Ok, I'm trying to understand Bi Amping 80's with seperate monoblock amps. I've read many articles online that talk about "true" bi amping is when you disable the speakers "passive" crossover and use a seperate external "high pass" and "low pass" crossover. See schematic below.
Now, I'm trying to decide if the Axiom m80's have a "passive" type crossover or not, I do not believe they do. Below is a portion of a website that was talking about biamping. You see it mentions most speakers that have dual speaker terminals have a built in "high" and "low" pass crossover design, versus a passive design.
Bi-amping and bi-wiring
It's becoming more common for higher-performance speakers to include dual sets of terminals, usually binding posts. Models with dual terminals almost always also feature a special type of crossover with separate "high-pass" and "low-pass" sections.
Speakers with dual sets of terminals work fine when used with a single set of speaker cables. In fact, they usually come from the factory set up for conventional operation, with "jumpers" installed between the two sets. These jumpers can be easily removed for bi-amping or bi-wiring.
Bi-amping means that instead of driving a speaker full-range with a single channel of amplification through a single set of speaker cables, you actually connect two sets of cables, with each set carrying the signal from a separate amplifier (or amp channel). This way, both low-frequency drivers (woofers) and high-frequency drivers (tweeters) receive dedicated amplification.
Bi-wiring involves connecting two sets of cables to your speakers, like bi-amping, but both sets of cables connect to the same set of output connectors on your receiver or amplifier. Bi-wiring doesn't deliver more wattage to your speakers, so it doesn't offer as dramatic a sonic improvement as bi-amping. Still, many audiophiles find that it offers subtle improvements in imaging and detail.So since the 80's are the top of the line Axiom speaker, do they have a high and low pass design, or passive? If they are setup with a high and low pass crossover design, they should be able to be "truely" bi amped. I also talked to JC at Axiom tonight and he said if you have seperate monoblock amps that are 300 watts each, you would then be providing the 80's 600 watts, not 300watts like many of you have said would happen?
Thanks, Randy
I used the search function and could not find anything in regards to the 80's, however, I did find this statement by Alan in regards to the 60's.
I agree that in the M60s, it's a low-pass filter to the woofers, a high-pass to the midrange (above 200 Hz), and then another high-pass to the tweeter for frequencies at 2 kHz and higher.
So, I can only assume the 80's have a similar design. With that said, I'm thinking they can "truely" be "bi-amped" using 2 seperate monoblock amps (not multi channel), 2 seperate speaker wires, and removing the gold strap on the speaker terminals? And, you would be "truely" dedicating 300 watts to the woofers, and 300 to the mid/highs?
Thanks, Randy
No Randy, the requirement for "true" biamping(which might be of no worthwhile benefit anyway)is that there has to be an external crossover ahead of the amplifiers(as shown in that schematic)and any internal speaker crossover(dividing the amps' output in the same frequencies)has to be removed or bypassed. Also, that quoted material contains a liberal serving of drivel.
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So since the 80's are the top of the line Axiom speaker, do they have a high and low pass design, or passive? If they are setup with a high and low pass crossover design, they should be able to be "truely" bi amped. I also talked to JC at Axiom tonight and he said if you have seperate monoblock amps that are 300 watts each, you would then be providing the 80's 600 watts, not 300watts like many of you have said would happen?
Randy,
Page 2 of the manual is very clear. Based on the description in the manual, I would expect the 80s to have two passive cross-overs: one for the bass drivers and one for the mids and tweeters. These are effectively connected in parallel when using a single amp and disconnected from each other when the bridging bars are removed for bi-amping.
You really do need to contact Axiom about power handling however. The 80s are rated to 400W RMS continuous. How exactly this is divided between the drivers when bi-amping is not clear. I know that Axiom claims to drive these at 700W but will Axiom warrant them at these levels? And if so, the question still stands, how is this power divided amongst the drivers? And what exactly is the impedance of each section (I would expect 12 Ohms for the mids and tweeters and 6 Ohms for the woofers; which would translate to 133W for the mids and tweeters section and 267W for the woofers).
So I guess you are considering two MPS-1s 
?
And if you did feed 300W into each, the total would be 600W. Just make sure Axiom is willing to warrant this.
The mids and tweeters should handle less power than the woofers. In two-way prosound active speakers you typically see 300 - 400 watts provided to the woofer and 100 watts to the tweeter/horn. 300 to the mids and tweeters seems like alot.
You could run the mids and highs off of your Denon and the lows off the MPS-1 the passive crossovers in the M80's will protect the drivers from unwanted frequencies, But both amplifiers will waste energy amplifying the whole frequency range which the passive crossovers in the M80's will dissapate as heat. Not as efficient as an active crossover system which prevents the amplifier from wasting power on frequencies that are not used by removing them before the amplifier.
Hi all, MoJo is correct in that the manual states how to bi-amp and mentions nothing of external x-overs. The reason they include the dual binding posts is because of the speakers abilty to be bi-amped in this manner without any external devices.
When you bi-amp you are still ONLY running 300wpc (in this case) into each section of the speaker, i.e. tweeters, mids, woofers. You are in effect increasing power overall but not in each section as it were. 300 wpc into the bass section is 300wpc not 600.
Next point, speakers that are rated at 400wpc are in no way limited to this size of amp, in fact most companies will tell you the more power the better. One is far more likely to damage speakers by trying to drive them too loud with a small or under rated amp and clipping the amp which really frys speakers in a hurry. This is why I cringe when I see folks on here telling people"yeah that receiver will drive those 80's no problem" this is ill advised for MOST Avr's. I agree there are exceptions but they are limted. There is currently posts here dealing with this exact problem and is forever an ongoing issue with the uninitiated.
NOTE: if your speakers make popping, rattling, or are making distorted type noises, they are telling you...hey dummy! turn that amp down I'm hurting over here. Unless you are deaf its unmistakeable when a speakers is in severe ditsress. However, soft clip may be much harder to detect to the untrained ear and this is why good amps have protection circuitry, to protect your speakers!
Randy, I would go ahead and try bi-amping, its not possible to hurt your speakers in this manner and as I said last week I think it will really boost your output, just try one speaker even and see what happens, you have the amps in your cage already. Good luck.
These are all my opinions only of course and are from what I have learned in 31 years of serious audio gear playing.
Regards, Chris
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This is why I cringe when I see folks on here telling people"yeah that receiver will drive those 80's no problem" this is ill advised for MOST Avr's.
I agree and maybe we should be qualifying these kinds of statements with quantitative results based on our own experience. Something like "My room is 4000 cubic feet, very live, I sit 8 feet away from my M80s and during music I achieve an SPL of 80 dB with less than one watt input per channel using the Denon AVR2105 which is rated a clean 90W into 8 Ohms.".
When we say "XYZ receiver will drive M80s no problem" we mean "the receiver will not artificially shut down at low output levels when driving 4 ohm speakers because of protection circuitry or overheating", not "the reciever will drive the M80s to their full potential".
There are a number of receivers out there which seem to run into problems at *lower* SPLs with M80s than they would with M60s or another good 8 ohm speaker. Those are the ones we try to steer people away from...
I guess we could make this more clear, and probably should.
I guess I am left wondering why you would want to do this in the first place?
I can't imagine driving the 80s with the power that some suggest on this thread. I would probably destroy my ears! LOL!!!
Not sure how big your room is Rat, but you need to keep in mind as I've told others, my room is 8,000 cubic feet. 100dB from 12ft away in my room which is moderately loud, would kill someone in a smaller room.
Randy 100db is 100db no matter the size of the room. It's like going 100mph, it doesn't matter what car it is.
Yes, but it takes more power to achieve the same SPL in a larger room.
Say Randy's amps and speakers are playing at 100dB in his room. If you move them to a smaller room and leave the levels the same, it will sound louder.
No, it will sound quieter because the speakers will be in another room :rimshot:
I think that there is a little confusion going on with this thread. In general (neglecting reflections, etc.), the sound level falls off as the square of the distance from the speaker. So, 100 dB at 5 feet is 100 dB at 5 feet. Now, if you are at the back of the room at 10 feet versus the back of the room at 15 feet, you would need more power for the same effective sound level.
My current TV room is at least 6400 sq ft and I sit about 13 ft from the TV and front speakers. Anything above 90 dB SPL is TOO LOUD for me. But, that is just me.
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In general (neglecting reflections, etc.), the sound level falls off as the square of the distance from the speaker.
You're correct if you are referring to sound intensity (watts/square meter). The sound pressure however is inversely proportional to the distance...not the square of the distance.
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My current TV room is at least 6400 sq ft
Dang! 30 of my living rooms would fit in there.
>>Dang! 30 of my living rooms would fit in there.
Second that. Even in the worst "medieval castle" stages of planning the new house the great room didn't get that big.
We may be talking cubic feet here, or we may have found the perfect host for the next Axiom get-together (GTG).
Of course, if a reasonably accurate estimate of power required for a given sound level is to be made, "reflections, etc" shouldn't be neglected, since they significantly add to the sound level and reduce the calculated power required(compared to the simple 6dB loss per doubling of distance assumption). Methods of calculating this differ, but about a year ago when a lengthy power analysis was made here by Gena et al, I cited Linkwitz, especially
this section , showing a method and example of how to take into account room factors.