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K-402 in wood!

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Unfortunately conduct measurements fail. I live in a rented apartment, which has bad acoustic properties get rid of which I can not. When it can immediately make measurements and show them on the forum.

Regarding the possibility of absorbing wood I managed to some extent overcome by using а shellac.

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Quadrokot,

 

Also look at the concentricity of the driver on the horn's throat - a millimetre or two of offset relative to truly concentric is definitely measurable acoustically.  Increasing the depth of the hard shellac layer on the inside of the horn's walls in the throat area will also improve performance. 

 

When you get a chance, a calibration microphone connected to your computer (assuming it is at your manufacturing/test location) like the UMIK-1 from miniDSP, along with a cable to connect to your preamp (HDMI, USB, RCA analog, etc.) to drive upsweeps from your computer running  Room EQ Wizard (REW) or something similar will allow you to make measurements, even in a cramped apartment.  Use a close microphone distance like a half metre or even closer to the plane of the horn's mouth to get reasonable in-room measurements.

 

Really nice woodwork, by the way.  I bet it's a real time investment.  It looks a bit intimidating for the average DIYer.

 

Chris

Edited by Chris A
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What are the views on the use of driver JBL 2485? Now use Faital 200.

  I was a bit lacking midbass and lower middle. The frequency distribution of crossover 500 Hz 6000Hts.

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What are the views on the use of driver JBL 2485? Now use Faital 200.

I was a bit lacking midbass and lower middle. The frequency distribution of crossover 500 Hz 6000Hts.

I have those faitals, they sounded good on the EV hp640. I now have Ev hp9040 with evdh1a, i have not had an opportunity to switch the Faitals in place of the EV drivers to compare. My Jamboree can be crossed as high as 600hz if not higher. Have you tried higher crossover point, you may not gain much other than taking stress off of the faital at lower frequency. If you have access to them, give the EV dh1a a try.

Sent from my SM-N920P using Tapatalk

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A bit of a sidenote. Are there any compression drivers that have low distortion down to 500 Hz?

I haven't any seen any. Drivers like JBL 2445, 2446, 2447 and other brands have an increasing distortion below 800 Hz. And those who have experienced a lot with this (measured and listened) say the absolute lowest crossover should be 600 Hz but they claim it often sounds better when crossed over somewhat higher (700-800 Hz).

 

So despite that a horn like K-402 can be crossed over very low, and I'm not certain it's the better solution all together. Personally I haven't experience much with this though.

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"Distortion" is a bit ambiguous.  I suppose you're talking about harmonic distortion, which is easy to measure.  If so, then...

post-26262-0-83220000-1445464684_thumb.p

 

I'm crossing the K-402 with TAD TD-4002 driver at 425 Hz,48 dB/octave L-R to the Jubilee bass bins, then at 40 Hz to the TH subs.  Microphone 1 metre in front of the left Jubilee centered at the K-402/bass bin interface.

 

I don't see any evidence of what you're describing.  In fact, it gets better.  The in-room SPL is about 100 dB instead of the 120 dB shown.

 

Chris

Edited by Chris A

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"the absolute lowest crossover should be 600"

 

I found the minimum on the 2380/2445 combo was 650hz, and that was at a 100mW drive level (about 100dB).

 

There are aluminum diaphragms still available, Meyer Sound removed titanium from new drivers and replaced with aluminum. 

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"Distortion" is a bit ambiguous.  I suppose you're talking about harmonic distortion, which is easy to measure.  If so, then...

attachicon.gifLeft Jub + subs 2 Dec 2014.png

 

I'm crossing the K-402 with TAD TD-4002 driver at 425 Hz,48 dB/octave L-R to the Jubilee bass bins, then at 40 Hz to the TH subs.  Microphone 1 metre in front of the left Jubilee centered at the K-402/bass bin interface.

 

I don't see any evidence of what you're describing.  In fact, it gets better.  The in-room SPL is about 100 dB instead of the 120 dB shown.

 

Chris

Yes. I meant harmonic distortion.

 

You say the in-room level SPL is 100 dB. Is that the correct level at 1 meter and what you have measured with?

Could you measure with 105 or 110 dB and post it?

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That plot was ~100 dB at my listening position, 3+ metres away, as measured by my handheld SPL meter ("C" scale).  The microphone was at 1 metre from the mouth/front panel of the Jubilee.

 

Chris

Edited by Chris A

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Bjorn,

 

I looked up a succeeding plot that I made at 1 metre on my right surround Cornwall (EQed flat but without time delay correction) where I obviously recalibrated the microphone level.  The average is 105 dB at 1 metre for that and succeeding plots on that day, all taken at a measured 1 metre in front of each loudspeaker.  I've attached the plot below for reference. Sorry for the delay in showing you the data that proves the calibrated in-room SPL. 

 

Schu,

 

You asked about the time delays in a Cornwall in Cornman's thread where he was selling his Jubilees.  The plot below will show you how much the bass bin leads the midrange in a 1979 Cornwall.  I can't show you all the phase shift between the tweeter and midrange because REW cannot scale out far enough to show the total phase shift: it's an even bigger shift--measured in a few wavelengths (multiples of 360 degrees). The current plot is zoomed out all the way in terms of the phase vertical axis, and I'm still having trouble getting it all on the plot.

 

post-26262-0-42400000-1445972300_thumb.p

 

Chris

Edited by Chris A

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"does anyone know if it is possible to put K402 in a 3D scanner?"

 

Sure (but you will go broke).

 

"I would like to hear PSE-144 and K402 in a A/B test. I think PSE-144 will outperform K402."

 

Might.

 

I intend to build a 27hz 100dB+ dual 12 PPSL crossed at 300hz to that style of mid-HF, it will be the same size as the LaScala.

 

unity28.jpg

 

This is William Cowan's copy of a Danley product, I would use smaller drivers, perhaps 6-1/2's or even 5's (the Danley uses 8's and goes to 90hz). I can make the horn elliptical out of FG and resin.

Are there plans for something like this?  I have seen several of these online, built by diyers.

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Yes.  Here is Bill Waslo's Synergy Horn Spreadsheet:  http://www.libinst.com/SynergyDIY/V3/Synergy%20Calc%20v3.xls and the help file: http://libinst.com/SynergyCalc/Synergy%20Calc%20V5.pdf

 

...and a DIY thread discussing all the crossover-related stuff: http://www.diysoundgroup.com/forum/index.php?topic=19.0

 

The spreadsheet will tell you the cuts required and the thread will discuss specific construction stuff

 

Chris

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By the way, the original Unity Horn patent expired in late 2013 due to non-payment of mid-life update fees.  That patent was assigned to Sound Physics Labs.  The patent number is US 6,411,718, 25 July 2002.

 

The follow-on patent by Danley Sound Labs (US 8,284,976, 29 Oct 2012) on Synergy Horns cannot patent the same invention twice, so the original Unity Horn patent is now public domain:  you can build Unity Horns--exactly the same thing as a Synergy Horn without the special passive crossovers having the proprietary (i.e., never discussed in the patent) essentially zero phase errors--without any interference from the original patent holders or from Danley Sound Labs, who never owned that original multiple-entry horn patent by Sound Physics Labs.

 

Chris

Edited by Chris A
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The EAW CP621, and various Renkus-Heinz predate the Danley.

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Yes, that is correct, but those designs make use of multiple apertures, while the Unity horn was the first to use a single conical horn aperture.  That's Danley's claim to fame.  Unfortunately, Danley didn't own the patent of the invention that he created, and the owner of the company that did let it lapse. That was a big mistake, IMO.

 

Chris

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EAW%20CP621.png

Two mid drivers on a single conical horn with the HF driver at the apex of the horn.

Edited by djk

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Yes.  Here is Bill Waslo's Synergy Horn Spreadsheet:  http://www.libinst.com/SynergyDIY/V3/Synergy%20Calc%20v3.xls and the help file: http://libinst.com/SynergyCalc/Synergy%20Calc%20V5.pdf

 

...and a DIY thread discussing all the crossover-related stuff: http://www.diysoundgroup.com/forum/index.php?topic=19.0

 

The spreadsheet will tell you the cuts required and the thread will discuss specific construction stuff

 

Chris

This is some good info, I have done a little reading and am intrigued.  Once done with the build I am on now, I would like to look at mid/hf horn builds.

 

Thanks

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Yes.  Here is Bill Waslo's Synergy Horn Spreadsheet:  http://www.libinst.com/SynergyDIY/V3/Synergy%20Calc%20v3.xls and the help file: http://libinst.com/SynergyCalc/Synergy%20Calc%20V5.pdf

 

...and a DIY thread discussing all the crossover-related stuff: http://www.diysoundgroup.com/forum/index.php?topic=19.0

 

The spreadsheet will tell you the cuts required and the thread will discuss specific construction stuff

 

Chris

This is some good info, I have done a little reading and am intrigued.  Once done with the build I am on now, I would like to look at mid/hf horn builds.

 

Thanks

 

 

I was just thinking the same thing.

 

Can't find any squawkers for my La Scala build without blowing the whole budget out of the water. :(

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Funny I was looking at trying to use my four 3.3" drivers with possibly a DE250 CD on a mid horn over an 18". Keep seeing threads like these to remind me to start something already. :D

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