John Warren Posted October 26, 2003 Share Posted October 26, 2003 Quote Link to comment Share on other sites More sharing options...
hwatkins Posted October 26, 2003 Share Posted October 26, 2003 Thanks John - I need just a tad more info on the Zoebel effect. Can you layman terms the issue? It looks like the Zoebel filter really manages the impedence well in the frequency range you want the two speakers to be working in. Quote Link to comment Share on other sites More sharing options...
John Warren Posted October 26, 2003 Author Share Posted October 26, 2003 ---------------- On 10/26/2003 8:36:16 AM hwatkins wrote: Thanks John - I need just a tad more info on the Zoebel effect. Can you layman terms the issue? It looks like the Zoebel filter really manages the impedence well in the frequency range you want the two speakers to be working in. ---------------- , Quote Link to comment Share on other sites More sharing options...
hwatkins Posted October 27, 2003 Share Posted October 27, 2003 Ok - time to show my ignorance (and squeeze in some learning). Taking your tact on this - if I was looking to use a speaker for mid bass (instead of the LF) that may be fuller range with an Fs below the range that I wanted to use the speaker, this combination of Zoebel/Bessel could (tweaked accordingly) be a reasonable option. As a matter of fact - in your example you are doing a very good job of covering that heavy frequency data (the 'voice' range) without any crossover nuances - with most of the nuances occurring below and above the frequencies that are so often used in sound reproduction (other than you might want to take the low end to around 300hz). Did I miss the mark (be kind ) or am I getting close? Quote Link to comment Share on other sites More sharing options...
John Warren Posted October 29, 2003 Author Share Posted October 29, 2003 ---------------- On 10/27/2003 9:35:05 AM hwatkins wrote: . Quote Link to comment Share on other sites More sharing options...
hwatkins Posted October 29, 2003 Share Posted October 29, 2003 Thx John - that is closer to what i should be thinking and makes better sense than my query. As always - good to have your knowledge here. Quote Link to comment Share on other sites More sharing options...
WMcD Posted October 29, 2003 Share Posted October 29, 2003 John, The Zobel was placed before or after the network? It usually goes between the network and the driver. Best, Gil Quote Link to comment Share on other sites More sharing options...
John Warren Posted October 29, 2003 Author Share Posted October 29, 2003 ---------------- . Quote Link to comment Share on other sites More sharing options...
John Warren Posted October 29, 2003 Author Share Posted October 29, 2003 ---------------- On 10/29/2003 6:38:41 PM hwatkins wrote: Thx John - that is closer to what i should be thinking and makes better sense than my query. As always - good to have your knowledge here. ---------------- My pleasure. Fun stuff isn't it? Quote Link to comment Share on other sites More sharing options...
WMcD Posted October 29, 2003 Share Posted October 29, 2003 If I may give some observations and perhaps answer the question of why use a Zobel. Classic crossover network design assumes the load has a given impedance which is purely resistive. The numbers are easy to work out if the driver looks like an 8 ohm (or whatever) resistor. The problem is that the driver doesn't actually act like a resistor. At higher frequencies, and increasingly dominant factor is the fact that the voice coil is a coil of wire sitting in the iron magnet structure. So it is acting like an inductor (which it is). The impedance of an inductor depends on frequency. It is Z(l) = 2 pi f L. L is the value of the inductor. So as f goes up, so does the impedance Z(l). Actually, in this range, the total impedance, is the DC voice coil resistance (our nominal resistive value or Rdc) plus the X(l) of the voice coil inductance. That really doesn't explain everything. Importantly, the Z(l) formed by the voice coil becomes part of the overall circuit of the crossover network. So the Z(l) of the voice coil messes up the crossover design; there is an extra component not accounted for in classic theory. Remember, the load was not supposed to have an inductor in there, rather being only an R. Why is that bad? It is because now the crossover doesn't have the circuit components originally envisioned. the Z(l) of the voice coil has been added. We see that in the peak of impedance on the graph What to do? One thing to do is to add some more components which exactly compensate for the voice coil inductance. This is usually a resistor and capacitor wired across the voice coil. (There are more sophisticated Zobels but this is a classic). When properly designed and these components are added, the input to the combination is mostly resistive. This is good, because then we're back to the pure resistive load which the crossover design assumed. We need diagrams, but that is how it works. Gil Quote Link to comment Share on other sites More sharing options...
John Warren Posted October 29, 2003 Author Share Posted October 29, 2003 ---------------- On 10/29/2003 10:07:44 PM William F. Gil McDermott wrote: If I may give some observations and perhaps answer the question of why use a Zobel. , Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.