Matching Amp and Subs......

PHOENIX · 01-28-2009, 04:10 AM

If I purchase 2 of these....
INFINITY 850W REFERENCE 8" 850W CAR BASS SUBWOOFER NEW - eBay (item 120357137448 end time Jan-30-09 12:42:40 PST)

and 1 of these.....
INFINITY REFERENCE 475A 4-CHANNEL SILVER CAR AMPLIFIER - eBay (item 220352042820 end time Feb-06-09 14:20:18 PST)

will they "compliment" each other if I bridge the Amp? I'm assuming because the subs are 4 ohm and the Amp is 4 ohm they will work for each......or do I have that all wrong?

Sound systems are definitely not my strong points.

mr.ac · 01-28-2009, 11:36 PM

you'll be fine.

djskorch · 01-28-2009, 11:46 PM

yep, that will be a nice little combo setup with the boxes you have. shoud sound pretty good.

PHOENIX · 01-29-2009, 12:27 AM

Thanks guys.

So if I buy an 8 ohm amp and have 4 ohm subwoofers......would that be bad? I'm confused by this and cant really find anything in laymens terms so I can understand what the hell is going on.

djskorch · 01-29-2009, 01:16 AM

yes that would not work unless the 8ohm amp is able to bridge to 4 or 2 ohms. its a little complicated at first but if you do some quick searchin on the net about running subs in series and in parallel, the difference between single and dual voice coil subs, and the difference that running amps at 4ohm vs 2ohm ect, you will understand alot quicker.

just a quick example. if you have a 4 channel amp that will run 4ohms per channel and put out 75 watts rms per channel, then if the amp can handle running at 2 ohms, you would bridge the from channels together, and the rear channels together to drop to 2ohms and then the amp would run 150w watts rms per channel. as far as running subs in series or parallel, if you have 2 single voice coil subs at 4 ohms each, you would run them in parallel meaning the positive on one sub connects to the negative on the other, and then the remaining positive and negative wires would run to your amp. doing this would drop the ohm load on the subs to 2ohms to match with the amp. i know it gets complicated but a quick bit of research should help you out. gl

PHOENIX · 01-29-2009, 02:13 AM

you lost me at "yes"

djskorch · 01-29-2009, 02:15 AM

mr.ac · 01-29-2009, 02:26 AM

laymens: lower ohms suck up/pull more power. 1 ohms subs/amps are more powerful than 4+ohms amps/subs.

8ohm amp will die with a 4ohm sub. It will drain it dry.
on the other hand.
4ohm amp will live forever with a 8ohm sub. The sub sucks less power.

PHOENIX · 01-29-2009, 02:48 AM

okay......so a 4ohm setup is kinda in the middle as far as power sucking/pulling out of the car. 4ohms plus 4ohms is not 8ohms in the stereo community. And I'm a big idiot.

Think I'm getting it.

Ku-sama · 01-29-2009, 12:23 PM

To put it simply:

if you have a 4ohm sub
and you get another 4 ohm sub

if you have a 2 channel bridgeable amp, you can have some fun

with ohms for subwoofers you can go many ways.

4 ohm plus 4 ohm sub wires in series would give you 8 ohms to the single channel, or if you went with 4 ohm and 4 ohm in parallel, it would give you 2 ohms.

with a 2 channel in stereo or a 4 channel bridged to 2 channel stereo you can use:
single 4 ohm sub - easy hook up
dual 2 ohm sub - series
dual 8 ohm sub - parallel
two 2 ohm subs - series
two 8 ohm subs - parallel
per channel.

Luni · 01-29-2009, 02:38 PM

Your driver dictates the impedance not the amplifier.

If you have an 8 ohm amp, it just means it makes x watts at 8 ohms. If its stable at 4 ohms, it will make almost twice that. And if its stable at 2 ohms, it will make almost twice what it made at 4.

Most car audio amplifers base out at 4 ohms. Most home audio ones base out at 8.

The impedance of your subwoofers only varies to allow you wiring configuration options. So you can get the right load you want to get your amp at the correct impedance so it performs where it should.

If you have 2 4 ohm subs, and you wire then im PARALLEL, youll be at about 2 ohms load. If you wire them in SERIES, youll be at 8 ohms.

If you had 2 2 ohm subs, and you wired them in parallel, youd be at 1.33 ohms or roughly there, and if you wired them in series youd be at 4 ohms.

Ideally if youre running 2 subs, in parallel, you want 2 4 ohm single voice coil subwoofers, and you want an amplifier thats bridgable down to a 2 ohm mono load.

01-28-2009, 04:10 AM	#1 (permalink)
PHOENIX Beams Owners Group Join Date: Mar 2005 Location: On Hiatus....... Posts: 8,343 Thanks: 88 Thanked 275 Times in 211 Posts Blog Entries: 1 My Google Map iTrader Rating: (46/100% )	Matching Amp and Subs...... If I purchase 2 of these.... INFINITY 850W REFERENCE 8" 850W CAR BASS SUBWOOFER NEW - eBay (item 120357137448 end time Jan-30-09 12:42:40 PST) and 1 of these..... INFINITY REFERENCE 475A 4-CHANNEL SILVER CAR AMPLIFIER - eBay (item 220352042820 end time Feb-06-09 14:20:18 PST) will they "compliment" each other if I bridge the Amp? I'm assuming because the subs are 4 ohm and the Amp is 4 ohm they will work for each......or do I have that all wrong? Sound systems are definitely not my strong points. __________________ - Dave

01-29-2009, 02:15 AM	#7 (permalink)
djskorch djskorch Join Date: Feb 2007 Location: Idaho Posts: 549 Thanks: 5 Thanked 21 Times in 19 Posts My Google Map iTrader Rating: (3/100% )	lol.

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01-28-2009, 11:36 PM	#2 (permalink)
mr.ac Just Say NO to Snorkes Join Date: Nov 2008 Location: Central Coast, CA Posts: 360 Thanks: 0 Thanked 16 Times in 16 Posts iTrader Rating: (1/100% )	you'll be fine.

01-28-2009, 11:46 PM	#3 (permalink)
djskorch djskorch Join Date: Feb 2007 Location: Idaho Posts: 549 Thanks: 5 Thanked 21 Times in 19 Posts My Google Map iTrader Rating: (3/100% )	yep, that will be a nice little combo setup with the boxes you have. shoud sound pretty good.

01-29-2009, 12:27 AM	#4 (permalink)
PHOENIX Beams Owners Group Join Date: Mar 2005 Location: On Hiatus....... Posts: 8,343 Thanks: 88 Thanked 275 Times in 211 Posts Blog Entries: 1 My Google Map iTrader Rating: (46/100% )	Thanks guys. So if I buy an 8 ohm amp and have 4 ohm subwoofers......would that be bad? I'm confused by this and cant really find anything in laymens terms so I can understand what the hell is going on.

01-29-2009, 01:16 AM	#5 (permalink)
djskorch djskorch Join Date: Feb 2007 Location: Idaho Posts: 549 Thanks: 5 Thanked 21 Times in 19 Posts My Google Map iTrader Rating: (3/100% )	yes that would not work unless the 8ohm amp is able to bridge to 4 or 2 ohms. its a little complicated at first but if you do some quick searchin on the net about running subs in series and in parallel, the difference between single and dual voice coil subs, and the difference that running amps at 4ohm vs 2ohm ect, you will understand alot quicker. just a quick example. if you have a 4 channel amp that will run 4ohms per channel and put out 75 watts rms per channel, then if the amp can handle running at 2 ohms, you would bridge the from channels together, and the rear channels together to drop to 2ohms and then the amp would run 150w watts rms per channel. as far as running subs in series or parallel, if you have 2 single voice coil subs at 4 ohms each, you would run them in parallel meaning the positive on one sub connects to the negative on the other, and then the remaining positive and negative wires would run to your amp. doing this would drop the ohm load on the subs to 2ohms to match with the amp. i know it gets complicated but a quick bit of research should help you out. gl

01-29-2009, 02:13 AM	#6 (permalink)
PHOENIX Beams Owners Group Join Date: Mar 2005 Location: On Hiatus....... Posts: 8,343 Thanks: 88 Thanked 275 Times in 211 Posts Blog Entries: 1 My Google Map iTrader Rating: (46/100% )	you lost me at "yes"

01-29-2009, 02:26 AM	#8 (permalink)
mr.ac Just Say NO to Snorkes Join Date: Nov 2008 Location: Central Coast, CA Posts: 360 Thanks: 0 Thanked 16 Times in 16 Posts iTrader Rating: (1/100% )	laymens: lower ohms suck up/pull more power. 1 ohms subs/amps are more powerful than 4+ohms amps/subs. 8ohm amp will die with a 4ohm sub. It will drain it dry. on the other hand. 4ohm amp will live forever with a 8ohm sub. The sub sucks less power.

01-29-2009, 02:48 AM	#9 (permalink)
PHOENIX Beams Owners Group Join Date: Mar 2005 Location: On Hiatus....... Posts: 8,343 Thanks: 88 Thanked 275 Times in 211 Posts Blog Entries: 1 My Google Map iTrader Rating: (46/100% )	okay......so a 4ohm setup is kinda in the middle as far as power sucking/pulling out of the car. 4ohms plus 4ohms is not 8ohms in the stereo community. And I'm a big idiot. Think I'm getting it.

01-29-2009, 12:23 PM	#10 (permalink)
Ku-sama Cage Fighter Join Date: Mar 2008 Location: Germantown, MD Posts: 1,594 Thanks: 8 Thanked 42 Times in 39 Posts My Google Map iTrader Rating: (3/100% )	To put it simply: if you have a 4ohm sub and you get another 4 ohm sub if you have a 2 channel bridgeable amp, you can have some fun with ohms for subwoofers you can go many ways. 4 ohm plus 4 ohm sub wires in series would give you 8 ohms to the single channel, or if you went with 4 ohm and 4 ohm in parallel, it would give you 2 ohms. with a 2 channel in stereo or a 4 channel bridged to 2 channel stereo you can use: single 4 ohm sub - easy hook up dual 2 ohm sub - series dual 8 ohm sub - parallel two 2 ohm subs - series two 8 ohm subs - parallel per channel.

01-29-2009, 02:38 PM	#11 (permalink)
Luni ST185 Powered SW20 Join Date: Oct 2005 Location: Salt Lake City Utah Posts: 2,961 Thanks: 9 Thanked 106 Times in 92 Posts My Google Map iTrader Rating: (8/100% )	Your driver dictates the impedance not the amplifier. If you have an 8 ohm amp, it just means it makes x watts at 8 ohms. If its stable at 4 ohms, it will make almost twice that. And if its stable at 2 ohms, it will make almost twice what it made at 4. Most car audio amplifers base out at 4 ohms. Most home audio ones base out at 8. The impedance of your subwoofers only varies to allow you wiring configuration options. So you can get the right load you want to get your amp at the correct impedance so it performs where it should. If you have 2 4 ohm subs, and you wire then im PARALLEL, youll be at about 2 ohms load. If you wire them in SERIES, youll be at 8 ohms. If you had 2 2 ohm subs, and you wired them in parallel, youd be at 1.33 ohms or roughly there, and if you wired them in series youd be at 4 ohms. Ideally if youre running 2 subs, in parallel, you want 2 4 ohm single voice coil subwoofers, and you want an amplifier thats bridgable down to a 2 ohm mono load.