Flex Your PCD Mettle:

[Pete Schumacher ®]

Zilch, what is the mic distance and driver placement relative to the mic location?

I'm getting ready to PCD it and would like to get the vertical offsets from the mic location so I can see if I can pull out the Z offset from your published data.

Thanks

[penngray]

Once again, awesome guys!!

Zilch, why did you choose to 1425 over the 1745? The 1745 would have been easier to manage down low.

[Zilch]

Ooops, mic distance 44", c/c = 10" (I'll confirm that), and all measurements from midway between woofer and waveguide centers.

Hi, Penn. 1425 because that's what QSC uses in 122i, no?

[It's also cheaper.... ]

[Pete Schumacher ®]

One last question.

What's the opening diameter of the WG?

Looks like the woofer acoustic center is about 40mm in front of the WG acoustic center.

[Skywave-Rider]

Very cool, boys.

[Pete Schumacher ®]

Ooops, mic distance 44", c/c = 10" (I'll confirm that), and all measurements from midway between woofer and waveguide centers.

Hi, Penn. 1425 because that's what QSC uses in 122i, no?

[It's also cheaper.... ]

Is there any more available from that tweeter? I'd sure like to see just a tad more output from it on the top end. Sure would make tweaking the response a bit easier.

[Zilch]

One last question.

What's the opening diameter of the WG?

Looks like the woofer acoustic center is about 40mm in front of the WG acoustic center.

1" throat on the compression driver/waveguide.

First shot at Z is delta 62 mm from the measured inverse null location.

[Pete Schumacher ®]

Are you padding the tweeter with the L-pad to that level? Can you set it for just a tad more output at the high end?

[Zilch]

Yes and yes; we can probably grab as much as 1.5 dB more. It's set at 1:00, and up to 3:00 would be fine.

C/c distance is 10.6875".

For wavelet heads:

[penngray]

Ooops, mic distance 44", c/c = 10" (I'll confirm that), and all measurements from midway between woofer and waveguide centers.

Hi, Penn. 1425 because that's what QSC uses in 122i, no?

[It's also cheaper.... ]

Yeah, the 1425 is what is in the 122i, the 1745 is in the 152i but the 1745 fits the 122i waveguide also and I remember it being maybe $10 more for a better response.

I will ship you the 1745 if you guys wanted to switch? btw, I just received some Radian 745Bs so I have a new build with rear-mounted woofers, etc.

[penngray]

Yes and yes; we can probably grab as much as 1.5 dB more. It's set at 1:00, and up to 3:00 would be fine.

C/c distance is 10.6875".

For wavelet heads:

Cool, Im a wavelet head that geddes doesnt like

[Zilch]

Forward axis = +3.01°, drivers in-phase:



[2:41 AM.... ]


Vertical polar maps:





Compare to Delite 10 w/XT1086:

http://techtalk.parts-express.com/at...6&d=1271575232

[W/10.69" c/c and 2.16 kHz XO, the forward lobe is getting short; still usable, though.... ]

[Skywave-Rider]

Wow performance on a 6 buck part.
Nice how the Celestion tapers off at the high end.

For comparo, is red the measurement axis on the XT1086 graph?

Thanks for doing this.

[Zilch]

Wow performance on a 6 buck part.
Nice how the Celestion tapers off at the high end.

For comparo, is red the measurement axis on the XT1086 graph?

Yes, red is the first button in CLIO, and thus, the forward axis in vertical polar maps, unless otherwise stated.

In this case, it's +3° from the midpoint between the drivers, so the up direction runs into its null sooner (Lt. Gry).

The PCD sim on this round is nearly perfect:



Crossover (preliminary):

[Zilch]

Pete requested some additional measurements with the L-pad set at 3:00 in lieu of 1:00, which are attached below.

Also, here are the offsets as I presently have them, on the forward axis:

[Zilch]

With Pete's suggested mods:



Both drivers normal polarity.

Forward axis moves down 0.33° @ 1:00.

[Pete Schumacher ®]

Had to adjust things because I had the acoustic offset reversed, with the woofer behind the tweeter.

Added a bit of BSC

Woofer XO:

1.8mH .3 Ohm
15uF
.4mH .2 Ohm

Tweeter XO:

4uF
.15mH .2 Ohm
3.3 uF in parallel with 1.8 Ohm before the XO.
change 2.7uF to 3.3uF in notch circuit.

I'm using Jeff's latest version of PCD with the corrected vertical spinners and sign switched acoustic offset.

So 7 degrees above tweeter axis appears to be the design axis where the deep reverse null occurs.

[scitizen17]

Looking forward to seeing the data posted here.

I am unfamiliar with that horn. May we have a link, please?

Here are plots I ran today. 1 meter on axis with crossover. The composite plot is with smoothing N=3.

[Zilch]

Our waveguide axis is 5.3438" above the midpoint between woofer and waveguide. At an 8' listening distance, that'd be arctan 5.3438/96 = 3.1860°, and at 10', 5.3438/120 = 2.5498°, assuming we are listening at waveguide height, per normal practice. That's where I target the design axis.

Standing, I'm 22", or arctan 22/120 = 10.3889° higher at 10' listening distance.

It'd be good if there was no hole in the response there.

[OR at reasonable angles below the waveguide axis, either.... ]

[Zilch]

That's certainly looking good, Scitizen.

Try some off-axis measurements, say, in 10° increments; they don't tell us the dispersion pattern of that horn anywhere that I could see....