Hello,
I know that amplifier will give more power to lower impedance speaker, but it can damage the amplifier if impedance is lower than what amplifier is rated for.
And I know that is cheaper to get 4 ohm 1000w amp than 8 ohm 1000w amp.
So what would be the cons of amplifier with 1000w output at 8 ohm and 8 ohm speaker over amp with 1000w output at 4 ohm and 4 ohm speaker?
I understand that 4 ohm systems are used in cars because there is 14.4v voltage limit if not using smps to make voltage higher.
But why are 8-16ohm systems widely used in households?
I know that amplifier will give more power to lower impedance speaker, but it can damage the amplifier if impedance is lower than what amplifier is rated for.
And I know that is cheaper to get 4 ohm 1000w amp than 8 ohm 1000w amp.
So what would be the cons of amplifier with 1000w output at 8 ohm and 8 ohm speaker over amp with 1000w output at 4 ohm and 4 ohm speaker?
I understand that 4 ohm systems are used in cars because there is 14.4v voltage limit if not using smps to make voltage higher.
But why are 8-16ohm systems widely used in households?
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To get 1000w into 16ohms takes around 180 volts peak, or 360v between rails. Very few semiconductors will take these kinds of voltage. Its much easier to increase current by parralleling transistors. And with thise kinds of voltages people can electrocute themselfs swaping speaker wires.
Where are all these 16 ohm speakers? Sure there are some old 16 ohm drivers floating around from the 1960's from tube consoles, but not in more modern times.
jeff
We only really have the choice of 4 and 8 ohm in modern systems with 2 ohms with subwoofers perhaps. You'll get twice the damping factor with 8 ohms however a passive crossover will destroy this benefit. Naturally you'll get more power from lower voltage rails. By definition there are going to be more amplifiers compatible with lower voltages than high ones as nearly all the high voltage amps work on lower voltages, too.
Even at 100w the peak voltage for 16ohms is 56v. In many places that takes it above the low voltage (safe) cable spec. and legaly it needs to be installed by an electrician.
16 Ohm speakers you find them in pro-speaker production, as they are made for arrays.
For example, there's this new arrival from 18Sound which is an AMT tweeter....
Eighteen Sound - Professional loudspeakers
For example, there's this new arrival from 18Sound which is an AMT tweeter....
Eighteen Sound - Professional loudspeakers
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True, true, I cant remember when I last saw 16 ohm speakers, I mostly saw 6-16ohm ratings on older amplifiers from 80s, 90s (the real stuff from golden age), but not the speakers.
Some older headphones were 32ohm if I remember it right?
But I still don't understand why 8ohm systems are so widely used over 4 ohm systems.
Some older headphones were 32ohm if I remember it right?
But I still don't understand why 8ohm systems are so widely used over 4 ohm systems.
The lower the load, the higher distortion. 8 Ohm had become the standard because of that and because it's in the middle... It's the average!
Painting with a *broad* brush, it`s a matter of convenience.
In the tube era, OTs were mandatory.
Winding secondaries, making thick wire bend properly around corners is a PITA; it`s far easier, call it more comfortable if you wish, to wind, say, 120 turns of 0.80mm wire for a 16 ohm secondary than, say, 84 turns of 1.10mm wire.
Flexing rigidity grows with the square of diameter.
Some Fender OT rated for 2 ohm (4 x 10" Bassman and some Deluxe Reverb) used *three* finer wire windings in parallel, go figure.
So that tends to favor 16 ohm output if at all `possible.
Won`t develop the full Math, just finishing my mid afternoon coffee cup and back to work, but in two *identical* speakers, the 16 ohm version will be slightly more efficient and have more extended response than the 8 ohm one.
Easy to see comparing Guitar speaker curves, which are still built like 50`s "console speakers".
In the old gramophone days, with a single full range speaker, no tweeters or crossovers, it was an asset.
When Transistors became popular, the big limiting factor was Vce so 8 ohm was much preferrable to 16 ohm, twice the power for same voltage, a huge advantage.
Although British, conservative as they are, kept making 16 ohm speakers widely available at least until the 80`s.
I still remember those full page Wilmslow Audio ads in British Electronics magazines. 😛
No kidding. Maybe post some examples of these amps from the golden era, cause I don't recall there being any in mainstream hifi.😕
jeff
See D. Self. Degradation of the amplification of transistors with increased current. For 8-16 ohms at the output there is a deuce, for 4-8 there is a parallel deuce, 4 ohms and below - a triplet.
For high current windings you simply use multi-filar windings, not thicker and thicker wire. Wire flexibility is therefore not a convincing factor in transformer design to my mind.
[ Flexural rigidity actually goes with the fourth power of diameter, and deformation energy with the cube. ]
[ Flexural rigidity actually goes with the fourth power of diameter, and deformation energy with the cube. ]
In the 70s, the British standard was 15, 8 and 3 ohm, with the odd 4 ohm and 16 ohm thrown in for good measure!
Attached, is some nostalgia for you - a 1977 Wilmslow Audio Advert!
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'But why are 8-16ohm systems widely used in households?'
almost every amplifier has much lower distortion at higher resistance
almost every amplifier has much lower distortion at higher resistance
Those amplifiers put the speakers in *series* when you selected two pair simultaneously. They would usually run blazing hot or blow up at anything less than 8 ohms. Even 6 was a stretch. Those weren’t the “real stuff”. The old school solid state receivers from the 70’s could deal with 4 ohms (both speaker sets in parallel). But those started to cost too much because they actually had parallel TO3 output trannies, big heat sinks and big trafos.