New Posts  All Forums:Forum Nav:

Can I bi-amp like this...?

post #1 of 17
4/3/08 at 11:11pm
Thread Starter 
If I wanted to bi-amp my l/r mains in a 5.1 setup, couldn't I just use the DVD player optical out and go into my receiver, then hook the l/r outs on the DVD player into another amp? Of course from there I can send the signal to whichever set of speakers I choose. This is the only way I can think of to do this since my receiver isn't cut out for this task.

I've been reading for a few hours(mostly in random forums I guess) and this method has not been mentioned yet. There seems to be a bit of confusion about bi-amping in general on a lot of forums.

The crossovers in the speakers would be used though, right? Is this necessarily a bad thing though? I mean, if the speakers were built with two sets of terminals, wouldn't they take into consideration that a lot of people would use them bi-amped?

Hmmm...?? Can someone shed some light on this? Thanks!
Reply
post #2 of 17
4/3/08 at 11:36pm

Re: Can I bi-amp like this...?

Removed
Reply
post #3 of 17
4/4/08 at 10:40am

Re: Can I bi-amp like this...?

The L/R outputs going to a separate amp should work out quite well.

A crossover is still needed before the midrange and tweeter speakers. The crossover is used here to block lower frequencies that would overload and burn out those speakers.

If the speaker unit has two sets of terminals that are connected to each other, those terminals are meant only to accept one amplifier channel feed together with a daisy chain to another speaker system. Do not connect two different amplifier channels to those terminal pairs respectively. You will need to rewire the speaker system so one set of terminals goes only to the woofer and the other set of terminals goes only to the crossover.

Video hints: Video Technicalia Made Easy
Reply
post #4 of 17
4/4/08 at 11:51am
Thread Starter 

Re: Can I bi-amp like this...?

I've noticed that most speakers that can be bi-amped have a strip of metal to connect the like terminals together. You're saying that just removing the strip of metal between the posts and hooking them up like I described above isn't really the best option then(which would use the speaker crossovers)? Like, in a 3 driver speaker with a tweeter and midrange driver hooked to one x-over and a bass driver hooked up to a separate x-over, wouldn't that take care of what frequencies go where(to a point at least)?
I'm thinking another issue would be getting the surround/center speakers balanced to the l/r set of speakers hooked up to the receiver since it's all on one volume control.
I think I'm missing the point. Heh. Thanks.
Reply
post #5 of 17
4/4/08 at 2:22pm

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.
Reply
post #6 of 17
4/4/08 at 6:42pm
Thread Starter 

Re: Can I bi-amp like this...?

I see what you're saying. But...
The amps have to be identical to do this? Seems like they could be similar in output and work fine(I don't know though obviously).

Also, isn't the optical out and the composite outs on the DVD player the same signal? As in, what you hear from them will be ultimately be interpreted as the same analog sound.

I still don't understand how it would be possible to do this without a high end receiver. Actually, I still don't even know the proper way to even do it at all...
And I don't see how I'm going to damage something unless I crank it too hard or use mismatched stuff.

Now do you see what I mean about the confusion in forums?

Thanks for replying.
Reply
post #7 of 17
4/4/08 at 7:32pm

Re: Can I bi-amp like this...?

I don't think you need identical amps.

If amplifiers of different powers are used, arrange the inputs so that the higher powered amp channels go to the woofers.

You might even use unused channels in the same amplifier unit for biamping, for example a 7.1 amp feeding a 5.1 system has two leftover channels. But there must be individual inputs for each channel in order for you to do this.
Reply
post #8 of 17
4/4/08 at 8:09pm
Thread Starter 

Re: Can I bi-amp like this...?

I've read about using the left over channels in a 7.1 receiver to bi-amp. I've only a 5.1 so that isn't an option for me. I wish that speaker b was actually a separate amp and I could use it with surround. Oh well, maybe more expensive receivers can do this?

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.

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. The signals would just be processed in a different way in the DVD player but I'd think that the actual signal would be the same because they, well, sound the same. Or no?

Yeah, this might end up sounding like crap but I don't think I'm going to destroy anything. I'm just experimenting folks.
Reply
post #9 of 17
4/4/08 at 10:18pm

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...

Regards,
Wayne A. Pflughaupt
Reply
post #10 of 17
4/5/08 at 7:57am

Re: Can I bi-amp like this...?

Quote:
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.
Reply
post #11 of 17
4/5/08 at 9:40am

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.

Regards,
Wayne A. Pflughaupt
Reply
post #12 of 17
4/5/08 at 1:47pm

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.
Reply
post #13 of 17
4/5/08 at 8:27pm
Thread Starter 

Re: Can I bi-amp like this...?

JRice: Sorry if I sounded like an arse.. I thought it was obvious that I'm clueless. I was just telling you how it makes sense to me. If I really thought I knew what I was talking about I would already have it hooked up this way and every other way...

I think I lack the money and current knowledge to do this in a correct manner right now. I think a sub is in order first(and maybe last) from what you're saying(I don't even have one yet). I want one but until I'm able to put money towards that, and not something else, I wanted to "improve" my sound with stuff I already have. Simple as that.

I might be starting to get it a little more but hmm.. perhaps I should read more and then come back with questions.

I'll just save for a sub for now. Do you guys have your speakers bi-amped and, if so, do you find that it's worthwhile? Thanks for the replies.
Reply
post #14 of 17
4/5/08 at 9:46pm

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.
Reply
post #15 of 17
4/5/08 at 11:18pm

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.
Reply
post #16 of 17
11/27/08 at 10:28pm

Re: Can I bi-amp like this...?

Hello Guys, I have another idea on how to biamp a 5.1 a/v receiver, hope some of you would post a comments on this, here it goes:

I have an old 5.1 a/v receiver with multi-channel input, and when you select this input on the receiver, other features on digital and surround processing are disabled. I am thinking that, using my 2-channel integrated amp with
preamp-out L+R, I will connect this preamp-out L+R to an electronic crossover (2 way only), then I will connect the LHPFout and RHPFout to the
5.1 receiver's REAR LEFT + RIGHT analog input of the multi-channel jacks,
and then the LLPF and RLPF to the FRONT LEFT + RIGHT analog input of the
multi-channel jacks. On this setup I will be practically using the 4 channel of the 5.1 a/v receiver as individual amplifier to drive separate woofer and tweeter of each left and right speaker. Now, I cannot just used this 5.1 receiver for surround sound but only served as dedicated 2-channel or stereo system, in a biamp configurations. To connect the tweeter on the 5.1 receiver, I have to use the REAR L+R speakers out, and then the woofer to the FRONT L+R respectively. But first, I have to modify my old school speakers with 12" woofer, midrange and tweeter for bi-wiring connections.
Reply
post #17 of 17
11/28/08 at 5:35am

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
Reply
New Posts  All Forums:Forum Nav:
  Return Home