Will a 16 ohm compression driver be better for home audio than the same driver with an 8 ohm diaphragm? Will this cut the hiss from noise in half along with the voltage sensitivity for a better match to hifi woofers so less padding will be required. Will resonant frequency stay the same? The radian 475 is reported to have a nice low FS of 535Hz on a big horn which I would want to keep while cutting down the noise sensitivity.
Do not know about that specific horn driver but in all my testing 16 ohm always have had better characteristics than their 8 ohm conterpart.
I think the main benefit of using 16 ohm is that the passive high-pass filters use capacitors that are 1/2 capacitance of the 8 ohm versions. Fs remains the same and sensitivity is usually padded down anyways so no reduction in overall components is realized.
One could also use an Lpad transforming a 16 to 8 ohm across most of the band negating the need for resonance zobels.
One could also use an Lpad transforming a 16 to 8 ohm across most of the band negating the need for resonance zobels.
Theoretically the 16ohm driver will also need a bigger attenuation resistor
On the 8ohm driver you might just as well mount a series resistor between cap and driver, and achieve the same smaller cap mentioned by infinia
Some tweeter have a peak above 10khz, and may improve by a small series inductor instead of a zobel
But it might be more interesting to see impedance curve, and look fore differences in smoothness and ressonance peak
Frequency response may be slightly different too
If they show the actual ones, and not just a duplicated one
On the 8ohm driver you might just as well mount a series resistor between cap and driver, and achieve the same smaller cap mentioned by infinia
Some tweeter have a peak above 10khz, and may improve by a small series inductor instead of a zobel
But it might be more interesting to see impedance curve, and look fore differences in smoothness and ressonance peak
Frequency response may be slightly different too
If they show the actual ones, and not just a duplicated one
Using a series resistor to raise a 8 ohm up to 16 comes with increasing need for zobels to tame resonance, also a decrease in damping. Some drivers sound OK with less damping but generally not.
Most compression drivers loaded with real horns have decreasing HF response, so some HF lift can be added by several means if a pad is used.
Impedance curves are really only useful when the drivers are loaded into the actual horns to be used, otherwise when using a 16 ohm shunt pad with a 16 ohm driver the whole resultant 8 ohm-ish impedance become flattened and less susceptible to several horn reflected impedance variations.
Series Inductors are used for LF lift not HF attenuation in horns. If you use these in HP designs you are either very advanced or are in trouble or both.
see http://www.pispeakers.com/Speaker_Crossover.doc
See it depends what your goals and methods are?
Are you direct couped to an Amplifier ?
Higher power available with most amps using 8
Resale maybe better with 8
There maybe subtle differences between drivers within same family
need to give all the details.
I'm afraid there are no general rules here, just trade-offs like any engineering.
EDIT> I'm sorry if I test 3 different makes of drivers and the 16 ohm is better than the all the 8 versions. What things have I tested to be able make a global statement like this? AND if I test a 4th make, how can I be sure even if i tested the right thing that the 8 ohm version might be better?
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assuming you've enough sensitivity for the horn/waveguide for good high end, you can parallel a damping/swamping resistor across the 16 ohm driver and treat it like 8 ohm/whatever - may sometimes help as interaction from Z peaks with xover is reduced
I remember a good discussion on this site (couple years ago) about using resistors (Lpad, damping) reducing the sound quality. I didnt believe it then and I do not believe it now but I wanted to read about it again. I can not find that thread though.
Series resistor
I have read in Lynn's Ariel thread that a series resistor is always a step backward.
Sometimes, It's really a system Q issue and what sounds better.
It's the same deal with woofers sometimes adding series loss improves the apparent bass to taste.
Is that the current Ariel thread or is there an original one?
I would think anyone that owns a tube amp would disagree with it being a step backwards because aren't Tube amps adding resistance to the mix?
Like that original thread (Still can not find it), its a highly subjective discussion. In my own subjective experience adding resistance in series to a CD is a perfect solution for lowering the hiss. I moved forward after that 😀
A 16 ohm driver is easier for an amplifier to drive than an 8 ohm driver.
Active crossover with EQ is always better than a passive crossover.
A 16 ohm driver always has a lower Q and less resonant peaking than its 8 ohm counterpart.
A 16 ohm driver can allow for a tighter gap on a different magnet structure than its 8 ohm counterpart. When built with the tighter gap this lowers Q and increases efficiency.
A 16 ohm driver has a lighter voice coil than an 8 ohm driver so is a better mechanical match to the diaphragm portion of the driver. Ideal is voice coil/bobbin assembly mass should equal effective diaphragm/air load/surround assembly mass. This matches mechanical impedance of the two parts and moves toward ideal coupling of the voice coil to the diaphragm.
Because a 16 ohm driver is usually more efficient than its 8 ohm counterpart the 16 ohm takes less power for the same SPL. Please note to achieve this power a higher voltage will be required than for the 8 ohm driver.
Active crossover with EQ is always better than a passive crossover.
A 16 ohm driver always has a lower Q and less resonant peaking than its 8 ohm counterpart.
A 16 ohm driver can allow for a tighter gap on a different magnet structure than its 8 ohm counterpart. When built with the tighter gap this lowers Q and increases efficiency.
A 16 ohm driver has a lighter voice coil than an 8 ohm driver so is a better mechanical match to the diaphragm portion of the driver. Ideal is voice coil/bobbin assembly mass should equal effective diaphragm/air load/surround assembly mass. This matches mechanical impedance of the two parts and moves toward ideal coupling of the voice coil to the diaphragm.
Because a 16 ohm driver is usually more efficient than its 8 ohm counterpart the 16 ohm takes less power for the same SPL. Please note to achieve this power a higher voltage will be required than for the 8 ohm driver.
As I said most amplifiers give more power into a 8 vs a 16 ohm load. Any good reasonable amp should not have difficulty driving 8 ohms infact 4 ohm should give acceptable distortion compared to to the driver at higher SPLs.
I think you compare sensitivity of 16 vs 8 driver in the same structure using dB Volts, you find it's very similar. So system sensitivity is higher using 8 ohms, allowing either higher headroom or could probably use a smaller amp if actively driven.
Debatable for mid to high crossovers. Most Pros don't here!
"Always" comes with added complexity and its trade-off there. Usually with a $$ to match making the decision easier.
Any examples or explanations would be great. Using the word "always" is a particularly strong statement in my way of thinking?
Being the mass of the VC and diaphragm together as one of the most important parameters for HF as you implied, the driver designer could readily optimize with either 8 or 16 ohm as the basis for the initial design for that particular VC gap and chosen diaphragm weight. I think the important thing to understand is what impedance the designer started with, and what the trade offs mean given an alternate impedance. It would be interesting to note that if more 8 ohm HF drivers are sold, then the design of a HF driver would start with an 8 ohm impedance ie being the basis of the initial design, with the higher impedance taking the hit in the other trade offs?
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Most amplifiers will produce a higher output voltage before clipping into 16 ohms than 8 ohms.
As for easier to drive by amplifier- I mean the load the amp sees is smaller so all the problems with loading an amplifier are reduced. If amplifiers had no problems driving low Z loads there would be a lot of low Z woofers and indeed in car audio these are becoming more common like 1 ohm and ½ ohm voice coil.
All voice coils are pretty solid metallic assemblies with very strong baked adhesive. Compare this to a floppy plastic or composite paper cone or diaphragm and one can see this is a coupled system whereas the motor (voice coil) drives the load (cone or diaphragm). It is well established that maximum power transfer occurs when the Z or the motor equals the Z of the load. For diaphragm the velocity of propagation through the diaphragm is high so the delay is small and a good first approximation is the masses of the two parts should be nearly equal as plausible. This is basic physics.
Many manufacturers do not show individual specifications for 4, 8, and 16 ohm versions of their products. Testing these products has always revealed exactly what I have posted if all things are equal otherwise like magnet or cone. Some manufacturers modify things like voice coil length to make the specs of the 8 and 4 ohm version match up better.
I have heard of no debate where there are those that believe passive high level crossovers test better in distortion, power handling, or linearity than active low level crossovers. Where has such a debate occurred? Possibly you mean people like the sound of the muddy passive high level crossover because it hides the other problems in their sound reproduction systems better and therefore the listening experience is more satisfactory. Yes I believe that can happen but passive is impossible to be lower distortion, more linear, or higher power handling producing higher SPL than active crossover. This fact is well established through documentation in journals like AES and well know.
As for easier to drive by amplifier- I mean the load the amp sees is smaller so all the problems with loading an amplifier are reduced. If amplifiers had no problems driving low Z loads there would be a lot of low Z woofers and indeed in car audio these are becoming more common like 1 ohm and ½ ohm voice coil.
All voice coils are pretty solid metallic assemblies with very strong baked adhesive. Compare this to a floppy plastic or composite paper cone or diaphragm and one can see this is a coupled system whereas the motor (voice coil) drives the load (cone or diaphragm). It is well established that maximum power transfer occurs when the Z or the motor equals the Z of the load. For diaphragm the velocity of propagation through the diaphragm is high so the delay is small and a good first approximation is the masses of the two parts should be nearly equal as plausible. This is basic physics.
Many manufacturers do not show individual specifications for 4, 8, and 16 ohm versions of their products. Testing these products has always revealed exactly what I have posted if all things are equal otherwise like magnet or cone. Some manufacturers modify things like voice coil length to make the specs of the 8 and 4 ohm version match up better.
I have heard of no debate where there are those that believe passive high level crossovers test better in distortion, power handling, or linearity than active low level crossovers. Where has such a debate occurred? Possibly you mean people like the sound of the muddy passive high level crossover because it hides the other problems in their sound reproduction systems better and therefore the listening experience is more satisfactory. Yes I believe that can happen but passive is impossible to be lower distortion, more linear, or higher power handling producing higher SPL than active crossover. This fact is well established through documentation in journals like AES and well know.
Hmmm interesting...
Could you explain this in more detail in-regards to a compression driver/horn combo 8 vs 16.
The poweramp having more swing at 16 vs 8 is negligible unless using really really cheap stuff with power supplies sagging.
The 16 ohms voice coil and bobbin assembly is closer in mass to the diaphragm than the 8 ohm version therefore it couples more efficiently because the Z match is closer. The 16 ohm being less mass than the 8 ohm because the wire is smaller and therefore lighter. The wire mass of the 16 ohm will be something like about 50-80% the mass of the 8 ohm wire. The diaphragm with air will be less mass than the voice coil bobbin assembly.
Of course this can all vary quite a lot in the event the manufacturer decides to make the 8 ohm and 16 ohm versions match. In practice I always use the 16 ohm when available.
A power amp output will usually be about 1dB more voltage into 16 ohms than 8 ohms. Not very much as you say.
Of course this can all vary quite a lot in the event the manufacturer decides to make the 8 ohm and 16 ohm versions match. In practice I always use the 16 ohm when available.
A power amp output will usually be about 1dB more voltage into 16 ohms than 8 ohms. Not very much as you say.
Sorry, I mean the mechanical impedance of the voice coil and the mechanical impedance of the diaphragm. These are mechanical systems of coupled mass and are best analyzed that way. What the reflected electrical Z may do can be quite different than the reality of the mechanical system. Observing the quality match of the voice coil to the cone can be quite difficult to determine by only looking at the electrical impedance curve.
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