Horn loaded JXR6 which contour HOM suppression

[jzagaja]

Oblate spheroid is a good choice for flat wave input (compression driver). What about cone speakers? Is there any contour that is more suitable?

I need more waveguide than a horn so maybe this is a matter of proper phasing plug (which one?). Geddes in OS waveguide uses 30ppi open cell polyurethane foam but I'm not sure if this is a HOM suppression or a phasing plug.

 

[jzagaja]

Jordan JXR6 has a cone breakup at 2800Hz. It is a resonance that can be annoying in a horn systems (see Bert website, Oris horn) however I cannot say that it is bad after listening my raw driver:

http://www.audiostereo.pl/zalaczniki/670986_1.gif

As you can see the decay <1,5kHz is superb. If we attach front horn then we amplify the mid bass and its rising freq. will help.

What do you think using it in free air with horn? Is it dangerous for the driver working without restoring force?

Corrected JXR6:

http://www.audiostereo.pl/zalaczniki/671895_1.gif

Best Regards and Merry Christmas,

 

[jzagaja]

Horn loaded JXR6 seems to be promising. As expected the amplified frequencies lies on 2Fs/Qe=~500Hz. CSD is very good - better than disc like enclosure I made without taking care of vibration control.

See:

1) Disc like enclosure, ground measurement:

http://ucz.tme.szczecin.pl/~jacek/temp/Measurements/JXR6_vibration.gif

2) Horn loaded:

http://www.audiostereo.pl/zalaczniki/676751_1.gif

3) Rise time example:

http://www.audiostereo.pl/zalaczniki/675250_1.gif

Happy New Year 2007!!!

 

[Bill poster]

jxr6 resonance at 2800 hz? 😕 was thinking to use this for front horn.. will this break up be noticeable?

 

[jzagaja]

Don't waste time on horn loading - phase cancellation is huge. Better take 8" or 12" bass driver from Bandor. Horn requires compression driver.

 

[Bill poster]

Ah ok- I have only seen the jx92s in front horns - so the smaller driver wouldnt work.. I wanted to try it in an Oris type horn or rectangular horn down to 250 hz or so, then cross over to a 15" pro speaker in a BR

 

[jzagaja]

Larger JX92 will be even worse. Do you have any SPL plot for Jordan+horn? It will have falling response and large dip on the mids. Whizzers are different - it's like horn in a horn. Usually such a fullrange in a front horn sounds unaturally big. I don't have Jordan but have 350Hz horn so I can check with 2" fullrange if I find one.

 

[Bill poster]

So wd you class a tannoy westminster as a full ranger? Of course its a much bigger unit and I think the rectangular front horn section goes to 250 hz or so, altho its quite a shallow profile

 

[jzagaja]

Tannoy Dual Concentric is a very nice coax - a true classic. WLM for instance uses cheapest Emminence coax with GDWT compression driver and people love them even if they measure so so. Cone speaker can be used rather as a midrange only. Dome tweeter or ringradiator can be used in a horn with very good results but compression driver offers extra gain and headroom. Few years ago I had JXR6 and Bandor 150. Hope that helps.

 

[Bill poster]

I'm a bit confused - 'horn within a horn' etc.. whats the difference between a small fostex driver and a jordan FR in a front horn, ie not performance, but physically they are similar, right?
The design, contour, shape of the front horn makes a huge difference to the sound - can lead to a closed in or too 'in your face' sound

 

[jzagaja]

If you don't have a whizzer cone (its like conical horn) then high frequencies cancel each other at there's dip corresponding to driver diameter. Jordan resonances at around 10kHz will stand up at least 15dB over the falling response. You need a capacitor to correct falling response and net gain will be small then. Fostex are usually without whizzers so performance will be similar to Jordan. If you like experiment I can supply horns up to 1 meter in diameter - see Auto-Tech

 

[Bill poster]

Yes jx92 has that break up issue but the jordan 2" wouldnt benefit from a wizzer; i just had a look at the freq resp and its pretty flat through the highs (cant see any real break up issues) so am I right in saying its down to the small size of the drive unit that causes problems in a horn? still a bit confused

 

[jzagaja]

Below I've found "horn" loaded JXR6. These are very old graphs from above links that doesn't work. With optimum horn results will be a bit better.