Vas – how are you measuring this on compression drivers?

[Alexander]

 

 

How is this being done? With the horn removed and test it that way? What if the diaphragm has an attached phase plug? Calibrated mic? I am guessing here.....

Is this not a factor at these frequencies > than say 1k Hz?

[MechEngVic]

7 hours ago, Alexander said:

 

 

How is this being done? With the horn removed and test it that way? What if the diaphragm has an attached phase plug? Calibrated mic? I am guessing here.....

Is this not a factor at these frequencies > than say 1k Hz?

I don't think I've seen vas measurements for horns or other high frequency drivers, they tend not to be cabinet dependent.

[Alexander]

1 hour ago, MechEngVic said:

I don't think I've seen vas measurements for horns or other high frequency drivers, they tend not to be cabinet dependent.

 

Thanks, that makes sense. I ask as I have seen a number of YouTube videos using the weighted method on dome tweeters.

 

BTW, is there a “rule of thumb” guide for the weight to use on a cone driver?

[pzannucci]

9 hours ago, Alexander said:

 

Thanks, that makes sense. I ask as I have seen a number of YouTube videos using the weighted method on dome tweeters.

 

BTW, is there a “rule of thumb” guide for the weight to use on a cone driver?

Weighting method on dome tweeters?  Where are you seeing this?  I'd love to add weight to my high end Morels and watch the dome collapse.  Not that practical with many tweeters.

Most domes have their own chamber specifically designed for the dome and the amount of compression along with damping/reflection reducing technologies behind it.

 

You don't usually change the volume of the dome's implementation though I did think of this several times when replacing the padding in mid-range drivers.  There to me it makes much more sense as they extend much lower.

 

Please share a link to one of the youtube videos.

[Alexander]

2 hours ago, pzannucci said:

Weighting method on dome tweeters?  Where are you seeing this?  I'd love to add weight to my high end Morels and watch the dome collapse.  Not that practical with many tweeters.

Most domes have their own chamber specifically designed for the dome and the amount of compression along with damping/reflection reducing technologies behind it.

 

You don't usually change the volume of the dome's implementation though I did think of this several times when replacing the padding in mid-range drivers.  There to me it makes much more sense as they extend much lower.

 

Please share a link to one of the youtube videos.

 

 

Previously I had gone through a very large number of videos and so far haven't been able to come across any of them. But one that stands out was they used something like fun-tak putty as the weight. And if IIRC they were testing a Dayton dome tweeter of some sort with a DATS V2  or V3 program.

[pzannucci]

29 minutes ago, Alexander said:

 

 

Previously I had gone through a very large number of videos and so far haven't been able to come across any of them. But one that stands out was they used something like fun-tak putty as the weight. And if IIRC they were testing a Dayton dome tweeter of some sort with a DATS V2  or V3 program.

Unless you redesign the chamber, which on most tweeters can't be done unless you start from scratch on the chamber design, I don't see how you can attach anything to most of the soft domes let alone why you would want to anyway.  As far as trying to increase the lower cut off, I can see this though for most uses of a small dome, this wouldn't make sense to me unless again you are building one from scratch.  For the network the impedance sweep should be enough.

 

Again, I'd love to see a youtube of this.  Do you have a pointer?

[Alexander]

4 hours ago, pzannucci said:

Unless you redesign the chamber, which on most tweeters can't be done unless you start from scratch on the chamber design, I don't see how you can attach anything to most of the soft domes let alone why you would want to anyway.  As far as trying to increase the lower cut off, I can see this though for most uses of a small dome, this wouldn't make sense to me unless again you are building one from scratch.  For the network the impedance sweep should be enough.

 

Again, I'd love to see a youtube of this.  Do you have a pointer?

 

When I come back across one I will post it. But that is what brought me to this question .

 

I understand that dome tweeters (or any type of driver) with a closed back design would not be influenced by the enclosure they are mounted in. I was curious though if there were some other kind of mechanical property(s) that might effect the drivers electrical performance that was needed to be taken into account.

 

It appears this has turned out to be a dumb question, just thought it was odd that they were doing it.

I am sure this is not my first or my last that I will ask.

 

[glens]

4 hours ago, pzannucci said:

Again, I'd love to see a youtube of this.  Do you have a pointer?

 

Go to https://YouTube.com and search for "Justin Bieber"?  Didn't he do one?

[glens]

49 minutes ago, Alexander said:

It appears this has turned out to be a dumb question ...

 

"They" say the only dumb question is the one that's not asked...

[pzannucci]

2 hours ago, glens said:

 

"They" say the only dumb question is the one that's not asked...

Very true.  Assumptions are not good.

[boom3]

As the OP has probably figured out by now, Vas is meaningless for compression drivers. Compression drivers, and well-engineered domes, have back chambers and internal damping tailored to their characteristics. Attempting to extend the lower range of these drivers by enlarging the back chamber means you lose the damping and the voice coil/diaphragm assembly will injure itself trying to go lower.