Ohms an amp sees when bridged

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=30171
Printed Date: May 16, 2024 at 8:04 AM

Topic: Ohms an amp sees when bridged

Posted By: kfr01
Subject: Ohms an amp sees when bridged
Date Posted: April 11, 2004 at 2:37 PM

New to audio. I'm looking at buying two smaller bridgeable amps instead of one large one to drive some mb quart components.

A 2 channel amp, bridged, still sees only a 4-ohm load even though the power is increased, right?

Are there any disadvantages to doing this?

Thinking of running an Xtant A2002 to each side of the PCE 6.5" mb's.

thanks!

Replies:

Posted By: irhino2
Date Posted: April 11, 2004 at 2:41 PM

Well, that depends on if you are running svc or dvc, and whether they are wired in series or in parrallel. There are a few factors involved.

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Posted By: bberman1
Date Posted: April 11, 2004 at 2:44 PM

This tutorial should help you out https://www.bcae1.com/bridging.htm but if you bridge (2) 4 ohm speakers to one channel that channel will see a 2 ohm load.

Posted By: irhino2
Date Posted: April 11, 2004 at 2:45 PM

My mistake!!!!!!!!! I missed the part about components..

It there a reason you are wanting to run seperate amps???? You can get just good of quality, and just as much power from a single amp if you know what you are doing.

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Rhino - Bringing you only the best in car audio!!

Posted By: kfr01
Date Posted: April 11, 2004 at 2:59 PM

Well. I'm considering a few 2 channel amps, but I'm mainly just concerned about price. It seems that I might be able to run those 2 Xtant a2002 amps w/ 200 watts to each side of the components for much less than I can buy a clean 200x2 amp.

Thanks for any help or advice you can give!

Posted By: irhino2
Date Posted: April 11, 2004 at 3:02 PM

Why not consider a clean 4 channel amp? By the time you by a few inexpensive 2 channel amps, you could have gotten a high quality 4 channel.

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Rhino - Bringing you only the best in car audio!!

Posted By: kfr01
Date Posted: April 11, 2004 at 3:07 PM

Ok. I read that site. Just to clarify - each side of a component set (effectively one speaker) will still be seen as a 4-ohm load when bridged, right?

THanks

Posted By: DYohn
Date Posted: April 11, 2004 at 3:53 PM

Right. Each amplifier channel will in effect "see" 2-ohms. The bridged mono amp created when you connect it that way "sees" a total 4-ohm load. So it should be safe.

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Posted By: haemphyst
Date Posted: April 12, 2004 at 12:26 AM

However, if you are as serious about sound as you might indicate by buying Quart components, you would be better off buying a stereo amplifier with the target wattage AT 4 ohms... When you bridge an amp, you quadruple the distortion, halve the damping factor, and halve the slew rate... all bad things. More distortion, less control, and slower transient response? Not good... buy a more powerful 2 channel amp, and do it right.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Posted By: stevdart
Date Posted: April 12, 2004 at 5:59 AM

...Because everybody wants to get the most voltage, not the best specs. That is evidenced on almost every post. So people start to believe that wiring to reach full potential from the amp is a necessity, and that if you don't, then it means you just don't know how to do it right. Components are best wired in stereo, and bridging should not be a consideration.

Subs, on the other hand, are often bridged so that the two stereo signals are mixed as one mono signal. This is used when only one sub is being driven, and very often used also when a stereo configuration could have been utilized.

I would always think to wire in stereo first for subs; bridge only if it works out better. And for components or any other drivers, wire only in stereo, one speaker per channel.

Posted By: kfr01
Date Posted: April 12, 2004 at 8:12 AM

Awesome .. These last two posts are what I was looking for. I will completely rule out briding an amp to my components and just look for a good quality 2 channel amp to run at 4 ohms. Thank you haemphyst and stevdart!

Karl

Posted By: haemphyst
Date Posted: April 13, 2004 at 4:42 AM

one thing i did forget to add, however... buy a nice 4 channel amp (one with a VERY flexible crossover included within, both high pass and low pass), or a small GOOD QUALITY two-way electronic crossover (ideally, with a 24 or 48dB slope - maintains absolute phase, a good thing), one that will allow you to crossover exactly where the passives included with your components do. this is the ultimate in decadence, run your tweeters off two channels, and the mid-bass from the other two... and you WILL get better sound without all of those lossy passive components in the signal path... if you had decided on 150wX2, then look for something around 50-75wX4... this might even cost you less than the big 2 channel... the eclipse ea3422, while not their premium line, but a grat bargain amplifier, will get you half way there... an additional benefit to this setup option? is your sound too bright? turn JUST the tweeters down... without using the noisy tone controls in your HU. the bi-wiring/bi-amping solution is FAR more flexible than a two channel setup. posted_image

2001 Honda Civic LX
Eclipse 8051 E8 deck
Eclipse 3122 driving Infinity emit Kappa tweeters 80w X 2
Eclipse 32440 driving Eclipse 89940 Point source 6X9's 120w X 4, bi-wired, bi-amped
Eclipse 34230 driving Morel MW-162 6" midbass in doors 370w X 2
Eclipse DA7122 driving Eclipse SW9122 12" Titanium sub 1350w X 2
RedTop Optima 12v under the hood
2 RedTop Optima 6v in trunk, one each side wired in series
2 Rockford Fosgate 1 Farad caps on custom hand built power bars
Alterstart 165 Amp alternator with Datel 150A Current Shunt and blue LED meter for monitoring current output

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Posted By: kfr01
Date Posted: April 13, 2004 at 8:24 PM

haemphyst - thanks for the suggestion. Now that you mention it, the Musicomp crossovers that come with the mb quart pce's allow bi-amping right on the crossover. I think I'm going to pick up a 4-channel amp and go this route. I like the idea of the tweater and woofer getting a separate dose of power. Thanks again for the suggestion!

kfr