[hesster]

What are the advantages, if any, of Bi-Amping?  Does it matter from a crossover standpoint if the crossover circuitry is totaly separated, and driven by separate channels of an amplifier set to mono/dual out?  For example, driving the woofers and tweeters of a LS-9, and splitting the crossover to Bi-Amp feed.

[WireNut]

After bi-amping for 30+ years I can't go back

[AKLegal]

You really only gain increased headroom unless you are also using a external crossover to separate the mids and highs from the lows before sending the signal to the amp.

[hesster]

What if I was to change Amps on my LS-9's (go to major upgrade using dual monoblocks), and go from single Amp per speaker set to mono dual out isolating tweeters/woofers to a single monoblock per speaker and connect the speaker wires toghther?  Would the LS-9's care? 

[Danny Richie]

What you really want to separate is the back EMF that the woofer creates as it moves from the rest of the speaker.

A small two way speaker or something with a small voice coil doesn't create much of a back EMF. So the gain is very little.

Now a big three way that uses a couple of large woofers with big voice coils is a different story. The back EMF can be much larger and there can be notable advantages in separating them from the rest of the speaker.

On the LS-9 considerable SPL levels can be hit without the woofers even having to move much to begin with. So each woofer creates very little if any at all real back EMF. But then again there are a lot of woofers. How much there is to gain from the separation might be very little. But if you are constantly driving them with 500 watt peaks and hitting super high SPL levels (moving those woofers) then there may be some gain there to be had.

[Tyson]

IMO, the main advantages of multi-amping come from removing the passive components from your signal path.  And Danny is right on - the  largest improvement comes when you go "active" with the bass woofers.  But I also think that pulling the passive parts between the mids and tweeters gives advantages too.  Capacitors in particular seem to be quite detrimental to the sound, causing smearing and blunted dynamics. 

[Danny Richie]

Just to build on what Tyson just said...

If you can relieve your amp from seeing or having to produce just the first octave (20Hz to 40Hz) then you are relieving it of about half of its work load. Now you have some headroom...

[mlundy57]

Just to build on what Tyson just said...

If you can relieve your amp from seeing or having to produce just the first octave (20Hz to 40Hz) then you are relieving it of about half of its work load. Now you have some headroom...

In your new, yet to be released, models, the plate amp will take care of this and then some, will it not? If so, then will there be much to gain by separating the mid's from the high's?

Mike

[*Scotty*]

One of the biggest reasons to bi-amp,if possible, is that when you bi-amp a speaker system you reduce the bandwidth that the partnering amplifiers have to reproduce. The reduction of band-width that the amplifier is responsible for reduces the amount of intermodulation distortion that the amplifier produces especially at higher power levels. The improvement that having lower levels of IM distortion confers is easy to hear as IM is the most objectionable form of distortion to your ears.
Scotty

[Danny Richie]

In your new, yet to be released, models, the plate amp will take care of this and then some, will it not? If so, then will there be much to gain by separating the mid's from the high's?

Mike

Yes, in some of the new designs I am working on the powered servo amps will handle all of the lower end. I see little to gain from separating the mids and highs.

Think of it this way and this is a generalization.

Remove the first octave and you remove about half of the work load and current demand of the amp (20Hz to 40Hz).

Remove the next octave (40Hz to 80Hz) and now you have removed about 60 to 70% of the work load and current demand.

Remove one more octave (80Hz to 160Hz) and now you have removed about 70 to 80% of the work load and current demand from the amp.

You take away those lower ranges and a typical amp will just breeze through the rest of it with head room to spare.

[Early B.]

Yes, in some of the new designs I am working on the powered servo amps will handle all of the lower end. I see little to gain from separating the mids and highs.

Think of it this way and this is a generalization.

Remove the first octave and you remove about half of the work load and current demand of the amp (20Hz to 40Hz).

Remove the next octave (40Hz to 80Hz) and now you have removed about 60 to 70% of the work load and current demand.

Remove one more octave (80Hz to 160Hz) and now you have removed about 70 to 80% of the work load and current demand from the amp.

You take away those lower ranges and a typical amp will just breeze through the rest of it with head room to spare.

Danny --

What effect does speaker sensitivity have on the work load of the amp? I have an OB sub that handles the lows beneath 50Hz, so my my amp only has to handle about 50Hz and above. However, my speakers are 86 dB. Is my amp working hard to handle my speakers even though it doesn't have to handle the first octave? Thanks.

[Danny Richie]

Danny --

What effect does speaker sensitivity have on the work load of the amp? I have an OB sub that handles the lows beneath 50Hz, so my my amp only has to handle about 50Hz and above. However, my speakers are 86 dB. Is my amp working hard to handle my speakers even though it doesn't have to handle the first octave? Thanks.

Well, you are eating up some of its headroom by having to drive it harder to get higher SPL levels, but you aren't demanding much current from it if from 50Hz and down is being filtered out.

The real question is are you running it out of power or not to play what you are playing?

[hesster]

Hmmmm..
I think what I am reading here is that, simply stated, that a bi amp setup on the LS-9's will naturally split off the woofers and the advantage is it will "reduce the bandwidth that the partnering amplifiers have to reproduce. The reduction of band-width that the amplifier is responsible for reduces the amount of intermodulation distortion that the amplifier produces".  To bi amp a LS-9 out of a typical HT receiver, you run a pre-out cable from each L/R channel to separate amp's that have the capability to split to mono out and run the woofers/tweeters on separate channels.  Most of these amps (like the Behringers I am using) are not exactly in the class of some of the mono blocks that are out there .  I would assume splitting the pre out reduces the signal in an unacceptable manner (run (4) bridged amps, (2) each to each bi amped LS-9).  Thus my question on going to (2) powerful mono blocks (like the new Emotiva 1000w amps) and reconnecting the speaker wires on the LS-9's. Would this be a waste of time? 

Danny says - and I am thinking all of this applies to the LS-9's woofers:-
"Remove the first octave and you remove about half of the work load and current demand of the amp (20Hz to 40Hz).

Remove the next octave (40Hz to 80Hz) and now you have removed about 60 to 70% of the work load and current demand.

Remove one more octave (80Hz to 160Hz) and now you have removed about 70 to 80% of the work load and current demand from the amp.

[AKLegal]

Ask Danny about making pair filters for you.  They can be RCA or XLR.  If you decide to biamp you could then just put the filters between your preamp and the amp that drives your tweeters/mids.  I have a pair of the XLR version and they work perfectly.

Danny says - and I am thinking all of this applies to the LS-9's woofers:-
"Remove the first octave and you remove about half of the work load and current demand of the amp (20Hz to 40Hz).

Remove the next octave (40Hz to 80Hz) and now you have removed about 60 to 70% of the work load and current demand.

Remove one more octave (80Hz to 160Hz) and now you have removed about 70 to 80% of the work load and current demand from the amp.

I am pretty sure that this applies to whatever speakers/drivers and amps that you DON'T want producing low bass.  So this would apply to the mids/tweeter section of the LS-9 not the woofers.  It could apply to the woofers if you want it to.  Like say you wanted to augment the low end with servo subs instead of running the LS-9s full range.

   

[Danny Richie]

From what my amp gurus tell me the Emotiva amps are well designed. But thee is a reason that they are priced so low. The parts quality is not real high. Not from a reliability standpoint, but from a performance standpoint. I have heard that with a bunch of upgrades to the parts they wind up being pretty good amps. 

You could drop a filter like the ones Serenity Acoustics is using in line with your main amp driving the LS-9's to roll off the lows.



Then add some servo subs to handle the lower ranges.

[hesster]

Now this filter is a interesting concept.  Being a very skilled "speaker builder" of the LS-9 and LS-C kits (mine are probably some the finest examples of a kit build, built like bomb shelters and Rosewood elegance), but a total novice on exactly how the crossovers and a filter like this works, I would welcome clarification of just how and what this thing does, and I assume it splits the pre-out of any HT's channel's output.  My real goal is to get the utmost out of my LS-9's, LS-C, and independent subwoofer from a typical HT setup.   My Yamaha HT Receiver has the typical pre-outs for independent amplification, which makes sense since I assume the internal amps cannot match the performance of external amps.  So I have separate amps driving the Bi Amped LS-9's, my Bi-Amped LS-C, then amps driving Surround L/R, Surround Back L/R, and my "House Wrecker" design sub with dual 15" subwoofers. So what I find is that the cheapo Behringer amps will get sucked dry at louder listening levels (occasional party and listening sessions), and have even tripped out the amps and my Fuhrman power sequencers/conditioners.  Hence my thought of "time for a better set of amps for the LS-9's".  Since my LS-9s are Bi-Amped, again I welcome recommendations.  What exactly will this filter do "You could drop a filter like the ones Serenity Acoustics is using in line with your main amp driving the LS-9's to roll off the lows." if I upgraded the amps on my Bi-Amped LS-9's?
Appreciate everyone's patience with all of my questioning, and welcome recommendations. 

[Danny Richie]

Now this filter is a interesting concept.  Being a very skilled "speaker builder" of the LS-9 and LS-C kits (mine are probably some the finest examples of a kit build, built like bomb shelters and Rosewood elegance), but a total novice on exactly how the crossovers and a filter like this works, I would welcome clarification of just how and what this thing does, and I assume it splits the pre-out of any HT's channel's output.  My real goal is to get the utmost out of my LS-9's, LS-C, and independent subwoofer from a typical HT setup.   My Yamaha HT Receiver has the typical pre-outs for independent amplification, which makes sense since I assume the internal amps cannot match the performance of external amps.  So I have separate amps driving the Bi Amped LS-9's, my Bi-Amped LS-C, then amps driving Surround L/R, Surround Back L/R, and my "House Wrecker" design sub with dual 15" subwoofers. So what I find is that the cheapo Behringer amps will get sucked dry at louder listening levels (occasional party and listening sessions), and have even tripped out the amps and my Fuhrman power sequencers/conditioners.  Hence my thought of "time for a better set of amps for the LS-9's".  Since my LS-9s are Bi-Amped, again I welcome recommendations.  What exactly will this filter do "You could drop a filter like the ones Serenity Acoustics is using in line with your main amp driving the LS-9's to roll off the lows." if I upgraded the amps on my Bi-Amped LS-9's?
Appreciate everyone's patience with all of my questioning, and welcome recommendations.

Well you do have a lot of improvement ahead by upgrading your amps.

Blending the LS-9's with standard subs is not so easy and can lead to some trade offs. Since the LS-9's play down to 20Hz real easy often subs are not used. And the LS-9's are usually much quicker, have more control, and a much faster settling time compared to large subs. So as you hand off the first octave to a set of big subs your actual quality may go down.

What might work best is to put the subs in the back of the room and run them out of phase from the LS-9's and let the LS-9's play full range. Then set the sub setting down real low. This can take away a ton of room loading and bass boom and give you some cleaner overall sound.

If you had a stack of servo subs then rolling off the first octave of the LS-9's and letting the servo subs handle the lower range would free up the load on you main amp and give you back some headroom.

Either way you really need to upgrade those amps though.

Thanks,
Danny

[harley52]

Wow,
 I been schooled by Danny again. The 2nd paragraph in your last post is a brilliant idea for the subs. I don't know how to do quotes.

[WireNut]

Again, I've been bi-amping for 30+ years. I can't go back, and I don't wont to.