Hello experts,
Sitting with a friend having a glass of wine we were wondering what physical background supports the message at ted jordans site:
"The JXR6 HD has no rear suspension, so the effective low frequency can be adjusted by the volume of the cabinet."
Does anyone know the reason for this?
I can cut off any driver by reducing the size of the enclosure - why should the missing rear suspension make any difference?
Thanks for any comments
kind regards
michael
Sitting with a friend having a glass of wine we were wondering what physical background supports the message at ted jordans site:
"The JXR6 HD has no rear suspension, so the effective low frequency can be adjusted by the volume of the cabinet."
Does anyone know the reason for this?
I can cut off any driver by reducing the size of the enclosure - why should the missing rear suspension make any difference?
Thanks for any comments
kind regards
michael
Here's a technical note from the website:DR ANALOGUE said:
The low frequency response of the JXr-6HD has been extended to a remarkably low limit to enable its in-box performance to be directly matched to appropriate, high quality sub-woofers. To achieve this, the conventional rear suspension has been omitted and the system resonant frequency and 'Q' values are set primarily by the acoustic suspension provided by the volume of air enclosed within a small box.
What I take this to mean, is that to get Fs low enough they did without the spider and therefore recommend only using the driver in sealed cabinet.
I assume it could also be used in open baffle, but would check with Jordan first.
Re: Re: Re: JX6r HD cut off ???
what do you reckon is the safe db/F3 level for the JX6. if they claim it can be mated to a subwoofer it should be able to perfrom pretty low (say 100-120hz) and a reasonable volume (say 95db/1m).
My guess (based on the small size of the cone is that even if teh driver canbe used from 200hz-20kHz and produce 95-100db peaks at 1m it is a fantastic acheivement.
soongsc said:
You might see flying cones at very high listening volume.
what do you reckon is the safe db/F3 level for the JX6. if they claim it can be mated to a subwoofer it should be able to perfrom pretty low (say 100-120hz) and a reasonable volume (say 95db/1m).
My guess (based on the small size of the cone is that even if teh driver canbe used from 200hz-20kHz and produce 95-100db peaks at 1m it is a fantastic acheivement.
Re: Re: Re: Re: JX6r HD cut off ???
The flying cone was referring to open baffle implementation.
I have used the JX53 crossed over at about 450Hz, the main reason is allowing both drivers to take an even amount of the average power spectrum. If I went to using the JX6r HD, I probably would do the same to get the best dynamics. If I used an array, I would probably consider going down to 200Hz.
navin said:
The flying cone was referring to open baffle implementation.
I have used the JX53 crossed over at about 450Hz, the main reason is allowing both drivers to take an even amount of the average power spectrum. If I went to using the JX6r HD, I probably would do the same to get the best dynamics. If I used an array, I would probably consider going down to 200Hz.
The note about using the JXR6 in sealed enclosures is partly to indicate the recommended use. Although I've seen it chugging away happily at low frequencies whilst placed on Ted's workbench, he mentioned that he couldn't guarentee it's performance in anything other than a sealed enclosure. That's not to say he ruled it out if you want to experiment ... MLTL anyone?
I've tried the JX53 in an Augsperger offset TL (tuned to 120Hz) but it didn't work too well - it sounded very thin, with almost no output below 200Hz. I've put the JXR6 in the same line and it did better and was audible to 90Hz. The balance was still a bit off, so maybe the line CSA wasn't high enough. Sealed boxes should be up and running this weekend ...
I've tried the JX53 in an Augsperger offset TL (tuned to 120Hz) but it didn't work too well - it sounded very thin, with almost no output below 200Hz. I've put the JXR6 in the same line and it did better and was audible to 90Hz. The balance was still a bit off, so maybe the line CSA wasn't high enough. Sealed boxes should be up and running this weekend ...
Re: Re: Re: Re: JX6r HD cut off ???
You really need a 4-array for these have acceptable headroom at 100hz. You could get away with a 2-array if you HP it at about 100hz, prefferable active 2:nd order. A single driver cant produse much soundpreassure down at 100hz. You need to stay out of mehanical clipping, it sounds awful on these drivers. However, if you fullfill the above, you're have a very very nice sounding speaker.
/Jesper
navin said:
You really need a 4-array for these have acceptable headroom at 100hz. You could get away with a 2-array if you HP it at about 100hz, prefferable active 2:nd order. A single driver cant produse much soundpreassure down at 100hz. You need to stay out of mehanical clipping, it sounds awful on these drivers. However, if you fullfill the above, you're have a very very nice sounding speaker.
/Jesper
WHat do you guys think about using the JX6R as nearfield monitor with a single driver per speaker and active 2nd order HP filter @100Hz? You dont need such huge SPLs with when listening from a couple of feet away, in fact its more like a headphone experience.
Colin made a note in a different thread that this speaker needs to be toed in, so the front baffle of the speaker could be made with a relevant toe in slope left to right. I'm also not convinced that the off axis response of a driver is such a big issue when listening nearfield as it appears to be much less critical than when listening in a 'farfield' or normal room situation where the speakers are many feet away from the listener.
Regards,
Dean
Colin made a note in a different thread that this speaker needs to be toed in, so the front baffle of the speaker could be made with a relevant toe in slope left to right. I'm also not convinced that the off axis response of a driver is such a big issue when listening nearfield as it appears to be much less critical than when listening in a 'farfield' or normal room situation where the speakers are many feet away from the listener.
Regards,
Dean
deandob said:
2:nd order @100hz will be fine for nearfield. If you sit some feets away and use somthing like 1.8-2L closed box you might get away without the filter.
I think the Jxr6 is pretty flat on-axis as is. The reckommendation of listening 30 deg off-axis require some compensation to lift the HF on-axis. However, doing this provides a good, stabile stereo image.
/Jesper
JXR6 used nearfield would be pretty good and the toe in would be less of an issue (it's recommended to provided lateral stability when moving left and right in front of the speakers, ie it compensates for precedence effect when the nearest speaker sounds loudest and shifts the image that way). I think Ted recommends near 4 litres for 100Hz response but it depends on what Q you're aiming for. There's something about it on the site. My little boxes will be around 2.4 litres so when done I'll put some test tones through them and see how low they go.
Re interpolar whatsits - Ted designs the units so they are used close together to reduce this in his array. FWIW, I've only ever noticed a shift in response when moving above the level of the top driver, out of the vertical field, then the HF drops off slightly. this was sitting about six feet away. Farther away the effect would be less.
Re interpolar whatsits - Ted designs the units so they are used close together to reduce this in his array. FWIW, I've only ever noticed a shift in response when moving above the level of the top driver, out of the vertical field, then the HF drops off slightly. this was sitting about six feet away. Farther away the effect would be less.
To be honest I've floated this question multiple times with no satisfactory response. Seventh Veil uses same idea with four Bandor drivers per side, and no-one seems to find problem with those, either.navin said:
My guess is that such a short array (8 inches, after all) mitigates these issues. If it were longer, I suspect it would become audible.
P.S. When I have the time I'll try running numbers using formulae from Jim Griffin's nflawp.
Some time ago Steve from 7th Veil ran a test where he filtered his drivers to roll off the outer two and reduce interference. If I call right, he said it did reduce the loss of HF when above the line of the drivers but he prefered the sound without the crossover components.
I wonder if some people are more sensitive than others to this effect. In any case, Ted's drivers tend to confound some of the usual rules.
I wonder if some people are more sensitive than others to this effect. In any case, Ted's drivers tend to confound some of the usual rules.
Interesting. Thanks for the post.Colin said:
Have you checked out this driver:
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=264-830
Of course not nearly as good as Jordan or Bandor, but could conceivably work in mini-array. CTC distance the same as JX53. Fs=150Hz though.
An externally hosted image should be here but it was not working when we last tested it.
Colin said:
I suspect you are right. The funny thing is that in a HT-AV application like I was planning it may work since there are 5 speakers. however even if one was to limit it is 2 drivers per speaker it becomes 10 drivers at $150 each that is $1500 only on drivers. Expensive right? :-(
In a stereo application since the needs are a bit more stringent Steve's system would still cost $1200 for drivers alone.
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