Audio Speaker Correction (The Zobel)

[raytork]

I remember fighting my through this in circuits. What an eye opener! In the end you do get the transfer function he wants, but it is so complex you had to solve by computer, essentially by simulation, or break it up into sections and sum the response with log plots (only if planar).

I have learned something here. Nowhere in my classes did anyone call a low pass filter a 'Zobel'. Actually, I think the name obscures, rather than illuminates.

 

[kc0iv]

I remember fighting my through this in circuits. What an eye opener! In the end you do get the transfer function he wants, but it is so complex you had to solve by computer, essentially by simulation, or break it up into sections and sum the response with log plots (only if planar).

I have learned something here. Nowhere in my classes did anyone call a low pass filter a 'Zobel'. Actually, I think the name obscures, rather than illuminates.

Doing a little web looking I came across an article that talks about a 'Zobel' Passive Crossover Network. If you want to see what one author has to say check out https://sound.westhost.com/lr-passive.htm Needless to say it is more involved than simply adding a RC circuit.

While calling it a low pass filter is true. Where the problem occurs is the addition of the coil with its resistance connect to the RC network. Let alone the coils changing inductance with the change in frequency.

While I think I could design a good cross-over network I no longer have the required test equipment to properly test the results. Plus, it is not high on my list of things to do.

I'm more like Thom said way back in post #3. "Hey I turn the stereo on. If it works good if not the go buy another." In fact a AM radio (tuned to talk radio) doesn't sound that bad as I get older.

Have a great day.

Leon
(kc0iv)

 

[raytork]

Very interesting read. I haven't looked at this for awhile. I have a question, though.
Why bother to flatten woofer response anywhere near its upper cutoff since the point of the crossover is to roll off the response by 3 dB (or more if it is higher order) there, so throwing away the response 'improvement'? If the intent is to reduce high frequency response, would not a higher order crossover accomplish the job with less effort and expense?

Thanks,

--Ray

 

[kc0iv]

Very interesting read. I haven't looked at this for awhile. I have a question, though.
Why bother to flatten woofer response anywhere near its upper cutoff since the point of the crossover is to roll off the response by 3 dB (or more if it is higher order) there, so throwing away the response 'improvement'? If the intent is to reduce high frequency response, would not a higher order crossover accomplish the job with less effort and expense?

Thanks,

--Ray

Ray,

I'm getting out side my field when it comes to audio. As I said -- An AM radio tuned to talk radio sounds fine to me.

What I gathered from the little bit of reading I did it appears the idea is to present the load from the speaker as clean as it can be made. This would allow the shaping network to have a constant known load. In addition changing the speaker to a new speaker all one would have to do is change the speaker circuit. Leaving the shaping network intact.

Leon
(kc0iv)

 

[Resasi]

Bryan it would appear that limited response on the internet may have ended. One trusts that the members of the Rotary Wing Forum have satisfied a desire for feedback.

 

[Fliterisk1]

Resasi wrote,

Bryan it would appear that limited response on the internet may have ended. One trusts that the members of the Rotary Wing Forum have satisfied a desire for feedback.

From lack of interest? From manner of presentation; whether it be mine, or the spam interfering with discussion. Or maybe they don't know what to ask, or comment on. I have no idea of the percentage of people interested in the technical aspects of speakers. Maybe there aren't that many. Maybe they prefer avoiding a war they are not quite sure of.

It is a do-it-yourself project, and takes time to understand, then to act upon. I'll monitor the thread for a while, and ignore the spam.

It is technical, and has nothing to do with gyroplanes; so it is an unrequested burden. I posted the header with a claim of knowledge, but also of not being an expert. So that leaves ALL of us are scratching our heads wondering what to do with this.

What I had hoped is that enough would just add a Zobel, then note the improvement in sound, then advertise it. THAT is simple. But one can't touch a speaker without doing something about balancing. Balancing was my intent from the start. So balancing became part of the header post.

The first time I used the balancing method it was without the Zobel. It came out very twangy, lots of highs. The boosted highs caused me to recall some info off the net which had pointed out the effects of inductance. I went back and studied, and saw the simple solution to the impedance problem.

With a bit of anger at Speakerlab, and after adding Zobels to woofer and midrange, and rebalancing, that problem was solved. (And praising Speakerlab, for going to the effort to prevent resonance, which I cannot fix.) That anger grew because Speakerlab can't be the only manufacturer not telling the truth. But it was a relief to finally be able to listen to my speakers without saying, "I know something is not quite right..."

I forgot to note that tests should be made while the drivers are in their enclosure. And it wouldn't hurt to repeat the balancing test; to refind the crossover frequencies after attenuating, then re-attenuating. For they can change; especially if there was no attenuation at the start. The procedure is tedious, but I think understandable. This was a major discovery for me.
--
Bryan

 

[Fliterisk1]

Oh, and by the way, we're going to burn it...
Thoroughly, exhaustively; if you get my drift.
Bye the way.
--
Michael