Zobel with Jordan JX92s fullrange?

[cheesehead]

So, I've built the GM/Abpea "first draft" Jordan JX92s MLTL's. Described right here. They're beautiful. Right now I'm listening to Michael McDonald's "Motown" - I still jump at some of the percussion, it's that good.

But I want to add baffle step compensation, 'cuz Michael's a little weak. OK, I can do inductors & follow formulas, and get about a 2 mH inductor || with a resistor I'll play around with to match the room. But I noticed that Martin King & Bob Brines have included a zobel with their Fostex full-range designs... on the other hand, from what I can find Jim Griffin's Jordan design does not.

Should I include a zobel for the Jordan?

mk

[cheesehead]

oh, and, doh, I'm driving it with your average commercial 5.1 solid state receiver...

[GM]

Interesting! You are the first person I am aware of that has felt it needed some BSC. Anyway, yes, I would try a Zobel. Just using the published specs/plot, I get 5.625 ohms/5.053 uF to reactance annul Re (assumes 4.5 ohms). Really, with a Zobel, you may not feel the need for any BSC.

Anyway, please let us know the results and what you wound up using.

GM

[tcpip]

Newbie question: the Jordan Website has recommendations of RL pairs to use with the JX92S in their standard boxes. These, I thought, were to strengthen the bottom end. Are these for BSC purposes?

[navin]

hey TCPIP what box did you build for your JX92?

[Timn8ter]

I'm driving it with your average commercial 5.1 solid state receiver.

Could we be seeing the difference between voltage and current source and/or a damping factor contribution?

[GM]

Originally posted by tcpip
Newbie question: the Jordan Website has recommendations of RL pairs to use with the JX92S in their standard boxes. These, I thought, were to strengthen the bottom end. Are these for BSC purposes?

Yes, though different values may be required for your app.

Originally posted by Timn8ter

Could we be seeing the difference between voltage and current source and/or a damping factor contribution?

AFAIK, all the other folks who have built the various ML-TLs are using SS, and while it's possible the receiver is 'laying down' if it's not rated for < a nominal 8 ohm load, I doubt it. Regardless, a Zobel and/or series resistor should remedy the problem.

GM

[tcpip]

Originally posted by navin
hey TCPIP what box did you build for your JX92?

Ordinary ported box, a little less than 18" tall on the outside. This is from the Jordan Website. I haven't tried GM's MLTL yet, though he had posted some of those details on this Website in response to one of my questions. GM and 7V had both been very helpful and encouraging. But I've since got caught up in another project.

[tcpip]

Originally posted by GM
Yes, though different values may be required for your app.

Okay, thanks. Will try it out and listen... haven't fitted any BSC on my ported box, and the sound does sound thin half the time.

[cheesehead]

Originally posted by GM
Interesting! You are the first person I am aware of that has felt it needed some BSC. Anyway, yes, I would try a Zobel. Just using the published specs/plot, I get 5.625 ohms/5.053 uF to reactance annul Re (assumes 4.5 ohms). Really, with a Zobel, you may not feel the need for any BSC.

Anyway, please let us know the results and what you wound up using.

GM

Preliminary report - I used this Zobel & a parallel 1.2 mH/2.5 ohm resistor for BSC. Yuck! Sounds muddy, boomy, like I put the speakers inside of a cardboard box. High end treble gone? I've gotta get a mic & preamp & start measuring frequency.

FWIW, I also included a driver brace as recommended in the original thread.

Of course, I put the zobel & BSC inside of the box, since I was "finishing" it . (They now they look great, just sound awful) This weekend I'm going to pull it out, re-stuff, and try the darned thing again, but with just zobel, just BSC (and do them external), just driver brace... the way I should have.