Bi-amping - AVS Forum
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post #1 of 18 Old 01-21-2013, 01:10 PM - Thread Starter
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Hello all. Looking to change my current setup. I am currently running an Adcom 5400 to my front B&W 603.3's and a second Adcom 5400 to a pair of DS3 surrounds. I am looking to add my Adcom 5503 to cover the center and surround channels, then run a separate 5400 to each 603.3. Thus increasing the left and right channels from 125wpc to 250wpc. My question is, has anyone done anything similar? I will run half a 5400 to the highs, and the other half to the lows. This will be done to both LR sides. Does anyone have any thoughts on using one amp dedicated to the low frequency drivers, and the other to the high frequency? Or just run a left and right matching pair? Are you confused yet?

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post #2 of 18 Old 01-21-2013, 03:17 PM
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If you don't bypass the internal crossovers and use an electronic crossover prior to the amps there will be little, if any, benefit from using two amps.

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post #3 of 18 Old 01-21-2013, 03:41 PM - Thread Starter
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I will need to communicate to B&W about bypassing the internal x-overs. I do have an external electronic x-over the I could put inline. Just wanted to hear some feedback from forum replies.

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post #4 of 18 Old 01-21-2013, 06:36 PM
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I don't see any useful benefit for biamping for you. Unless perhaps you intend to run the amp into clipping regardless. Then you might get some protection for your tweeter.
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post #5 of 18 Old 01-21-2013, 08:21 PM
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Bi-amping does not double the power to the speakers. A single 125 W amp can provide 125 W to the bass and treble. Splitting into two bands you still have a maximum of 125 W in each band. As mentioned above, if you are driving well into clipping you would probably still clip the bass amp but probably not the treble since the higher frequencies generally require less power. However, the only way to send 250 W to either (or both) band(s) is to buy a 250 W amplifier.

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post #6 of 18 Old 01-22-2013, 12:37 AM
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Yeah, take it from many that have tired passive bi-amping and bi-wiring. Not much really takes place. Try it of course, so you can see for for yourself. What really makes a difference is; a bigger badder external amplifier to feed those hungry speakers.

IF YOU FEED THEM, THEY WILL PLAY

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post #7 of 18 Old 01-22-2013, 06:37 PM - Thread Starter
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Let me clarify in case my situation is unclear. I own (2) Adcom 5400`s. Each amplifier is rated at 125 wpc. This is a two channel amplifier, thus the amplifier's total output is 250 watts. What I'm planning on doing, because I have the amplifiers is run a 5400 to each side. Total of four channels each with 125wpc capability. Are you saying that this would NOT equal 250 watts per side? I have the two amps at my disposal, so rather than just use one amp driving a left and right side. One amp will be biamped and run the left. The other amp will be biamped and run the right. With this known, do you have another opinion?

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post #8 of 18 Old 01-22-2013, 07:54 PM
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^^^^the only way to get 250 watts into each speaker is if your adcom amp
was bridgeable.

It is not!!! What you are proposing is passive biamping. What the other
Posters say is correct... Small benefit at best.

If you want more power to your speakers you need to purchase a more
Powerfully external amp. (Emotiva)
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post #9 of 18 Old 01-22-2013, 08:19 PM
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Hi, I read your post and I have one similiar,, BUT, I do have 2 Adcom gfa 550a amps at 200w per ch both driven and they are bi-ampable.. Both only have about 50-60 hrs on them and not a scratch, if you are interested in coming up to nice power bi-amp do-ables, let me know by reply. No home runs hit by me in selling and sharing fine equipment with others who appreciate! bob800adcmlogn,, Bobby G
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post #10 of 18 Old 01-22-2013, 08:22 PM
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Sorry, it's bob800adcmlogn here.. the amps are 555's
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post #11 of 18 Old 01-22-2013, 08:35 PM
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Quote:
Originally Posted by grasshoppers View Post

^^^^the only way to get 250 watts into each speaker is if your adcom amp
was bridgeable.

Absolutely, it's a great idea in theory, but as said here, you need to be able to bridge them. Emos are bridgeable.

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post #12 of 18 Old 01-22-2013, 08:47 PM
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Quote:
Originally Posted by bob800adcmlogn View Post

Hi, I read your post and I have one similiar,, BUT, I do have 2 Adcom gfa 550a amps at 200w per ch both driven and they are bi-ampable.. Both only have about 50-60 hrs on them and not a scratch, if you are interested in coming up to nice power bi-amp do-ables, let me know by reply. No home runs hit by me in selling and sharing fine equipment with others who appreciate! bob800adcmlogn,, Bobby G

What he has can do bi-amping quite well for all it's worth...

...that's the problem, bi-amping isn't worth it.

Now, are your 555s bridgeable? His 5400s aren't.

btw. Adcoms are great amps - I have a GFA-535 in my 2.1 system smile.gif

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post #13 of 18 Old 01-22-2013, 08:54 PM - Thread Starter
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Thank you to all for the feedback. I guess that's why we are all online.

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post #14 of 18 Old 01-22-2013, 08:59 PM
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Quote:
Originally Posted by chewee0922 View Post

What I'm planning on doing, because I have the amplifiers is run a 5400 to each side. Total of four channels each with 125wpc capability. Are you saying that this would NOT equal 250 watts per side?
What they're saying, or should be anyway, is that it doesn't matter. What determines output isn't power, it's voltage swing, and what you propose will give exactly the same voltage swing you have now. Output will remain the same. The benefit to bi-amping lies in reducing distortion, by removing the passive crossover and by separately amplifying two reduced bandwidth signals rather than one full bandwidth signal. With the high quality passives used by B&W the improvement realized by bypassing them probably will be slight, perhaps too slight to hear, and the reduced IM distortion alone may not be worth the added system cost. You'd gain some additional headroom in the amp used to drive the HF section, and that might be audible. But it might not.

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post #15 of 18 Old 01-23-2013, 05:58 AM
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yes they are and I actually have four of them..Bobby
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post #16 of 18 Old 01-23-2013, 07:48 AM
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Note the 603 specs list 3 ohm minimum impedance, a value too low for many amps in bridged configuration. I am not sure Adcom specs their low limit in bridged mode. They are 8-ohm nominal so might be OK but I would watch the amp (since Adcom's tend to run hot anyway). Bridging effectively halves the load impedance seen by the amp, so that 3-ohm min becomes 1.5 ohms to a bridged amp. I know Emotiva will not warrant their amps for less than 8-ohm speakers in bridged mode, although Adcom by all accounts (and past experience) will drive lower impedance loads fine in normal mode.

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post #17 of 18 Old 01-23-2013, 08:39 AM
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I recently did this, but it's not as easy as just bi-passing the x-over and hooking up an external, electic one. In my case, I was able to buy an amp (actually 3 amps) that has preset DSP values installed for my specific speakers. Otheriwse I would have had to take measurements and tweak, tweak, tweak. Among the DSP variables are crossover, delay, EQ filters and output limiting. A little daunting unless you are comfortable in setting these.
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post #18 of 18 Old 01-23-2013, 08:50 AM
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There are programs that simplify it, like RPlusD with the speaker filter option, but of course you must buy the SW, any needed HW, and learn how to use it all...

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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