When customizing Axiom speakers, you have a section titled "Audio Jewelry", with two options
1. Standard or Die Cast woofers
2. Standard or Biwire/Biamp inputs
On most tower speakers nowadays, biwire inputs are quite standard it seems. Why is it only an option? And why under a section called "Audio Jewelry"? Are they saying these two options provided are for aesthetics only?
I've been doing some reading on bi-wiring and have read SOME articles claiming that to "truly" biwire/biamp, the crossover must be removed or modified or something?
If I bought M80's with dual inputs, wouldn't feeding them 120 watts down one speaker wire and 120 watts down the other mean I'm feeding the speaker a total of 240 watts? As opposed to single input...then I'd only be feeding them 120 watts total.
Just looking for clarification and opinions. Thanks again
I do preffer the appearance of the cast over the stamped basket.
I've read it doesn't make a differnce with audio quality and I can't say either way.
Theres no doubt in my mind that the cost of going cast is worth it.
I consider my speakers an investment, one that should look as good as it sounds.
Take the hint that the title of that section is giving us: neither of the options results in an audible improvement and they're there to satisfy the misconceptions of the misinformed/uninformed. Andrew touched on the stamped/cast frame point
here .
On the inputs, you can't "feed" a speaker any more power than it needs at any given instant in time to play at the needed volume level(typically about 1 watt at a comfortably loud average level). The maximum needed on a brief peak is much more, of course, but the capacity of the amplifier's power supply section is the limiting factor, and feeding that same supply through two wires rather than one can't double the max available or increase it in any amount.
In the day's of yore, bi-amping was common. True bi-amping would mean a separate and dedicated amplifier for the lower bass frequencies and another for the tweeters and mids. The tweeter's and mids use much less power than the woofers to produce similar perceived volume levels. When you order the bi-amp option there is a connector between the 2 sets of speaker posts , these are removed when you are bi-amping , thus nothing is needed to be done to the crossover as it has already had the Mid/tweets separated from the bass portion of the crossover. These days most people use a subwoofer with a dedicated amp , and as such the requirement put on your main amp is much relieved , making bi-amping pointless and expensive. The guys out there who say interconnects and speaker wire make a difference are going to disagree with this position, so I guess what matters is which camp you are in.
As for cast baskets, Ian has done extensive testing and has proven to his satisfaction that cast baskets are not necessary and are eye candy. I personally believe that small drivers do not benefit from cast baskets but large bass drives do. I think there may be a small advantage in heat dissipation but have no way to prove it. All my car audio subs that I buy have cast baskets based on my preference'.
k thanks guys. All great info
john: I ready that full thread months before I created an account. Quite a troll fest going on in that one. lol Thanks again though for linking me to it.
I was most likely just going to go with standard options, but wanted to make sure before I make my final order.
I also like the detail on the cast which confirm the manufaturer as being "axiom".
I'd compare it to purchasing a new vehicle with steel rims.
Lightweight, alloy wheels are actually a performance enhancement to a vehicle. Provided, that is, they are actually lighter (going from a 17" steel wheel to a 20" alloy probably isn't going to help). When removing weight from a car unsprung, rotating mass (tires, wheels, brake discs*) offers the most improvement for the least decrease.
*Some high performance cars move the brake disc "inboard", that is they sit on the sprung side of the suspension, and use the axles to slow the wheel rather than being bolted directly to it.
Lightweight, alloy wheels are actually a performance enhancement to a vehicle.
this is very true, in fact when building a track car this is one of the first changes that are made to a stock car, as it is the easiest thing to do to get perceived horsepower back... Then, you strip the interior. However, reducing rotating mass has a multiplier of 3 over what a static load is.. But then again, an average interior weights about 3-400lbs...
Oh, wait... This isn't the race car forum... Crap... Oh well...... :~)
I got cast drivers in my LFR's because i wanted them, and they weren't that expensive to add... Even though from a material science point of view, there is no difference. The more folds you put in a sheet of metal the more ridged it becomes, and a combination of the thickness of the initial metal used as well as the number of bends/radius/location will determine the final rigidity of the manufactured piece.
Since Axiom uses a relatively thick piece of sheet metal to begin the process with that is a wonderful starting point, then they press the piece which has multiple folds to add rigidity.. Oh, wait... I'm rambling again....
Both options are only good for re-sale to those who think they make a difference. Audio gear is anything but an investment unless you are buying McIntosh electronics - which are often collected.
If I had it to do over I'd have went with the dual imputs on my m80's.Beause the amp I am using is rated 340 watts into 4 ohms with dynamic power of 640 watts at the same 4 ohm impedance and 850 watts dynamic into 2 ohms, I felt I didn't need it.the dual imputs would have provided me with down the road amplification options.
For my thinking a perfect driver basket would have absolute rigidity and be totally transparent to airflow.Nobody's building it.Haven't seen a lot of driver baskets, but the one that really got my attention was was the oval driver on the polk lsim.I've got steel baskets in my speakers.Like was previously mentioned the sonic benifits of the upgrade for these speakers aren't there, unless you are pushing them right to the edge.
Both options are only good for re-sale to those who think they make a difference. Audio gear is anything but an investment unless you are buying McIntosh electronics - which are often collected.
While I agree in this application cast baskets are only different in appearance its the difference I consider to be the investment.
Put 2 M80's side by side. One with cast baskets one with stamped. Now pick one...oh wait that ones a few bucks more....but...I want it. It looks cool and I feel slightly happier with them than I would otherwise.
I don't get the opposition. I couldn't justify spending the $1500 without them looking as good as possible.
Just my opinion.
Can you even tell from the outside?
Covers off, yes.
Worth the consideration before forking over $1500, yes.
Didn't realize that. That's something, at least.
If I had it to do over I'd have went with the dual imputs on my m80's.Beause the amp I am using is rated 340 watts into 4 ohms with dynamic power of 640 watts at the same 4 ohm impedance and 850 watts dynamic into 2 ohms, I felt I didn't need it.the dual imputs would have provided me with down the road amplification options.
But john said:
The maximum needed on a brief peak is much more, of course, but the capacity of the amplifier's power supply section is the limiting factor, and feeding that same supply through two wires rather than one can't double the max available or increase it in any amount.
I'm confused now...mikesk, do you mean you wish you had them so you could do bi-amping(not bi-wiring)?
Biamping still doesn't double the power.
Biamping still doesn't double the power.
ok, so without trying to step on anyone's toes, is his above statement uninformed then?
can anyone find a picture of the M80's with diecast vs standard? I'd like to see the difference with grilles off
Yes I was thinking in terms of a future bi amp setup.On a dual input setup if you pull those gold straps out you should effectively be splitting the speaker into 2separate top and bottom speakers.If it doesn't then what is the point of them?It should also raise your impedance on both top and bottom to the point of allowing a couple of amps that want to start to clip the minute you drop the load below 8 ohms to drive them quite nicely.
Can you even tell from the outside?
Ken, the cast baskets look completely different from the exterior. Since they are cast from a form, they "look" more more stout than the regular ones. Steve posted some photos in the LFR thread of the differences.. The cast ones do look much better, in my opinion.
Yes I was thinking in terms of a future bi amp setup.On a dual input setup if you pull those gold straps out you should effectively be splitting the speaker into 2separate top and bottom speakers.If it doesn't then what is the point of them?It should also raise your impedance on both top and bottom to the point of allowing a couple of amps that want to start to clip the minute you drop the load below 8 ohms to drive them quite nicely.
as I'm being told, and from what I'm reading on it so far, the point of them is exactly nothing. The point of them is to please the misinformed/uninformed. Hence Axioms term for it "audio jewelry".
I'm not really informed on this subject myself, just been reading lots on it the past couple days.
Even if it "technically" does make a difference, it doesn't sonically make a difference in double blind listening tests. This is what I've gathered so far.
Steve posted some photos in the LFR thread of the differences.
I have searched the forums for the last hour. the search engine sucks by the way. lol
Can you link me to it?
So, you want me to share in your misery eh????
Yeah, give me a bit of time, to see if i can find it :~)
So, you want me to share in your misery eh????
Yeah, give me a bit of time, to see if i can find it :~)
haha thanks man
I'm still searching too. lol
edit: since the only difference is appearance, maybe in the audio jewelry section(or somewhere) axiom could post a side by side picture, grilles off, of the two options?
I'm trying to figure out photobucket.
Use the IMG code instead....
I have a set of rti 10's with dual inputs and have pulled them out before to see how they subsequently hook into the crossover network.The bottom inputs go to the circuit board that handles the bottom end speakers and the top inputs go topside.Actually axiom mistakenly sent me a dual input manual with my m80's and reading between the lines if you pull the bridgeing bars you are effectively separating the top half of the speaker from the bottom half, that can then be powered with 2 separate power amps.Now if you have 2 amps each putting out 120 watts/ch it adds up to 240 going into the speaker in a bi or 2amp configuration.In a biamp configuration the axiom manual tells you to set the gain of each amp equal unless you want to alter the spectral balance, essentially saying the top and bottom of the speaker are now totally separated.So in a true biamp configuration you are splitting the speaker in half electronically and feeding the top and bottom half from 2 different amps. Hope this makes sense.
Thanks for posting these pics. That logo cast into the frame is a nice touch.In regards to cast vs stamped baskets one of the questions I asked Brent was if they were altering any of the cap values in the crossover when they put the cast basketed drivers in the m80...His answer was no so I went with the steel.
Thanks for posting these pics. That logo cast into the frame is a nice touch.In regards to cast vs stamped baskets one of the questions I asked Brent was if they were altering any of the cap values in the crossover when they put the cast basketed drivers in the m80...His answer was no so I went with the steel.
Yeah, I like the logo as well. I think im goimg to go with it. I always get nervous of altering anything from factory stock tho
Now if you have 2 amps each putting out 120 watts/ch it adds up to 240 going into the speaker in a bi or 2amp configuration.
Being a pedant, I must point out that in this configuration you now have 240 amp
available to the speaker. You need to turn it up to 11 to draw all 240 amps.
OTOH. If you buy an amp capable of delivering 240 watts per channel and hook it up in a non-biamped configuration, you are in exactly the same position. You can deliver 240 amps when you turn it up to 11. Put your earplugs in first (unless this is outside on a dock and you are sitting 40+ feet from the speakers
).
PS: if I were a true pedant, I'd point out that 240 watts at the amp will not turn into 240 watts at the speakers, but that's a whole other conversation.
Now if you have 2 amps each putting out 120 watts/ch it adds up to 240 going into the speaker in a bi or 2amp configuration.
Being a pedant, I must point out that in this configuration you now have 240 amp
available to the speaker. You need to turn it up to 11 to draw all 240 amps.
OTOH. If you buy an amp capable of delivering 240 watts per channel and hook it up in a non-biamped configuration, you are in exactly the same position. You can deliver 240 amps when you turn it up to 11. Put your earplugs in first (unless this is outside on a dock and you are sitting 40+ feet from the speakers
).
PS: if I were a true pedant, I'd point out that 240 watts at the amp will not turn into 240 watts at the speakers, but that's a whole other conversation.
You are correct.Thought my wordyness was already getting into too much detail.
Thanks for the pics.
We've fought this biamping fight so many times now. If you tried to put 120W (or even probably 60W) into a tweeter, you'd have a very small smoking lump of metal.
Being a pedant, I must point out that in this configuration you now have 240 amp available to the speaker. You need to turn it up to 11 to draw all 240 amps.
I just wanted to point out, the difference between watts and amps... Normal residential houses only have about 100 amp service... And that is for the ENTIRE house.... @ 120 volts, 240 watts will use 2 amps...
Below is a calculator to determine what is being used... I used 120 volts because that is wall outlet voltage in north america.
http://www.supercircuits.com/resources/tools/volts-watts-amps-converterMy 1200 watt amp only draws 10-15 amps at most, and hasn't yet as i hasn't tripped its 15amp breaker, yet...
Any 2-way(or more)speaker has the high and low frequency sections separated at the latest when the signals enter the crossover. Using dual inputs with the connecting bar removed, the separation point is simply moved back from inside the enclosure to the output terminals of the receiver. This makes no electrical difference as to impedance or anything else of significance.
If two 120 watt amplifiers are connected to separate sections of a speaker, the maximum available to either section is 120 watts, not 240 watts.
yeah, i've been sold. I'm going to stick with single inputs on the axiom's when I order. I'll be giving them more then enough available power as well.
Just extra parts, the extra gold bracket, that could potentially screw up or go missing
Any 2-way(or more)speaker has the high and low frequency sections separated at the latest when the signals enter the crossover. Using dual inputs with the connecting bar removed, the separation point is simply moved back from inside the enclosure to the output terminals of the receiver. This makes no electrical difference as to impedance or anything else of significance.
If two 120 watt amplifiers are connected to separate sections of a speaker, the maximum available to either section is 120 watts, not 240 watts.
See!! this stuff is so confusing. Far better to stick to one amp, plug it in, turn to 11, enjoy.
But, what about tri-amping?
But, what about tri-amping?
Bi-, or bi- not. There is no tri-.
It looks like the dragon thing is eating the horsey thing.
I like the idea that the dragon tried to eat a unicorn and its horn is protruding through the skull of the dragon...
and thus the last dragon and the last unicorn lived happily ever after...
Any 2-way(or more)speaker has the high and low frequency sections separated at the latest when the signals enter the crossover. Using dual inputs with the connecting bar removed, the separation point is simply moved back from inside the enclosure to the output terminals of the receiver. This makes no electrical difference as to impedance or anything else of significance.
If two 120 watt amplifiers are connected to separate sections of a speaker, the maximum available to either section is 120 watts, not 240 watts.
So help me out here...If I chose to power the top and bottom of my m80's with 2 separate amps I couldn't change or wouldn't change the low frequency low impedance line as it shows on the graph?When I read somehwere that impedance was a function of the number of drivers I made an assumption I could alter it by separating them in a bi amp configuration.Now with what yu are saying it looks to me that it is being set/controlled in the crossover itself.
Why would you want to alter the impedance of your speakers?
If you were convinced that bi-amping makes a difference, wouldn't you necessarily need to connect both sections to an amplifier with exactly the same amount of gain?
Fred i dont think he wants to alter the impedence. Impedance is the sum of all connected parts. If only the tweeter's ,mids and associated crossover parts are seperated from the woofers ,the overall impedance seen by the amplifier would change.If someone was to run 2 wires from the same amp ,the impedance seen by the amp would remain unchanged. I will run some impedance sweeps on my M80's tonite and see what the difference is.
As can be seen here,takeing out the bridgeing would result in two seperate crossovers.
Fred i dont think he wants to alter the impedence. Impedance is the sum of all connected parts. If only the tweeter's ,mids and associated crossover parts are seperated from the woofers ,the overall impedance seen by the amplifier would change.If someone was to run 2 wires from the same amp ,the impedance seen by the amp would remain unchanged. I will run some impedance sweeps on my M80's tonite and see what the difference is.
As can be seen here,takeing out the bridgeing would result in two seperate crossovers.
Yes this is what I am getting at.
Go
HERE and read what Kal Rubinson has to say. He basically says no , impedance should not change. I plan to run some impedance sweeps on my M80's hopefully tonight depending on whether I can get near them. Kids watching tv atm.
Mike, I thought that my brief previous reply was adequate to point out the principles involved, but I'll go into greater detail to help out more. Yes, as you question, the impedance is partly the result of the crossover circuitry, not the impedance or number of the individual drivers alone. When loads(such as speaker drivers)are connected in parallel the combined impedance is such that its reciprocal is equal to the sum of the reciprocals of the impedances of the individual drivers. So, if an 8 ohm mid-woofer and and an 8 ohm tweeter were simply connected in parallel without intervening crossover circuitry, the combined impedance would in fact be 1/X=1/8+1/8, 1/X=2/8, 2X=8, X=4(ohms). The crossover circuitry changes this, however. For example, on a bass frequency the impedance of the low frequency section of the crossover would be 8 ohms, but the capacitor and other components in the high frequency section would make the impedance the amplifier "sees" there for bass frequencies far higher than 8 ohms. For a relatively simple calculation, say that the impedance of the high frequency crossover section on the bass note is 160 rather than 8 ohms. The resultant combined impedance would be 1/X=1/8+1/160, 1/X=21/160, 21X=160, X=7.6(ohms). The point therefore is that a 4 ohm speaker impedance isn't the result of two 8 ohm drivers connected in parallel.
The other point previously mentioned is that the high and low frequency sections of the crossover are always separate. They have to be or they couldn't send the separate frequency ranges to the low and high frequency drivers. This is the case regardless of whether the speaker inputs are single or dual, or if dual, regardless of whether the connecting link is or isn't removed. As was pointed out previously the only difference(when removed)is that the wiring separates at the receiver output rather than inside the enclosure.
John, I will admit I don't know all the fancy formula's since I hold no electronics degree of any sort, though I do mess around a bit building speakers and crossovers. I purchased a Dayton Audio test system, with this, I can take many measurements of raw drivers etc. It also allows me to take an impedance frequency sweep . I took 3 different sweeps, one of the tweeter/mids, one of the woofers and another of all the drivers. I include a screen shot of all three purely for reference purposes.
Sorry you may have to save the pic and open it with paint. Its a screen capture.
It seems clear to me that 2 separate amplifiers will each see an entirely different impedance when bi-amped (bars removed) than will be seen by a single amp (jumper bar in) .
None of this really matters imho since bi-amping or bi-wireing passively is for all intents and purposes of no use.
john, the load would not be a constat 8ohms. you are using dc equations to explain an AC circuit... your freely interchanging resistance and impedance. resistance is a term used to explain DC circuits, impedance is used for AC circuits. the impedance will change, as it is a function of frequency within a curcuit. this is the whole reason mafacturers publish impedance graphs, to show the impedance across a range of frequencies.. the "nominal" or reported impedance is what the resistance is at a constant voltage. as the frequency changes, the voltage changes, both in volts and in vectors.. it becomes a 3 dimentional eqn, where the equns your using are 2d eqns that are used for DC circuit analysis....
i'm on my phone, so i am not going to google ac voltage eqns... Also, please forgive any typos, as i'm on my phone...
I found a better way of displaying my graph's for anyone who is interested.
The bottom graph is Axiom's impedance curve and it is virtually identical to the impedance graph that I generated.
Once the jumpers were removed from the speakers, I measured the impedance of the tweeter/mids and the woofers. The impedance changed dramatically once the the crossover was separated.
Sunfire amps have some interesting feature's for bi-amping. They allow you to bi-amp using either current or voltage depending on speakers and configuration. Using one of their 7 channel amps you can run it 5 channel and use the extra 2 channel to bi-amp. Each amp channel has 2 inputs so you can jump one amp channel to another with a simple patch cord.
Cary Audio has some interesting insight to bi-amping as well.
the impedance changed dramatically once the the crossover was separated.
So from a technical standpoint it makes a difference?
There seems to be quite a split group on this.
My dad has Cerwin Vega XLS 215's and his Pioneer Elite 57 has a biamp/bi wire configuration. I believe you hook one speaker wire into the front main and another into the front height on the back of the amp. Then he has to go into the amp's menu and switch it to "biamp/biwire" mode. You can hear something in the amp click over.
I haven't had a chance to directly compare, but he swears there is a difference, but only at very high levels. My dad and me like to sometimes partake in hearing damage levels. lol Again, he says it's only noticeable at those very high levels.
Lots of opinions all over the net, some pooh pooh it while other praise it. I suggest you read the article linked at carey audio, it very informative then you can form your own opinion and decide if it is something worth trying. I don't have the coin to try it though I may do so one day since the M80's have the feature. A 7 channel sunfire amp is 3500 so that's a no go lol. Maybe another Emo 2 channel .
Still with using a powered sub to do the heavy lifting I am on the fence whether it would be beneficial.
Alex, the point wasn't that the impedance would be a constant 8 ohms. A previous post appeared to suggest that a 4 ohm speaker was the result of two 8 ohm drivers connected in parallel, and that separating the wires in the manner described would increase the speaker impedance substantially above 4 ohms. It's certainly recognized that impedance isn't a constant and varies widely with frequency.
The purpose of the simplified calculations was to show the effect of the crossover circuitry on the impedance. The formula used is the basic one for calculating impedances in parallel. An 8 ohm impedance(without the crossover effect)for both drivers was selected for convenience and familiarity, not because it was a fixed value. The well-known effect of the crossover circuitry to increase the "seen" impedance of the driver not playing the particular frequency by a very large amount results in the speaker impedance(at that particular test frequency)being just slightly lower, not cut in half(two 8 ohm drivers forming a 4 ohm speaker).
the impedance changed dramatically once the the crossover was separated.
So from a technical standpoint it makes a difference?
No, it doesn't.. All an amp is, is a voltage source.... The speakers are the load... If you have an amp that is designed to be a constant voltage source, then as the impedance halves the output power doubles.
If you look at the large Krells, or Mark levensons they double in power down to .5ohms.. some even lower than that..
By Bi amping, you can buy two less powerful amps than buying one large amp.. Granted this is not the most efficient way..
A prime example of this is the Bryston Model T's as they are designed to be Tri-amped.. Each different set of speakers requires a different amp. James most likely did this because he wanted to use an active cross over to have maximum control over the frequency curves. This is slightly different than the conversation in this thread, but still loosely applicable.
First off a big thankyou to all axiomites for their inputs on this bi amping principle. I am learning a lot, and have cleared up one point of inaccuracy in my thinking as a result.My hypothetical thinking in terms of trying to do a biamp on the m80 was to do with an idea surrounding any vintage type super clean amp whose distortion characteristics went postal the minute the the resistance load dropped below 8 ohms at any point on the frrequency spectrum.If the m80's impedance vs frequency sweeps with the top and bottom of the m80 separated raised the lowest impedance above the 8 ohm threshold then get an identical amp and do a biamp,giving each amp a load it can comfortably handle.
I found a better way of displaying my graph's for anyone who is interested.
The bottom graph is Axiom's impedance curve and it is virtually identical to the impedance graph that I generated.
Once the jumpers were removed from the speakers, I measured the impedance of the tweeter/mids and the woofers. The impedance changed dramatically once the the crossover was separated.
Sunfire amps have some interesting feature's for bi-amping. They allow you to bi-amp using either current or voltage depending on speakers and configuration. Using one of their 7 channel amps you can run it 5 channel and use the extra 2 channel to bi-amp. Each amp channel has 2 inputs so you can jump one amp channel to another with a simple patch cord.
Cary Audio has some interesting insight to bi-amping as well.
And I just got done looking at these graphs my idea is a no go.The 2 woofers in paralell with the crossover setup just put the impedance too low.Thankyou rof giong to the trouble of doing this...I can't believe by brain told my fingers to type rof instead of for.Looks like there is somethng screwy going on in MY crossover.
Alex, the point wasn't that the impedance would be a constant 8 ohms. A previous post appeared to suggest that a 4 ohm speaker was the result of two 8 ohm drivers connected in parallel, and that separating the wires in the manner described would increase the speaker impedance substantially above 4 ohms. It's certainly recognized that impedance isn't a constant and varies widely with frequency.
The purpose of the simplified calculations was to show the effect of the crossover circuitry on the impedance. The formula used is the basic one for calculating impedances in parallel. An 8 ohm impedance(without the crossover effect)for both drivers was selected for convenience and familiarity, not because it was a fixed value. The well-known effect of the crossover circuitry to increase the "seen" impedance of the driver not playing the particular frequency by a very large amount results in the speaker impedance(at that particular test frequency)being just slightly lower, not cut in half(two 8 ohm drivers forming a 4 ohm speaker).
ah, gotya.
So a question I have to ask...
whether it makes a difference or not...if I had the extra money to blow on putting the feature on the speakers, does it effect the integrity of the speaker in any way? I mean, stock they come without, so getting axiom to add it, is it a big deal?
And say I have dual inputs but never use it, is there any loss of quality or performance(putting my trust in making sure there is tight connection on the jumper bars)?
If you didn't know it was there you would never have known that it was there. Get it for the what if scenario. I doesn't hurt anything by having it.
So a question I have to ask...
whether it makes a difference or not...if I had the extra money to blow on putting the feature on the speakers, does it effect the integrity of the speaker in any way? I mean, stock they come without, so getting axiom to add it, is it a big deal?
And say I have dual inputs but never use it, is there any loss of quality or performance(putting my trust in making sure there is tight connection on the jumper bars)?
the answer to both questions is, it wont make any difference... both from a materials point of view, as well as an electrical point of view. You will never hear the difference for any of the options you have asked about... Now, if you want them because you do.. Well, that is a different question, which isn't really a question...
Thanks for all the great responses axiomites!
Ive got a bit of extra money I can blow...since it wont effect the integrity or performance having dual inputs...im goimg to order the feauture just because I can :p
Remember, too, that you don't even see the feature unless the back of your speakers are visible.
Mike, you appear to have a concern about lower speaker impedance that isn't justified by either principles of audio technology or real world experience. There's no brick wall that amplifiers run into when speaker impedance drops below some critical number. As Alex(dakkon)pointed out, amplifiers output voltage. When the voltage meets an impedance in the speaker, a certain current results(following Ohm's Law)and the product of the voltage and current is power in watts used. As the impedance gets lower with a given voltage output from the amplifier, the current gets higher and the heating effect on the amplifier increases. If this heating effect was high enough and continued long enough, the protective circuits in the amplifier would shut it down until it cooled. This just doesn't happen with typical quality receivers in the 100-150 watt range and they have no problem with M80s(as many of our members have reported)or similar speakers operating at safe(to your hearing)sound levels. As an extreme example for your information and/or amusement, I'll cite Mojo's heroic surgery done on the 2 watt amplifier in his wife's Sony boombox and resulting M80 blind listening results
here .
You also seem to have partially misinterpreted Richard's(Socketman)measurement results. There's no increase in M80 impedance with the top and bottom inputs separated by removing the connecting links. As I noted previously, the high and low frequency sections of the crossover always have to be separate for there to be a crossover. The graphs in Richard's fine measurements simply are showing the different driver combinations which are being measured through the separated top and bottom terminals, with the big impedance increase a little over 2KHz reflecting the tweeter crossover(the Axiom spec is 2.3KHz) and the impedance hike above 100Hz reflecting the woofer crossover(160Hz Axiom spec). This is the way the M80 crossover works and removing the connecting links can't change it. The graphs would be the same with the links still on if the measurements were made inside the enclosure at the beginning of the crossover circuitry where the wiring normally splits for the separate crossover sections.
Mike, you appear to have a concern about lower speaker impedance that isn't justified by either principles of audio technology or real world experience. There's no brick wall that amplifiers run into when speaker impedance drops below some critical number. As Alex(dakkon)pointed out, amplifiers output voltage. When the voltage meets an impedance in the speaker, a certain current results(following Ohm's Law)and the product of the voltage and current is power in watts used. As the impedance gets lower with a given voltage output from the amplifier, the current gets higher and the heating effect on the amplifier increases. If this heating effect was high enough and continued long enough, the protective circuits in the amplifier would shut it down until it cooled. This just doesn't happen with typical quality receivers in the 100-150 watt range and they have no problem with M80s(as many of our members have reported)or similar speakers operating at safe(to your hearing)sound levels. As an extreme example for your information and/or amusement, I'll cite Mojo's heroic surgery done on the 2 watt amplifier in his wife's Sony boombox and resulting M80 blind listening results
here .
You also seem to have partially misinterpreted Richard's(Socketman)measurement results. There's no increase in M80 impedance with the top and bottom inputs separated by removing the connecting links. As I noted previously, the high and low frequency sections of the crossover always have to be separate for there to be a crossover. The graphs in Richard's fine measurements simply are showing the different driver combinations which are being measured through the separated top and bottom terminals, with the big impedance increase a little over 2KHz reflecting the tweeter crossover(the Axiom spec is 2.3KHz) and the impedance hike above 100Hz reflecting the woofer crossover(160Hz Axiom spec). This is the way the M80 crossover works and removing the connecting links can't change it. The graphs would be the same with the links still on if the measurements were made inside the enclosure at the beginning of the crossover circuitry where the wiring normally splits for the separate crossover sections.
John I hole heartedly agree. Most if not all quality modern receivers will have no trouble drivining the m80.My Pondering revolved around a vintage yamaha amp refered to as the m70 rated at 200watts into 8 ohms 20hz to 20khz freq. that clips at 250 watts 1khz 4 ohms. A very different amp then say the m80 which has dynamic power to 640 watts 4 ohms.The m70 still has lots of power but is limited compared to its newer brother. Anyway, all my ideas are a bust but it is good to aquire accurate knowledgeWhen you talked about the high frequency part of the crossover network having influence over the low frequency resistance that the amp sees I kinda knew my biamping ideas were shot.(if I read what you said correctly in your previous post)Answer me this so i get it right.Does the high frequency section of the crossover raise or lower the low freq.resistance the amp sees?
Ok you don't have to bother I just reread the earlier post and got the answer.Thankyou for your insights.
Ive got a bit of extra money I can blow...
i got a 4&6 letter word and a for you then man....
Gold & Silver.....
Investments first... Then spend cash on something that will not net a return.....
*End responsible advice.....*
I had a random thought this morning. There is no point in bi-amping if a person like myself uses a sub or multiples there of. All frequencies typically below 80hz are routed to your sub. Even for 2 channel, I like lots of bass and I use the sub for that duty and set my receiver to LFE+Main. So really no need for bi-amp except pure direct mode 2 channel.
