Higher impedance = cleaner volume?

[JonnySwitchblade]

It seems that if I run 16 ohm loads on my amps, yes the volume loss at the current master setting is vast but when I really push big volumes, the 16 ohm version of my woofers stay cleaner.

I'm sure I'm not the only one experiencing this but I am curious, would a power resistor wired to increase resistance to the 8 ohm version of this speaker I have yield similar results?

Opinions are appreciated, I'm going to order some resistors soon just to do some experimenting. I'm a firm believer that nothing is certain until it is attempted but some heads up would be appreciated.

Oh and I've heard coils sound better at doing the same job but they're of course not cost efficient as so many books and sites have remarked.
I still have to wonder if the investment is worth it granted you're not buying a dozen coils every 2 months.

[Cal Weldon]

Originally posted by 1400WATTSRMS+

I'm sure I'm not the only one experiencing this but I am curious, would a power resistor wired to increase resistance to the 8 ohm version of this speaker I have yield similar results?

You don't want to waste the power in a resistor in the bass region. That doesn't make much sense. If you wish, add a second woofer in series to get your 16 ohms but remember, as you change the impedance, you change the XO point.

I can't say I've had the same results as you.

[Willitwork]

Originally posted by 1400WATTSRMS+
Oh and I've heard coils sound better at doing the same job but they're of course not cost efficient as so many books and sites have remarked. I still have to wonder if the investment is worth it granted you're not buying a dozen coils every 2 months.

I picture one heck of a jumbo crossover with at least 22 air-core inductors in series.

[tubewade]

All other things being equal, a 16 ohm speaker will lose 3 dB of SPL compared to an 8 ohm speaker when driven by the same output terminals.

Wiring an 8 ohm resistor in series with an 8 ohm speaker will result in a 50 percent loss of total power with 50 percent of what's left being wasted in the resistor. So the SPL loss would be 1/4th power, or 6 dB. Damping factor, for all practical purposes becomes 1:1.

Another identical 8 ohm speaker wired in series with the first one will cut the power in half, a 3 dB loss, but the membrane area is doubled for a 3 dB gain. So you are right back where you started as far as SPL, but with less load on the amplifier. Plus the damping factor is now twice whatever is was at 8 ohms.

All of this holds true only if you do not have multiple taps to choose from, such as most valve amplifiers have. I run valves, have 16 ohm taps, and prefer 16 ohm speakers to 8 ohm speakers. I suffer no loss in SPL for using them as I would with a solid state amplifier. I do not have the filter woes mentioned because I use active filtering.

Best

[jnb]

Hi 1400WATTSRMS+,

As you've probably worked out, there is a best load for your amp and supply, and you seem to have found the best and worst.

Some thoughts:

Don't use power resistors to increase impedance, it's a waste.

Coils will cut the high frequencies when used in this way, probably not what you're looking for.

If you can't get enough volume without using a low impedance speaker, you can always shop for a higher impedance speaker that has a higher sensitivity (efficiency).

[sreten]

Hi,

Adding an 8R resistor will give your amplifier a damping factor of 1.
In other words a half voltage / half current source that will be an
absolute disaster interacting with most speakers (fr's excepted).

/sreten.

[JonnySwitchblade]

Originally posted by tubewade

All of this holds true only if you do not have multiple taps to choose from, such as most valve amplifiers have. I run valves, have 16 ohm taps, and prefer 16 ohm speakers to 8 ohm speakers. I suffer no loss in SPL for using them as I would with a solid state amplifier. I do not have the filter woes mentioned because I use active filtering.

Best [/B]

I think that endorses what I've come to believe in general, more coil wire can often mean better sound quality.

I've experimented with more configurations than I can even make sense of, regardless of parallel, series or a variety of series parallel configurations, as long as I had just enough wattage to push the speakers at a desirable level of performance, more coil has generally delivered better quality sound. Even using dumby coils from scrapped speakers, high volume sounds cleaner and smoother to me.

I had wanted to experiment with increasing impedance on a guitar speaker cabinet so I would lose some volume and hopefully clean up the high volume.
With the master on 3, you really can't turn it up much louder without it making you feel sorta head sick. If you DO push more volume, you of course have to back down the EQ controls to eliminate or reduce power amp distortion.

Adding more speakers just isn't an option.

My hope is that a power resistor used to step up impedance will let me get that master volume a bit higher before the volume is getting unbearable AND, I will be able to push it a fair bit louder before the power amp starts to distort.
I am really thinking that some resistance to compensate the sensitivity of the master volume and it's high volume power amp distortion issues, is the perfect solution to these issues.

Do any of you feel a power resistor will do what I suspect?
I'm pretty confident it will.
I know going to at least a 16 ohm load by adding more speakers is of course the best solution with maximum benefit but for now I can't do it.

Hey..maybe if I just add 100 feet of speaker wire left right on the spindle??

wutcha guys think?

[jnb]

1400WATTSRMS+,

You sound like you're not afraid to experiment. For a way to scale your impedance and to use coils in the process, why not try connecting your speaker through an old unused power transformer? If you connect the wall socket side across your amplifier output and the low voltage side to the speaker, you'll make the speaker look like a much higher impedance. You'll get less volume out in the process. To get a more subtle effect, use a transformer that was designed to produce a higher output voltage.

Enjoy

[BlueWizard]

Well, it's just my opinion, but I think it is all about current.

Whether you are using a single 16 ohm speaker, or a 16 ohm multi-speaker cabinets, or two 8 ohm speakers in series, I think the quality of sound gain is because the current load is less.

While we generally think of sound as either signal (meaning voltage) or as power, but it is really current that is doing all the work.

Let us assume we have similar speakers in similar cabinets. In one cabinet we have two 16 ohm speakers in parallel for an 8 ohm load, and in the other we have two 8 ohm speakers in series for a 16 ohm load. Now we apply the same signal voltage to each.

One system is going to use twice the power (P=E^2/R), and therefore demand twice the current (I=E/R) as the other. That current demand, when it becomes unreasonable, either by excess volume or extremely low impedance, is going to strain the amp, and therefore 'strain' the sound. If the impedance drops too low, then we are going to dangerously strain the amp.

Note both cabinets are moving the same amount of air. The perceive loudness between the two is going to be noticable but not great. I think in theory, it should be about a 3db difference (off the top of my head).

So, looking at the speakers as a closed system, I think the perception of improved sound quality, is really just the amp working less hard to deliver the sound you hear.

I'm sure it's more complicated than that, but on general principle, I think I am on to something.

What would be an interesting and fair test is to take two Dual-Voice Coil speakers, put one in series with itself for 16 ohms, and the other in parallel with itself for 4 ohms, then connect them each to a channel of a stereo and compare how they sound side by side.

I'm actually considering making a pair of speakers using dual-voice coil woofers. I would be nice to know if there was an advantage or disadvantage to two 4's in series vs two 16's in parallel.

Or to compare two 4 ohms speakers wired in series for 8 ohms against two identical 8 ohm speakers wired in series for 16 ohms.

Steve/BlueWizard