[neobop]

You're missing (or not understanding) the points that are being made.  Not only by me, but Pete, Scotty, and Quiet Earth as well. 

Anyways, the 10k resistor comment was a retort to your comment that "you can't put anything across the speaker terminals without its affecting the sound."  I think you missed the point there too, which was....that a 10k resistor will not affect the sound.  It's completely innocuous in that position.

Cheers,

Dave.

I see your point, but you refuse to move on.   The orig question was about any possible negative consequences of a zobel.  You're not offering anything about that question other than what has already been said.  I also see your point about the 10K resistor,  I don't concede that point, but it doesn't matter.  Your point is moot and you know it.  Are you debating me or addressing the question?

Why does Scotty hear a difference with a zobel on his tweeter?  There's no low pass filter in front of that driver.  It's because a zobel will change the sound of a driver irrespective of crossover considerations.  It's true with tweeters and full range drivers.  Debate that.

Cheerio,
neo

[Davey]

I already answered the question....early on...you just didn't like the answer. 
I'll answer it again...there are no drawbacks to adding a Zobel network.  (As long as the amp output and the rest of the interface between there and the transducer is considered.)

I offered one possible explanation for Scotty's preference......did you understand it?

You appear to be hung up on audible differences.  I'm trying to explain what conditions might cause audible differences and what conditions would not.  I'm not sure if you're considering audible differences "drawbacks" or not.

Cheers,

Dave.

[*Scotty*]

As I said I suspect that the amplifier is producing less distortion driving the tweeter with a zobel in place. We can certainly say that we have changed the sound of the tweeter for better when it is producing less distortion. This should be a measurable phenomena via REW or some other type software.
Scotty

[neobop]

My point is that a zobel will change the sound of a driver even if there is no passive crossover. 

Whether or not that change is desirable, is a matter of opinion in the specific circumstance.  To say there is no possible downside to using a zobel is wrong, IMO.  A downside is still in the realm of possibilities. 

Conjecture about why a change occurs doesn't matter, it's conjecture. 

From the Loudspeaker Design Cookbook:
You can also use this circuit for tweeter domes, not to facilitate network operation, but to help eliminate harshness and to insure accurate application of L type shelving networks.

Eliminating harshness is changing the sound of a driver.  It will also change the sound of a full range driver sans crossover.  I'm not saying it's necessarily a bad thing, but it might not always be desirable.
neo

[Pete Schumacher]

The difficulty for most solid state amps with direct coupled outputs is not usually inductive loading.  Capacitive loading is actually more difficult and pushing the amplifier toward oscillation.  Since most tweeters present an inductive load at high frequencies, the likelihood of any issues with a direct connection to the amp are nil.  Adding a zobel to the tweeter will do nothing to reduce distortion in the tweeter. 

In this case, with solid state amps and direct connection to the drivers (no XOs), a zobel is really just a waste of parts and $$$.

And usually, for safety sake, the tweeter should be coupled to the amp with a large film-type capacitor to prevent any issues with DC offsets.

[*Scotty*]

Pete, any idea why dome tweeters sound better when their impedance curve is flattened.
Scotty

[Quiet Earth]

I always thought that the effectiveness of a Zobel was not for what it does in band, but for what it does out of band. And also, not for what it does to improve the speaker that it's attached to, but to give the amplifier something to chew on. Out of the band of interest.

Also, why would capacitive loading be bad if it is terminated into a proper load?

[Pete Schumacher]

Pete, any idea why dome tweeters sound better when their impedance curve is flattened.
Scotty

If the tweeter is connected directly to the solid state amp, with no XO components in between, I'd say they sound better due to the power of suggestion.

[FullRangeMan]

If the tweeter is connected directly to the solid state amp, with no XO components in between, I'd say they sound better due to the power of suggestion.

  Dont underestimate the power of the mind.

[Davey]

If the tweeter is connected directly to the solid state amp, with no XO components in between, I'd say they sound better due to the power of suggestion.

I give Scotty more credit than that. 

It's certainly possible that if amplifier output impedance is significant and the Zobel component values are causing a change to the voltage function applied to the driver there would be an audible difference.

Neo,

You appear to be dug in on this.    A Zobel will not always change the sound of a driver.  It may, it may not.....depending upon the power amp, the Zobel component values, and the transducer characteristics.

Cheers,

Dave.

[neobop]

Pete, any idea why dome tweeters sound better when their impedance curve is flattened.
Scotty

You keep getting evasive answers.  I don't doubt that the tweeter sounds different, whether or not you're using a passive crossover.

Other speaker designers agree with this viewpoint.  It's not necessarily about distortion or your amps ability to drive the load, it's about the sound of the driver.
neo

[brj]

Considering any one component of the relevant chain (amp, speaker cables, possible passive crossover, and driver(s)) in isolation is often problematic.  They act as a system whose behavior changes with impedance, and therefore frequency (due to the reactive components of inductance and capacitance).  Swapping speaker cables is probably the biggest example of this.  Changing out a pair having low inductance/high capacitance for one having higher inductance/lower capacitance can easily change the behavior of the entire system.  Even if you don't have a passive crossover in the mix, your installed driver will have mechanical, acoustic and electrical resonance points that will interact, and changing the speaker cable can change the electrical resonance points of the system which will then still interact with the other two.

Interesting... I'd never considered until just now that Zobel could very well reduce a system's sensitivity to speaker cable swaps, especially if you retuned the Zobel for each different pair of speaker cables you tried.  Assuming each pair were of sufficient wire gauge (to deal with the resistive part of the equation), I wonder how much difference you'd still hear with each new swap?  It would still depend on your amp to some degree, but still... interesting!

[neobop]

I give Scotty more credit than that. 

It's certainly possible that if amplifier output impedance is significant and the Zobel component values are causing a change to the voltage function applied to the driver there would be an audible difference.

Neo,

You appear to be dug in on this.    A Zobel will not always change the sound of a driver.  It may, it may not.....depending upon the power amp, the Zobel component values, and the transducer characteristics.

Cheers,
Dave.

I don't see how you can say that last part.  You must be considering only the transfer function between amp and speaker, but even that will be changed.  A zobel puts a parallel load on part of the frequency band of a driver.  This will impact on efficiency and relative frequency response of the driver, its "sound".

Look at the impedance curve of any conventional woofer.  You're using a fixed value resistor in parallel with this rising impedance and results might not change the sound?  Maybe the change will be beneficial, or rather benign, depending on application, but I don't think it's necessarily desirable to put 2 more reactive components in an AC circuit. 

You say, " It may, it may not.....depending upon the power amp, the Zobel component values, and the transducer characteristics." 

What are you saying?   Use enough qualifiers and it's not much.  If the transducer characeristics are such that it would not benefit from a zobel, why use one?   I too have little doubt that Scotty hears a real change whether he's using an active or passive crossover.  He said he's using a dome tweeter, not an air motion transformer or other ribbon tweeter.  Documentation (much of it subjective) about changing the response of a dome with a zobel, is extensive.
neo

[Davey]

You appear to view everything as black or white.  I'm more pragmatic....it comes from years of experience. 

Why is it so difficult to grasp the concept that a Zobel might not change the sound of a driver?

Here's an example.....what if I attach a 10 ohm / 0.33uF Zobel across the speaker leads to my dome tweeter?  (My amplifier has really low output impedance.) 
That will terminate the speaker leads with 10 ohms above the audio band, but should not change the drive level to the tweeter within the audio band.

Do you think removing/attaching that Zobel will change the audible sound of said tweeter?

Cheers,

Dave.

[a.wayne]

A Zobel is a shunting network and not a crossover filter.  I've seen a number of full-range systems that employ impedance leveling devices.

That shouldn't violate the "fullrange" mandate/requirement, should it? 

Dave.

 

Zobels, conjugates , et al , are all tools and as all things on the planet , too much of anything will kill yah, the only negative i have experienced is a lack of dynamics if not used judiciously, sucks the life out of speakers , the opposite is usually achieved when not used at all , shouty uneven sounding ,some tend to call this kind of sound "open"  ..

You usually find  those with these wide  open speakers with EQ's , which happen to bring another round of nasties to the table ..

Regards ...

[neobop]

You appear to view everything as black or white.  I'm more pragmatic....it comes from years of experience. 

Why is it so difficult to grasp the concept that a Zobel might not change the sound of a driver?

Here's an example.....what if I attach a 10 ohm / 0.33uF Zobel across the speaker leads to my dome tweeter?  (My amplifier has really low output impedance.) 
That will terminate the speaker leads with 10 ohms above the audio band, but should not change the drive level to the tweeter within the audio band.

Do you think removing/attaching that Zobel will change the audible sound of said tweeter?

Cheers,
Dave.

I already posted about possible benefits in the ultrasonic region.  If that network is actually accomplishing anything, removing it could change the sound of the tweeter.  I was specifically talking about conventional zobels designed to counter rising impedance of the driver, in bandwidth, not Scanspeak speaker wire networks.

If you think a conventional zobel has no affect, why use it in the first place?  If it allows a tube amplifier to successfully drive the speaker then at the least it's changing the sound of the speaker with that amp.  This seems like semantics.  I don't think you can use a zobel to limit impedance in a crossover region without changing the sound of the driver.

Why is it so difficult for you to grasp the concept that someone might have a different opinion than yours, based on experience?
neo

[Davey]

I give up.  I can't keep up with the strawman arguments.
You're right and I'm wrong.  Sorry to have bothered you.

Cheers,

Dave.

[Pete Schumacher]

I already posted about possible benefits in the ultrasonic region.  If that network is actually accomplishing anything, removing it could change the sound of the tweeter.  I was specifically talking about conventional zobels designed to counter rising impedance of the driver, in bandwidth, not Scanspeak speaker wire networks.

If you think a conventional zobel has no affect, why use it in the first place?  If it allows a tube amplifier to successfully drive the speaker then at the least it's changing the sound of the speaker with that amp.  This seems like semantics.  I don't think you can use a zobel to limit impedance in a crossover region without changing the sound of the driver.

Why is it so difficult for you to grasp the concept that someone might have a different opinion than yours, based on experience?
neo

Why are you bringing up crossovers?  This discussion isn't about crossovers.  It's about an active setup, using solid state amps as sources, and no crossover components between the amp and drivers.

Zobel networks inside a crossover have an effect on the transfer function of the crossover.  They may, or may not, be a necessary network to achieve the desired acoustic slopes.  It's a sure bet that adding a zobel to a crossover network will affect the response of the driver to which it is attached, and not necessarily a good result.  Plenty of crossovers exist that work very well without needing to add a zobel to compensate for a rising impedance of a driver.

 But adding a zobel to a driver that is directly connected to the amplifier output will have no effect on the output of the driver if the amplifier has a low output impedance to start with, which is case here using solid state amplification.

[neobop]

But adding a zobel to a driver that is directly connected to the amplifier output will have no effect on the output of the driver if the amplifier has a low output impedance to start with, which is case here using solid state amplification.

You're saying if I hook up a zobel to an 8" full range driver which is connected directly to an amplifier, it will sound the same as w/o the zobel?

I find this hard to believe.

neo

[FullRangeMan]

You're saying if I hook up a zobel to an 8" full range driver which is connected directly to an amplifier, it will sound the same as w/o the zobel?

I find this hard to believe.

neo

Another paradox that has been said here is zobel flatten the impedance but not harm the music.