hooking up sub to amp

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vbel

Copper - Posts: 246

Joined: July 15, 2004

Location: Canada

Posted: October 02, 2004 at 9:48 AM / IP Logged

I want temporarily to hook up my sub to my 4 channel amp by bridging (I guess) the rear channels together until my distribution block stuff arrives and then I will hook it up to a seperate amp.

The amp is a PG 8.0:4

4 ohm stereo 75x4

2 ohm stereo 125x4

4 ohm bridged 250x2

Minimum load stability: 2 ohm stereo/4 ohm bridged

The sub is 2 ohm. So how can I do this?

PS. I need it for tonight, so I hope someone can help me out fast. Thanks.

DYohn

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Joined: April 22, 2003

Location: Arizona, United States

Posted: October 02, 2004 at 9:58 AM / IP Logged

If your sub is SVC at 2-ohms, the only thing you could do is run it off ONE channel of the amp. If it is DVC at 2-ohms, connect the coils in series for a 4-ohm load and connect that across two channels bridged. Be sure to re-set your input gain for the new load.

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vbel

Copper - Posts: 246

Joined: July 15, 2004

Location: Canada

Posted: October 02, 2004 at 10:14 AM / IP Logged

It is a DVC 4 ohm and is connected in parallel that gives me 2 ohm (that what I was told to do). Can I leave it in parallel (2 ohm) and run it bridged? 'Cause I already wired it in parallel and don't feel like redoing it. I will have then 4 ohm going into 2 ohm sub, is it ok?

And bridging...that means I take (+) from both rear outputs and connect them together to the (+) of the sub and do the same thing for (-)?

DYohn

Moderator - Posts: 10,741

Joined: April 22, 2003

Location: Arizona, United States

Posted: October 02, 2004 at 10:33 AM / IP Logged

No, it is not OK. Your amp cannot handle a 2-ohm load if you bridge two channels. The amp will go into protection or blow. At 2-ohms use only one channel of the amp. Your only other option is to re-wire the sub for 8-ohms and use the bridged output.

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vbel

Copper - Posts: 246

Joined: July 15, 2004

Location: Canada

Posted: October 02, 2004 at 11:42 AM / IP Logged

Ok, I will just use 1 channel at 2 ohms. So all I have to do is take either rear channel and connect it to the sub? Will the amp adjust automatically for 2 ohm for that only 1 channel and the other channels will stay at 4 ohms? Or how does it work, I'm not sure...

DYohn

Moderator - Posts: 10,741

Joined: April 22, 2003

Location: Arizona, United States

Posted: October 02, 2004 at 12:09 PM / IP Logged

Yes, connect either channel to your sub. activate the low-pass filter. Leave the other channel un-used. Amps don't care what load you connect them to and they do not 'adjust." Any ohm load above their minimum loading is fine. Connect too low an impedence (ohms) and too much current flows until they stop working. The ratings on amplifiers simply indicate how they will perform based on specific speaker loadings. But you can safely connect an amplifier to any load above it's minimum (in your case, 2-ohms per channel.)

Oh by the way, to "bridge" an amplifier, the connection is usually the + on one channel and the - on the other channel. Check your owner's manual. NEVER connect two outputs + or - to each other!

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vbel

Copper - Posts: 246

Joined: July 15, 2004

Location: Canada

Posted: October 02, 2004 at 12:54 PM / IP Logged

Thanks for the explanation of the amp "adjustment" and "how to" bridge properly :) Good thing I asked...just in case sometime in the future I might have to bridge something... Manual by the way has nothing on how to bridge.

For the low-pass filter part, do I have to do it because the amp will feed my sub the whole frequency range (high notes like >1khz) or is it just 'cause my sub's range is upto 150 hz? Will it blow or anything if you give it more than 150 hz? And just for more information, my hu (pioneer) has seperate RCA outputs for subwoofers, so I will run another pair of RCA's and connect them to the rear channels of my 4ch amp, until I can hook up my mono amp. Is that seperate sub RCA output on hu is any different from the normal RCA outputs? Is it like filtered or something?

DYohn

Moderator - Posts: 10,741

Joined: April 22, 2003

Location: Arizona, United States

Posted: October 02, 2004 at 1:13 PM / IP Logged

On your Pacific Gold amp, look at the marking on the amplifier. Under the connections for the rear output, it should be marked "Bridged" and indicate + under L+ and - under R-. These are the two connections you would use for a mono bridged output.

You do not want to send high frequencies to your sub because you do not want to hear them from the sub. It will waste power and sound bad. The sub output on your head should have a crossover setting in the head unit controls. I suggest using 80Hz and see how it sounds. Set the amplifier crossover switch to "BY."

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vbel

Copper - Posts: 246

Joined: July 15, 2004

Location: Canada

Posted: October 02, 2004 at 1:22 PM / IP Logged

You're right, it does says "bridged" under the channel outputs. The hu has settings on it specifically for subs, so it makes sense now, why it got seperate sub rca's.

Thanks for all the help, I think I understand everything I need before I start the install.

PS. It's a Phoenix Gold amp, not Pacific...

DYohn

Moderator - Posts: 10,741

Joined: April 22, 2003

Location: Arizona, United States

Posted: October 02, 2004 at 1:37 PM / IP Logged

Oops, of course. "Pacific Gold" is the brand of my favorite beef jerkey... hooking up sub to amp -- posted image.

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