Amplifier stability with very low impedance, high efficiency mid/tweeter section???
I've been looking for this information everywhere but can't seem to find a clear cut answer. I understand that a very low minimum impedance like 2Ohms is a very difficult task for most amplifiers to drive and may even damage it. But it's also my understanding that this is a current, not a voltage problem. In other words, say we had an MTM speaker that was used ONLY as a midrange from 200hz up, so it wouldn't have to play bass where most current is required. And say it also has a very high efficiency of 97db but also a very low impedance of 2 ohms. Would this be a problem for most amps? Could it damage the speakers? I'm thinking no since the amplifier wouldn't have to put out much voltage or current to output sufficient SPL. But what's the actual answer????
Yeah, but that's wiht a simulated 4 Ohm speaker. :) Lower speaker impedance = more fluctuation. I'm not saying it will be unbearable. Just explaining how a more robust amp with a lower output impedance would behave. In some cases the interaction could be euphonic. |
@erik_squires You might want to leave ESLs out of this since they are not 'voltage driven' loudspeakers, unlike most box speakers. Their efficiency is not mapped by their impedance curve. So you need the same amount of power at 10KHz as you do at 100Hz to obtain the same sound pressure- and these two frequencies will be very different impedances! If you put an amp that acts as a voltage source on a speaker like that it will tend to be bright and lack bass impact as a result. There are exceptions- for example the Sound Lab ESLs have controls and switches on the back to allow you to address this problem. @poseidon1500 There is not an amplifier made that will be harmed by the low impedance of your midrange/tweeter array. But there is a different issue which you might want to take into account! All amplifiers make greater distortion into lower impedances. In addition, the ear uses higher ordered harmonics to sense sound pressure and so is keenly sensitive to their presence either natural or generated by amplifier distortion. It interprets them as 'bright and harsh'. To complicate matters the ear has its greatest sensitivity at higher frequencies: between about 4-7KHz. This sensitivity is often called the 'Fletcher-Munson curve'. Something to keep in mind is that if you have an amp that can double power as impedance is halved (IOW, acts as a voltage source), harmonics of the bass notes will be audible coming from the high frequency array. This will contribute to brightness. Of course this will always be the case, the problem is that with many amplifiers as frequency is increased, there is a certain point where the feedback falls off inside the audio band. This causes the amp to make more distortion and this is very likely at or near the frequencies your MTM array is operating. If you are planning a conventional solid state amp this really sounds to me like a recipe for brightness and harshness. If it were me I would insist on auditioning the speaker and amplifier combo in your home!
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My answer you found humorous was funny yes but intended to make a point and get you thinking. I mean actually really thinking not bandying words about which is all that is going on now. No progress being made towards answering your question, which except for one detail was pretty well thought out. The "for example" you are talking about, a MTM array used 200Hz and up, is of course what Tekton does. If you want to make this a guessing game going round and round nobody ever really getting anywhere because nobody really knows what you’re talking about, you don’t need me you got the right guys on the job already. This is the point where usually I would give some deal clinching examples of precisely why they are the right guys for that particular job. But not today. If you want to know why it is no problem at all for your amp or any other, in fact is an advantage inherent in the design that helps explain why they sound so doggone good, let me know I will fill you in. |
MC, I didn't just laugh at your post. I definitely get what you're saying. To a large degree I agree with you. If it won't blow up and it sounds great then that's all I care about. I know the principle behind Tekton and why people like them. If you want to tell me more though I'd be happy to hear what you have to say. |
