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Old 23rd January 2006, 07:02 PM   #1
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Default JX6r HD cut off ???

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
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Old 24th January 2006, 01:11 AM   #2
soongsc is offline soongsc  Taiwan
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Default Re: JX6r HD cut off ???

Quote:
Originally posted by DR ANALOGUE
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
Not really that simple, there are lots more design issues involved. If you do that on any driver, all you will get is a damaged driver.
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Old 24th January 2006, 01:27 AM   #3
Dumbass is offline Dumbass  British Antarctic Territory
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Default Re: JX6r HD cut off ???

Quote:
Originally posted by DR ANALOGUE
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?
Here's a technical note from the website:

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.
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Old 24th January 2006, 03:31 AM   #4
soongsc is offline soongsc  Taiwan
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Default Re: Re: JX6r HD cut off ???

Quote:
Originally posted by Dumbass
Here's a technical note from the website:

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.
You might see flying cones at very high listening volume.
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Old 24th January 2006, 09:02 AM   #5
navin is offline navin  India
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Default Re: Re: Re: JX6r HD cut off ???

Quote:
Originally posted by soongsc


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.
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Old 24th January 2006, 09:42 AM   #6
soongsc is offline soongsc  Taiwan
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Default Re: Re: Re: Re: JX6r HD cut off ???

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Originally posted by navin


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.

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.
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Old 24th January 2006, 11:42 AM   #7
Colin is offline Colin  United Kingdom
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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 ...
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Old 24th January 2006, 12:05 PM   #8
soongsc is offline soongsc  Taiwan
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I normally add some compensation to raise the low end, and then JX53 seems more balanced on it's own without a woofer. Great for vocals and easy listening.
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Old 24th January 2006, 04:20 PM   #9
Colin is offline Colin  United Kingdom
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Yeah, I think it was the combination of line and 53 which wasn't working. Adding compensation did balance it out but I'd still heard it sounding better in a 3 litre sealed box.
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Old 24th January 2006, 07:43 PM   #10
Dumbass is offline Dumbass  British Antarctic Territory
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I don't believe that an open baffle unloads the driver at low freqs the way a vented enclosure does. Somebody correct me if I'm wrong.
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