location:	this whole ohm thing Ok, you guys got me all paranoid now, i am also running 2 infinity perfects (4 ohm each). My amp is a new alpine MRD-500 mono channel amp. Just let me know if i have it hooked up right.... Ok all i did was connect both the positive speaker wires to the 1 positive terminal and i connected both the negative wires to the negative terminal. Do my subs then make a 2 ohm load? Is this setup okay or are my subs gonna blow up? (well, not blow up...you know what i mean) And since i have 2 subs connected to a mono channel amp does the power from the amp get cut in half?
BECKS Location:

9-30-02, 20:50	#24 (permalink)
Burningcrap Join Date: Oct 2000 Location: San Diego Age: 26 iTrader: (0)	similar question here I want to get the sony xm-1600gxd, which is at 1200 max at 2 ohms. It only does 300 rms at 4 ohms. I'd like to either get a 12 inch 4ohm sub or 2 10 inch 4ohm subs. Assuming that the wattage ratings are fine, i'm trying to figure which would let me better use the amps 400 watt rms the best. The amp has 2 speaker outs despite it being mono, a guy at bestbuy said that that autmatically bridges for you. I'm wondering if i can make the amp think that the 12inch 4ohm sub is 2 ohms, or if there is no way of doing that. I would like to get 2 10s, and i know i can do the 2 4 ohm subs in parallel to make the amp see 2 ohms, but i want to keep the box size small, because I have to put snowboards back there coming thanks giving. I now have a 99 mustang, and that has a little less room, if you needed to know. Thanks again, your faq helped a lot on my understanding of impedance, even after taking advanced physics.
	trying to sell my beloved 6, needs work too

10-1-02, 17:19	#25 (permalink)
mxmissile Join Date: Jan 2002 Location: Back in Vegas, baby!, NV, USA Age: 33 iTrader: (0)	OK.... BECKS - You are fine, it is connected correctly, and since the amp is a single channel amplifier, not a 2channel model running "bridged", it's seeing the normal 2 ohm load, not 1/2. All is well, and that combo should make some very nice bass!! Burningcrap - If you're set on that Sony, do watcha' gotta' do, but I think there are better amps out there. As to the rest of your post.... That guy at Best Buy sounds like an idiot. The only reason a monoblock amplifier has two output terminals (many of them do) is to simplify the connection of multiple woofers. The 2 +'s and -'s you see there are actualy only one connection, with 2 screws on it. If you put a single 4 ohm speaker to it, you get the 4 ohm power, if you put 2 4 ohm woofers to it ion parallel, you get the 2 ohm power. Heck, it doesn't even matter which + and - you use on the amp, 'cause they're the same!! I hope that helped rather than making it more confusing!
	Car audio guy and resident domestic 4 banger advocate

1-6-03, 8:57	#26 (permalink)
wowo76 Join Date: Dec 2000 Location: Orange, NJ iTrader: (0)	Question What would be the best way to wire 3 4-ohm SVC subs to get as close to a 4 ohm load as possible?
	What's a ZE?

1-6-03, 19:18	#27 (permalink)
mxmissile Join Date: Jan 2002 Location: Back in Vegas, baby!, NV, USA Age: 33 iTrader: (0)	from one amp, you get either 12 ohms or 1.3, those are your only options. Get a 4th woofer, and you're in buiness.
	Car audio guy and resident domestic 4 banger advocate

1-13-03, 18:43	#28 (permalink)
wowo76 Join Date: Dec 2000 Location: Orange, NJ iTrader: (0)	that's the problem - i have a 3 subwoofer enclosure and 3 MTX subs
	What's a ZE?

1-16-03, 21:17	#29 (permalink)
mxmissile Join Date: Jan 2002 Location: Back in Vegas, baby!, NV, USA Age: 33 iTrader: (0)	Than either get a new box, or a new amp with high current capability! Sorry!
	Car audio guy and resident domestic 4 banger advocate

3-11-03, 3:08	#30 (permalink)
kennyc28 Banned Join Date: Mar 2003 Location: The Boogie Age: 34 iTrader: (0)	so you are saying jonathan that if you hook up two 4ohm speakers on a mono amp it automatically makes it 2ohms because in a sense it is already parallel? or do I sill have to make the wires parallel to make it 2 ohms?