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Bi-Wire/bi-Amp Question


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#1 mmu16

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Posted 22 February 2012 - 02:40 PM

Was about to hijack the theatron 7 F.S thread in true pirate style but.... :pirate:

Chopsus stated that a pre-amp with bi-amp capability will transmit the exact same signal through both terminal sets (normal + bi-amp terminals). As suggested, a RCA y-splitter could be used to effectively 'split' the singular signal and feed into a bi-wire capable speaker system for better effect.

Is this true on all cases (pre-amps)? I was under the impression that the bi-wire terminals transmitted a different signal (mid-high presumably) compared to the 'standard' terminal. Any yoda's out there who can clarify this?

Cheers

mmu16

#2 ajm

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Posted 22 February 2012 - 02:55 PM

Im not really sure why you'd bother bi-wiring to be honest. You're splitting the signal at the amp then joining it again at the speaker only to have the speaker's x-over do it's thing and feed the drivers. It's probably more a gimic than anything else.

If you're going to bi-amp then you really need to be using two (or more) separate and discrete amplifies, one to feed high frequencies and the other to feed low frequencies. The idea there is to bypass the speaker's x-over and manage it at the pre-amp.

And you'll need to be sure that your speakers are truly bi-ampable and that the speaker terminals aren't just wired together before they hit the crossover. Ive heard of many that are even though their advertised as being bi-wire/amp-able.

#3 myrantz

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Posted 22 February 2012 - 03:21 PM

Not sure what you're asking? Are you saying terminals from the pre-amps? That will only work if it has some form of active or external crossover (whether built into the pre-amp or via something else)...

For passive setup. The speaker/ic cable carries the full range. It's the internal crossover that says what goes through to the respective driver. i.e. (usually) if you connect to the top set, the tweeters will sound, and the bottom set woofer/mid will sound...

If you try both terminals and all drivers make a sound, then it means the terminals on the speakers are just for bling.

For bi-wiring/bi-amp setup these type of speakers - there are folks who use different amps for different drivers, usually class D for bass, then something else for mid/tweeter, etc... Some will use different speaker cable materials (e.g. silver for the highs for the "sparkle", and solid core for the bass).

YMMV as to what combination will sound good. For me, a single amplifier, a single set of cables, and a jumper cable (flat ribbon) works best. Simple, but YMMV.

---

But what happens if you connect two amplifiers (or two sets of terminals from the same amp) to the same binding post? :P That I don't really know... Is that like connecting in series? Will the whole thing just blow up? :ninja:

Edited by myrantz, 22 February 2012 - 03:29 PM.


#4 ajm

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Posted 22 February 2012 - 03:45 PM

I think what the OP is suggesting is splitting signal from pre-amp or AVR into power amp then using the power amp to bi-wire into speakers.

#5 davep

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Posted 22 February 2012 - 03:51 PM

Thats how I read it. I would have thought a passive splitter will attenuate the signal. I wouldnt bother.

#6 myrantz

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Posted 22 February 2012 - 04:15 PM

I think what the OP is suggesting is splitting signal from pre-amp or AVR into power amp then using the power amp to bi-wire into speakers.

For passive system? If yes, then both terminals will be full range... AFAIK anyway...

Thats how I read it. I would have thought a passive splitter will attenuate the signal. I wouldnt bother.

No need for splitter I reckon as most AVRs and even some pres or power amps will split the signal internally these days..


I do have one from bunnings which seem to do ok (all metal).. But TBH I couldn't find any benefits at all from bi-wiring, although YMMV.. Never really tried bi-amping as it involves way too much work carrying stuffs around. TBH if I wanna go bi/tri-amping I'd much prefer to set it up as an active system instead ^_^.

#7 Chopsus

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Posted 22 February 2012 - 05:01 PM

OK - what I know from experience.

The Yamaha RXV3800 advertises that it is Bi Amp capable, and it is, but it sends the FULL RANGE to both channels on the pre-outs .... this means that it is NOT doing the active crossover work (ie: hi to one low to the other) that I and many others had assumed.

The net result is this is exactly the same as if you use a Y adaptor..... now Davep believes this will attenuate the signal, but the advice I have been given on this forum and over on AVS is that this does not occur (and if it did it would pose real problems with interconnect length)

Ideally bi-amping should be done with an active crossover that splits the signal, however this does not mean that a good deal of sonic improvement can;t be had from bi-amping even if you are sending the full range to both the high and low end drivers.

The way I understand it, the drivers can only use the power available to them at the frequency range they are capable of - it is when you are trying to get more out of your speaker than they can get from your amp that problems occur, thus having a separate amp for the low end stops the system from starving the high end (usually) and this results in better sound .... I can attest to this as I have bi-wired, biamped via the 3800 and now bi amped via the Theatron and the latter two are distinctly better with a much richer, clearer soundstage.

To Bi Amp your speakers must have two sets of binding posts and you must remove the joiners (not the correct term) or risk shorting your amp.

From what I understand you can Bi Amp any speaker if you are prepared to rewire the speakers, but this would also include adding passive crossovers for the high and low end (or mid range .... tri amp if you like)

The perfect setup has and active crossover between the pre amp and the power amp then feeding the drivers with no passive crossovers at all .... but this normally requires butchering your speakers as the are not built to do this from stock.

IIRC there is at least one member on the forum here who has a pretty elaborate setup of external passive crossovers mounted on the wall behind his fronts .... I also think they are adjustable - optimized for 2 channel versus surround listening.

#8 Chopsus

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Posted 22 February 2012 - 05:20 PM

Also - what Treb was talking about .... connecting two channels of an amp to one speaker ... this is called Bridgeing and can be done, provided the Amp is bridgeable, in theory this multiplies the amount of power available to the speaker by 4 (from memory), in practice a factor of 3.

#9 :)

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Posted 22 February 2012 - 06:19 PM

easy way to look at it is twin terminals at the speaker required no matter whether bi-wiring or bi-amping.

if using twin outputs on a pre amp, then your looking to bi-amp. note you can horizontaly or vertically bi-amp as well. horzontally gives better physical channel separation. vertically gives better separation between HF and LF. this is the case if using two stereo power amps.

if using one output from the pre amp to an active xover (ie one that is powered) that splits HF and LF is active bi-amping. seing this is a multichannel subforum, most people be using an avr or processor and inbuilt crossover and an active sub. so in effect the large majority of people would be actively bi-amping in that case anyways :)

as to ripping out crossovers in speakers etc. I'd suggest to rather evaluate at speaker purchase time passive vs active solutions. theres good and bad in both. there are some very average active speakers as there are passive. and some of best speakers money can buy can be passive in some cases and active in other brand / models. no givens in this kind of stuff.

for existing systems a case of trying for yourself is best. as the different arrangements can bring benefit in some scenarios as opposed to others.

:)

ps do have a peep at our htfaq (link in signature) as can be a valuable resource for these kind of topics that have been covered quite a few times.

#10 davep

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Posted 22 February 2012 - 06:24 PM

Maybe I read it wrong, I was thinking the OP wanted to use a y-splitter on a pre-out to feed two channels of a power amp?

#11 :)

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Posted 22 February 2012 - 06:30 PM

Maybe I read it wrong, I was thinking the OP wanted to use a y-splitter on a pre-out to feed two channels of a power amp?


that is what most people do to bi-amp. just need to be carefull. a line signal is extremely low level. and if splitting with a y cable the pre amp might not have the guts behind it to drive a couple of channels. some will cope better with "spitting" than others. for most its not an issue :)

my point just most people are actively bi-amping in a ht/mucltichannel situation in anycase. anyone using the inbuilt xover in their avr/processor and an active sub are actively bi-amping :)

#12 Chopsus

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Posted 22 February 2012 - 06:32 PM

Yes and that is what I am doing from my 3800 serving as pre/pro to the Elektra Theatron. Many others on this forum are bi mapping the same way.

I did this after discovering that the 3800 does not serve as an active crossover in its bi amp setting, meaning a passive bi amp either way, but by using a y splitter I am able to use the internal amps on the receiver to power presence or rear surround speakers when I set these up.

#13 Chopsus

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Posted 22 February 2012 - 06:34 PM

my point just most people are actively bi-amping in a ht/mucltichannel situation in anycase. anyone using the inbuilt xover in their avr/processor and an active sub are actively bi-amping :)


Yes .,, so Y splitting makes it Tri-amping! (passive high/mid ..... Active high/mid / low)

#14 perthpete

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Posted 22 February 2012 - 07:27 PM

ok, from a newbee in bi-amping and amplifier world...

Would most (advanced / higher specc'd) not work like mine (Denon 3808), where you use two non -used surround B channels as bi-amp channels for your speakers? That's what I have done... So like my case: 7 channel AVR driving 5 speakers (and sub) with channel 6 and 7 used for bi wiring speakers.

Then adding an external amp (assuming enough channels obviously so in my case at least 7) where those two extra bi-amp channels just use channel 6 and 7 again on the amp .. and the bi-amp'd speakers receive one channel per connection ...

#15 Chopsus

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Posted 22 February 2012 - 07:30 PM

Exactly what I have done with an Elektra and Yamaha rxv3800 (having previously bi amped with just the 3800 as you describe)

Yes on both counts ... I have now opted for a y cable to bi amp to 5 channels with the Elektra, leaving the 6 and 7 the channels on the receiver to drive presence/height speakers.

Edited by Chopsus, 22 February 2012 - 07:32 PM.


#16 MarkTecher

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Posted 22 February 2012 - 08:59 PM

When you bi-wire, you are effectively halving the resistance of the cable assuming you run two equal lengths of the same cable. Most good cable offer a resistance per foot figure (some offering inductance as well), so the length of cable could be seen as a resister. Running a pair of resisters in parallel will halve the total resistance. OHM's Law states that if we decrease resistance we can increase amps. Volts times amps equal watts and the theory goes that the more amps the better.

Inside the speaker, the crossover is made up so that there is a High Pass circuit and a Low Pass. The bridge straps can be left on for bi-wiring.
Lets assume that the speakers x-over a 2 way at 3K. The LP side of the network recieves a full 20~20K signal, passes 20~3K and the rest is discarded.
The HP section also receives 20~20K but it only uses 3K~20K. So again, there is waste.

Bi-amping 1: This is technically the same as bi-wiring. The differences are
  • you use two amplifier channels to drive the HP and LP sections
  • you must remove bridging straps
Because each section still receives 20~20K, the system still relys on passive filtering and power is wasted.

Bi-amping 2: This invoves using an electronic crossover to divide the signal into bands before amplifiaction.

The same two power amps can be used. The LP section only amplifies 20~3K. The HP section amplifies 3K~20K. There is no power wastage and each band may also gain "in band gain" which makes the system more dynamic.

The one reason an AVR can not bi-amp properly (#2) is because the crossover would need to be custom designed to match that of the passive devices. Crossovers for SW are typically (THX spec) 80Hz @ 24dB and so become straight forward in design compared to what is required for mids and highs. It is not as easy to match to a tweeter and mid-range set up because there are many variances the speaker manufacture may have designed into their crossover so it performs a certain way.

When I first tested the plate amps I use in my own active LCRs, I did so using a VAF Reseach speaker with bi-amping capabilities. The system just didn't 'perform' the way I had hoped and this was due to the fact that passive tweeter attenuation had been used as a part of the passive crossover in the speaker. The amp plates I use have 70 (Mids) + 30 (Highs) watt ampliers where tweeters are generally more sensitive and therefore would produce have higher SPL, so don't need the same size amp. As mentioned, the VAF Reseach HP had tweeter attenuation, so the only way to make this 'work' would be to power each section with the same amplifer power.

#17 Chopsus

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Posted 22 February 2012 - 09:09 PM

Hi Mark,

With Bi-amping 2, wouldn't there still be waste if the passive crossover filters are still in place? hence resistance .... to do this properly one would need to do some DIY on the internal wiring of the speakers (ie: most, if not all. bi-ampable speakers are intended for passive bi amping, not active).

#18 :)

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Posted 22 February 2012 - 09:17 PM

legend audio's dr Rods comments re bi-amping and bi-wiring are a good read on the subject.

http://www.legendspe...u/biwiring.html

#19 MarkTecher

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Posted 22 February 2012 - 10:18 PM

Hi Mark,

With Bi-amping 2, wouldn't there still be waste if the passive crossover filters are still in place? hence resistance .... to do this properly one would need to do some DIY on the internal wiring of the speakers (ie: most, if not all. bi-ampable speakers are intended for passive bi amping, not active).


My LCRs are done on the Bi-amping 2 method and there is no passive crossover. It is 2K @ 24dB electronic. The only passive components used are for 'impedence matching'. I also use BM, so SW is 20~80, LP is 80~2K and HP is 2K~20K. Technically my front stage is 3 way active. The dynamics went right up after the conversion. You hear this for both film sound and music, especially lossless like DVD-A. It has a 'punch' that the previous passive version of itself did not have.

I was reading a thread on THE ISLAND at AVS and one poster was commenting about how he remembers certain parts of the soundtrack slammed in the cinema, yet no matter how loud he played this at home, the slam was not there. He blamed the soundtrack. Curious about his comments, I loaded the BD and went to same chapter he was referencing and I could felt the impact he described from his cinema visit. Cinemas have 3 way active speakers for LCR and why I felt I needed to have the same for my system at home.

if your were to convert a hifi speaker to active, you'd probably want to pull the passive crossover out completely. This is basically what I did when I converted my LCRs from passive to active.

#20 Chopsus

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Posted 22 February 2012 - 10:54 PM

if your were to convert a hifi speaker to active, you'd probably want to pull the passive crossover out completely. This is basically what I did when I converted my LCRs from passive to active.


Yep .... good to know as I was thinking the same.

Now, to clarify some language, Seaton Active speakers have their own (matched) internal amp, but they do not contain multiple amps for HF/MR/LF so they are not "active" in the way we are talking here, are they?

#21 mmu16

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Posted 23 February 2012 - 08:55 AM

Good info flow here! Apologies if I wasn't too explicit in the detail before. I'm in the same boat as perthpete (comment above). I've got a yamaha aventage 2010 which offers bi-amp capability through the use of Front L&R and Rear presence channels to bi-amp the front speakers. Obviously this requires a bi-wire capable speaker with the 'connectors/bridge' removed (the little metal thingos). I've got an emotiva XPA-5 so my initial plan was to run the bi-wire set up through the power amp (Ch1,2 = main left; Ch3 = Centre; Ch4,5 = Main right) so I can get a fuller front sound stage. However my receiver does not have pre-outs for the rear presence speakers (which act as terminal 2 for bi-amping). This means if i want to bi-amp the fronts I would have to use the receiver's power stage.
But, according to Mr. Chopsus, the bi-amp signal is the same through both terminals so potentially by using a RCA Y-splitter I can split the front signal and send it through to the power amp to effectively bi-amp (still remove the connectors in the speaker).
I'm not sure if the receiver has an internal crossover which switches on when in Bi-amp mode - need to go through that infernal manual :hmm:.....

BTW my speakers are Paradigm Monitor 11 V6.

#22 Chopsus

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Posted 23 February 2012 - 09:04 AM

If you use a Y splitter you don't need to worry about internal crossovers in the receiver. As I mentioned before, my Yamaha rxv3800 is bi-ampable but in practice I discovered that all it does is split the signal internally with no active crossover at all (full range is sent to both outputs) .... I would suggest the later model (that you have) operates exactly the same.

Edited by Chopsus, 23 February 2012 - 09:05 AM.


#23 shmb

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Posted 23 February 2012 - 09:43 AM

Interesting topic, I would question the removal of passive crossovers in high quality speaker systems.

Any decent speaker system with well designed passive crossovers would probably sound much worse if they were removed for active crossovers, because in those speaker systems the crossover cap/coil/resistor values are generally not text book values, they may have different roll off slopes, different Q's in their LP and HP sections to achieve the desired tone/performance. These values would be achieved by system measurments and listening tests, they can't be achieved by mathematics.
Also any phase shifts in the crossover components (which is meant to be a disadvantage of passive crossovers) can actually be used to its advantage, by bringing phase response more in line. (if you know what I mean) Makes sense?

So fitting an active crossover in this case means it will probably sound worse.

But, I've found Bi wiring still helps even with passive crossovers still fitted, especially with improved tone around the crossover region. Sounds hard to believe I know, as bi wiring technically should do nothing, but then again speaker wires should sound the same technically too. But we all know they don't.
I think maybe it probably has something to do with current draw through the individual wires, the tweeter wire will only carry current at high frequencies, wheras the woofer wire will only carry high current at lower frequencies??? (Due to the LP and HP passive crossovers)

Who knows???? But it seems to work.

Bi amping will be an extension of this, each amp does less work, even with passive crossovers fitted.

Interesting.

Edited by shmb, 23 February 2012 - 09:45 AM.


#24 MarkTecher

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Posted 23 February 2012 - 09:48 AM

Yep .... good to know as I was thinking the same.

Now, to clarify some language, Seaton Active speakers have their own (matched) internal amp, but they do not contain multiple amps for HF/MR/LF so they are not "active" in the way we are talking here, are they?


When I went to CEDIA in Atlanta 2010, I got to have dinner with Mark Seaton and he was quite willing to discuss his designs. What I could gather is that he does have active crossovers for bass to mids and passive from mids to highs on his active speakers. So the bass amp runs 20~800(?) and the mids/highs amp runs 800~20K. The passive X-Over then divides this 800~20K into mids and highs. Apparently he uses a coaxial tweeter which means it is built into the mid range driver. From what I understood, he could not actually mod that part to be fully active. I could be wrong here.

Procella Audio also seemed to be doing the same thing where they had active bass to mids and passive crossover for mid to highs. They had various parts on a “show and tell” when I did their “THX Baffle Wall” course. They of course promote the use of horns for HF dispersion which are really efficient anyway.
Running four amp channels as full range to the front L and R may or may not provide improvements because in the end of the day, you are still relying on the passive components to filter the sound. Only an active system feeds the speakers the diet they need.

#25 M&K Freak

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Posted 05 March 2012 - 01:00 PM

Thought I might resurrect this topic, and pass on my (limited) experience with bi-amping.

I recently managed to move the MA A5 cr power amp from it's box (from the UK) into my enlarged hi-fi cabinet. (OT - the improvement in 2ch sound over the multi-ch Rotel is quite noticeable).

This freed up a couple of channels on the Rotel 1075, one of which I used to bi-amp my centre speaker. Without re-running Audessey, or changing any settings, this has given me a much clearer centre channel for dialogue in movies, which was a real problem with my previous setup (Raising the height of my centre speaker has also helped a lot in this regard).

One question for Mark, which may have been covered already, my apologies if so:

Does bi-amping (still sending the (same freq range/signal) to both sets of speaker terminals (Krix Vortex) bypass the passive xover in the speaker, and send the full signal to the speakers, and they sort out the frequencies?

I have checked, and 1 set of terminals on the Vortex definitely respond to / produce High frequencies and the other set of terminals the Mid/Low frequencies.