Bridgeable???

Pycroft

Hi all...

What does it mean if an amp is bridgeable? I'm taking a stab in the dark, but I'm guessing that means you can run two amps together to form one big powerful amp? If so, do they have to be the SAME amp or can you bridge two different amps? Please teach me :0

FYI, I have a Soundcraftsmen PCR800 - 205 watts x 2 channels at 8 ohms. Someone local has a Niles SI-2125 that is 125wpc x 2, and it's bridgeable to 300 watts. I'm not sure if that means I can run these two amps together or something like that.

Looking forward to the knowledge.

James

treitz3

In laymen's terms, it means that you can take the stereo amp and bridge it into one mono-block amp. Be careful. Some bridgeable amps do not like being ran on anything other than an 8 ohm load.

tonyb

Useing both channels,lets say,on a 2 channel amp and useing it as one channel. Not really an ideal way to go.

Pycroft

I'm curious why it isn't the best way to go. If I can get a good 2 channel amp, and just use it for a center channel, what's the negatives? Is it unsafe?

Systems

Pycroft wrote: »

I'm curious why it isn't the best way to go. If I can get a good 2 channel amp, and just use it for a center channel, what's the negatives? Is it unsafe?

The load seen by the amp when it's bridged will be half of the real impedance of the speaker.If this is still within acceptable limits for the amp then bridging it would be fine and will give you an approximate 4x increase in power.Whether the power increase is sonically benificial will depend on a number of factors.

kevhed72

What about this scenario...one amp, say an Adcom 545i, to run the highs and mids of both front speakers. Then a second identical amp to drive the 2nd binding post for the bass speakers on both fronts...does this make sense at all(?)

BlueFox

GV#27 wrote: »

The load seen by the amp when it's bridged will be half of the real impedance of the speaker.If this is still within acceptable limits for the amp then bridging it would be fine and will give you an approximate 4x increase in power.Whether the power increase is sonically benificial will depend on a number of factors.

I can speak from everyday experience that the Cambridge-Audio 840W in bridged mode is audibly better in mono mode than stereo. I suspect that its original design was mono, and stereo was added for better sales. In stereo, the amp makes 350W/ch @ 4 ohms, while in mono mode it is 800W/ch @ 4 ohm. When I added my second amp I was immediately struck by the increase in clarity, while achieiving the same sound levels at lower volume settings. All in all, a perfect upgrade.

As a side note, I tried to hear a left/right differance between the 3 month old amp, and the new amp, but was unable to tell any differance. My conclusion there is that either I am deaf (possible), or there is no audible burn-in effect on these amps.

Systems

BlueFox wrote: »

I can speak from everyday experience that the Cambridge-Audio 840W in bridged mode is audibly better in mono mode than stereo.

Assuming an acceptable load, a well executed(good matching of parts in the input and feedback sections etc), good sounding stereo amp can/should retain it's good qualities when strapped in bridge mode.In fact there exists several excellent amplifiers that utilize bridged ouput stages.This bridged/balanced config is usually found in the big high powered mono blocks. I know of atleast one well regarded example were the mono bloc is basically an adaptation of it's lower powered stereo brethren.

BrettT1

kevhed72 wrote: »

What about this scenario...one amp, say an Adcom 545i, to run the highs and mids of both front speakers. Then a second identical amp to drive the 2nd binding post for the bass speakers on both fronts...does this make sense at all(?)

One for the highs and one for the lows sounds good to me.

Systems

kevhed72 wrote: »

What about this scenario...one amp, say an Adcom 545i, to run the highs and mids of both front speakers. Then a second identical amp to drive the 2nd binding post for the bass speakers on both fronts...does this make sense at all(?)

It's called passive biamping and yes it makes sense and is doable because the amps are the same thus having identical gains.However the added headroom may or may not prove benificial.

kevhed72

GV#27 wrote: »

It's called passive biamping and yes it makes sense and is doable because the amps are the same thus having identical gains.However the added headroom may or may not prove benificial.

Cool, but I am guessing I would have to come up with a custom pair of RCA IC's to run from my AVR pre-outs to the 2 Amps....right?

Systems

kevhed72 wrote: »

Cool, but I am guessing I would have to come up with a custom pair of RCA IC's to run from my AVR pre-outs to the 2 Amps....right?

Just use one of these http://www.parts-express.com/pe/showdetl.cfm?Partnumber=091-510 and two set's of cables.


Alternatively if you only want to use one set of cables you could vertically biamp. This would mean using one amp for each speaker with one channel driving the tweeter and the other driving the woofer.Simply run your cable from the AVR's pre out and use a Y adaptor at the amp end to feed the signal to both channels.

kevhed72

Thanks for the info. After thinking about it, I'm wondering if the way to go would be 2 Adcom 545ii 's, or just upgrade to one 555ii. So far I really like the sound of the 545, and have read elsewhere that many have generally preferred it over the 555ii's sound.

Systems

As I mentioned in first reply in post #10,using 2x 545's is doable but the additional gain in power headroom may not be found to be much of an advantage sonically.The real benifits of biamping occur when active low level crossovers are used. If one 545 is doing it for you now what area are you looking to improve upon?

kevhed72

I guessing, being a novice to separate amplification, more power must be a better thing ie. pushing a separate 100wpc amp through each speaker may 'open up' the speaker more and give more detail and depth than just the single 545ii