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Re: Can I bi-amp like this...?
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JohnRice
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Re: Can I bi-amp like this...?
No, the method you describe in your initial post is NOT the proper way to bi-amp and it could result in tragically screwed up sound. Beyond that, essentially everything that has been posted so far in the thread (I don't know about Troy, since he deleted his post) is incorrect.
If a speaker is configured for bi-amping, it will have two sets of connectors with jumpers connecting each positive and neagtive set. To bi-amp, you remove the jumpers and feed them with identical signals, coming from two identical amps. You can't do this with just any piece of equipment you have sitting around, and most lower end receivers aren't even capable of configuring this setup. You are FAR better off in virtually every situation to just use a better, single, power amp to power the speakers conventionally. Of course, from previous experience, I have found that when someone gets the idea to bi-amp speakers, they are hell bent on doing it regardless of the risk of destroying their equipment or if there will even be any sonic improvement.
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Re: Can I bi-amp like this...?
Quote:
| Now I'm confused about whether or not I should use the l/r outs on the DVD player for this. I'm thinking that the composite signal would be identical to the optical signal. |
It isn’t. The former is two-channel analog. The latter is a digital signal that is decoded to 5.1 analog channels by a Dolby Digital processor. What would be coming from the front two channels from the digital output would be much different from what’s coming from the L/R outputs.
You can check it yourself by plugging the DVD player’s L/R outs to a separate input on your receiver. Compare that input to the DVD input with the center channel disconnected.
The reason you can’t really use the DVD L/R outputs in the manner you mentioned, “hooking the l/r outs on the DVD player into another amp” is because you’d then have two separate and fully independent volume controls. Not a pretty picture, having to turn the tweeters up separately from the woofers...
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Wayne A. Pflughaupt
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Re: Can I bi-amp like this...?
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Originally Posted by FranklinD
Not saying anyone's wrong here but I agree that the amps wouldn't have to be same. My, probably flawed, thinking is power is power.
Yeah, this might end up sounding like crap but I don't think I'm going to destroy anything. I'm just experimenting folks.  |
The problem is, you are asking questions when you think you know the answers already. Wayne already pointed out the significant problem with one approach you suggested. I will continue. The amps for bi-amping really do need to be identical. Power is NOT power. The most significant aspect which must match for both amps is the gain. It is also ideal for every other aspect to match, such as how the amp responds to varying loads. In theory, you could find two different amps which would match for bi-amping, but it is just simplest to use matching units, or four channels from a multi channel amp, as mentioned.
And yes, you CAN destroy equipment. If you don't know what you are doing and mistakenly run two amps head-to-head into each other, which is a distinct possibility when you are bi-amping and don't understand how it works. Also, the jumpers and multiple speaker inputs are most definitely NOT for daisy chaining, which can also lead to destroying amps.
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Re: Can I bi-amp like this...?
To hopefully further explain what John said, “The amps for bi-amping really do need to be identical. Power is NOT power. The most significant aspect which must match for both amps is the gain.”
When you biamp, the amp’s levels need to matched so that the tweeter’s volume is correct in relation to the woofer. This is done via the amp’s input stage, as some amps are more “sensitive” to the input signal they are fed (a.k.a “gain”) than others. IOW, in order to be driven to its maximum output level, some amps require a hotter input signal to accomplish that, others require less.
Most pro audio and car audio amplifiers have “gain” controls to adjust the level of the input signal. Curiously, many (if not most) home amplifiers do not. And this is why you would need both amps to be make-and-model identical if you biamp: If they are not you may end up with a mismatch between the woofer and tweeter levels – the tweeter being way too loud, for example. If this happens, you would have no recourse for balancing the levels between the tweets and woofs. Using identical amps, this problem would not occur.
Hope this makes sense.
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Wayne A. Pflughaupt
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Re: Can I bi-amp like this...?
Trying to direct you in a more productive direction, here is an over simplified assessment of the benefits of bi-amping. You are basically splitting the power used between the tweeter (and midrange, if the speaker has one) and the woofer. The problem is, low frequencies consume the lion's share of power, so there is really little to gain. IOW, just to throw out an general analysis. The higher frequencies may take 20% of the total power, with the woofer consuming 80%. So, by bi-amping, all you really gain is a reduction in power demand of 20%, since the woofer amp still has to deliver the vast majority of the power, and the tweeter is essentially unchallenged.
You will gain significantly more benefit by adding a powered sub, crossed over at a reasonable point, say 100 Hz, and staying with one amp for the speakers. The significant load of the lowest bass will be stripped off thhe main amps and sent to the sub, which is specifically designed to deal with it. The main amps are far less stressed, plus the speakers are also not driven to their limit. Everything improves, so long as you get a decent sub and set up up correctly.
EDIT: Adding even more to what Wayne and I are saying, there is also the factor of the amps' input impedance. Just matching the sound level won't necessarily produce consistent output across the audible range, since the input impedance of different amps can vary widely, and the pre-amp will not always handle them consistently. So, you see, this is actually quite complicated, and the only way to guarantee proper results is with two matched amps.
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Re: Can I bi-amp like this...?
No problem. This is one of the hazards of the internet. You can't tell the people who give bad advice from the others. Wayne always gives reliable advice. I often give unpopular advice, but I always try to make it fully thought out.
I do not bi-amp. My speakers are not capable of that because the designer (Jim Thiel) does not believe in the practice. Instead I use a single, massively powerful amp for the fronts, plus a sub. Even if I had speakers capable of being bi-amped, I doubt I would do it.
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Re: Can I bi-amp like this...?
I don't bi-amp either. Like John said, if you think about it, a subwoofer basically bi-amps your whole system. It seems to me when you go through the trouble of hooking up a seperate receiver to bi-amp a system that has a subwoofer you're, in a sense, being redundant. I think getting a good sub will make you far happier. You say you have a 5.1 system. So, set all your speakers to "small" in the system set-up menu. This will send the woofer portion below the crossover setting to the subwoofer. Set the crossover to 100 or as high as it allows to remove low-end from the channels and, if you have a sub that came with the system, you're set.
" I think it's time we go to plan B". "What's plan B?" "That's the one where we don't do something stupid".
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Re: Can I bi-amp like this...?
As long as the old receiver's multi-channel inputs bypass all processing (especially bass management) it could work. You will probably have the old receiver's pre-amp section in the signal chain, though...
Regards,
Wayne
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If I really thought I knew what I was talking about I would already have it hooked up this way and every other way...