So went ahead and bought a pair to play and learn.
Intention was to take them to about 800-1k in a 2 way monitor
Unboxed last night and did some measurements.
I gota say I am not impressed but will temper my thoughts a bit as I have limited experience with drivers of this type.
My concern is the range from about 500-2k. Theres quite a sharp peak at about 800hz, not too tall in freq response BUT the energy storage here is quite ugly. Theres a thick tall and long tail in CSD at this spot. Theres also some trouble at around 2k but it appears to be in the dust cap and a very light touch around the bass of that dome drops the 2 khz stuff about 5 db.
Anyway Im looking for some experience with large high serns woofers taken to about 1 khz. Is the issue at 800 hz I see in the PA310 typical of this type of woofer??
I see some systems done to what I assume is a high level performance with 12-15 inch pro woofers crossed at 800 hz or so BUT Im stuggling to see how these systems deal with cone action this high up? Is there that much difference in cone performance between the pa310 and say the JBL or B & C cones??
Intention was to take them to about 800-1k in a 2 way monitor
Unboxed last night and did some measurements.
I gota say I am not impressed but will temper my thoughts a bit as I have limited experience with drivers of this type.
My concern is the range from about 500-2k. Theres quite a sharp peak at about 800hz, not too tall in freq response BUT the energy storage here is quite ugly. Theres a thick tall and long tail in CSD at this spot. Theres also some trouble at around 2k but it appears to be in the dust cap and a very light touch around the bass of that dome drops the 2 khz stuff about 5 db.
Anyway Im looking for some experience with large high serns woofers taken to about 1 khz. Is the issue at 800 hz I see in the PA310 typical of this type of woofer??
I see some systems done to what I assume is a high level performance with 12-15 inch pro woofers crossed at 800 hz or so BUT Im stuggling to see how these systems deal with cone action this high up? Is there that much difference in cone performance between the pa310 and say the JBL or B & C cones??
What was the baffle measures the driver was measured on, if there was any? You could be looking nasty diffraction artifacts. The measurements are most embelished in an infinite baffle.
Ok yes good point,
These measure were done close mic about 1 inch, then move mic around cone and at 5 inch and 10 inch positions to see if the artifact is still there.
Ive been doing this for a while now on a bunch of drivers, 10 inch AL cone, polyprop mid, some ribbons and planer magnetics.
Basically I find I can see the energy storage issues better with close mic and short gate. Perhaps Im missing something big here ? This technique seems to have worked well in past.
These measure were done close mic about 1 inch, then move mic around cone and at 5 inch and 10 inch positions to see if the artifact is still there.
Ive been doing this for a while now on a bunch of drivers, 10 inch AL cone, polyprop mid, some ribbons and planer magnetics.
Basically I find I can see the energy storage issues better with close mic and short gate. Perhaps Im missing something big here ? This technique seems to have worked well in past.
Last edited:
PA-310
Interesting you are seeing a major break up around 800 Hz. I did not see anything major in that area with the ones I purchased a year or so ago. Yes, the usual 2Khz breakup dust cap, voice coil and former was there and spread out for an octave or so above that.
I see the current advertised FS has change since I purchased the 8 units I have tested and used. IIRC, FS with my units was around 45 Hz, vs the current 39 Hz.
With your break up being around 800 Hz, there may have been some changes to the cloth surround, or the driver needs to be extensively broken in and retested. Just my $0.02 worth.
Interesting you are seeing a major break up around 800 Hz. I did not see anything major in that area with the ones I purchased a year or so ago. Yes, the usual 2Khz breakup dust cap, voice coil and former was there and spread out for an octave or so above that.
I see the current advertised FS has change since I purchased the 8 units I have tested and used. IIRC, FS with my units was around 45 Hz, vs the current 39 Hz.
With your break up being around 800 Hz, there may have been some changes to the cloth surround, or the driver needs to be extensively broken in and retested. Just my $0.02 worth.
Thanks Lojzek
I do understand what that article is saying. Because I am involved in development of ribbons and planers I have often used the close mic method to "see" what the diaphragm is doing and where. This means really close mic like less than an inch often at maybe just 1/4 inch. It has its issues for sure BUT what I do is just move around to a bunch of places and distances using various baffles etc etc until I get some confidence that what im seeing is actual diaphragm issue and not a diffraction etc issue.
I have some 10 inch AL cones that show none of this behavior as well as some others cones. I could be doing something wrong I suppose but damn that tail in the CSD is a whooper. Starts from the first slice and doesnt hit the ground till about 7-10 ms out
I do understand what that article is saying. Because I am involved in development of ribbons and planers I have often used the close mic method to "see" what the diaphragm is doing and where. This means really close mic like less than an inch often at maybe just 1/4 inch. It has its issues for sure BUT what I do is just move around to a bunch of places and distances using various baffles etc etc until I get some confidence that what im seeing is actual diaphragm issue and not a diffraction etc issue.
I have some 10 inch AL cones that show none of this behavior as well as some others cones. I could be doing something wrong I suppose but damn that tail in the CSD is a whooper. Starts from the first slice and doesnt hit the ground till about 7-10 ms out
Thanks John
Yea my first thought was " this cant be right". I mean if ya cant get a reasonably clean response through 1k or so whats the point?
I too immediately thought I need to put these things on 50hz and rattle them for a while. Maybe they need a couple million hard flexures to loosen the bonds a bit IDK.
I will stress them and see if theirs a change.
Yea my first thought was " this cant be right". I mean if ya cant get a reasonably clean response through 1k or so whats the point?
I too immediately thought I need to put these things on 50hz and rattle them for a while. Maybe they need a couple million hard flexures to loosen the bonds a bit IDK.
I will stress them and see if theirs a change.
Last edited:
Ok, if you are confident you have done everything right then the resonance does exist. If you were to measure impedance in free air, the noteworthy resonance should be there as well.
edit: Dayton's zma shows a couple of wiggles
Attachments
Last edited:
Yes that Z plot shows the wiggles close where I see the issues.
BTW more investigation suggests, as John pointed out, that the surround is responsible for the energy store around 6-800 hz.
Also interesting to note, I ran driver at 50hz sine wave at full Xmax for about 2 hrs. There was a change in the 6-800 bump. The wiggle in FR is down a bit and the tail in the CSD is better, not eliminated but its at least down into the foot hills now.
We will see what happens over time
BTW more investigation suggests, as John pointed out, that the surround is responsible for the energy store around 6-800 hz.
Also interesting to note, I ran driver at 50hz sine wave at full Xmax for about 2 hrs. There was a change in the 6-800 bump. The wiggle in FR is down a bit and the tail in the CSD is better, not eliminated but its at least down into the foot hills now.
We will see what happens over time
- Status
- Not open for further replies.