DIY Newbie; JX92S vs. FE207E ?

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Hello everyone,

I'm new to this forum and to speakerbuilding. I like to build speakers with a fullrange driver for music and HT. My currently favoured drivers would be:

- Jordan JX92S
- Fostex FE207E
- Fostex FE207E + Super-Tweeter

Music quality is more important than HT usability. My favorit music is jazz and classical music. I would use any of these system only down to 70-80 Hz (with a active crossover) and add a subwoofer fol LF.

I hope you can help me with the following questions:

1. Is the JX92S capable to create enough dynamical output to reproduce large symphonics (e.g. Mahler, Beethoven, Tchaikovsky etc.)?

2. How well/clean will a FE207E reproduce upper-midrange and trebles?

3. Will a Super-Tweeter for a FE207E only extend the frequency range to 30 kHz or will it also enhance imaging and soundstage with and depth?

4. Since I want to use a LF crossover-frequency between 70 and 80 Hz is relevant if the driver is in a BR-cabinet or ML(TW)TL-cabinet?

Thanks for any help/input

Frank
 
It is just free advice, but here goes:

4. Since I want to use a LF crossover-frequency between 70 and 80 Hz is relevant if the driver is in a BR-cabinet or ML(TW)TL-cabinet?

I would advice crossing at 100 Hz, use a second order on the Jordan and fourth order low pass on the sub woofer. This will allow you to play the Jordan to its power limit and not exceed Xmax. To further decrease excursion demands for the Jordan, I advise using a sealed cabinet design (and for better matching of sub to Jordan).

1. Is the JX92S capable to create enough dynamical output to reproduce large symphonics (e.g. Mahler, Beethoven, Tchaikovsky etc.)?

How loudly do you need it to play? Where would you be sitting in the concert hall for a large symphonic performance? If you have enough input power, the Jordan will easily reproduce 100db SPL at typical listening location. Generally the lower you go, the louder sound becomes. With the sub woofer, the Jordan should be able to do what you want it to.

2. How well/clean will a FE207E reproduce upper-midrange and trebles?

I know that there are fans of Fostex, but if you value accuracy of reproduction, then the choice is the Jordan.

3. Will a Super-Tweeter for a FE207E only extend the frequency range to 30 kHz or will it also enhance imaging and soundstage with and depth?

For beginners, simple is always best. Good sounding crossovers are difficult to design. Adding a super tweeter will most likely decrease reproduction accuracy.

As a self-described beginner, the simpler the design the better. Start with high quality drivers keep crossovers and augmentation in the regions where hearing sensitivity is low.

Good designing and good building,

Mark
 

I would advice crossing at 100 Hz, use a second order on the Jordan and fourth order low pass on the sub woofer.


The HT-Amp (Cambridge Audio 540R) has a fixed XO-frequency of 80 Hz and I thought it would be best to use with this frequency or just a little lower for the Front-LS. I also planed to have only a single subwoofer and I thought 80 Hz is the limit for not locating the sub?


To further decrease excursion demands for the Jordan, I advise using a sealed cabinet design (and for better matching of sub to Jordan).


I thought a driver in a sealed cabinet has to do more excursion to produce the same SPL as if it would be in a BR cabinet?


How loudly do you need it to play? Where would you be sitting in the concert hall for a large symphonic performance? If you have enough input power, the Jordan will easily reproduce 100db SPL at typical listening location. Generally the lower you go, the louder sound becomes. With the sub woofer, the Jordan should be able to do what you want it to.


My livingroom is 12 x 20 x 8.5 ft. Speakers at the 12 ft wall 6-7 ft apart and listening distance of 6-8 ft. Moderate average listening level for the low dynamic parts of the music (60-75 dB ????).

Frank
 
The one and only
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Certainly the Fostex is much more efficient than the Jordan
and will generally deliver more dynamic range, but the
J92s is a bit smoother.

The FE206E and FE207E both could use a little shaping, which
I like to accomplish by loading a current source amp, but which
can also be done with a voltage source. The Jordans do not
need any equalization.

And of course the Fostex is less expensive.
 
Frank,

I thought a driver in a sealed cabinet has to do more excursion to produce the same SPL as if it would be in a BR cabinet?

Of course it all depends. At resonance, the BR design requires less cone motion because the box air mass in resonance is producing the sound. Below this tuning frequency, excursion with decreasing frequency increases more rapidly than it would in a sealed box. This even while acoustic output is falling off faster than in sealed. This complicates crossover design. While the polarity at box resonance is constant, off this peak (both above and below), there are some complex acoustic center, phase, polarity (however you want to describe it) stuff going on with ported designs. Also, tuning the box to say 80 or 100 Hz may cause complications just in the ported design (ripple or a bigger/more ringing bump in midbass output than in a too small sealed). You may have less excursion at 100 Hz but not like the sound.

If you can handle all the complications of ported designs, then there is no absolute reason not to. If you are a sensible beginner and feel intimidated by all the complications, then sealed may be for the best (sound). Remember, this is all just free advice and does not cost you anything to ignore it.

Again, best of luck to you. Let us know when you are finished and what you think of your completed project,

Mark
 
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