Please feel free to move if better posted elsewhere.
Is this the expected handoff problem from mid to whizzer phase plugged with this driver?
Design problem(s)?
Recording/measuring error(s)?
All the above?
Drivers DA PS180-8
Hemisphere baffle internally lined with LOTS of silicone to minimize resonance problem(s)
Cabinet 42 liters/1.5cu ft good amount on cotton batting but not over stuffed
Rear ported (tuned at 80Hz) 4inch diameter 1inch length
Is this the expected handoff problem from mid to whizzer phase plugged with this driver?
Design problem(s)?
Recording/measuring error(s)?
All the above?
Drivers DA PS180-8
Hemisphere baffle internally lined with LOTS of silicone to minimize resonance problem(s)
Cabinet 42 liters/1.5cu ft good amount on cotton batting but not over stuffed
Rear ported (tuned at 80Hz) 4inch diameter 1inch length
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Frequency response recording with an iPhone 14+ at 7cm and utilizing the House Curve app.
Right speaker and then left…..then DA IEC baffle FR
Right speaker and then left…..then DA IEC baffle FR
The first thing which comes to mind is: did you tried to measure it at angles of 10 to 30 degrees?
This is high freq dip not likelly to be caused by the cabinet, the cause is within driver diameter. So - IMO, it is by design (bad or purely related to physics), and the angle of listening can make miracles here
This is high freq dip not likelly to be caused by the cabinet, the cause is within driver diameter. So - IMO, it is by design (bad or purely related to physics), and the angle of listening can make miracles here
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Thank you…I’ll make some more measurements…this time at listening position (about 2.5 meters away)….both at 10 degrees horizontal and 10 degrees vertical off axis
You have a step from the driver to the baffle. That will lead to all sorts of interference effects and may explain the deep notch. You could try to make a temporary cardboard baffle flush around the driver and measure once more.
Make also at 20 and 30 deg.
6kHz is around 6cm in wavelength, so the main cause may be in the driver itself. I do not think that this is some kind of heavy interference from the cabinet - inside or out, as the dip is very deep to and the driver is at least 2x size of the wavelength at that freq.
Or maybe....
That is EXACTLY because the driver moving diaphragm diameter is at the twice of the dip freq wavelength.
Also - you may got the bad luck here... A, B is the multiple of the C or is very nice rational number, as 1.5, 2.5, 1.333 or smth. Image attached.
I do not want to make this thread a flame of wide baffle vs narrow baffle, but... ... ... ...
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stv,
Yes, it may be the cause, but I am more looking at the distance from the centre of the speaker. The dip is very narrow-sharp, so it may be single big cause of a very unlucky multiple of the wavelength stuff.
The part you pictured can be ~2x of the wavelength of 5,8kHz from center.
Yes, it may be the cause, but I am more looking at the distance from the centre of the speaker. The dip is very narrow-sharp, so it may be single big cause of a very unlucky multiple of the wavelength stuff.
The part you pictured can be ~2x of the wavelength of 5,8kHz from center.
Box way too big?
The dip could be form the encosure as svp suggests ot it could be the whizzer being out of phase witht he main cone.
dave
Thanks all for the analysis.
Yes, 1.5 ft ^3 or 42 liters is larger than ideal (mostly for structural support of the wood half bowl and desired ear height (without tall stands)
Wavelength cancellation is a good thought.
Listening position (30 degrees off horizontal)
Right ear and the left ear. Most notable dip at listening position is around 500Hz
Looks like the left speaker consistently dips more. …the left speaker did provide more challenges during construction (required more wood screws to secure wood half bowl to the front…thus applied more wood glue and then more silicone to seal)
Yes, 1.5 ft ^3 or 42 liters is larger than ideal (mostly for structural support of the wood half bowl and desired ear height (without tall stands)
Wavelength cancellation is a good thought.
Listening position (30 degrees off horizontal)
Right ear and the left ear. Most notable dip at listening position is around 500Hz
Looks like the left speaker consistently dips more. …the left speaker did provide more challenges during construction (required more wood screws to secure wood half bowl to the front…thus applied more wood glue and then more silicone to seal)
98¢ Lowther Trick, i use open cell foam, but many things have been used.
A couple coats of ZIG 2-way glue on the back lip of the whizzer.
dave
if its from internal damping try glueing a piece of damping foam 20x20cm on the magnet leaving out the hole of the ventilated pole piece if it exists.
This helped a lot in some reflex boxes killing vagabonding standing waves.
If you want to tweak the paper cone try this tweak with small damping rubbers acting as a mass load at certain swinging nodes
i once removed from this Pfleid FRS20 loudspeaker (legend) the rubber pieces and glued them back in a listening session and they really had positive effect
This helped a lot in some reflex boxes killing vagabonding standing waves.
If you want to tweak the paper cone try this tweak with small damping rubbers acting as a mass load at certain swinging nodes
i once removed from this Pfleid FRS20 loudspeaker (legend) the rubber pieces and glued them back in a listening session and they really had positive effect
I did a very quick and rough simulation with Jeff Bagby's Baffle edge and boundary simulator.
While the step between baffle and driver will introduce some interference effects, it's indeed not very likely that it affects the (very much directed) 6 kHz range!
Cabinet dimensions (internal)
14.5 inches (37cm)
24 inches (61cm)
5.5 inches (14cm)
= 1.1 ft^3 or 31 liters
Plus about 3/4 the volume of the hemisphere (I guesstimated 300 cubic inches 0.2 ft^3 or 5 liters)
Total internal volume 1.3ft^3 or 37 liters
14.5 inches (37cm)
24 inches (61cm)
5.5 inches (14cm)
= 1.1 ft^3 or 31 liters
Plus about 3/4 the volume of the hemisphere (I guesstimated 300 cubic inches 0.2 ft^3 or 5 liters)
Total internal volume 1.3ft^3 or 37 liters