Silly question about bridging amps and 4 ohm speakers.

Shicks18

If I have an amp that is 2x80 watts in 8ohms and 2x120watts in 4 ohms. If I bridge the amp to 1x160 watts in 8ohms, can that drive a center channel speaker that is 4 ohms (a la LSiC)? The amp I am referring too is a Parasound

If that is not possible, would it be a good idea to Bi-Amp the LSiC? If so, what kinda power would the LSiC be getting?
Thanks

Face

I don't believe it's recommended.

It may work fine for a while, then one day...poof!

McLoki

When you bridge, you add alot of power, but also half the impedance that the amp sees. (and double the distortion the amp creates)

Basically - if your amp is 2 ohm stable, you should be ok, but if its not - I would not try it.

Michael

Serendipity

Face wrote: »

I don't believe it's recommended.

It may work fine for a while, then one day...poof!

I run 4 ohm speakers with a receiver. It's not recommended.

Face

appadv wrote: »

I run 4 ohm speakers with a receiver. It's not recommended.

Yes, and it shuts off at half volume. :rolleyes:

Serendipity

Face wrote: »

Yes, and it shuts off at half volume. :rolleyes:

That's what the protect feature is for...

heiney9

appadv wrote: »

That's what the protect feature is for...

Yes, but current limiting circuits in the signal path really degrade the sound. A car has a rev limiter to keep you from over revving..........but it's not good for the car to constantly be at redline even though the rev limiter theoretically keeps you from over revving the car. In the end it shortens the life.

Same principle to your receiver, it will shorten the life and puts unnecessary stress on the entire unit. If you run the receiver well within it's limits you're fine.

To the OP, it's not recommended. Why do you feel you need more power to the center channel than what you have?

H9

Serendipity

heiney9 wrote: »

Same principle to your receiver, it will shorten the life and puts unnecessary stress on the entire unit. If you run the receiver well within it's limits you're fine.

H9

I've had this receiver since Dec. 2004 and it still works fine. Note most of my listening is at low volumes.

Shicks,

Why don't you bi-amp the LsiC instead?

McLoki

Congrats, but the op is interested in bridging his amplifier into a 4 ohm load, not running your AVR. Do you have an relevent help for him?

Serendipity

I don't think it is good to bridge his amplifier with a 4 ohm speaker.

Serendipity

McLoki wrote: »

Congrats, but the op is interested in bridging his amplifier into a 4 ohm load, not running your AVR. Do you have an relevent help for him?

Yes, he should just use one channel of the amp or bi-amp the speaker.

McLoki

appadv wrote: »

Yes, he should just use one channel of the amp or bi-amp the speaker.

I agree. Not a huge fan of bi-amping (vs just using a single better large amp) but if you have the extra channel available - give it a shot. With bi-amping, your speaker would still just see 80wpc. The benefit would be if you clip the bass driver, it should not destroy your tweeter.

Michael

Shicks18

So, if I were to Bi-Amp the LSiC using the Parasound would I be doubling the power to it or would it remain the same?

Shicks18

So, if I were to Bi-Amp the LSiC using the Parasound would I be doubling the power to it or would it remain the same? If it is 120 watts of 4ohms in the bottom and another 120 watts of 4ohms in the top, then it would be great!

McLoki

It would stay the same.... Think of it this way - if you have two fans and plug them into the same outlet or plug them into outlets on different breakers - do they get any more power?

There would be some benefits to 2 different outlets - isolation, redundancy and such, but more power would not be one of them.

Now replace the fans in that analogy with 2 driver arrays (one with a tweeter and the other with 2 woofers). Same thing applies...

Michael

Shicks18

Bummer, then whats the point of Bi-amping? Do you need 2 seperate amps or an amp with built in monoblocks?

Face

It would receive 240watts(120x2@4ohms) if you were to run one channel on the highs, one on the lows. It would also be considered bi-amped.

McLoki

Face wrote: »

It would receive 240watts(120x2@4ohms) if you were to run one channel on the highs, one on the lows. It would also be considered bi-amped.

exactly the same as it would receive without being bi-amped.

Face

No, if it was connected to a single channel off of his Parasound it would only receive 120watts.

McLoki

Face wrote: »

No, if it was connected to a single channel off of his Parasound it would only receive 120watts.

Assuming his speaker is set up for bi-amping - the ONLY place the top and bottom terminals are connected is the brass strip (or speaker cable) connecting the terminals themselves....

Plugging an amp into one set of terminals and hooking the two sides together with the brass strips feeds both the tweeter and woofers with 120wpc. Taking out the brass strip and hooking up 2 channels of the same amplifier to the two separate terminals also feeds each set of terminals 120wpc.

The only difference would be if they were not the same amp, (i.e. - voiced or powered slightly differently), or the amp were not strong enough and at high volumes would actually run out of current going to the woofers and send a power surge to the tweeters (burning it out by clipping).

The amp power is not rated differently depending on how many drivers are in the speaker connected to it. It is providing the same power whether it is being sent to just the tweeter or two woofers or the tweeter and both woofers. It is the crossover and speaker design that provides more or less power to each driver in a speaker.

Make sense?

speakergeek

appadv wrote: »

I've had this receiver since Dec. 2004 and it still works fine. Note most of my listening is at low volumes.

Shicks,

Why don't you bi-amp the LsiC instead?

A large part of the equation is also the speaker's sensitivity. A very efficient 4 ohm speaker will cause less trouble than one that has low efficiency(86 db /watt/meter or less). An average AVR could drive a 4 ohm high efficiency (90 db/w/m or greater) speaker pretty decently. You would have to be cautious of distortion though at higher volumes and make sure the receiver has adequate ventillation.

Face

McLoki wrote: »

Assuming his speaker is set up for bi-amping - the ONLY place the top and bottom terminals are connected is the brass strip (or speaker cable) connecting the terminals themselves....

Plugging an amp into one set of terminals and hooking the two sides together with the brass strips feeds both the tweeter and woofers with 120wpc. Taking out the brass strip and hooking up 2 channels of the same amplifier to the two separate terminals also feeds each set of terminals 120wpc.

Correct.

The only difference would be if they were not the same amp, (i.e. - voiced or powered slightly differently), or the amp were not strong enough and at high volumes would actually run out of current going to the woofers and send a power surge to the tweeters (burning it out by clipping).

I believe what you're describing is more typical of biamping with a receiver than a separate power amp.

The amp power is not rated differently depending on how many drivers are in the speaker connected to it. It is providing the same power whether it is being sent to just the tweeter or two woofers or the tweeter and both woofers. It is the crossover and speaker design that provides more or less power to each driver in a speaker.

Make sense?

The amp's rating is partially based on the speaker's resistive load, the speaker's impedance. Since it's tweeter is 4ohms, and the mids are (I believe) two 8ohm woofers in parallel, the woofer circuit is also rated at 4ohms. With the jumpers removed, one pair of binging posts connected to each channel, the Psound should be able to supply the center speaker 120watts x 2(240watts) @ 4ohms, which could also be considered "bi-amped". It is also known as vertical bi-amping.

McLoki

Looks like we have to agree to disagree until someone else posts with an opinon that matches yours or mine.

I assert that power to the speakers (i.e. volume capability) will not be increased with bi-amping. (there are other benefits, but if more power is what you are really wanting - bi-amping will not give it to you.)

Long story short - there is a big difference between a speaker getting 240wpc from an amp rated at 240wpc than there is from the same speaker running off of 2 120wpc lines in a bi-amp fashion. (like about 120wpc)

Michael

AudioGenics

check this site out
and pictures.....

http://www.oregondv.com/Audio_FAQ_Bi-Wire_Bi-amp%20.htm

can you provide a diagram of what you are proposing to do ?

Serendipity

Face wrote: »

Correct.

I believe what you're describing is more typical of biamping with a receiver than a separate power amp.

The amp's rating is partially based on the speaker's resistive load, the speaker's impedance. Since it's tweeter is 4ohms, and the mids are (I believe) two 8ohm woofers in parallel, the woofer circuit is also rated at 4ohms. With the jumpers removed, one pair of binging posts connected to each channel, the Psound should be able to supply the center speaker 120watts x 2(240watts) @ 4ohms, which could also be considered "bi-amped". It is also known as vertical bi-amping.

+1

With a separate power amp, the amp has more headroom because the impedance of the tweeter and woofer are constantly varying with respect to time. The loudspeaker is a complex resistive load which constantly changes.

I learned this in my electrical engineering course last year.

Serendipity

McLoki wrote: »

Looks like we have to agree to disagree until someone else posts with an opinon that matches yours or mine.

I assert that power to the speakers (i.e. volume capability) will not be increased with bi-amping. (there are other benefits, but if more power is what you are really wanting - bi-amping will not give it to you.)

Long story short - there is a big difference between a speaker getting 240wpc from an amp rated at 240wpc than there is from the same speaker running off of 2 120wpc lines in a bi-amp fashion. (like about 120wpc)

Michael

I'll have to agree with Face - with the jumpers removed, the amp is not "seeing" the other half of the speaker (i.e. the tweeter or woofer).