Bridging vs Bi amping

[[DANGERDAN]]

I know my basics about bi wiring and bi amping but im having a little bit of difficulty getting my head around it, so supposedly if you have a amp that is bridge capable you can combine the terminals to double your amp output to speakers.

When you bi amp you have to have one amp for the low frequency and one for the high frequency (tri amp for 3 way systems) and then you can passive crossover or active crossover. But what happens when you bridge ?, also what amps allow for this i have a marantz a/b 2 channel 4 speaker output amp, would this be able to bridge ?.

Please and Thanks.

[STEvil]

There are two types of bridging.

The first and most common type is using a single amplifier with multiple speaker outs. This means a two or more channel amplifier. To bridge you basically use the positive lead of channel one and the negative lead of channel two and hook them to your speaker (assuming single voice coil and no crossovers/etc to monkey with).

Basically any kind of amplifier that is two channels or more (in multiples of 2) is capable of this mode. Of special importance is your impedance load of the speaker you are attaching. With a two channel amplifier attached to an 8 ohm load the amplifier will see an effective 4 ohm load. If your amplifier is not rated at 4 ohms it will probably be unstable and/or let out some magic smoke.. ;)

The second type of bridging is more commonly known as "strapping" and involves two completely different amplifiers (same make/model though) being attached to the same speaker (assuming a single voice coil). To do this most amplifiers that support the function will have a master/slave control function and are generally only a single channel each. You attach the positive lead of one amplifier to the positive lead of the speaker and the positive lead of the other amplifier to the negative terminal. The negative leads are attached to each other. Some amplifiers are slightly different, but that is the general way it is done. The impedance load acts somewhat similar but it is recommended that you use a higher impedance load for this mode. For example an 8 ohm load acts more like a 2 ohm load to the amplifiers, but you might get away with ones only rated to 4 ohms since strapable amplifiers are generally a little better build than "common" low range model.


Your marantz can likely be bridged to a single channel, but then you only have mono sound output... ;)

[[DANGERDAN]]

Thanks for that info, but in saying my amp does have 8 terminals on a a/b or a+b selection, so it can handle 4 speakers at the same time. Two speakers on Channel A and another two on channel B, so couldnt i bridge it for a stereo sound output ?.

Thanks again.

[Bobsama]

;4691338']Thanks for that info, but in saying my amp does have 8 terminals on a a/b or a+b selection, so it can handle 4 speakers at the same time. Two speakers on Channel A and another two on channel B, so couldnt i bridge it for a stereo sound output ?.

Thanks again.

If it's a 2-channel amp, running A+B means the speakers are already running in parallel. So a 100W×2ch would be capable of delivering 100W×2ch or 50W×2ch×2spk. The problem there is most amps that have A+B(+C) modes will not be entirely quiet. For example, if Set A is in your living room and turned on but Set B is in your study and turned off, you may still hear music playing via Set B despite it getting minimal power.

[[DANGERDAN]]

cool thanks for clearing that up for me.

[EniGmA1987]

;4691262']and then you can passive crossover or active crossover.
Please and Thanks.

With bi-amping or tri-amping you use an active crossover. The active crossover splits the signal to the different frequency bands prior to the signal going to the power amplifier.

Lets say you have a 2-way system. Your left channel comes from your computers sound card, goes into an active crossover. Then coming out of the crossover are 2 signals, both are still the left channel but they are not split to be only certain frequencies in each of the signals. We will call these 2 signals LL and LH, meaning LeftLow and LeftHigh. You would take your LL signal and go into your power amp, then wire that channel of the power amp into the low frequency driver of your speaker. Next you take the LH signal into another channel of your power amp, and then wire that signal into the high frequency driver in your speaker.


The reason this is done can be a few different reasons. One might be the HF driver can only handle 20 watts while the LF driver can handle 100 watts. In which case a smaller amp would be used to power the high's and a bigger amp would be used to power the low's.
Or it could be to preserve a cleaner signal to the speaker as the amplifier channel has less to concentrate on.
Or it could be that you just need more power to the speaker. Instead of using one amp channel to the speaker you are using 2 channels to it thus giving more power. Although this could probably be achieved with bridging instead and be much easier. However the bridging method might not be usable in certain situations such as with low impedance speakers which would be why an additional amp is used instead.

[[DANGERDAN]]

what about avr receivers 5.1,7.1 etc, can they be bridged ?, or is it multi channel power/intergrated amps only ?. And i see alot or pretty much all 2 channel power amps have 8 terminals, im guessing this is to run 2 channels across 4 speakers or if desired a bi wire connection.

[SabreWulf69]

Reason to use active x-overs, whilst more expensive, they are better.

"The best crossovers ...
The best electrical crossover filter is one that maintains the acoustic polar response of a loudspeaker throughout the crossover frequency range as output shifts from one driver to the next. The sum of acoustic lowpass and highpass outputs must have allpass behavior without high Q peaks in the group delay. The highpass filter section must attenuate out-of-band driver terminal voltages at a sufficiently high rate so that cone excursion decreases with decreasing frequency and nonlinear distortion is minimized.

The crossover must be inaudible

The crossover must be inaudible on program material. This also implies that the power response of the two drivers must be similar in the crossover region, and that requires special attention during the loudspeaker's concept and design phases.

Crossovers may be implemented either as passive RLC networks, as active filters with operational amplifier circuits or with DSP engines and software. The only excuse for passive crossovers is their low cost. Their behavior changes with the signal level dependent dynamics of the drivers. They block the power amplifier from taking maximum control over the voice coil motion. They are a waste of time, if accuracy of reproduction is the goal."

Do you know what way gets you the absolute best damping factor? I can't believe I forgot about this from TAFE and that would be to use active crossovers. It's what they use in big gigs for PA's and what not, and why the Rise and many decent clubs have such high stacks of amps I believe. Not to be confused with commercial active vs passive speakers i.e. simplistic views of a speaker that's passive is just one that's solely being connected to an amp or one that's active is one having a built in amp.

No, true active vs passive is this. Most, if not all speakers you have probably come across are passive. That is, from the preamp the signal is directly fed into an amp then into the speakers which have passive crossovers whether they be located in or outside of the speaker box. Active systems are this, the signal from the preamp is fed into an active crossover which splits the signal into separate crossed over frequencies at line level signal, these signals in turn are then fed into separate amplifiers, then the already crossed over then amplified signals are fed straight to the appropriate driver. This = more power and theoretical better control of the amplifiers driving the individual drivers.

Wiring up to an active crossover in my books, is the true methodology behind bi-wiring and bi-amping. Some cheaper commercial methods for bi-wiring/amping is having an amplifier that can handle a lower impedance, then using a bridge from the speakers (high) and (low) terminals for the extra power to go to the lower impedance amplifier.

You can also leave out the active x-over and bi-amp via speakers a and speakers b. Hook the positive and negative terminals of speakers a to the appropriate left and right side's high range driver, then hook up the positive and negative terminals of speakers b to the appropriate left and right side's low range driver(s). It is this configuration in which I believe there has been so much controversy over whether it actually does anything of any significance, because all I believe this is doing is once again creating extra impedance load, and doubling the gauge of the speaker wire overall.

Whilst theoretically possible under the right amplifier / receiver conditions, I would NOT try and bi-amp to other speaker outputs unless specified that one can do so under the amplifier's / receiver's manual.

Sorry if any of this is confusing, it's just that there are sooo many configurations when it come to audio. Get this, without blowing up an amplifier, you can technically wire up as many speakers you want for better coverage, from series to parallel wiring and back again. EG, 1000W amplifier, driving 1000x 1W speakers, though at a dramatically reduced damping factor.

[EniGmA1987]

;4692879']what about avr receivers 5.1,7.1 etc, can they be bridged ?, or is it multi channel power/intergrated amps only ?. And i see alot or pretty much all 2 channel power amps have 8 terminals, im guessing this is to run 2 channels across 4 speakers or if desired a bi wire connection.

I have never seen an option to enable bridging in a receiver. It is normally limited to a standard stereo power amp or integrated amp.

Also, I dont know where you are looking as I have never seen a stereo amp with 8 output terminals, 6 is the most I have ever seen a stereo amp.
Unless you are talking about different types of outputs, like an amp may have a set of binding post outputs as well as speakon outs? I have seen that before, but it is not for connecting lots of different speakers.

[SabreWulf69]

I have never seen an option to enable bridging in a receiver. It is normally limited to a standard stereo power amp or integrated amp.

Also, I dont know where you are looking as I have never seen a stereo amp with 8 output terminals, 6 is the most I have ever seen a stereo amp.
Unless you are talking about different types of outputs, like an amp may have a set of binding post outputs as well as speakon outs? I have seen that before, but it is not for connecting lots of different speakers.

I think he means all individual positive and negative terminals of both speakers a + b added together = 8.



;4691338']Thanks for that info, but in saying my amp does have 8 terminals on a a/b or a+b selection, so it can handle 4 speakers at the same time. Two speakers on Channel A and another two on channel B, so couldnt i bridge it for a stereo sound output ?.

Thanks again.

Unless the amplifier is specifically designed for bridging, then if you try this you may end up killing something. As mentioned I also have never seen a receiver that can be bridged. I tried this with my Cambridge Audio Azur 740A integrated amplifier via running a positive off of left channel speaker a, a negative off left channel speaker b and then the same for the right channel. This did nothing what-so-ever. Then I tried a parallel bridge by using a bridging wire between the remaining empty terminals which resulted in my amp's short circuit protection circuitry being activated. In short, I can not bridge my amplifier even if I wanted to, and if you try the same thing you may very well destroy something, if your gear does not have adequate protection systems built into it. When in doubt, consult your equipment's manual(s).


;4692879']what about avr receivers 5.1,7.1 etc, can they be bridged ?, or is it multi channel power/intergrated amps only ?. And i see alot or pretty much all 2 channel power amps have 8 terminals, im guessing this is to run 2 channels across 4 speakers or if desired a bi wire connection.

2 channel power amps have the 8 terminals for exactly that. I put mine to a different use. I have a 2 channel system, with the main speakers hooked up speakers a, and from speakers b I have connected to my subwoofer's high level inputs, so at the flick of a button on the amp I can just have either the mains, the sub or both going.

[[DANGERDAN]]

cool thanks for that.

[Donnie27]

;4692879']what about avr receivers 5.1,7.1 etc, can they be bridged ?, or is it multi channel power/intergrated amps only ?. And i see alot or pretty much all 2 channel power amps have 8 terminals, im guessing this is to run 2 channels across 4 speakers or if desired a bi wire connection.

Mine is connected to two receivers but not bridged. I use a splitter for the Front channels out from my computer, to 7.1 receiver's Main or Front L&R and My old school receiver's CD, yes, CD's are old tech LOL! Please, you either have to set the out on the Computer's Sound Card to Headphones or Full Range. (edit for SW--> when using headphones or speakers respectively) If not, you'll end up at whatever crossover point you're using. Most are set at the THX recommended 80Hz or the default 100Hz.

For music I switch mine to HP and NOT 2.1 because I don't use my overpowering Sub and I want the Natural Bass from the 15" woofers in my speakers, either Fisher 9Vs or Optimus Mach ones:) I'm not using a STX or built in amp type sound card. Using Full Range will nullify the Sub in most instances.

That said, I listen to most new school music in 5.1 and use the Sub. A good example of Bass making great use of the LFE channel is Creed and Fun Loving Criminals LOL!

[SabreWulf69]

Hnnng, I don't understand you sorry :confused: Certain things I picked up on like 80Hz being the recommended THX crossover point between mains and subwoofers, but everything else is a little blurry. Care to re-iterate? When I use my 'headphone' output on my Xonar Essence STX for a stereo it sounds like crap. There is better SNR on the output's designed for it. At the same time the output for headphones is for headphones as it has a headphone amp in it. A bit of an audiophile thing, but you should never use splitters, unless primarily backed up by the appropriate decent hardware. I have a comparatively cheap system as to what is available out there in the world. I send full range signals to my mains, and cover everything else below the effective low-frequency to sub-low frequency coverage range with my subwoofer. Such things as tuning via proper techniques like sound level metering, EQ'ing, phase measurement, time alignment measurement, amongst other subjective tests.

[STEvil]

He means the software setting of headphone/fullrange in the audio devices control panel, not the connector on the card.

Really its going to depend on if you bypass the windows audio controls (best way) and what DAC's/etc are on your sound card since not all are equal, and even using an amped jack (headphone out) vs a non-amped one (front/rear speaker out) will for sure change the audio quality.

[SabreWulf69]

My bad I didn't read that properly. Yeah, I'm guessing the headphone setting cuts off bass or something. Never really looked into that one, as I said my configuration is using the front out of my sound card via thick RCA's straight to my amp. Then from my amp, I have my speakers plugged into speakers 'A' of the amp, and I have connected my subwoofer to the speakers 'B' output, as my subwoofer supports high level inputs. For my headphones I use the built in dedicated amplifier on my sound card (ASUS Xonar Essence STX). For music use, I use XMPlay with the ASIO output plugin and I have measured my rooms response using various meters from my stereo and adjusted accordingly with EQ's.

Feel free to take a look at my current system at anytime here for some ideas --> http://www.nrnl.org/my-current-audio-system-specs-t72.html

[EniGmA1987]

THe headphone output would have a different impedance and is a powered output (although a small amount of power). It is very different from the RCA line level output that you found to sound better. It sounds better because it was designed for going into a receiver or power amp. The headphone out was designed specifically to go into headphones, specifically 600-32Ohm headphones at that. A normal line level signal is normally a 10,000 Ohm input.

[Donnie27]

THe headphone output would have a different impedance and is a powered output (although a small amount of power). It is very different from the RCA line level output that you found to sound better. It sounds better because it was designed for going into a receiver or power amp. The headphone out was designed specifically to go into headphones, specifically 600-32Ohm headphones at that. A normal line level signal is normally a 10,000 Ohm input.

QFT!


Hnnng, I don't understand you sorry Certain things I picked up on like 80Hz being the recommended THX crossover point between mains and subwoofers, but everything else is a little blurry. Care to re-iterate? When I use my 'headphone' output on my Xonar Essence STX for a stereo it sounds like crap. There is better SNR on the output's designed for it. At the same time the output for headphones is for headphones as it has a headphone amp in it. A bit of an audiophile thing, but you should never use splitters, unless primarily backed up by the appropriate decent hardware. I have a comparatively cheap system as to what is available out there in the world. I send full range signals to my mains, and cover everything else below the effective low-frequency to sub-low frequency coverage range with my subwoofer. Such things as tuning via proper techniques like sound level metering, EQ'ing, phase measurement, time alignment measurement, amongst other subjective tests.

Eruummm, who's talking to you? LOL! If you ASSume things you usually end up being the first 3 letters of the word. I said I, ME, not something universal or meant for everyone, get it? I wasn't talking to you.

[STEvil]

If you werent talking to anyone what was the point of the post, donnie?

[SabreWulf69]

THe headphone output would have a different impedance and is a powered output (although a small amount of power). It is very different from the RCA line level output that you found to sound better. It sounds better because it was designed for going into a receiver or power amp. The headphone out was designed specifically to go into headphones, specifically 600-32Ohm headphones at that. A normal line level signal is normally a 10,000 Ohm input.

Definitely and fully agreed :up: There's also preamp level too, such as use for certain microphones and turntables amongst possible other things. There are 3 Levels, being - Source level, Line level and Speaker / Headphone level.


If you werent talking to anyone what was the point of the post, donnie?

Yeah, I believe if you want to just randomly says things and not get opinions and help then there are blogging sites for that.

[Donnie27]

If you werent talking to anyone what was the point of the post, donnie?

I was talking to the person I posted it to. I don't know that seemed pretty obvious to me LOL!

[STEvil]

I said I, ME, not something universal or meant for everyone, get it? I wasn't talking to you.

so..

[Donnie27]

so..

Steve my sound card doesn't feature a dedicated HP AMP so that user wouldn't know anyway. Switching to HP or splitters have no ill affect on my receiver. Besides that, I was only using it as an example of a Full Range signal. I don't have his system and wasn't making a universal setting blog LOL!

[STEvil]

So you're just cluttering the thread, great.

[[DANGERDAN]]

I understood his post i think which was directed at me, i can see how you have yours setup and why i have myn connected via HDMI lossless and let the reciever handle the x-over and channels.
I also have my headphones hooked up to my pc via 3.5m jack and whenever i need to switch between the two i just adjust the main default sound device and it switches over easy.

:)