Bottlehead Forum

Other Gear => Speakers => Topic started by: keto on June 22, 2011, 11:02:01 AM

Title: 550hz Azura horn on a JBL 2420 driver
Post by: keto on June 22, 2011, 11:02:01 AM

I just got a pair of Martin Seddon's "Jean LeCleac'h" expansion horns. I'm using the parts from a pair of JBL 4320's and the new horn is a major improvement -- to my ears -- compared to the original exponential one.

Title: Re: 550hz Azura horn on a JBL 2420 driver
Post by: xcortes on June 22, 2011, 06:38:40 PM

cool!

Title: Re: 550hz Azura horn on a JBL 2420 driver
Post by: Grainger49 on June 23, 2011, 01:06:35 AM

Looks like it should have a stamen in the middle (part of a flower).  Cool looking!

Title: Re: 550hz Azura horn on a JBL 2420 driver
Post by: keto on June 23, 2011, 08:09:04 AM

Hey Grainger, and if it were a BH product, we'd call it a phase-pistil :-) Come to think of it, the sound does seem to "blossom" from these horns. Hmm, now I'm jonesing to take some real-life measurements.

Title: Re: 550hz Azura horn on a JBL 2420 driver
Post by: groomster on June 23, 2011, 08:11:46 AM

Keto,

     Horns look kewl!!!  Perhaps you can shed some light on them?  How do they compare to regular speakers?  You are opening up a whole new area to my hobby!!!

groomster

Title: Re: 550hz Azura horn on a JBL 2420 driver
Post by: keto on June 23, 2011, 08:29:01 AM

Here's a link to Martin Seddon's site...
http://www.azurahorn.com/index.html
and the close-mic frequency response of the combo that first caught my attention...
http://www.azurahorn.com/JBL2420_on_550.pdf
Also, I have a too-big PDF file of a Jean LeCleac'h article that I can send via e-mail

Title: Re: 550hz Azura horn on a JBL 2420 driver
Post by: xcortes on June 23, 2011, 08:30:24 AM

You're crossing over at 800hz?

Title: Re: 550hz Azura horn on a JBL 2420 driver
Post by: keto on June 23, 2011, 08:53:48 AM

The JBL 3110 network is 2nd/2nd order (phase inverted) @ 800hz.
Jean LeCleac'h recommends an octave above cut-off as optimum.
Martin Seddon's measurements include 4th order high passes @ 350 and 700hz.

If only there was a multi-amped system nearby, SET-up with a high-pass @ about 800hz....

Title: Re: 550hz Azura horn on a JBL 2420 driver
Post by: Grainger49 on June 23, 2011, 09:26:52 AM

Keto,

You are not near Bottlehead World Headquarters, are you?  Doc has multi-amped speakers.

Your horns remind me of these at VSAC 2008 (this is the first time I have seen time aligned drivers in horns, first one I know about):

Title: Re: 550hz Azura horn on a JBL 2420 driver
Post by: xcortes on June 23, 2011, 09:30:25 AM

Actually he's near Bottlehead International HQs. And there's a multiamped system there too. I guess I was the recipient of his message :)

Title: Re: 550hz Azura horn on a JBL 2420 driver
Post by: tubeglow on June 23, 2011, 10:10:10 AM

Quote from: Grainger49 on June 23, 2011, 09:26:52 AM

Keto,

You are not near Bottlehead World Headquarters are you?  Doc has multi-amped speakers.

Your horns remind me of these at VSAC 2008 (this is the first time I have seen time aligned drivers in horns, first one I know about):

I was there and saw those monstrosities. How big of a room would you need to get them to their potential? I showed my wife a picture of them and told her I had ordered a pair. She nearly fainted.

Title: Re: 550hz Azura horn on a JBL 2420 driver
Post by: keto on June 23, 2011, 12:02:14 PM

I was thinking of Xavier's rig, which is a little closer. Of course, his RCA field coils would probably eat my JBL2420's for lunch :-)

Title: Re: 550hz Azura horn on a JBL 2420 driver
Post by: xcortes on June 23, 2011, 01:03:32 PM

I don't think my midbasses can be xoed as high as 800 hz.

But we could use my two sex amps and implement a pllxo on the bass (maybe 2nd order) and a first pass on the other reducing the size of the parafeed cap.

What impedance are your CDs?

Title: Re: 550hz Azura horn on a JBL 2420 driver
Post by: keto on June 23, 2011, 02:01:39 PM

The CD's are 16-ohms. I think it would be best to head towards a net 4th-order alignment, especially if below 1khz. Maybe when the sun comes back out I could bring 'em over and we could measure their output vs frequency, and go from there? At the moment there's distortion on orchestral peaks and I'm suspecting/hoping that its due to the aging passive XO's. Here's the passive XO schematic which in addition to compensating for varying impedance on both drivers, predicts slopes which seem pretty bizarre. Both drivers are -7.5dB @ 900hz, for example.