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Multi-Way Conventional loudspeakers with crossovers

SynTripP: 2-way 2-part Virtual Single Point Source Horn
SynTripP: 2-way 2-part Virtual Single Point Source Horn
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Old 8th November 2014, 03:59 AM   #11
ErnieM is offline ErnieM  United States
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Quote:
Originally Posted by weltersys View Post

"Classic" HF drivers do not use FF, if operated in clean air (no floating ferrous metal particulate) they will last almost forever. FF, like any oil, will be contaminated by airborne debris and eventually "go bad".
My replacement apt-80 diaphram job must be filthy lol. It was my first project which was mainly used in a shop setting. Will take a look at it sometime.
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Old 8th November 2014, 05:02 PM   #12
BYRTT is online now BYRTT  Denmark
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SynTripP: 2-way 2-part Virtual Single Point Source Horn
Default XO and filter data studied

Quote:
Originally Posted by xrk971 View Post
.....Is that 800Hz -24dB/oct?.....
By curiosity i studied picture two post 9 allow me from that study to post this:

LF section
HP 75Hz BW24dB gain 0dB / LP 950Hz LR24dB gain -3dB
PEQ 132Hz Q2,63 +7dB
PEQ 560Hz Q2,03 -7,5dB

HF section
HP 800Hz BW24dB gain 0dB
PEQ 1180Hz Q1,22 -2dB
PEQ 4250Hz Q2,03 -4,5dB
PEQ 12500Hz Q3,41 +4dB

More unshure parameters:
A parameter says 250Hz gain -1,5dB, guess could be a high shelfe in LF section.
A parameter says delay 0,4mS the other 0,0mS, quick guess LF delayed 0,4mS because of physical placement but don't known if the acoustic bandpass for LF section would take time and demand the HF section to wait fire and the delay placed here.
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Old 8th November 2014, 08:34 PM   #13
weltersys is offline weltersys  United States
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Quote:
Originally Posted by xrk971 View Post
Art,
Thanks for posting the XO plot - looks beautiful. Is that 800Hz -24dB/oct?
The 10" "mid" is using a 800 Hz BW (Butterworth- sharper cutoff at the crossover frequency) and the 1.4" exit "high" is using a 950 Hz LR (Linkwitz-Rieley, softer cutoff at the crossover frequency), the high output is delayed by .4 ms. The 10"s have more clean output potential at 800 Hz than the HF driver, raising the HF crossover point to 950 Hz reduces HF THD (total harmonic distortion) by quite a bit at high drive levels, the electrical "underlap" (gap between mid and HF crossover points) results in a smooth acoustic frequency and phase response in the crossover region.

Previous tests had used a production sample of the CDX14-3050 HF driver with a 16 ohm diaphragm, for best phase alignment the output polarity had to be reversed when wired with the positive (+) signal to the right hand side red terminal.

The 16 ohm version of the CDX14-3050 is only available to OEM (original equipment manufacturers) in orders of 96 units or more, so to get a matched pair required purchase of a standard CDX14-3050 (8 ohm) and an additional 8 ohm replacement diaphragm.
If anyone is looking for a spare 16 ohm CDX14-3050 let me know!

After replacing the old 16 ohm diaphragm with a new 8 ohm diaphragm, the polarity now had to be "normal" with the positive wire to the right terminal. This particular diaphragm is self aligning, the terminals go through holes in the compression chamber back cover, the back holes align the diaphragm so the flexible lead in flat wires are properly placed in two "divots" in the magnetic gap.

There are three possible reasons for the change in polarity:
1) I accidentally installed the diaphragm upside down, then plugged the spade connector to the right terminal, which had become the negative terminal.
2) The 16 ohm production sample I received is wired opposite polarity to the current 8 ohm version.
3) One of the two diaphragms was labeled incorrectly at the factory.

#1 is the most likely, I'll find out when I finish cabinet #2 and check it's HF polarity, and will probably have to open up the box for the fifth time to flip the diaphragm.

Art
Attached Images
File Type: jpg Celestion CDX14-3050.jpg (218.4 KB, 2378 views)
File Type: png Celestion CDX14-3050 16 ohm Side.png (424.7 KB, 1881 views)

Last edited by weltersys; 8th November 2014 at 08:46 PM.
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Old 9th November 2014, 11:17 PM   #14
nc535 is offline nc535
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Hi Art;
Nice result!

I'm intrigued by the fact that your measurements showing response with 1,2,3,4 mid vents plugged showed the response changing at both the low and high ends. The change of box tuning is of course expected. Why does the response change up near crossover? Is that simply evidence that the holes are too large too hide in the corners, so to speak? (assuming that is where they are, they aren't visible in the photos)

Jack
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Old 10th November 2014, 02:21 AM   #15
xrk971 is online now xrk971  United States
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SynTripP: 2-way 2-part Virtual Single Point Source Horn
How is it possible to mount diaphragm upside down? Isn't concave?
Click the image to open in full size.
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Old 10th November 2014, 02:48 AM   #16
weltersys is offline weltersys  United States
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Quote:
Originally Posted by nc535 View Post
Hi Art;
Nice result!

I'm intrigued by the fact that your measurements showing response with 1,2,3,4 mid vents plugged showed the response changing at both the low and high ends. The change of box tuning is of course expected. Why does the response change up near crossover? Is that simply evidence that the holes are too large too hide in the corners, so to speak? (assuming that is where they are, they aren't visible in the photos)
Jack,

The upper 10" response changes because the BR (bass reflex) port has a pipe resonance peak that is out of phase with the woofer's offset horn output, causing differing null depth depending on the amount of ports used.

The 10" offset port holes also affect the HF (high frequency) response slightly, they don't completely "hide in the corners", but that is a different issue than the BR (bass reflex, AKA phase inversion) port response pipe resonance, a "feature" any BR design shares to a lesser or greater degree dependent on the length of the BR port.

As mentioned in the OP, the slight HF response changes the 10" offset port holes cause in the SynTripP are more than offset by the smooth vertical polar response that can't be achieved with LF and HF drivers located with a vertical separation distance near the wavelength at the crossover frequency.

Art
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File Type: png SynTripP port response.png (137.4 KB, 1736 views)

Last edited by weltersys; 10th November 2014 at 02:52 AM.
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Old 10th November 2014, 04:25 PM   #17
unaHm is offline unaHm  United States
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Originally Posted by xrk971 View Post
How is it possible to mount diaphragm upside down? Isn't concave?
I wonder if Art meant that it was rotated 180 degrees, so the 'top' of the diaphragm was on the bottom, and the terminals were reversed...?

I may have a PA application for these at some random point, but that would involve that particular band buying the drivers

Are the SynTripP speakers completely unnecessary for home use?
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Old 10th November 2014, 05:00 PM   #18
weltersys is offline weltersys  United States
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Quote:
Originally Posted by unaHm View Post
I wonder if Art meant that it was rotated 180 degrees, so the 'top' of the diaphragm was on the bottom, and the terminals were reversed...?

Are the SynTripP speakers completely unnecessary for home use?
Correct, diaphragm reversal left and right, "upside down" in reference to the driver's orientation in the cabinet.

Have not listened to the SynTripP indoors yet, after the second is complete will compare them with my home stereo speakers, and report if they then become a necessity .
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Old 10th November 2014, 05:20 PM   #19
Zero D is offline Zero D  United Kingdom
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I've known drivers, LF & HF, to have their magnets reversed by mistake during manufacture. Famous makes too Something to be aware of !
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Old 10th November 2014, 06:32 PM   #20
xrk971 is online now xrk971  United States
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SynTripP: 2-way 2-part Virtual Single Point Source Horn
Quote:
Originally Posted by Zero D View Post
I've known drivers, LF & HF, to have their magnets reversed by mistake during manufacture. Famous makes too Something to be aware of !
Never thought of that possibility. Maybe VC windings are clockwise vs counter clockwise or vice versa?
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