1" Compression driver 8 ohm vs 16ohm

[sendler]

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.

[sumaudioguy]

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.

[infinia]

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.

[tinitus]

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

[infinia]

Originally Posted by tinitus

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

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

[sendler]

I am using a pc crossover or DCX2496 so passive component values are not an issue although it sounds like the 16 ohm compression driver is a win - win on all counts.

[infinia]

Originally Posted by sendler

I am using a pc crossover or DCX2496 so passive component values are not an issue although it sounds like the 16 ohm compression driver is a win - win on all counts.

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?

[freddi]

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

[doug20]

Originally Posted by freddi

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.

[sendler]

Originally Posted by doug20

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.

I have read in Lynn's Ariel thread that a series resistor is always a step backward.